Commit graph

774 commits

Author SHA1 Message Date
Carsten Emde
a635cf0497 tracing: fix command line to pid reverse map
Impact: fix command line to pid mapping

map_cmdline_to_pid[] is checked in trace_save_cmdline(), but never
updated. This results in stale pid to command line mappings and the
tracer output will associate the wrong comm string.

Signed-off-by: Carsten Emde <Carsten.Emde@osadl.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Steven Rostedt <srostedt@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-03-18 10:10:18 +01:00
Thomas Gleixner
50d88758a3 tracing: fix trace_find_cmdline()
Impact: prevent stale command line output

In case there is no valid command line mapping for a pid
trace_find_cmdline() returns without updating the comm buffer. The
trace dump keeps the previous entry which results in confusing trace
output:

     <idle>-0     [000]   280.702056 ....
     <idle>-23456 [000]   280.702080 ....

Update the comm buffer with "<...>" when no mapping is found.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Steven Rostedt <srostedt@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-03-18 10:10:17 +01:00
Thomas Gleixner
2c7eea4c62 tracing: replace the crude (unsigned) -1 hackery
Impact: cleanup

The command line recorder uses (unsigned) -1 to mark non mapped
entries in the pid to command line maps. The validity check is
completely unintuitive: idx >= SAVED_CMDLINES

There is no need for such casting games. Use a constant to mark
unmapped entries and check for that constant to make the code readable
and understandable.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Steven Rostedt <srostedt@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-03-18 10:10:17 +01:00
Thomas Gleixner
18aecd362a tracing: stop command line recording when tracing is disabled
Impact: prevent overwrite of command line entries

When the tracer is stopped the command line recording continues to
record. The check for tracing_is_on() is not sufficient here as the
ringbuffer status is not affected by setting
debug/tracing/tracing_enabled to 0. On a non idle system this can
result in the loss of the command line information for the stopped
trace, which makes the trace harder to read and analyse.

Check tracer_enabled to allow further recording.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Steven Rostedt <srostedt@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-03-18 10:10:16 +01:00
Ingo Molnar
4176935b58 Merge branch 'tip/tracing/ftrace' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-2.6-trace into tracing/ftrace 2009-03-17 10:37:37 +01:00
Tom Zanussi
c269fc8c53 tracing: fix leak in event_format_read()
Impact: fix memory leak

If event_format_read() exits early due to nonzero ppos, the
previous kmalloc doesn't get freed - might as well do the
check before the kmalloc and avoid the problem.

Signed-off-by: Tom Zanussi <tzanussi@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: =?ISO-8859-1?Q?Fr=E9d=E9ric?= Weisbecker <fweisbec@gmail.com>
LKML-Reference: <1237270859.8033.141.camel@charm-linux>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-03-17 08:38:23 +01:00
Steven Rostedt
6adaad14d7 tracing: stop comm recording on tracing off
Impact: fix for losing comms in trace

The command lines of tasks are cached at sched switch to not need
to record them at every trace point.  Disabling the tracing on stops
the recording of traces, but does not stop the caching of command lines.
When the tracing is off the cache may overflow and cause the tracing
to show incorrect tasks matching the PIDs.

This patch disables prevents updates to the comm cache when the ring buffer
is off.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
2009-03-16 23:31:15 -04:00
Steven Rostedt
4ca5308523 tracing: protect reader of cmdline output
Impact: fix to one cause of incorrect comm outputs in trace

The spinlock only protected the creation of a comm <=> pid pair.
But it was possible that a reader could look up a pid, and get the
wrong comm because it had no locking.

This also required changing trace_find_cmdline to copy the comm cache
and not just send back a pointer to it.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
2009-03-16 23:27:06 -04:00
Frederic Weisbecker
03303549b1 tracing/ftrace: fix the check on nopped sites
Impact: fix a dynamic tracing failure

Recently, the function and function graph tracers failed to use dynamic
tracing after the following commit:

fa9d13cf13
(ftrace: don't try to __ftrace_replace_code on !FTRACE_FL_CONVERTED rec)

The patch is right except a mistake on the check for the FTRACE_FL_CONVERTED
flag. The code patching is aborted in case of successfully nopped sites.
What we want is the opposite: ignore the callsites that haven't been nopped.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
2009-03-16 22:15:36 -04:00
Frederic Weisbecker
2fc1dfbe17 tracing/core: fix early free of cpumasks
Impact: fix crashes when tracing cpumasks

While ring-buffer allocation, the cpumasks are allocated too,
including the tracing cpumask and the per-cpu file mask handler.
But these cpumasks are freed accidentally just after.
Fix it.

