In sparse_init(), two temporary pointer arrays, usemap_map and map_map
are allocated with the size of NR_MEM_SECTIONS. They are used to store
each memory section's usemap and mem map if marked as present. With the
help of these two arrays, continuous memory chunk is allocated for
usemap and memmap for memory sections on one node. This avoids too many
memory fragmentations. Like below diagram, '1' indicates the present
memory section, '0' means absent one. The number 'n' could be much
smaller than NR_MEM_SECTIONS on most of systems.
|1|1|1|1|0|0|0|0|1|1|0|0|...|1|0||1|0|...|1||0|1|...|0|
-------------------------------------------------------
0 1 2 3 4 5 i i+1 n-1 n
If we fail to populate the page tables to map one section's memmap, its
->section_mem_map will be cleared finally to indicate that it's not
present. After use, these two arrays will be released at the end of
sparse_init().
In 4-level paging mode, each array costs 4M which can be ignorable.
While in 5-level paging, they costs 256M each, 512M altogether. Kdump
kernel Usually only reserves very few memory, e.g 256M. So, even thouth
they are temporarily allocated, still not acceptable.
In fact, there's no need to allocate them with the size of
NR_MEM_SECTIONS. Since the ->section_mem_map clearing has been deferred
to the last, the number of present memory sections are kept the same
during sparse_init() until we finally clear out the memory section's
->section_mem_map if its usemap or memmap is not correctly handled.
Thus in the middle whenever for_each_present_section_nr() loop is taken,
the i-th present memory section is always the same one.
Here only allocate usemap_map and map_map with the size of
'nr_present_sections'. For the i-th present memory section, install its
usemap and memmap to usemap_map[i] and mam_map[i] during allocation.
Then in the last for_each_present_section_nr() loop which clears the
failed memory section's ->section_mem_map, fetch usemap and memmap from
usemap_map[] and map_map[] array and set them into mem_section[]
accordingly.
[akpm@linux-foundation.org: coding-style fixes]
Link: http://lkml.kernel.org/r/20180628062857.29658-5-bhe@redhat.com
Signed-off-by: Baoquan He <bhe@redhat.com>
Reviewed-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Cc: Pasha Tatashin <Pavel.Tatashin@microsoft.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Oscar Salvador <osalvador@techadventures.net>
Cc: Pankaj Gupta <pagupta@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
It's used to pass the size of map data unit into
alloc_usemap_and_memmap, and is preparation for next patch.
Link: http://lkml.kernel.org/r/20180228032657.32385-4-bhe@redhat.com
Signed-off-by: Baoquan He <bhe@redhat.com>
Reviewed-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Pasha Tatashin <Pavel.Tatashin@microsoft.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Pankaj Gupta <pagupta@redhat.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In sparse_init(), if CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER=y, system
will allocate one continuous memory chunk for mem maps on one node and
populate the relevant page tables to map memory section one by one. If
fail to populate for a certain mem section, print warning and its
->section_mem_map will be cleared to cancel the marking of being
present. Like this, the number of mem sections marked as present could
become less during sparse_init() execution.
Here just defer the ms->section_mem_map clearing if failed to populate
its page tables until the last for_each_present_section_nr() loop. This
is in preparation for later optimizing the mem map allocation.
[akpm@linux-foundation.org: remove now-unused local `ms', per Oscar]
Link: http://lkml.kernel.org/r/20180228032657.32385-3-bhe@redhat.com
Signed-off-by: Baoquan He <bhe@redhat.com>
Acked-by: Dave Hansen <dave.hansen@intel.com>
Reviewed-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Pasha Tatashin <Pavel.Tatashin@microsoft.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Pankaj Gupta <pagupta@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "mm/sparse: Optimize memmap allocation during
sparse_init()", v6.
In sparse_init(), two temporary pointer arrays, usemap_map and map_map
are allocated with the size of NR_MEM_SECTIONS. They are used to store
each memory section's usemap and mem map if marked as present. In
5-level paging mode, this will cost 512M memory though they will be
released at the end of sparse_init(). System with few memory, like
kdump kernel which usually only has about 256M, will fail to boot
because of allocation failure if CONFIG_X86_5LEVEL=y.
In this patchset, optimize the memmap allocation code to only use
usemap_map and map_map with the size of nr_present_sections. This makes
kdump kernel boot up with normal crashkernel='' setting when
CONFIG_X86_5LEVEL=y.
This patch (of 5):
nr_present_sections is used to record how many memory sections are
marked as present during system boot up, and will be used in the later
patch.
Link: http://lkml.kernel.org/r/20180228032657.32385-2-bhe@redhat.com
Signed-off-by: Baoquan He <bhe@redhat.com>
Acked-by: Dave Hansen <dave.hansen@intel.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Pasha Tatashin <Pavel.Tatashin@microsoft.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Pankaj Gupta <pagupta@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The patch introduces a special value SHRINKER_REGISTERING to use instead
of list_empty() to differ a registering shrinker from unregistered
shrinker. Why we need that at all?
Shrinker registration is split in two parts. The first one is
prealloc_shrinker(), which allocates shrinker memory and reserves ID in
shrinker_idr. This function can fail. The second is
register_shrinker_prepared(), and it finalizes the registration. This
function actually makes shrinker available to be used from
shrink_slab(), and it can't fail.
One shrinker may be based on more then one LRU lists. So, we never
clear the bit in memcg shrinker maps, when (one of) corresponding LRU
list becomes empty, since other LRU lists may be not empty. See
superblock shrinker for example: it is based on two LRU lists:
s_inode_lru and s_dentry_lru. We do not want to clear shrinker bit,
when there are no inodes in s_inode_lru, as s_dentry_lru may contain
dentries.
Instead of that, we use special algorithm to detect shrinkers having no
elements at all its LRU lists, and this is made in shrink_slab_memcg().
See the comment in this function for the details.
Also, in shrink_slab_memcg() we clear shrinker bit in the map, when we
meet unregistered shrinker (bit is set, while there is no a shrinker in
IDR). Otherwise, we would have done that at the moment of shrinker
unregistration for all memcgs (and this looks worse, since iteration
over all memcg may take much time). Also this would have imposed
restrictions on shrinker unregistration order for its users: they would
have had to guarantee, there are no new elements after
unregister_shrinker() (otherwise, a new added element would have set a
bit).
So, if we meet a set bit in map and no shrinker in IDR when we're
iterating over the map in shrink_slab_memcg(), this means the
corresponding shrinker is unregistered, and we must clear the bit.
Another case is shrinker registration. We want two things there:
1) do_shrink_slab() can be called only for completely registered
shrinkers;
2) shrinker internal lists may be populated in any order with
register_shrinker_prepared() (let's talk on the example with sb). Both
of:
a)list_lru_add(&inode->i_sb->s_inode_lru, &inode->i_lru); [cpu0]
memcg_set_shrinker_bit(); [cpu0]
...
register_shrinker_prepared(); [cpu1]
and
b)register_shrinker_prepared(); [cpu0]
...
list_lru_add(&inode->i_sb->s_inode_lru, &inode->i_lru); [cpu1]
memcg_set_shrinker_bit(); [cpu1]
are legitimate. We don't want to impose restriction here and to
force people to use only (b) variant. We don't want to force people to
care, there is no elements in LRU lists before the shrinker is
completely registered. Internal users of LRU lists and shrinker code
are two different subsystems, and they have to be closed in themselves
each other.
In (a) case we have the bit set before shrinker is completely
registered. We don't want do_shrink_slab() is called at this moment, so
we have to detect such the registering shrinkers.
Before this patch list_empty() (shrinker is not linked to the list)
check was used for that. So, in (a) there could be a bit set, but we
don't call do_shrink_slab() unless shrinker is linked to the list. It's
just an indicator, I just overloaded linking to the list.
