The buffer for the output is as small as 64 bytes, so it'll
overflow if we add more clock type. Use seq file instead.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <4B1DC4FB.5030407@cn.fujitsu.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
I've been asked a few times about how to find out what is calling
some location in the kernel. One way is to use dynamic function tracing
and implement the func_stack_trace. But this only finds out who is
calling a particular function. It does not tell you who is calling
that function and entering a specific if conditional.
I have myself implemented a quick version of trace_dump_stack() for
this purpose a few times, and just needed it now. This is when I realized
that this would be a good tool to have in the kernel like trace_printk().
Using trace_dump_stack() is similar to dump_stack() except that it
writes to the trace buffer instead and can be used in critical locations.
For example:
@@ -5485,8 +5485,12 @@ need_resched_nonpreemptible:
if (prev->state && !(preempt_count() & PREEMPT_ACTIVE)) {
if (unlikely(signal_pending_state(prev->state, prev)))
prev->state = TASK_RUNNING;
- else
+ else {
deactivate_task(rq, prev, 1);
+ trace_printk("Deactivating task %s:%d\n",
+ prev->comm, prev->pid);
+ trace_dump_stack();
+ }
switch_count = &prev->nvcsw;
}
Produces:
<...>-3249 [001] 296.105269: schedule: Deactivating task ntpd:3249
<...>-3249 [001] 296.105270: <stack trace>
=> schedule
=> schedule_hrtimeout_range
=> poll_schedule_timeout
=> do_select
=> core_sys_select
=> sys_select
=> system_call_fastpath
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Olof Johansson stated the following:
Comparing a va_list with NULL is bogus. It's supposed to be treated like
an opaque type and only be manipulated with va_* accessors.
Olof noticed that this code broke the ARM builds:
kernel/trace/trace.c: In function 'trace_array_vprintk':
kernel/trace/trace.c:1364: error: invalid operands to binary == (have 'va_list' and 'void *')
kernel/trace/trace.c: In function 'tracing_mark_write':
kernel/trace/trace.c:3349: error: incompatible type for argument 3 of 'trace_vprintk'
This patch partly reverts c13d2f7c32 and
re-installs the original mark_printk() mechanism.
Reported-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Carsten Emde <C.Emde@osadl.org>
LKML-Reference: <4B1BAB74.104@osadl.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
If the seq_read fills the buffer it will call s_start again on the next
itertation with the same position. This causes a problem with the
function_graph tracer because it consumes the iteration in order to
determine leaf functions.
What happens is that the iterator stores the entry, and the function
graph plugin will look at the next entry. If that next entry is a return
of the same function and task, then the function is a leaf and the
function_graph plugin calls ring_buffer_read which moves the ring buffer
iterator forward (the trace iterator still points to the function start
entry).
The copying of the trace_seq to the seq_file buffer will fail if the
seq_file buffer is full. The seq_read will not show this entry.
The next read by userspace will cause seq_read to again call s_start
which will reuse the trace iterator entry (the function start entry).
But the function return entry was already consumed. The function graph
plugin will think that this entry is a nested function and not a leaf.
To solve this, the trace code now checks the return status of the
seq_printf (trace_print_seq). If the writing to the seq_file buffer
fails, we set a flag in the iterator (leftover) and we do not reset
the trace_seq buffer. On the next call to s_start, we check the leftover
flag, and if it is set, we just reuse the trace_seq buffer and do not
call into the plugin print functions.
Before this patch:
2) | fput() {
2) | __fput() {
2) 0.550 us | inotify_inode_queue_event();
2) | __fsnotify_parent() {
2) 0.540 us | inotify_dentry_parent_queue_event();
After the patch:
2) | fput() {
2) | __fput() {
2) 0.550 us | inotify_inode_queue_event();
2) 0.548 us | __fsnotify_parent();
2) 0.540 us | inotify_dentry_parent_queue_event();
[
Updated the patch to fix a missing return 0 from the trace_print_seq()
stub when CONFIG_TRACING is disabled.
Reported-by: Ingo Molnar <mingo@elte.hu>
]
Reported-by: Jiri Olsa <jolsa@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This fixes a cut and paste error that had pipe_close get called
if pipe_open was defined (not pipe_close).