Reported-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <1237164303-11476-1-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-03-16 09:13:18 +01:00
Frederic Weisbecker
ac1d52d0b8 tracing/ftrace: fix double calls to tracing_start()
Impact: fix a warning during preemptirqsoff selftests

When the preemptirqsoff selftest fails, we see the following
warning:

[    6.050000] Testing tracer preemptirqsoff: .. no entries found ..
------------[ cut here ]------------
[    6.060000] WARNING: at kernel/trace/trace.c:688 tracing_start+0x67/0xd3()
[    6.060000] Modules linked in:
[    6.060000] Pid: 1, comm: swapper Tainted: G
[    6.060000] Call Trace:
[    6.060000]  [<ffffffff802460ff>] warn_slowpath+0xb1/0x100
[    6.060000]  [<ffffffff802a8f5b>] ? trace_preempt_on+0x35/0x4b
[    6.060000]  [<ffffffff802a37fb>] ? tracing_start+0x31/0xd3
[    6.060000]  [<ffffffff802a37fb>] ? tracing_start+0x31/0xd3
[    6.060000]  [<ffffffff80271e0b>] ? __lock_acquired+0xe6/0x1f2
[    6.060000]  [<ffffffff802a37fb>] ? tracing_start+0x31/0xd3
[    6.060000]  [<ffffffff802a3831>] tracing_start+0x67/0xd3
[    6.060000]  [<ffffffff802a8ace>] ? irqsoff_tracer_reset+0x2d/0x57
[    6.060000]  [<ffffffff802a4d1c>] trace_selftest_startup_preemptirqsoff+0x1c8/0x1f1
[    6.060000]  [<ffffffff802a4798>] register_tracer+0x12f/0x241
[    6.060000]  [<ffffffff810250d0>] ? init_irqsoff_tracer+0x0/0x53
[    6.060000]  [<ffffffff8102510b>] init_irqsoff_tracer+0x3b/0x53

This is because in fail case, the preemptirqsoff tracer selftest calls twice
the tracing_start() function:

int
trace_selftest_startup_preemptirqsoff(struct tracer *trace, struct trace_array *tr)
{
        if (!ret && !count) {
                printk(KERN_CONT ".. no entries found ..");
                ret = -1;
                tracing_start(); <-----
                goto out;
        }
        [...]
out:
        trace->reset(tr);
        tracing_start(); <------
        tracing_max_latency = save_max;

        return ret;
}

Since it is well handled in the out path, we don't need the conditional one.

Reported-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <1237159961-7447-1-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-03-16 09:13:18 +01:00
Frederic Weisbecker
59f586db98 tracing/core: fix missing mutex unlock on tracing_set_tracer()
Impact: fix possible locking imbalance

In case of ring buffer resize failure, tracing_set_tracer forgot to
release trace_types_lock. Fix it.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <1237151439-6755-5-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-03-16 09:13:17 +01:00
Frederic Weisbecker
0ea1c4156b tracing/syscalls: select kallsysms
Syscall tracing must select kallsysms.

The arch code builds a table to find the syscall metadata by syscall
number. It needs the syscalls names resolution from the symbol table
to know which name found on the syscalls metadatas match a function
pointer from the arch sys_call_table.

Reported-by: Andrew Morton <akpm@linux-foundation.org>
Reported-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <1237151439-6755-4-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-03-16 09:13:17 +01:00
Frederic Weisbecker
5be71b61f1 tracing/syscalls: protect thread flag toggling from races
Impact: fix syscall tracer enable/disable race

The current thread flag toggling is racy as shown in the following
scenario:

- task A is the last user of syscall tracing, it releases the
  TIF_SYSCALL_FTRACE on each tasks

- at the same time task B start syscall tracing. refcount == 0 so
  it sets up TIF_SYSCALL_FTRACE on each tasks.

The effect of the mixup is unpredictable.
So this fix adds a mutex on {start,stop}_syscall_tracing().