This was not the best solution, since it's better not to touch the
shrinker memory from shrink_slab_memcg() before it's completely
registered (this also will be useful in the future to make shrink_slab()
completely lockless).
So, this patch introduces better way to detect registering shrinker,
which allows not to dereference shrinker memory. It's just a ~0UL
value, which we insert into the IDR during ID allocation. After
shrinker is ready to be used, we insert actual shrinker pointer in the
IDR, and it becomes available to shrink_slab_memcg().
We can't use NULL instead of this new value for this purpose as:
shrink_slab_memcg() already uses NULL to detect unregistered shrinkers,
and we don't want the function sees NULL and clears the bit, otherwise
(a) won't work.
This is the only thing the patch makes: the better way to detect
registering shrinker. Nothing else this patch makes.
Also this gives a better assembler, but it's minor side of the patch:
Before:
callq <idr_find>
mov %rax,%r15
test %rax,%rax
je <shrink_slab_memcg+0x1d5>
mov 0x20(%rax),%rax
lea 0x20(%r15),%rdx
cmp %rax,%rdx
je <shrink_slab_memcg+0xbd>
mov 0x8(%rsp),%edx
mov %r15,%rsi
lea 0x10(%rsp),%rdi
callq <do_shrink_slab>
After:
callq <idr_find>
mov %rax,%r15
lea -0x1(%rax),%rax
cmp $0xfffffffffffffffd,%rax
ja <shrink_slab_memcg+0x1cd>
mov 0x8(%rsp),%edx
mov %r15,%rsi
lea 0x10(%rsp),%rdi
callq ffffffff810cefd0 <do_shrink_slab>
[ktkhai@virtuozzo.com: add #ifdef CONFIG_MEMCG_KMEM around idr_replace()]
Link: http://lkml.kernel.org/r/758b8fec-7573-47eb-b26a-7b2847ae7b8c@virtuozzo.com
Link: http://lkml.kernel.org/r/153355467546.11522.4518015068123480218.stgit@localhost.localdomain
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Josef Bacik <jbacik@fb.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In case of shrink_slab_memcg() we do not zero nid, when shrinker is not
numa-aware. This is not a real problem, since currently all memcg-aware
shrinkers are numa-aware too (we have two: super_block shrinker and
workingset shrinker), but something may change in the future.
Link: http://lkml.kernel.org/r/153320759911.18959.8842396230157677671.stgit@localhost.localdomain
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Josef Bacik <jbacik@fb.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
To avoid further unneed calls of do_shrink_slab() for shrinkers, which
already do not have any charged objects in a memcg, their bits have to
be cleared.
This patch introduces a lockless mechanism to do that without races
without parallel list lru add. After do_shrink_slab() returns
SHRINK_EMPTY the first time, we clear the bit and call it once again.
Then we restore the bit, if the new return value is different.
Note, that single smp_mb__after_atomic() in shrink_slab_memcg() covers
two situations:
1)list_lru_add() shrink_slab_memcg
list_add_tail() for_each_set_bit() <--- read bit
do_shrink_slab() <--- missed list update (no barrier)
<MB> <MB>
set_bit() do_shrink_slab() <--- seen list update
This situation, when the first do_shrink_slab() sees set bit, but it
doesn't see list update (i.e., race with the first element queueing), is
rare. So we don't add <MB> before the first call of do_shrink_slab()
instead of this to do not slow down generic case. Also, it's need the
second call as seen in below in (2).
2)list_lru_add() shrink_slab_memcg()
list_add_tail() ...
set_bit() ...
... for_each_set_bit()
do_shrink_slab() do_shrink_slab()
clear_bit() ...
... ...
list_lru_add() ...
list_add_tail() clear_bit()
<MB> <MB>
set_bit() do_shrink_slab()
The barriers guarantee that the second do_shrink_slab() in the right
side task sees list update if really cleared the bit. This case is
drawn in the code comment.
[Results/performance of the patchset]
After the whole patchset applied the below test shows signify increase
of performance:
$echo 1 > /sys/fs/cgroup/memory/memory.use_hierarchy
$mkdir /sys/fs/cgroup/memory/ct
$echo 4000M > /sys/fs/cgroup/memory/ct/memory.kmem.limit_in_bytes
$for i in `seq 0 4000`; do mkdir /sys/fs/cgroup/memory/ct/$i;
echo $$ > /sys/fs/cgroup/memory/ct/$i/cgroup.procs;
mkdir -p s/$i; mount -t tmpfs $i s/$i;
touch s/$i/file; done
Then, 5 sequential calls of drop caches:
$time echo 3 > /proc/sys/vm/drop_caches
1)Before:
0.00user 13.78system 0:13.78elapsed 99%CPU
0.00user 5.59system 0:05.60elapsed 99%CPU
0.00user 5.48system 0:05.48elapsed 99%CPU
0.00user 8.35system 0:08.35elapsed 99%CPU
0.00user 8.34system 0:08.35elapsed 99%CPU
2)After
0.00user 1.10system 0:01.10elapsed 99%CPU
0.00user 0.00system 0:00.01elapsed 64%CPU
0.00user 0.01system 0:00.01elapsed 82%CPU
0.00user 0.00system 0:00.01elapsed 64%CPU
0.00user 0.01system 0:00.01elapsed 82%CPU
The results show the performance increases at least in 548 times.
Shakeel Butt tested this patchset with fork-bomb on his configuration:
> I created 255 memcgs, 255 ext4 mounts and made each memcg create a
> file containing few KiBs on corresponding mount. Then in a separate
> memcg of 200 MiB limit ran a fork-bomb.
>
> I ran the "perf record -ag -- sleep 60" and below are the results:
>
> Without the patch series:
> Samples: 4M of event 'cycles', Event count (approx.): 3279403076005
> + 36.40% fb.sh [kernel.kallsyms] [k] shrink_slab
> + 18.97% fb.sh [kernel.kallsyms] [k] list_lru_count_one
> + 6.75% fb.sh [kernel.kallsyms] [k] super_cache_count
> + 0.49% fb.sh [kernel.kallsyms] [k] down_read_trylock
> + 0.44% fb.sh [kernel.kallsyms] [k] mem_cgroup_iter
> + 0.27% fb.sh [kernel.kallsyms] [k] up_read
> + 0.21% fb.sh [kernel.kallsyms] [k] osq_lock
> + 0.13% fb.sh [kernel.kallsyms] [k] shmem_unused_huge_count
> + 0.08% fb.sh [kernel.kallsyms] [k] shrink_node_memcg
> + 0.08% fb.sh [kernel.kallsyms] [k] shrink_node
>
> With the patch series:
> Samples: 4M of event 'cycles', Event count (approx.): 2756866824946
> + 47.49% fb.sh [kernel.kallsyms] [k] down_read_trylock
> + 30.72% fb.sh [kernel.kallsyms] [k] up_read
> + 9.51% fb.sh [kernel.kallsyms] [k] mem_cgroup_iter
> + 1.69% fb.sh [kernel.kallsyms] [k] shrink_node_memcg
> + 1.35% fb.sh [kernel.kallsyms] [k] mem_cgroup_protected
> + 1.05% fb.sh [kernel.kallsyms] [k] queued_spin_lock_slowpath
> + 0.85% fb.sh [kernel.kallsyms] [k] _raw_spin_lock
> + 0.78% fb.sh [kernel.kallsyms] [k] lruvec_lru_size
> + 0.57% fb.sh [kernel.kallsyms] [k] shrink_node
> + 0.54% fb.sh [kernel.kallsyms] [k] queue_work_on
> + 0.46% fb.sh [kernel.kallsyms] [k] shrink_slab_memcg
[ktkhai@virtuozzo.com: v9]
Link: http://lkml.kernel.org/r/153112561772.4097.11011071937553113003.stgit@localhost.localdomain
Link: http://lkml.kernel.org/r/153063070859.1818.11870882950920963480.stgit@localhost.localdomain
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Tested-by: Shakeel Butt <shakeelb@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Josef Bacik <jbacik@fb.com>
Cc: Li RongQing <lirongqing@baidu.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matthias Kaehlcke <mka@chromium.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Sahitya Tummala <stummala@codeaurora.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <longman@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We need to distinguish the situations when shrinker has very small
amount of objects (see vfs_pressure_ratio() called from
super_cache_count()), and when it has no objects at all. Currently, in
the both of these cases, shrinker::count_objects() returns 0.