Reported-by: Kosaki Motohiro <kosaki.motohiro@jp.fujitsu.com>
LKML-Reference: <20091209153204.F4CD.A69D9226@jp.fujitsu.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
An ftrace plugin can add a pipe_open interface when the user opens
trace_pipe. But if the plugin allocates something within the pipe_open
it can not free it because there exists no pipe_close. The hook to
the trace file open has a corresponding close. The closing of the
trace_pipe file should also have a corresponding close.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* 'tracing-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (40 commits)
tracing: Separate raw syscall from syscall tracer
ring-buffer-benchmark: Add parameters to set produce/consumer priorities
tracing, function tracer: Clean up strstrip() usage
ring-buffer benchmark: Run producer/consumer threads at nice +19
tracing: Remove the stale include/trace/power.h
tracing: Only print objcopy version warning once from recordmcount
tracing: Prevent build warning: 'ftrace_graph_buf' defined but not used
ring-buffer: Move access to commit_page up into function used
tracing: do not disable interrupts for trace_clock_local
ring-buffer: Add multiple iterations between benchmark timestamps
kprobes: Sanitize struct kretprobe_instance allocations
tracing: Fix to use __always_unused attribute
compiler: Introduce __always_unused
tracing: Exit with error if a weak function is used in recordmcount.pl
tracing: Move conditional into update_funcs() in recordmcount.pl
tracing: Add regex for weak functions in recordmcount.pl
tracing: Move mcount section search to front of loop in recordmcount.pl
tracing: Fix objcopy revision check in recordmcount.pl
tracing: Check absolute path of input file in recordmcount.pl
tracing: Correct the check for number of arguments in recordmcount.pl
...
When a string was written to <debugfs>/tracing/trace_marker, some
strange characters appeared in the trace output instead of the
string, since a vprint function erroneously called a vararg print
function with a va_list argument. This patch fixes the problem and
simplifies the related code.
Signed-off-by: Carsten Emde <C.Emde@osadl.org>
LKML-Reference: <4B01AE5D.1010801@osadl.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The function tracing_stats_read() mistakenly returns ENOMEM instead
of the negative value -ENOMEM.
Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
LKML-Reference: <4AFB2C0B.50605@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Instead of directly updating filp->f_pos we should update the *ppos
argument. The filp->f_pos gets updated within the file_pos_write()
function called from sys_write().
Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <20091023233646.399670810@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
set_cmdline_ftrace is a better match against what does this function:
apply a tracer name from the kernel command line.
Reported-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Do this rename because set_ftrace is too much generic and not enough
self-explainable as a name.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Li Zefan <lizf@cn.fujitsu.com>
The addition of trace_array_{v}printk used the wrong function for
trace_vprintk to call. This broke trace_marker and trace_vprintk
itself. Although trace_printk may not have been affected by those
that end up calling trace_vbprintk.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* 'tracing-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
modules, tracing: Remove stale struct marker signature from module_layout()
tracing/workqueue: Use %pf in workqueue trace events
tracing: Fix a comment and a trivial format issue in tracepoint.h
tracing: Fix failure path in ftrace_regex_open()
tracing: Fix failure path in ftrace_graph_write()
tracing: Check the return value of trace_get_user()
tracing: Fix off-by-one in trace_get_user()
Remove open-coded zalloc_cpumask_var() and zalloc_cpumask_var_node().
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Make all seq_operations structs const, to help mitigate against
revectoring user-triggerable function pointers.
This is derived from the grsecurity patch, although generated from scratch
because it's simpler than extracting the changes from there.
Signed-off-by: James Morris <jmorris@namei.org>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Leave the last slot for the tailing '\0'.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <4AB865FA.5080801@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
* 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
sched: Simplify sys_sched_rr_get_interval() system call
sched: Fix potential NULL derference of doms_cur
sched: Fix raciness in runqueue_is_locked()
sched: Re-add lost cpu_allowed check to sched_fair.c::select_task_rq_fair()
sched: Remove unneeded indentation in sched_fair.c::place_entity()
runqueue_is_locked() is unavoidably racy due to a poor interface design.
It does
cpu = get_cpu()
ret = some_perpcu_thing(cpu);
put_cpu(cpu);
return ret;
Its return value is unreliable.
Fix.
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <200909191855.n8JItiko022148@imap1.linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Limit the length of a tracer's name within 100 chars, and then we
don't have to play with max_tracer_type_len.
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
LKML-Reference: <4AB32377.9020601@cn.fujitsu.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Now that the pluging tracers use macros to create the structures and
automate the exporting of their formats to the format files, they also
automatically get a filter file.