Reported-by: Andrew Morton <akpm@linux-foundation.org>
Reported-by: Ingo Molnar <mingo@elte.hu>
LKML-Reference: <1237151439-6755-3-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-03-16 09:13:16 +01:00
Frederic Weisbecker
6404434525 tracing/syscalls: various cleanups
Impact: cleanup

- Drop unused cpu variable
- Fix some errors on comments

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <1237151439-6755-2-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-03-16 09:13:16 +01:00
Frederic Weisbecker
ac99c58c9e tracing/syscalls: fix missing release of tracing
Impact: fix 'stuck' syscall tracer

The syscall tracer uses a refcounter to enable several users
simultaneously.

But the refcounter did not behave correctly and always restored
its value to 0 after calling start_syscall_tracing(). Therefore,
stop_syscall_tracing() couldn't release correctly the tasks from
tracing.

Also the tracer forgot to reset the buffer when it is released.

Drop the pointless refcount decrement on start_syscall_tracing()
and reset the buffer when we release the tracer.

This fixes two reported issue:

- when we switch from syscall tracer to another tracer, syscall
  tracing continued.

- incorrect use of the refcount.

Reported-by: Andrew Morton <akpm@linux-foundation.org>
Reported-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <1237151439-6755-1-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-03-16 09:13:15 +01:00
Ingo Molnar
7243f2145a Merge branches 'tracing/ftrace', 'tracing/syscalls' and 'linus' into tracing/core
Conflicts:
	arch/parisc/kernel/irq.c
2009-03-16 09:12:42 +01:00
Frederic Weisbecker
bed1ffca02 tracing/syscalls: core infrastructure for syscalls tracing, enhancements
Impact: new feature

This adds the generic support for syscalls tracing. This is
currently exploited through a devoted tracer but other tracing
engines can use it. (They just have to play with
{start,stop}_ftrace_syscalls() and use the display callbacks
unless they want to override them.)

The syscalls prototypes definitions are abused here to steal
some metadata informations:

- syscall name, param types, param names, number of params

The syscall addr is not directly saved during this definition
because we don't know if its prototype is available in the
namespace. But we don't really need it. The arch has just to
build a function able to resolve the syscall number to its
metadata struct.

The current tracer prints the syscall names, parameters names
and values (and their types optionally). Currently the value is
a raw hex but higher level values diplaying is on my TODO list.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <1236955332-10133-2-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-03-13 16:57:42 +01:00
Lai Jiangshan
e94142a67f ftrace: remove struct list_head from struct dyn_ftrace
Impact: save memory

The struct dyn_ftrace table is very large, this patch will save
about 50%.

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Steven Rostedt <srostedt@redhat.com>
LKML-Reference: <49BA2C9F.8020009@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-03-13 11:36:20 +01:00
Lai Jiangshan
850a80cfaa ftrace: use seq_read
Impact: cleanup

VFS layer has tested the file mode, we do not need test it.

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Steven Rostedt <srostedt@redhat.com>
LKML-Reference: <49BA2BAB.6010608@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-03-13 11:35:31 +01:00
Zhaolei
fa9d13cf13 ftrace: don't try to __ftrace_replace_code on !FTRACE_FL_CONVERTED rec
Do __ftrace_replace_code for !FTRACE_FL_CONVERTED rec will always
fail, we should ignore this rec.

Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
Cc: "Steven Rostedt ;" <rostedt@goodmis.org>
LKML-Reference: <49BA2472.4060206@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-03-13 10:25:06 +01:00
Zhaolei
b00f0b6dc1 ftrace: avoid double-free of dyn_ftrace
If dyn_ftrace is freed before ftrace_release(), ftrace_release()
will free it again and make ftrace_free_records wrong.

Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
Cc: "Steven Rostedt ;" <rostedt@goodmis.org>
LKML-Reference: <49BA23D9.1050900@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-03-13 10:25:06 +01:00
Ingo Molnar
62a394eb77 Merge branches 'tracing/ftrace' and 'tracing/syscalls'; commit 'v2.6.29-rc8' into tracing/core 2009-03-13 10:23:39 +01:00
Frederic Weisbecker
ee08c6eccb tracing/ftrace: syscall tracing infrastructure, basics
Provide basic callbacks to do syscall tracing.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
LKML-Reference: <1236401580-5758-2-git-send-email-fweisbec@gmail.com>
[ simplified it to a trace_printk() for now. ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-03-13 06:25:43 +01:00
Steven Rostedt
7f96f93f02 tracing: move binary buffers into per cpu directory
The binary_buffers directory in /debugfs/tracing held the files
to read the trace buffers in a binary format. This held one file
per CPU buffer. But we also have a per_cpu directory that holds
a way to read the pretty-print formats.