The patch introduces new SHRINK_EMPTY return value, which will be used
for "no objects at all" case. It's is a refactoring mostly, as
SHRINK_EMPTY is replaced by 0 by all callers of do_shrink_slab() in this
patch, and all the magic will happen in further.
Link: http://lkml.kernel.org/r/153063069574.1818.11037751256699341813.stgit@localhost.localdomain
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Tested-by: Shakeel Butt <shakeelb@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Josef Bacik <jbacik@fb.com>
Cc: Li RongQing <lirongqing@baidu.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matthias Kaehlcke <mka@chromium.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Sahitya Tummala <stummala@codeaurora.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <longman@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The patch makes shrink_slab() be called for root_mem_cgroup in the same
way as it's called for the rest of cgroups. This simplifies the logic
and improves the readability.
[ktkhai@virtuozzo.com: wrote changelog]
Link: http://lkml.kernel.org/r/153063068338.1818.11496084754797453962.stgit@localhost.localdomain
Signed-off-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Tested-by: Shakeel Butt <shakeelb@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Josef Bacik <jbacik@fb.com>
Cc: Li RongQing <lirongqing@baidu.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matthias Kaehlcke <mka@chromium.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Sahitya Tummala <stummala@codeaurora.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <longman@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Using the preparations made in previous patches, in case of memcg
shrink, we may avoid shrinkers, which are not set in memcg's shrinkers
bitmap. To do that, we separate iterations over memcg-aware and
!memcg-aware shrinkers, and memcg-aware shrinkers are chosen via
for_each_set_bit() from the bitmap. In case of big nodes, having many
isolated environments, this gives significant performance growth. See
next patches for the details.
Note that the patch does not respect to empty memcg shrinkers, since we
never clear the bitmap bits after we set it once. Their shrinkers will
be called again, with no shrinked objects as result. This functionality
is provided by next patches.
[ktkhai@virtuozzo.com: v9]
Link: http://lkml.kernel.org/r/153112558507.4097.12713813335683345488.stgit@localhost.localdomain
Link: http://lkml.kernel.org/r/153063066653.1818.976035462801487910.stgit@localhost.localdomain
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Tested-by: Shakeel Butt <shakeelb@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Josef Bacik <jbacik@fb.com>
Cc: Li RongQing <lirongqing@baidu.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matthias Kaehlcke <mka@chromium.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Sahitya Tummala <stummala@codeaurora.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <longman@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Introduce set_shrinker_bit() function to set shrinker-related bit in
memcg shrinker bitmap, and set the bit after the first item is added and
in case of reparenting destroyed memcg's items.
This will allow next patch to make shrinkers be called only, in case of
they have charged objects at the moment, and to improve shrink_slab()
performance.
[ktkhai@virtuozzo.com: v9]
Link: http://lkml.kernel.org/r/153112557572.4097.17315791419810749985.stgit@localhost.localdomain
Link: http://lkml.kernel.org/r/153063065671.1818.15914674956134687268.stgit@localhost.localdomain
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Tested-by: Shakeel Butt <shakeelb@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Josef Bacik <jbacik@fb.com>
Cc: Li RongQing <lirongqing@baidu.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matthias Kaehlcke <mka@chromium.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Sahitya Tummala <stummala@codeaurora.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <longman@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This is just refactoring to allow next patches to have lru pointer in
memcg_drain_list_lru_node().
Link: http://lkml.kernel.org/r/153063063164.1818.55009531386089350.stgit@localhost.localdomain
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Tested-by: Shakeel Butt <shakeelb@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Josef Bacik <jbacik@fb.com>
Cc: Li RongQing <lirongqing@baidu.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matthias Kaehlcke <mka@chromium.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Sahitya Tummala <stummala@codeaurora.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <longman@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This is just refactoring to allow the next patches to have dst_memcg
pointer in memcg_drain_list_lru_node().
Link: http://lkml.kernel.org/r/153063062118.1818.2761273817739499749.stgit@localhost.localdomain
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Tested-by: Shakeel Butt <shakeelb@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Josef Bacik <jbacik@fb.com>
Cc: Li RongQing <lirongqing@baidu.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matthias Kaehlcke <mka@chromium.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Sahitya Tummala <stummala@codeaurora.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <longman@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This is just refactoring to allow the next patches to have memcg pointer
in list_lru_from_kmem().
Link: http://lkml.kernel.org/r/153063060664.1818.9541345386733498582.stgit@localhost.localdomain
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Tested-by: Shakeel Butt <shakeelb@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Josef Bacik <jbacik@fb.com>
Cc: Li RongQing <lirongqing@baidu.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matthias Kaehlcke <mka@chromium.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Sahitya Tummala <stummala@codeaurora.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <longman@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add list_lru::shrinker_id field and populate it by registered shrinker
id.
This will be used to set correct bit in memcg shrinkers map by lru code
in next patches, after there appeared the first related to memcg element
in list_lru.
Link: http://lkml.kernel.org/r/153063059758.1818.14866596416857717800.stgit@localhost.localdomain
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Tested-by: Shakeel Butt <shakeelb@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Josef Bacik <jbacik@fb.com>
Cc: Li RongQing <lirongqing@baidu.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matthias Kaehlcke <mka@chromium.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Sahitya Tummala <stummala@codeaurora.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <longman@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Do two list_lru_init_memcg() calls after prealloc_super().
destroy_unused_super() in fail path is OK with this. Next patch needs
such the order.
Link: http://lkml.kernel.org/r/153063058712.1818.3382490999719078571.stgit@localhost.localdomain
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Tested-by: Shakeel Butt <shakeelb@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Josef Bacik <jbacik@fb.com>
Cc: Li RongQing <lirongqing@baidu.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matthias Kaehlcke <mka@chromium.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Sahitya Tummala <stummala@codeaurora.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <longman@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Imagine a big node with many cpus, memory cgroups and containers. Let
we have 200 containers, every container has 10 mounts, and 10 cgroups.
All container tasks don't touch foreign containers mounts. If there is
intensive pages write, and global reclaim happens, a writing task has to
iterate over all memcgs to shrink slab, before it's able to go to
shrink_page_list().
Iteration over all the memcg slabs is very expensive: the task has to
visit 200 * 10 = 2000 shrinkers for every memcg, and since there are
2000 memcgs, the total calls are 2000 * 2000 = 4000000.
So, the shrinker makes 4 million do_shrink_slab() calls just to try to
isolate SWAP_CLUSTER_MAX pages in one of the actively writing memcg via
shrink_page_list(). I've observed a node spending almost 100% in
kernel, making useless iteration over already shrinked slab.
This patch adds bitmap of memcg-aware shrinkers to memcg. The size of
the bitmap depends on bitmap_nr_ids, and during memcg life it's
maintained to be enough to fit bitmap_nr_ids shrinkers. Every bit in
the map is related to corresponding shrinker id.
Next patches will maintain set bit only for really charged memcg. This
will allow shrink_slab() to increase its performance in significant way.