This patch adds the code to implement the filter logic in the trace
recordings.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The state of the function pair tracing_stop()/tracing_start() is
correctly considered when tracer data are updated. However, the global
and externally accessible variable tracing_max_latency is always updated
- even when tracing is stopped.
The update should only occur, if tracing was not stopped.
Signed-off-by: Carsten Emde <C.Emde@osadl.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Create a "trace_parser" that can parse the user space input for
separate words.
struct trace_parser is the descriptor.
Generic "trace_get_user" function that can be a helper to read multiple
words passed in by user space.
Signed-off-by: Jiri Olsa <jolsa@redhat.com>
LKML-Reference: <1252682969-3366-2-git-send-email-jolsa@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The userstack trace required the recording of the tgid entry.
Unfortunately, it was added to the generic entry where it wasted
4 bytes of every entry and was only used by one entry.
This patch moves it out of the generic field and moves it into the
only user (userstack_entry).
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The irqsoff tracer will fail to swap the cpu buffer with the max
buffer if it preempts a commit. Instead of ignoring this, this patch
makes the tracer report it if the last max latency failed due to preempting
a current commit.
The output of the latency tracer will look like this:
# tracer: irqsoff
#
# irqsoff latency trace v1.1.5 on 2.6.31-rc5
# --------------------------------------------------------------------
# latency: 112 us, #1/1, CPU#1 | (M:preempt VP:0, KP:0, SP:0 HP:0 #P:4)
# -----------------
# | task: -4281 (uid:0 nice:0 policy:0 rt_prio:0)
# -----------------
# => started at: save_args
# => ended at: __do_softirq
#
#
# _------=> CPU#
# / _-----=> irqs-off
# | / _----=> need-resched
# || / _---=> hardirq/softirq
# ||| / _--=> preempt-depth
# |||| /
# ||||| delay
# cmd pid ||||| time | caller
# \ / ||||| \ | /
bash-4281 1d.s6 265us : update_max_tr_single: Failed to swap buffers due to commit in progress
Note the latency time and the functions that disabled the irqs or preemption
will still be listed.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This patch adds a trace_array_printk to allow a tracer to use the
trace_printk on its own trace array.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The latency tracers (irqsoff and wakeup) can swap trace buffers
on the fly. If an event is happening and has reserved data on one of
the buffers, and the latency tracer swaps the global buffer with the
max buffer, the result is that the event may commit the data to the
wrong buffer.
This patch changes the API to the trace recording to be recieve the
buffer that was used to reserve a commit. Then this buffer can be passed
in to the commit.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Reseting the trace buffer without first disabling the buffer and
waiting for any writers to complete, can corrupt the ring buffer.
This patch makes the external version of tracing_reset safe from
corruption by disabling the ring buffer and calling synchronize_sched.
This version can no longer be called from interrupt context. But all those
callers have been removed.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Currently the latency tracers reset the ring buffer. Unfortunately
if a commit is in process (due to a trace event), this can corrupt
the ring buffer. When this happens, the ring buffer will detect
the corruption and then permanently disable the ring buffer.
The bug does not crash the system, but it does prevent further tracing
after the bug is hit.
Instead of reseting the trace buffers, the timestamp of the start of
the trace is used instead. The buffers will still contain the previous
data, but the output will not count any data that is before the
timestamp of the trace.
Note, this only affects the static trace output (trace) and not the
runtime trace output (trace_pipe). The runtime trace output does not
make sense for the latency tracers anyway.
Reported-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The function tracing_reset is deprecated for outside use of trace.c.
The new function to reset the the buffers is tracing_reset_online_cpus.
The reason for this is that resetting the buffers while the event
trace points are active can corrupt the buffers, because they may
be writing at the time of reset. The tracing_reset_online_cpus disables
writes and waits for current writers to finish.
This patch replaces all users of tracing_reset except for the latency
tracers. Those changes require more work and will be removed in the
following patches.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Resetting the ring buffers while traces are happening can corrupt
the ring buffer and disable it (no kernel crash to worry about).
The safest thing to do is disable the ring buffers, call synchronize_sched()
to wait for all current writers to finish and then reset the buffer.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
When reading the tracer from the trace file, updating the max latency
may corrupt the output. This patch disables the tracing of the max
latency while reading the trace file.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
During development of the tracer, we would copy information from
the live tracer to the max tracer with one memcpy. Since then we
added a generic ring buffer and we handle the copies differently now.