This patch moves the binary buffers into the per_cpu_directory:

 # ls /debug/tracing/per_cpu/cpu1/
trace  trace_pipe  trace_pipe_raw

The new name is called "trace_pipe_raw". The binary buffers always
acted similar to trace_pipe, except that they produce raw data.

Requested-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
2009-03-13 00:37:42 -04:00
Steven Rostedt
bdc067582b tracing: add comment for use of double __builtin_consant_p
Impact: documentation

The use of the double __builtin_contant_p checks in the event_trace_printk
can be confusing to developers and reviewers. This patch adds a comment
to explain why it is there.

Requested-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
LKML-Reference: <20090313122235.43EB.A69D9226@jp.fujitsu.com>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
2009-03-13 00:15:46 -04:00
Steven Rostedt
eb1871f343 tracing: left align location header in stack_trace
Ingo Molnar suggested, instead of:

        Depth    Size      Location    (27 entries)
        -----    ----      --------
  0)     2880      48   lock_timer_base+0x2b/0x4f
  1)     2832      80   __mod_timer+0x33/0xe0
  2)     2752      16   __ide_set_handler+0x63/0x65

To have it be:

        Depth    Size   Location    (27 entries)
        -----    ----   --------
  0)     2880      48   lock_timer_base+0x2b/0x4f
  1)     2832      80   __mod_timer+0x33/0xe0
  2)     2752      16   __ide_set_handler+0x63/0x65

Requested-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
2009-03-13 00:00:58 -04:00
Steven Rostedt
5cc9854888 ring-buffer: document reader page design
In a private email conversation I explained how the ring buffer
page worked by using silly ASCII art. Ingo suggested that I add
that to the comments of the code.

Here it is.

Requested-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
2009-03-12 22:24:17 -04:00
Steven Rostedt
f28e55765e tracing: show event name in trace for TRACE_EVENT created events
Unlike TRACE_FORMAT() macros, the TRACE_EVENT() macros do not show
the event name in the trace file. Knowing the event type in the trace
output is very useful.

Instead of:

   task swapper:0 [140] ==> ntpd:3308 [120]

We now have:

   sched_switch: task swapper:0 [140] ==> ntpd:3308 [120]

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
2009-03-12 22:00:19 -04:00
KOSAKI Motohiro
889a6c3672 tracing: Don't use tracing_record_cmdline() in workqueue tracer fix
commit c3ffc7a40b
"Don't use tracing_record_cmdline() in workqueue tracer"
has a race window.

find_task_by_vpid() requires task_list_lock().

LKML-Reference: <20090313090042.43CD.A69D9226@jp.fujitsu.com>
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
2009-03-12 21:23:47 -04:00
Steven Rostedt
e447e1df2e tracing: explain why stack tracer is empty
If the stack tracing is disabled (by default) the stack_trace file
will only contain the header:

 # cat /debug/tracing/stack_trace
        Depth    Size      Location    (0 entries)
        -----    ----      --------

This can be frustrating to a developer that does not realize that the
stack tracer is disabled. This patch adds the following text:

  # cat /debug/tracing/stack_trace
        Depth    Size      Location    (0 entries)
        -----    ----      --------
 #
 #  Stack tracer disabled
 #
 # To enable the stack tracer, either add 'stacktrace' to the
 # kernel command line
 # or 'echo 1 > /proc/sys/kernel/stack_tracer_enabled'
 #

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
2009-03-12 21:15:01 -04:00
Steven Rostedt
2da03ecee6 tracing: fix stack tracer header
The stack tracer use to look like this:

 # cat /debug/tracing/stack_trace
         Depth  Size      Location    (57 entries)
         -----  ----      --------
  0)     5088      16   mempool_alloc_slab+0x16/0x18
  1)     5072     144   mempool_alloc+0x4d/0xfe
  2)     4928      16   scsi_sg_alloc+0x48/0x4a [scsi_mod]