See the last patch for the numbers.
[ktkhai@virtuozzo.com: v9]
Link: http://lkml.kernel.org/r/153112549031.4097.3576147070498769979.stgit@localhost.localdomain
[ktkhai@virtuozzo.com: add comment to mem_cgroup_css_online()]
Link: http://lkml.kernel.org/r/521f9e5f-c436-b388-fe83-4dc870bfb489@virtuozzo.com
Link: http://lkml.kernel.org/r/153063056619.1818.12550500883688681076.stgit@localhost.localdomain
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Tested-by: Shakeel Butt <shakeelb@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Josef Bacik <jbacik@fb.com>
Cc: Li RongQing <lirongqing@baidu.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matthias Kaehlcke <mka@chromium.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Sahitya Tummala <stummala@codeaurora.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <longman@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Next patch requires these defines are above their current position, so
here they are moved to declarations.
Link: http://lkml.kernel.org/r/153063055665.1818.5200425793649695598.stgit@localhost.localdomain
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Tested-by: Shakeel Butt <shakeelb@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Josef Bacik <jbacik@fb.com>
Cc: Li RongQing <lirongqing@baidu.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matthias Kaehlcke <mka@chromium.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Sahitya Tummala <stummala@codeaurora.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <longman@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Introduce shrinker::id number, which is used to enumerate memcg-aware
shrinkers. The number start from 0, and the code tries to maintain it
as small as possible.
This will be used to represent a memcg-aware shrinkers in memcg
shrinkers map.
Since all memcg-aware shrinkers are based on list_lru, which is
per-memcg in case of !CONFIG_MEMCG_KMEM only, the new functionality will
be under this config option.
[ktkhai@virtuozzo.com: v9]
Link: http://lkml.kernel.org/r/153112546435.4097.10607140323811756557.stgit@localhost.localdomain
Link: http://lkml.kernel.org/r/153063054586.1818.6041047871606697364.stgit@localhost.localdomain
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Tested-by: Shakeel Butt <shakeelb@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Josef Bacik <jbacik@fb.com>
Cc: Li RongQing <lirongqing@baidu.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matthias Kaehlcke <mka@chromium.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Sahitya Tummala <stummala@codeaurora.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <longman@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Introduce new config option, which is used to replace repeating
CONFIG_MEMCG && !CONFIG_SLOB pattern. Next patches add a little more
memcg+kmem related code, so let's keep the defines more clearly.
Link: http://lkml.kernel.org/r/153063053670.1818.15013136946600481138.stgit@localhost.localdomain
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Tested-by: Shakeel Butt <shakeelb@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Josef Bacik <jbacik@fb.com>
Cc: Li RongQing <lirongqing@baidu.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matthias Kaehlcke <mka@chromium.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Sahitya Tummala <stummala@codeaurora.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <longman@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "Improve shrink_slab() scalability (old complexity was O(n^2), new is O(n))", v8.
This patcheset solves the problem with slow shrink_slab() occuring on
the machines having many shrinkers and memory cgroups (i.e., with many
containers). The problem is complexity of shrink_slab() is O(n^2) and
it grows too fast with the growth of containers numbers.
Let us have 200 containers, and every container has 10 mounts and 10
cgroups. All container tasks are isolated, and they don't touch foreign
containers mounts.
In case of global reclaim, a task has to iterate all over the memcgs and
to call all the memcg-aware shrinkers for all of them. This means, the
task has to visit 200 * 10 = 2000 shrinkers for every memcg, and since
there are 2000 memcgs, the total calls of do_shrink_slab() are 2000 *
2000 = 4000000.
4 million calls are not a number operations, which can takes 1 cpu
cycle. E.g., super_cache_count() accesses at least two lists, and makes
arifmetical calculations. Even, if there are no charged objects, we do
these calculations, and replaces cpu caches by read memory. I observed
nodes spending almost 100% time in kernel, in case of intensive writing
and global reclaim. The writer consumes pages fast, but it's need to
shrink_slab() before the reclaimer reached shrink pages function (and
frees SWAP_CLUSTER_MAX pages). Even if there is no writing, the
iterations just waste the time, and slows reclaim down.
Let's see the small test below:
$echo 1 > /sys/fs/cgroup/memory/memory.use_hierarchy
$mkdir /sys/fs/cgroup/memory/ct
$echo 4000M > /sys/fs/cgroup/memory/ct/memory.kmem.limit_in_bytes
$for i in `seq 0 4000`;
do mkdir /sys/fs/cgroup/memory/ct/$i;
echo $$ > /sys/fs/cgroup/memory/ct/$i/cgroup.procs;
mkdir -p s/$i; mount -t tmpfs $i s/$i; touch s/$i/file;
done
Then, let's see drop caches time (5 sequential calls):
$time echo 3 > /proc/sys/vm/drop_caches
0.00user 13.78system 0:13.78elapsed 99%CPU
0.00user 5.59system 0:05.60elapsed 99%CPU
0.00user 5.48system 0:05.48elapsed 99%CPU
0.00user 8.35system 0:08.35elapsed 99%CPU
0.00user 8.34system 0:08.35elapsed 99%CPU
The last four calls don't actually shrink anything. So, the iterations
over slab shrinkers take 5.48 seconds. Not so good for scalability.
The patchset solves the problem by making shrink_slab() of O(n)
complexity. There are following functional actions:
1) Assign id to every registered memcg-aware shrinker.
2) Maintain per-memcgroup bitmap of memcg-aware shrinkers, and set a
shrinker-related bit after the first element is added to lru list
(also, when removed child memcg elements are reparanted).
3) Split memcg-aware shrinkers and !memcg-aware shrinkers, and call a
shrinker if its bit is set in memcg's shrinker bitmap. (Also, there is
a functionality to clear the bit, after last element is shrinked).
This gives significant performance increase. The result after patchset
is applied:
$time echo 3 > /proc/sys/vm/drop_caches
0.00user 1.10system 0:01.10elapsed 99%CPU
0.00user 0.00system 0:00.01elapsed 64%CPU
0.00user 0.01system 0:00.01elapsed 82%CPU
0.00user 0.00system 0:00.01elapsed 64%CPU
0.00user 0.01system 0:00.01elapsed 82%CPU
The results show the performance increases at least in 548 times.
So, the patchset makes shrink_slab() of less complexity and improves the
performance in such types of load I pointed. This will give a profit in
case of !global reclaim case, since there also will be less
do_shrink_slab() calls.
This patch (of 17):
These two pairs of blocks of code are under the same #ifdef #else
#endif.
Link: http://lkml.kernel.org/r/153063052519.1818.9393587113056959488.stgit@localhost.localdomain
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Tested-by: Shakeel Butt <shakeelb@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Sahitya Tummala <stummala@codeaurora.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Roman Gushchin <guro@fb.com>
Cc: Matthias Kaehlcke <mka@chromium.org>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Waiman Long <longman@redhat.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Josef Bacik <jbacik@fb.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Li RongQing <lirongqing@baidu.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Most functions in memblock already use phys_addr_t to represent a
physical address with __memblock_free_late() being an exception.
This patch replaces u64 with phys_addr_t in __memblock_free_late() and
switches several format strings from %llx to %pa to avoid casting from
phys_addr_t to u64.
Link: http://lkml.kernel.org/r/1530637506-1256-1-git-send-email-rppt@linux.vnet.ibm.com
Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Reviewed-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Pasha Tatashin <Pavel.Tatashin@microsoft.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
sparse_init_one_section() is being called from two sites: sparse_init()
and sparse_add_one_section(). The former calls it from a
for_each_present_section_nr() loop, and the latter marks the section as
present before calling it. This means that when
sparse_init_one_section() gets called, we already know that the section
is present. So there is no point to double check that in the function.