Unfortunately, we never copied the critical section information, and
we lost the output:
# => started at: kmem_cache_alloc
# => ended at: kmem_cache_alloc
This patch adds back the critical start and end copying as well as
removes the unused "trace_idx" and "overrun" fields of the
trace_array_cpu structure.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The tracing_max_latency file should only be present when one of the
latency tracers ({preempt|irqs}off, wakeup*) are enabled.
This patch also removes tracing_thresh when latency tracers are not
enabled, as well as compiles out code that is only used for latency
tracers.
Reported-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
There are many clock sources for the tracing system but we can only
enable/disable one at a time with the trace/options file.
We can move the setting of clock-source out of options and add a separate
file for it:
# cat trace_clock
[local] global
# echo global > trace_clock
# cat trace_clock
local [global]
Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
LKML-Reference: <4A939D08.6050604@cn.fujitsu.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
"echo noglobal-clock > trace_options" can be used to change trace
clock but "echo 0 > options/global-clock" can't. The flag toggling
will be silently accepted without actually changing the clock callback.
We can fix it by using set_tracer_flags() in
trace_options_core_write().
Changelog:
v1->v2: Simplified switch() after Li Zefan <lizf@cn.fujitsu.com>'s
suggestion
Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
Cc: Steven Rostedt <srostedt@redhat.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
set_tracer_flags() have a local variable named trace_flags which has
the same name than a global one in the same scope.
This leads to confusion, using tracer_flags should be better by its
meaning.
Changelog:
v1->v2: Simplified another patch in this patchset, no change in this
patch.
Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
This patch implements the kernel side support for ftrace event
record sampling.
A new counter sampling attribute is added:
PERF_SAMPLE_TP_RECORD
which requests ftrace events record sampling. In this case
if a PERF_TYPE_TRACEPOINT counter is active and a tracepoint
fires, we emit the tracepoint binary record to the
perfcounter event buffer, as a sample.
Result, after setting PERF_SAMPLE_TP_RECORD attribute from perf
record:
perf record -f -F 1 -a -e workqueue:workqueue_execution
perf report -D
0x21e18 [0x48]: event: 9
.
. ... raw event: size 72 bytes
. 0000: 09 00 00 00 01 00 48 00 d0 c7 00 81 ff ff ff ff ......H........
. 0010: 0a 00 00 00 0a 00 00 00 21 00 00 00 00 00 00 00 ........!......
. 0020: 2b 00 01 02 0a 00 00 00 0a 00 00 00 65 76 65 6e +...........eve
. 0030: 74 73 2f 31 00 00 00 00 00 00 00 00 0a 00 00 00 ts/1...........
. 0040: e0 b1 31 81 ff ff ff ff .......
.
0x21e18 [0x48]: PERF_EVENT_SAMPLE (IP, 1): 10: 0xffffffff8100c7d0 period: 33
The raw ftrace binary record starts at offset 0020.
Translation:
struct trace_entry {
type = 0x2b = 43;
flags = 1;
preempt_count = 2;
pid = 0xa = 10;
tgid = 0xa = 10;
}
thread_comm = "events/1"
thread_pid = 0xa = 10;
func = 0xffffffff8131b1e0 = flush_to_ldisc()
What will come next?
- Userspace support ('perf trace'), 'flight data recorder' mode
for perf trace, etc.
- The unconditional copy from the profiling callback brings
some costs however if someone wants no such sampling to
occur, and needs to be fixed in the future. For that we need
to have an instant access to the perf counter attribute.
This is a matter of a flag to add in the struct ftrace_event.
- Take care of the events recursivity! Don't ever try to record
a lock event for example, it seems some locking is used in
the profiling fast path and lead to a tracing recursivity.
That will be fixed using raw spinlock or recursivity
protection.
- [...]
- Profit! :-)
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Gabriel Munteanu <eduard.munteanu@linux360.ro>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
The function graph events helpers which insert the function entry and
return events into the ring buffer currently reside in trace.c
But this file is quite overloaded and the right place for these helpers
is in the function graph tracer file.
Then move them to trace_functions_graph.c
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
The sched events helpers which insert the sched switch and wakeup
events into the ring buffer currently reside in trace.c
But this file is quite overloaded and the right place for these helpers
is in the sched switch tracer file.
Then move them to trace_functions.c
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Make the stacktrace event insertion helpers globals.
This has two effects:
- Prepare for moving the sched events insertion helpers to
the sched switch tracer file.
- Move some ifdef outside function definitions
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Ingo Molnar