Now it looks like this:

 # cat /debug/tracing/stack_trace

        Depth    Size      Location    (57 entries)
        -----    ----      --------
  0)     5088      16   mempool_alloc_slab+0x16/0x18
  1)     5072     144   mempool_alloc+0x4d/0xfe
  2)     4928      16   scsi_sg_alloc+0x48/0x4a [scsi_mod]

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
2009-03-12 21:15:01 -04:00
Steven Rostedt
7975a2be16 tracing: export trace formats to user space
The binary printk saves a pointer to the format string in the ring buffer.
On output, the format is processed. But if the user is reading the
ring buffer through a binary interface, the pointer is meaningless.

This patch creates a file called printk_formats that maps the pointers
to the formats.

 # cat /debug/tracing/printk_formats
0xffffffff80713d40 : "irq_handler_entry: irq=%d handler=%s\n"
0xffffffff80713d48 : "lock_acquire: %s%s%s\n"
0xffffffff80713d50 : "lock_release: %s\n"

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
2009-03-12 21:15:01 -04:00
Steven Rostedt
e9fb2b6d58 tracing: have event_trace_printk use static tracer
Impact: speed up on event tracing

The event_trace_printk is currently a wrapper function that calls
trace_vprintk. Because it uses a variable for the fmt it misses out
on the optimization of using the binary printk.

This patch makes event_trace_printk into a macro wrapper to use the
fmt as the same as the trace_printks.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
2009-03-12 21:15:00 -04:00
Steven Rostedt
828275574e tracing: make bprint event use the proper event id
The bprint record is using TRACE_PRINT when it should be TRACE_BPRINT.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
2009-03-12 21:15:00 -04:00
Frederic Weisbecker
48ead02030 tracing/core: bring back raw trace_printk for dynamic formats strings
Impact: fix callsites with dynamic format strings

Since its new binary implementation, trace_printk() internally uses static
containers for the format strings on each callsites. But the value is
assigned once at build time, which means that it can't take dynamic
formats.

So this patch unearthes the raw trace_printk implementation for the callers
that will need trace_printk to be able to carry these dynamic format
strings. The trace_printk() macro will use the appropriate implementation
for each callsite. Most of the time however, the binary implementation will
still be used.

The other impact of this patch is that mmiotrace_printk() will use the old
implementation because it calls the low level trace_vprintk and we can't
guess here whether the format passed in it is dynamic or not.

Some parts of this patch have been written by Steven Rostedt (most notably
the part that chooses the appropriate implementation for each callsites).

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
2009-03-12 21:15:00 -04:00
Steven Rostedt
db526ca329 tracing: show that buffer size is not expanded
Impact: do not confuse user on small trace buffer sizes

When the system boots up, the trace buffer is small to conserve memory.
It is only two pages per online CPU. When the tracer is used, it expands
to the default value.

This can confuse the user if they look at the buffer size and see only
7, but then later they see 1408.

 # cat /debug/tracing/buffer_size_kb
7

 # echo sched_switch > /debug/tracing/current_tracer

 # cat /debug/tracing/buffer_size_kb
1408

This patch tries to help remove this confustion by showing that the
buffer has not been expanded.

 # cat /debug/tracing/buffer_size_kb
7 (expanded: 1408)

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
2009-03-12 21:14:59 -04:00
Steven Rostedt
8aabee573d ring-buffer: remove unneeded get_online_cpus
Impact: speed up and remove possible races

The get_online_cpus was added to the ring buffer because the original
design would free the ring buffer on a CPU that was being taken
off line. The final design kept the ring buffer around even when the
CPU was taken off line. This is to allow a user to still read the
information on that ring buffer.

Most of the get_online_cpus are no longer needed since the ring buffer will
not disappear from the use cases.

Reported-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
2009-03-12 21:14:59 -04:00
Steven Rostedt
59222efe2d ring-buffer: use CONFIG_HOTPLUG_CPU not CONFIG_HOTPLUG
The hotplug code in the ring buffers is for use with CPU hotplug,
not generic hotplug.

Reported-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
2009-03-12 21:14:59 -04:00
Steven Rostedt
1027fcb206 tracing: protect ring_buffer_expanded with trace_types_lock
Impact: prevent races with ring_buffer_expanded

This patch places the expanding of the tracing buffer under the
protection of the trace_types_lock mutex. It is highly unlikely
that there would be any contention, but better safe than sorry.