This removes the check and makes the function void.
[ross.zwisler@linux.intel.com: fix error path in sparse_add_one_section]
Link: http://lkml.kernel.org/r/20180706190658.6873-1-ross.zwisler@linux.intel.com
[ross.zwisler@linux.intel.com: simplification suggested by Oscar]
Link: http://lkml.kernel.org/r/20180706223358.742-1-ross.zwisler@linux.intel.com
Link: http://lkml.kernel.org/r/20180702154325.12196-1-osalvador@techadventures.net
Signed-off-by: Oscar Salvador <osalvador@suse.de>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Pasha Tatashin <Pavel.Tatashin@microsoft.com>
Cc: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit 3812c8c8f3 ("mm: memcg: do not trap chargers with full
callstack on OOM") has changed the ENOMEM semantic of memcg charges.
Rather than invoking the oom killer from the charging context it delays
the oom killer to the page fault path (pagefault_out_of_memory). This
in turn means that many users (e.g. slab or g-u-p) will get ENOMEM when
the corresponding memcg hits the hard limit and the memcg is is OOM.
This is behavior is inconsistent with !memcg case where the oom killer
is invoked from the allocation context and the allocator keeps retrying
until it succeeds.
The difference in the behavior is user visible. mmap(MAP_POPULATE)
might result in not fully populated ranges while the mmap return code
doesn't tell that to the userspace. Random syscalls might fail with
ENOMEM etc.
The primary motivation of the different memcg oom semantic was the
deadlock avoidance. Things have changed since then, though. We have an
async oom teardown by the oom reaper now and so we do not have to rely
on the victim to tear down its memory anymore. Therefore we can return
to the original semantic as long as the memcg oom killer is not handed
over to the users space.
There is still one thing to be careful about here though. If the oom
killer is not able to make any forward progress - e.g. because there is
no eligible task to kill - then we have to bail out of the charge path
to prevent from same class of deadlocks. We have basically two options
here. Either we fail the charge with ENOMEM or force the charge and
allow overcharge. The first option has been considered more harmful
than useful because rare inconsistencies in the ENOMEM behavior is hard
to test for and error prone. Basically the same reason why the page
allocator doesn't fail allocations under such conditions. The later
might allow runaways but those should be really unlikely unless somebody
misconfigures the system. E.g. allowing to migrate tasks away from the
memcg to a different unlimited memcg with move_charge_at_immigrate
disabled.
Link: http://lkml.kernel.org/r/20180628151101.25307-1-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Greg Thelen <gthelen@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The deferred memory initialization relies on section definitions, e.g
PAGES_PER_SECTION, that are only available when CONFIG_SPARSEMEM=y on
most architectures.
Initially DEFERRED_STRUCT_PAGE_INIT depended on explicit
ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT configuration option, but since
the commit 2e3ca40f03 ("mm: relax deferred struct page
requirements") this requirement was relaxed and now it is possible to
enable DEFERRED_STRUCT_PAGE_INIT on architectures that support
DISCONTINGMEM and NO_BOOTMEM which causes build failures.
For instance, setting SMP=y and DEFERRED_STRUCT_PAGE_INIT=y on arc
causes the following build failure:
CC mm/page_alloc.o
mm/page_alloc.c: In function 'update_defer_init':
mm/page_alloc.c:321:14: error: 'PAGES_PER_SECTION'
undeclared (first use in this function); did you mean 'USEC_PER_SEC'?
(pfn & (PAGES_PER_SECTION - 1)) == 0) {
^~~~~~~~~~~~~~~~~
USEC_PER_SEC
mm/page_alloc.c:321:14: note: each undeclared identifier is reported only once for each function it appears in
In file included from include/linux/cache.h:5:0,
from include/linux/printk.h:9,
from include/linux/kernel.h:14,
from include/asm-generic/bug.h:18,
from arch/arc/include/asm/bug.h:32,
from include/linux/bug.h:5,
from include/linux/mmdebug.h:5,
from include/linux/mm.h:9,
from mm/page_alloc.c:18:
mm/page_alloc.c: In function 'deferred_grow_zone':
mm/page_alloc.c:1624:52: error: 'PAGES_PER_SECTION' undeclared (first use in this function); did you mean 'USEC_PER_SEC'?
unsigned long nr_pages_needed = ALIGN(1 << order, PAGES_PER_SECTION);
^
include/uapi/linux/kernel.h:11:47: note: in definition of macro '__ALIGN_KERNEL_MASK'
#define __ALIGN_KERNEL_MASK(x, mask) (((x) + (mask)) & ~(mask))
^~~~
include/linux/kernel.h:58:22: note: in expansion of macro '__ALIGN_KERNEL'
#define ALIGN(x, a) __ALIGN_KERNEL((x), (a))
^~~~~~~~~~~~~~
mm/page_alloc.c:1624:34: note: in expansion of macro 'ALIGN'
unsigned long nr_pages_needed = ALIGN(1 << order, PAGES_PER_SECTION);
^~~~~
In file included from include/asm-generic/bug.h:18:0,
from arch/arc/include/asm/bug.h:32,
from include/linux/bug.h:5,
from include/linux/mmdebug.h:5,
from include/linux/mm.h:9,
from mm/page_alloc.c:18:
mm/page_alloc.c: In function 'free_area_init_node':
mm/page_alloc.c:6379:50: error: 'PAGES_PER_SECTION' undeclared (first use in this function); did you mean 'USEC_PER_SEC'?
pgdat->static_init_pgcnt = min_t(unsigned long, PAGES_PER_SECTION,
^
include/linux/kernel.h:812:22: note: in definition of macro '__typecheck'
(!!(sizeof((typeof(x) *)1 == (typeof(y) *)1)))
^
include/linux/kernel.h:836:24: note: in expansion of macro '__safe_cmp'
__builtin_choose_expr(__safe_cmp(x, y), \
^~~~~~~~~~
include/linux/kernel.h:904:27: note: in expansion of macro '__careful_cmp'
#define min_t(type, x, y) __careful_cmp((type)(x), (type)(y), <)
^~~~~~~~~~~~~
mm/page_alloc.c:6379:29: note: in expansion of macro 'min_t'
pgdat->static_init_pgcnt = min_t(unsigned long, PAGES_PER_SECTION,
^~~~~
include/linux/kernel.h:836:2: error: first argument to '__builtin_choose_expr' not a constant
__builtin_choose_expr(__safe_cmp(x, y), \
^
include/linux/kernel.h:904:27: note: in expansion of macro '__careful_cmp'
#define min_t(type, x, y) __careful_cmp((type)(x), (type)(y), <)
^~~~~~~~~~~~~
mm/page_alloc.c:6379:29: note: in expansion of macro 'min_t'
pgdat->static_init_pgcnt = min_t(unsigned long, PAGES_PER_SECTION,
^~~~~
scripts/Makefile.build:317: recipe for target 'mm/page_alloc.o' failed
Let's make the DEFERRED_STRUCT_PAGE_INIT explicitly depend on SPARSEMEM
as the systems that support DISCONTIGMEM do not seem to have that huge
amounts of memory that would make DEFERRED_STRUCT_PAGE_INIT relevant.
