per cpu data section contains two types of data. One set which is
exclusively accessed by the local cpu and the other set which is per cpu,
but also shared by remote cpus. In the current kernel, these two sets are
not clearely separated out. This can potentially cause the same data
cacheline shared between the two sets of data, which will result in
unnecessary bouncing of the cacheline between cpus.
One way to fix the problem is to cacheline align the remotely accessed per
cpu data, both at the beginning and at the end. Because of the padding at
both ends, this will likely cause some memory wastage and also the
interface to achieve this is not clean.
This patch:
Moves the remotely accessed per cpu data (which is currently marked
as ____cacheline_aligned_in_smp) into a different section, where all the data
elements are cacheline aligned. And as such, this differentiates the local
only data and remotely accessed data cleanly.
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Acked-by: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: <linux-arch@vger.kernel.org>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Let's allow page-alignment in general for per-cpu data (wanted by Xen, and
Ingo suggested KVM as well).
Because larger alignments can use more room, we increase the max per-cpu
memory to 64k rather than 32k: it's getting a little tight.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Update all arch/*/kernel/vmlinux.lds.S to not include space for initramfs
when CONFIG_BLK_DEV_INITRAMFS is not selected. This saves another 4 kbytes
on most platfoms (some reserve PAGE_SIZE for initramfs).
Signed-off-by: Jean-Paul Saman <jean-paul.saman@nxp.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
While the recent cset 86384d5441 did improve
things it didn't resolve all the problems. So bite the bullet and discard
.exit.text and .exit.data at runtime. Which of course sucks because it
bloats binaries with code that will never ever be used but it's the only
thing that will work reliable as demonstrated by the function sd_major() in
drivers/scsi/sd.c.
Gcc may compile sd_major() using a jump table which it will put into
.rodata. If it also inlines sd_major's function body into exit_sd() which
gcc > 3.4.x does. If CONFIG_BLK_DEV_SD has been set to y we would like ld
to discard exit_sd's code at link time. However sd_major happens to
contain a switch statement which gcc will compile using a jump table in
.rodata on the architectures I checked. So, when ld later discards
.exit.text only the jump table in .rodata with its stale references to
the discard .exit.text will be left which any no antique ld will honor
with a link error.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Add a vmlinux.lds.h helper macro for defining the eight-level initcall table,
teach all the architectures to use it.
This is a prerequisite for a patch which performs initcall synchronisation for
multithreaded-probing.
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
[ Added AVR32 as well ]
Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
When debugging a kernel compiled by gcc 4.1 with gdb 6.4, gdb could
not show filename, linenumber, etc. It seems fixed if I used generic
DWARF_DEBUG macro. Although gcc 3.x seems work without this change,
it would be better to use the generic macro unless there were
something MIPS specific.
Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
At times gcc will place bits of __exit functions into .rodata. If
compiled into the kernle itself we used to discard .exit.text - but
not the bits left in .rodata. While harmless this did at times result
in a large number of warnings. So until gcc fixes this, discard
.exit.text at runtime.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Very much to my surprise Fuxin Zhang reports this is all it takes to get
the kernel to work for page sizes larger than 4kB. This also paves the
way for support for the R6000 and R8000 which don't support 4kB page size.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