Reported-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
2009-03-12 21:14:58 -04:00
Steven Rostedt
a123c52b46 tracing: fix comments about trace buffer resizing
Impact: cleanup

Some of the comments about the trace buffer resizing is gobbledygook.
And I wonder why people question if I'm a native English speaker.

This patch makes the comments make a bit more sense.

Reported-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
2009-03-12 21:14:58 -04:00
Steven Rostedt
51b643b404 Merge branch 'tracing/ftrace' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip into trace/tip/tracing/ftrace-merge 2009-03-12 21:12:46 -04:00
Steven Rostedt
554f786e28 ring-buffer: only allocate buffers for online cpus
Impact: save on memory

Currently, a ring buffer was allocated for each "possible_cpus". On
some systems, this is the same as NR_CPUS. Thus, if a system defined
NR_CPUS = 64 but it only had 1 CPU, we could have possibly 63 useless
ring buffers taking up space. With a default buffer of 3 megs, this
could be quite drastic.

This patch changes the ring buffer code to only allocate ring buffers
for online CPUs.  If a CPU goes off line, we do not free the buffer.
This is because the user may still have trace data in that buffer
that they would like to look at.

Perhaps in the future we could add code to delete a ring buffer if
the CPU is offline and the ring buffer becomes empty.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
2009-03-11 22:15:27 -04:00
Steven Rostedt
9aba60fe6e tracing: fix trace_wait to know to wait on all cpus or just one
Impact: fix to task live locking on reading trace_pipe on one CPU

The same code is used for both trace_pipe (all CPUS) and the per_cpu
trace_pipe file. When there is no data to read, it will check for
signals and wait on the trace wait queue.

The problem happens with the per_cpu wait. The trace_wait code checks
all CPUs. Thus, if there's data in another CPU buffer, then it will
exit the wait, without checking for signals or waiting on the wait queue.

It would then try to read the empty buffer, and since that will just
return nothing, then it will try to wait again. Unfortunately, that will
again fail due to there still being data in the other buffers. This
ends up with a live lock for the task.

This patch fixes the trace_wait to be aware that the iterator may only
be waiting on a single buffer.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
2009-03-11 22:15:25 -04:00
Steven Rostedt
1852fcce18 tracing: expand the ring buffers when an event is activated
To save memory, the tracer ring buffers are set to a minimum.
The activating of a trace expands the ring buffer size. This patch
adds this expanding, when an event is activated.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
2009-03-11 22:15:24 -04:00
Steven Rostedt
73c5162aa3 tracing: keep ring buffer to minimum size till used
Impact: less memory impact on systems not using tracer

When the kernel boots up that has tracing configured, it allocates
the default size of the ring buffer. This currently happens to be
1.4Megs per possible CPU. This is quite a bit of wasted memory if
the system is never using the tracer.

The current solution is to keep the ring buffers to a minimum size
until the user uses them. Once a tracer is piped into the current_tracer
the ring buffer will be expanded to the default size. If the user
changes the size of the ring buffer, it will take the size given
by the user immediately.

If the user adds a "ftrace=" to the kernel command line, then the ring
buffers will be set to the default size on initialization.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
2009-03-11 22:15:22 -04:00
Ingo Molnar
aecfcde920 Merge branch 'tip/tracing/ftrace' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-2.6-trace into tracing/ftrace 2009-03-11 20:47:23 +01:00
Ingo Molnar
e2b8b28085 Merge branch 'tip/tracing/ftrace' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-2.6-trace into tracing/ftrace 2009-03-10 22:55:31 +01:00
Steven Rostedt
80370cb758 tracing: use raw spinlocks for trace_vprintk
Impact: prevent locking up by lockdep tracer

The lockdep tracer uses trace_vprintk and thus trace_vprintk can not
call back into lockdep without locking up.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
2009-03-10 17:16:35 -04:00
Peter Zijlstra
6cc3c6e12b trace_clock: fix preemption bug
Using the function_graph tracer in recent kernels generates a spew of
preemption BUGs. Fix this by not requiring trace_clock_local() users
to disable preemption themselves.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-03-10 20:03:01 +01:00