Link: http://lkml.kernel.org/r/1530279308-24988-1-git-send-email-rppt@linux.vnet.ibm.com
Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Tested-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Pasha Tatashin <Pavel.Tatashin@microsoft.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
KASAN learns about hotadded memory via the memory hotplug notifier.
devm_memremap_pages() intentionally skips calling memory hotplug
notifiers. So KASAN doesn't know anything about new memory added by
devm_memremap_pages(). This causes a crash when KASAN tries to access
non-existent shadow memory:
BUG: unable to handle kernel paging request at ffffed0078000000
RIP: 0010:check_memory_region+0x82/0x1e0
Call Trace:
memcpy+0x1f/0x50
pmem_do_bvec+0x163/0x720
pmem_make_request+0x305/0xac0
generic_make_request+0x54f/0xcf0
submit_bio+0x9c/0x370
submit_bh_wbc+0x4c7/0x700
block_read_full_page+0x5ef/0x870
do_read_cache_page+0x2b8/0xb30
read_dev_sector+0xbd/0x3f0
read_lba.isra.0+0x277/0x670
efi_partition+0x41a/0x18f0
check_partition+0x30d/0x5e9
rescan_partitions+0x18c/0x840
__blkdev_get+0x859/0x1060
blkdev_get+0x23f/0x810
__device_add_disk+0x9c8/0xde0
pmem_attach_disk+0x9a8/0xf50
nvdimm_bus_probe+0xf3/0x3c0
driver_probe_device+0x493/0xbd0
bus_for_each_drv+0x118/0x1b0
__device_attach+0x1cd/0x2b0
bus_probe_device+0x1ac/0x260
device_add+0x90d/0x1380
nd_async_device_register+0xe/0x50
async_run_entry_fn+0xc3/0x5d0
process_one_work+0xa0a/0x1810
worker_thread+0x87/0xe80
kthread+0x2d7/0x390
ret_from_fork+0x3a/0x50
Add kasan_add_zero_shadow()/kasan_remove_zero_shadow() - post mm_init()
interface to map/unmap kasan_zero_page at requested virtual addresses.
And use it to add/remove the shadow memory for hotplugged/unplugged
device memory.
Link: http://lkml.kernel.org/r/20180629164932.740-1-aryabinin@virtuozzo.com
Fixes: 41e94a8513 ("add devm_memremap_pages")
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Reported-by: Dave Chinner <david@fromorbit.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Tested-by: Dan Williams <dan.j.williams@intel.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Alexander Potapenko <glider@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
khugepaged_enter_vma_merge() passes a stale vma->vm_flags to
hugepage_vma_check(). The argument vm_flags contains the latest value.
Therefore, it is necessary to pass this vm_flags into
hugepage_vma_check().
With this bug, madvise(MADV_HUGEPAGE) for mmap files in shmem fails to
put memory in huge pages. Here is an example of failed madvise():
/* mount /dev/shm with huge=advise:
* mount -o remount,huge=advise /dev/shm */
/* create file /dev/shm/huge */
#define HUGE_FILE "/dev/shm/huge"
fd = open(HUGE_FILE, O_RDONLY);
ptr = mmap(NULL, FILE_SIZE, PROT_READ, MAP_PRIVATE, fd, 0);
ret = madvise(ptr, FILE_SIZE, MADV_HUGEPAGE);
madvise() will return 0, but this memory region is never put in huge
page (check from /proc/meminfo: ShmemHugePages).
Link: http://lkml.kernel.org/r/20180629181752.792831-1-songliubraving@fb.com
Fixes: 02b75dc8160d ("mm: thp: register mm for khugepaged when merging vma for shmem")
Signed-off-by: Song Liu <songliubraving@fb.com>
Reviewed-by: Rik van Riel <riel@surriel.com>
Reviewed-by: Yang Shi <yang.shi@linux.alibaba.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed integer overflow is undefined according to the C standard. The
overflow in ksys_fadvise64_64() is deliberate, but since it is signed
overflow, UBSAN complains:
UBSAN: Undefined behaviour in mm/fadvise.c:76:10
signed integer overflow:
4 + 9223372036854775805 cannot be represented in type 'long long int'
Use unsigned types to do math. Unsigned overflow is defined so UBSAN
will not complain about it. This patch doesn't change generated code.
[akpm@linux-foundation.org: add comment explaining the casts]
Link: http://lkml.kernel.org/r/20180629184453.7614-1-aryabinin@virtuozzo.com
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Reported-by: <icytxw@gmail.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The mutexes swap_slots_cache_mutex and swap_slots_cache_enable_mutex are
local to the source and do not need to be in global scope, so make them
static.
Cleans up sparse warnings:
symbol 'swap_slots_cache_mutex' was not declared. Should it be static?
symbol 'swap_slots_cache_enable_mutex' was not declared. Should it be static?
Link: http://lkml.kernel.org/r/20180624182536.4937-1-colin.king@canonical.com
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The functions zs_page_isolate, zs_page_migrate, zs_page_putback,
lock_zspage, trylock_zspage and structure zsmalloc_aops are local to
source and do not need to be in global scope, so make them static.
Cleans up sparse warnings:
symbol 'zs_page_isolate' was not declared. Should it be static?
symbol 'zs_page_migrate' was not declared. Should it be static?
symbol 'zs_page_putback' was not declared. Should it be static?
symbol 'zsmalloc_aops' was not declared. Should it be static?
symbol 'lock_zspage' was not declared. Should it be static?
symbol 'trylock_zspage' was not declared. Should it be static?
[arnd@arndb.de: hide unused lock_zspage]
Link: http://lkml.kernel.org/r/20180706130924.3891230-1-arnd@arndb.de
Link: http://lkml.kernel.org/r/20180624213322.13776-1-colin.king@canonical.com
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The buffer_head can consume a significant amount of system memory and is
directly related to the amount of page cache. In our production
environment we have observed that a lot of machines are spending a
significant amount of memory as buffer_head and can not be left as
system memory overhead.
Charging buffer_head is not as simple as adding __GFP_ACCOUNT to the
allocation. The buffer_heads can be allocated in a memcg different from
the memcg of the page for which buffer_heads are being allocated. One
concrete example is memory reclaim. The reclaim can trigger I/O of
pages of any memcg on the system. So, the right way to charge
buffer_head is to extract the memcg from the page for which buffer_heads
are being allocated and then use targeted memcg charging API.
[shakeelb@google.com: use __GFP_ACCOUNT for directed memcg charging]
Link: http://lkml.kernel.org/r/20180702220208.213380-1-shakeelb@google.com
Link: http://lkml.kernel.org/r/20180627191250.209150-3-shakeelb@google.com
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Jan Kara <jack@suse.cz>
Cc: Amir Goldstein <amir73il@gmail.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "Directed kmem charging", v8.
The Linux kernel's memory cgroup allows limiting the memory usage of the
jobs running on the system to provide isolation between the jobs. All
the kernel memory allocated in the context of the job and marked with
__GFP_ACCOUNT will also be included in the memory usage and be limited
by the job's limit.
The kernel memory can only be charged to the memcg of the process in
whose context kernel memory was allocated. However there are cases
where the allocated kernel memory should be charged to the memcg
different from the current processes's memcg. This patch series
contains two such concrete use-cases i.e. fsnotify and buffer_head.
The fsnotify event objects can consume a lot of system memory for large
or unlimited queues if there is either no or slow listener. The events
are allocated in the context of the event producer. However they should
be charged to the event consumer. Similarly the buffer_head objects can
be allocated in a memcg different from the memcg of the page for which
buffer_head objects are being allocated.
To solve this issue, this patch series introduces mechanism to charge
kernel memory to a given memcg. In case of fsnotify events, the memcg
of the consumer can be used for charging and for buffer_head, the memcg
of the page can be charged. For directed charging, the caller can use
the scope API memalloc_[un]use_memcg() to specify the memcg to charge
for all the __GFP_ACCOUNT allocations within the scope.
This patch (of 2):
A lot of memory can be consumed by the events generated for the huge or
unlimited queues if there is either no or slow listener. This can cause
system level memory pressure or OOMs. So, it's better to account the
fsnotify kmem caches to the memcg of the listener.
However the listener can be in a different memcg than the memcg of the
producer and these allocations happen in the context of the event
producer. This patch introduces remote memcg charging API which the
producer can use to charge the allocations to the memcg of the listener.
There are seven fsnotify kmem caches and among them allocations from
dnotify_struct_cache, dnotify_mark_cache, fanotify_mark_cache and
inotify_inode_mark_cachep happens in the context of syscall from the
listener. So, SLAB_ACCOUNT is enough for these caches.
The objects from fsnotify_mark_connector_cachep are not accounted as
they are small compared to the notification mark or events and it is
unclear whom to account connector to since it is shared by all events
attached to the inode.
The allocations from the event caches happen in the context of the event
producer. For such caches we will need to remote charge the allocations
to the listener's memcg. Thus we save the memcg reference in the
fsnotify_group structure of the listener.
This patch has also moved the members of fsnotify_group to keep the size
same, at least for 64 bit build, even with additional member by filling
the holes.
[shakeelb@google.com: use GFP_KERNEL_ACCOUNT rather than open-coding it]
Link: http://lkml.kernel.org/r/20180702215439.211597-1-shakeelb@google.com
Link: http://lkml.kernel.org/r/20180627191250.209150-2-shakeelb@google.com
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Jan Kara <jack@suse.cz>
Cc: Amir Goldstein <amir73il@gmail.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Introduce the mem_cgroup_put() helper, which helps to eliminate guarding
memcg css release with "#ifdef CONFIG_MEMCG" in multiple places.
Link: http://lkml.kernel.org/r/20180623000600.5818-2-guro@fb.com
Signed-off-by: Roman Gushchin <guro@fb.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@kernel.org>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Some architectures just don't have PAGE_KERNEL_EXEC. The mm/nommu.c and
mm/vmalloc.c code have been using PAGE_KERNEL as a fallback for years.
Move this fallback to asm-generic.
Link: http://lkml.kernel.org/r/20180510185507.2439-3-mcgrof@kernel.org
Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
Suggested-by: Matthew Wilcox <willy@infradead.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Some architectures do not define certain PAGE_KERNEL_* flags, this is
either because:
a) The way to implement some of these flags is *not yet ported*, or
b) The architecture *has no way* to describe them
Over time we have accumulated a few PAGE_KERNEL_* fallback workarounds
for architectures in the kernel which do not define them using
*relatively safe* equivalents. Move these scattered fallback hacks into
asm-generic.
We start off with PAGE_KERNEL_RO using PAGE_KERNEL as a fallback. This
has been in place on the firmware loader for years. Move the fallback
into the respective asm-generic header.
Link: http://lkml.kernel.org/r/20180510185507.2439-2-mcgrof@kernel.org
Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Callers of register_mem_sect_under_node() are always passing a valid
memory_block (not NULL), so we can safely drop the check for NULL.
In the same way, register_mem_sect_under_node() is only called in case
the node is online, so we can safely remove that check as well.
Link: http://lkml.kernel.org/r/20180622111839.10071-5-osalvador@techadventures.net
Signed-off-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Tested-by: Reza Arbab <arbab@linux.vnet.ibm.com>
Tested-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Pasha Tatashin <Pavel.Tatashin@microsoft.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
link_mem_sections() and walk_memory_range() share most of the code, so
we can use convert link_mem_sections() into a dummy function that calls
walk_memory_range() with a callback to register_mem_sect_under_node().
This patch converts register_mem_sect_under_node() in order to match a
walk_memory_range's callback, getting rid of the check_nid argument and
checking instead if the system is still boothing, since we only have to
check for the nid if the system is in such state.
Link: http://lkml.kernel.org/r/20180622111839.10071-4-osalvador@techadventures.net
Signed-off-by: Oscar Salvador <osalvador@suse.de>
Suggested-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Tested-by: Reza Arbab <arbab@linux.vnet.ibm.com>
Tested-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Pavel Tatashin <pavel.tatashin@microsoft.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When hotplugging memory, it is possible that two calls are being made to
register_mem_sect_under_node().
One comes from __add_section()->hotplug_memory_register() and the other
from add_memory_resource()->link_mem_sections() if we had to register a
new node.
In case we had to register a new node, hotplug_memory_register() will
only handle/allocate the memory_block's since
register_mem_sect_under_node() will return right away because the node
it is not online yet.
I think it is better if we leave hotplug_memory_register() to
handle/allocate only memory_block's and make link_mem_sections() to call
register_mem_sect_under_node().
So this patch removes the call to register_mem_sect_under_node() from
hotplug_memory_register(), and moves the call to link_mem_sections() out
of the condition, so it will always be called. In this way we only have
one place where the memory sections are registered.
Link: http://lkml.kernel.org/r/20180622111839.10071-3-osalvador@techadventures.net
Signed-off-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Tested-by: Reza Arbab <arbab@linux.vnet.ibm.com>
Tested-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Pasha Tatashin <Pavel.Tatashin@microsoft.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This is a small cleanup for the memhotplug code. A lot more could be
done, but it is better to start somewhere. I tried to unify/remove
duplicated code.
The following is what this patchset does:
1) add_memory_resource() has code to allocate a node in case it was
offline. Since try_online_node has some code for that as well, I just
made add_memory_resource() to use that so we can remove duplicated
code.. This is better explained in patch 1/4.
2) register_mem_sect_under_node() will be called only from
link_mem_sections()
3) Make register_mem_sect_under_node() a callback of
walk_memory_range()
4) Drop unnecessary checks from register_mem_sect_under_node()
I have done some tests and I could not see anything broken because of
this patchset.
add_memory_resource() contains code to allocate a new node in case it is
necessary. Since try_online_node() also has some code for this purpose,
let us make use of that and remove duplicate code.
This introduces __try_online_node(), which is called by
add_memory_resource() and try_online_node(). __try_online_node() has
two new parameters, start_addr of the node, and if the node should be
onlined and registered right away. This is always wanted if we are
calling from do_cpu_up(), but not when we are calling from memhotplug
code. Nothing changes from the point of view of the users of
try_online_node(), since try_online_node passes start_addr=0 and
online_node=true to __try_online_node().
Link: http://lkml.kernel.org/r/20180622111839.10071-2-osalvador@techadventures.net
Signed-off-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Tested-by: Reza Arbab <arbab@linux.vnet.ibm.com>
Tested-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Pasha Tatashin <Pavel.Tatashin@microsoft.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Pavel Tatashin <pasha.tatashin@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
__list_lru_count_one() has a single callsite.
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
shadow_lru_isolate() disables interrupts and acquires a lock. It could
use spin_lock_irq() instead. It also uses local_irq_enable() while it
could use spin_unlock_irq()/xa_unlock_irq().
Use proper suffix for lock/unlock in order to enable/disable interrupts
during release/acquire of a lock.
Link: http://lkml.kernel.org/r/20180622151221.28167-3-bigeasy@linutronix.de
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "mm: use irq locking suffix instead local_irq_disable()".
A small series which avoids using local_irq_disable()/local_irq_enable()
but instead does spin_lock_irq()/spin_unlock_irq() so it is within the
context of the lock which it belongs to. Patch #1 is a cleanup where
local_irq_.*() remained after the lock was removed.
This patch (of 2):
In 0c7c1bed7e ("mm: make counting of list_lru_one::nr_items lockless")
the
spin_lock(&nlru->lock);
statement was replaced with
rcu_read_lock();
in __list_lru_count_one(). The comment in count_shadow_nodes() says
that the local_irq_disable() is required because the lock must be
acquired with disabled interrupts and (spin_lock()) does not do so.
Since the lock is replaced with rcu_read_lock() the local_irq_disable()
is no longer needed. The code path is
list_lru_shrink_count()
-> list_lru_count_one()
-> __list_lru_count_one()
-> rcu_read_lock()
-> list_lru_from_memcg_idx()
-> rcu_read_unlock()
Remove the local_irq_disable() statement.
Link: http://lkml.kernel.org/r/20180622151221.28167-2-bigeasy@linutronix.de
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There is no real reason to blow up just because the caller doesn't know
that __get_free_pages cannot return highmem pages. Simply fix that up
silently. Even if we have some confused users such a fixup will not be
harmful.
[akpm@linux-foundation.org: mask off __GFP_HIGHMEM]
Link: http://lkml.kernel.org/r/20180622162841.25114-1-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Jiankang Chen <chenjiankang1@huawei.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Yisheng Xie <xieyisheng1@huawei.com>
Cc: Hanjun Guo <guohanjun@huawei.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This is to take better advantage of the general huge page copying
optimization. Where, the target subpage will be copied last to avoid
the cache lines of target subpage to be evicted when copying other
subpages. This works better if the address of the target subpage is
available when copying huge page. So hugetlbfs page fault handlers are
changed to pass that information to hugetlb_cow(). This will benefit
workloads which don't access the begin of the hugetlbfs huge page after
the page fault under heavy cache contention.
Link: http://lkml.kernel.org/r/20180524005851.4079-5-ying.huang@intel.com
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Andi Kleen <andi.kleen@intel.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Shaohua Li <shli@fb.com>
Cc: Christopher Lameter <cl@linux.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Punit Agrawal <punit.agrawal@arm.com>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
To take better advantage of general huge page copying optimization, the
target subpage address will be passed to hugetlb_cow(), then
copy_user_huge_page(). So we will use both target subpage address and
huge page size aligned address in hugetlb_cow(). To distinguish between
them, "haddr" is used for huge page size aligned address to be
consistent with Transparent Huge Page naming convention.
Now, only huge page size aligned address is used in hugetlb_cow(), so
the "address" is renamed to "haddr" in hugetlb_cow() in this patch.
Next patch will use target subpage address in hugetlb_cow() too.
The patch is just code cleanup without any functionality changes.
Link: http://lkml.kernel.org/r/20180524005851.4079-4-ying.huang@intel.com
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Suggested-by: Mike Kravetz <mike.kravetz@oracle.com>
Suggested-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Andi Kleen <andi.kleen@intel.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Shaohua Li <shli@fb.com>
Cc: Christopher Lameter <cl@linux.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Punit Agrawal <punit.agrawal@arm.com>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Huge page helps to reduce TLB miss rate, but it has higher cache
footprint, sometimes this may cause some issue. For example, when
copying huge page on x86_64 platform, the cache footprint is 4M. But on
a Xeon E5 v3 2699 CPU, there are 18 cores, 36 threads, and only 45M LLC
(last level cache). That is, in average, there are 2.5M LLC for each
core and 1.25M LLC for each thread.
If the cache contention is heavy when copying the huge page, and we copy
the huge page from the begin to the end, it is possible that the begin
of huge page is evicted from the cache after we finishing copying the
end of the huge page. And it is possible for the application to access
the begin of the huge page after copying the huge page.
In c79b57e462 ("mm: hugetlb: clear target sub-page last when clearing
huge page"), to keep the cache lines of the target subpage hot, the
order to clear the subpages in the huge page in clear_huge_page() is
changed to clearing the subpage which is furthest from the target
subpage firstly, and the target subpage last. The similar order
changing helps huge page copying too. That is implemented in this
patch. Because we have put the order algorithm into a separate
function, the implementation is quite simple.
The patch is a generic optimization which should benefit quite some
workloads, not for a specific use case. To demonstrate the performance
benefit of the patch, we tested it with vm-scalability run on
transparent huge page.
With this patch, the throughput increases ~16.6% in vm-scalability
anon-cow-seq test case with 36 processes on a 2 socket Xeon E5 v3 2699
system (36 cores, 72 threads). The test case set
/sys/kernel/mm/transparent_hugepage/enabled to be always, mmap() a big
anonymous memory area and populate it, then forked 36 child processes,
each writes to the anonymous memory area from the begin to the end, so
cause copy on write. For each child process, other child processes
could be seen as other workloads which generate heavy cache pressure.
At the same time, the IPC (instruction per cycle) increased from 0.63 to
0.78, and the time spent in user space is reduced ~7.2%.
Link: http://lkml.kernel.org/r/20180524005851.4079-3-ying.huang@intel.com
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Andi Kleen <andi.kleen@intel.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Shaohua Li <shli@fb.com>
Cc: Christopher Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "mm, huge page: Copy target sub-page last when copy huge
page", v2.
Huge page helps to reduce TLB miss rate, but it has higher cache
footprint, sometimes this may cause some issue. For example, when
copying huge page on x86_64 platform, the cache footprint is 4M. But on
a Xeon E5 v3 2699 CPU, there are 18 cores, 36 threads, and only 45M LLC
(last level cache). That is, in average, there are 2.5M LLC for each
core and 1.25M LLC for each thread.
If the cache contention is heavy when copying the huge page, and we copy
the huge page from the begin to the end, it is possible that the begin
of huge page is evicted from the cache after we finishing copying the
end of the huge page. And it is possible for the application to access
the begin of the huge page after copying the huge page.
In c79b57e462 ("mm: hugetlb: clear target sub-page last when clearing
huge page"), to keep the cache lines of the target subpage hot, the
order to clear the subpages in the huge page in clear_huge_page() is
changed to clearing the subpage which is furthest from the target
subpage firstly, and the target subpage last. The similar order
changing helps huge page copying too. That is implemented in this
patchset.
The patchset is a generic optimization which should benefit quite some
workloads, not for a specific use case. To demonstrate the performance
benefit of the patchset, we have tested it with vm-scalability run on
transparent huge page.
With this patchset, the throughput increases ~16.6% in vm-scalability
anon-cow-seq test case with 36 processes on a 2 socket Xeon E5 v3 2699
system (36 cores, 72 threads). The test case set
/sys/kernel/mm/transparent_hugepage/enabled to be always, mmap() a big
anonymous memory area and populate it, then forked 36 child processes,
each writes to the anonymous memory area from the begin to the end, so
cause copy on write. For each child process, other child processes
could be seen as other workloads which generate heavy cache pressure.
At the same time, the IPC (instruction per cycle) increased from 0.63 to
0.78, and the time spent in user space is reduced ~7.2%.
This patch (of 4):
In c79b57e462 ("mm: hugetlb: clear target sub-page last when clearing
huge page"), to keep the cache lines of the target subpage hot, the
order to clear the subpages in the huge page in clear_huge_page() is
changed to clearing the subpage which is furthest from the target
subpage firstly, and the target subpage last. This optimization could
be applied to copying huge page too with the same order algorithm. To
avoid code duplication and reduce maintenance overhead, in this patch,
the order algorithm is moved out of clear_huge_page() into a separate
function: process_huge_page(). So that we can use it for copying huge
page too.
This will change the direct calls to clear_user_highpage() into the
indirect calls. But with the proper inline support of the compilers,
the indirect call will be optimized to be the direct call. Our tests
show no performance change with the patch.
This patch is a code cleanup without functionality change.
Link: http://lkml.kernel.org/r/20180524005851.4079-2-ying.huang@intel.com
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Suggested-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Andi Kleen <andi.kleen@intel.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Shaohua Li <shli@fb.com>
Cc: Christopher Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Baoquan He
Kirill Tkhai
Vladimir Davydov
Mike Rapoport
Oscar Salvador
Michal Hocko
Andrey Ryabinin
Song Liu
Colin Ian King
Greg Thelen
Shakeel Butt
Roman Gushchin
Luis R. Rodriguez
Andrew Morton
Sebastian Andrzej Siewior
Huang Ying