| Age | Commit message (Collapse) | Author |
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Impact: robust feature to disable ftrace on start or stop tracing on error
Currently only the initial conversion to nops will disable ftrace
on an anomaly. But if an anomaly happens on start or stopping of the
tracer, it will silently fail.
This patch adds a check there too, to disable ftrace and warn if the
conversion fails.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Impact: let module functions be recorded when dyn ftrace not enabled
When dynamic ftrace had a daemon and a hash to record the locations
of mcount callers at run time, the recording needed to stop when
ftrace was disabled. But now that the recording is done at compile time
and the ftrace_record_ip is only called at boot up and when a module
is loaded, we no longer need to check if ftrace_enabled is set.
In fact, this breaks module load if it is not set because we skip
over module functions.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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into tracing/core
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Since this scripts output is usually redirected, put error messages
on standard error and exit with error code if no data is found.
Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Acked-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Because it has goto out before ftrace_list == &ftrace_list_end,
that's to say, we never meet this condition.
Signed-off-by: walimis <walimisdev@gmail.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Pekka reported a crash when resizing the mmiotrace tracer (if only
mmiotrace is enabled).
This happens because in that case we do not allocate the max buffer,
but we try to use it.
Make ring_buffer_resize() idempotent against NULL buffers.
Reported-by: Pekka Paalanen <pq@iki.fi>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Impact: better handling of CPU buffer start annotation
Because of the confusion with the per CPU buffers wrapping where
one CPU might be more active at the end of the trace than the other
CPUs causing that one CPU to have a shorter history. Kernel
developers were confused by the "missing" data of that one CPU
at the beginning of the trace output. An annotation was added to
the trace output to show that the buffer had started:
# tracer: function
#
# TASK-PID CPU# TIMESTAMP FUNCTION
# | | | | |
##### CPU 3 buffer started ####
<idle>-0 [003] 158.192959: smp_apic_timer_interrupt
[...]
<idle>-0 [003] 161.556520: default_idle
##### CPU 1 buffer started ####
<idle>-0 [001] 161.592494: hrtimer_force_reprogram
[etc]
But this annotation gets a bit messy when tracers do not fill the
buffers. This patch does a couple of things:
One) it adds a flag to trace_options to disable these annotations
Two) it does not annotate if the tracer did not overflow its buffer.
This makes the output much cleaner.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Impact: rename file /debug/tracing/iter_ctrl to /debug/tracing/trace_options
The original ftrace had a file called "iter_ctrl" that would control
the way the output was iterated. But this file grew into a catch all
for different trace options. This patch renames the file from iter_ctrl
to trace_options to reflect this change.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Impact: change the units of buffer_size_kb to kilobytes
This patch changes the units of the buffer_size_kb file to kilobytes.
Reading and writing to the file uses kilobytes as units. To help
users to know what units are used, the output of the file now
looks like:
# cat /debug/tracing/buffer_size_kb
1408
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Impact: rename of debugfs file trace_entries to buffer_size_kb
The original ftrace had fixed size entries, and the number of entries
was shown and modified via the file called trace_entries. By converting
to the unified trace buffer, we now allow for variable size entries
which makes the meaning of trace_entries pointless.
Since trace_size might be confused to the size of the trace, this patch
names it "buffer_size_kb" (thanks to Arjan van de Ven for this idea).
[ mingo@elte.hu: changed from buffer_size to buffer_size_kb ]
( Note, the units are still bytes - the next patch changes that,
to keep the wide rename patch separate from the unit-change patch. )
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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'tracing/function-return-tracer' and 'tracing/urgent' into tracing/core
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Impact: Optimize a bit the function return tracer
This patch changes the calling convention of prepare_ftrace_return to
pass its arguments by register. This will optimize it a bit and
prepare it to support dynamic tracing.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Impact: remove spinlocks and irq disabling in function return tracer.
I've tried to figure out all of the race condition that could happen
when the tracer pushes or pops a return address trace to/from the
current thread_info.
Theory:
_ One thread can only execute on one cpu at a time. So this code
doesn't need to be SMP-safe. Just drop the spinlock.
_ The only race could happen between the current thread and an
interrupt. If an interrupt is raised, it will increase the index of
the return stack storage and then execute until the end of the
tracing to finally free the index it used. We don't need to disable
irqs.
This is theorical. In practice, I've tested it with a two-core SMP and
had no problem at all. Perhaps -tip testing could confirm it.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Impact: File name change of trace_unlikely.c
The "unlikely" name for the tracer is quite ugly. We renamed all the
parts of it to "branch" and now it is time to rename the file too.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Impact: added new branch tracer
Currently the tracing of branch profiling (unlikelys and likelys hit)
is only activated by the iter_ctrl. This patch adds a tracer called
"branch" that will just trace the branch profiling. The advantage
of adding this tracer is that it can be added to the ftrace selftests
on startup.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Impact: rename of iter_ctrl unlikely to branch
The unlikely name is ugly. This patch converts the iter_ctrl command
"unlikely" and "nounlikely" to "branch" and "nobranch" respectively.
It also renames a lot of internal functions to use "branch" instead
of "unlikely".
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Impact: name change of unlikely tracer and profiler
Ingo Molnar suggested changing the config from UNLIKELY_PROFILE
to BRANCH_PROFILING. I never did like the "unlikely" name so I
went one step farther, and renamed all the unlikely configurations
to a "BRANCH" variant.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Impact: cleanup
Fix the following warning from the perl syntax checking tool perlcritic.
This tool is a lint like tool that checks for perl best practices.
Loop iterator is not lexical at line 113, column 1.
See page 108 of PBP. (Severity: 5)
Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Steve suggested the to change the output from this:
> bash-3471 [003] 357.014755: [ MISS ] sched_info_dequeued:sched_stats.h:177
> bash-3471 [003] 357.014756: [ .... ] update_curr:sched_fair.c:489
> bash-3471 [003] 357.014758: [ .... ] calc_delta_fair:sched_fair.c:411
to this:
> bash-3471 [003] 357.014755: [ MISS ] sched_info_dequeued:sched_stats.h:177
> bash-3471 [003] 357.014756: [ ok ] update_curr:sched_fair.c:489
> bash-3471 [003] 357.014758: [ ok ] calc_delta_fair:sched_fair.c:411
as it makes it clearer to the user what it means exactly.
Acked-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Impact: fix bootup crash
the branch tracer missed arch/x86/vdso/vclock_gettime.c from
disabling tracing, which caused such bootup crashes:
[ 201.840097] init[1]: segfault at 7fffed3fe7c0 ip 00007fffed3fea2e sp 000077
also clean up the ugly ifdefs in arch/x86/kernel/vsyscall_64.c by
creating DISABLE_UNLIKELY_PROFILE facility for code to turn off
instrumentation on a per file basis.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Impact: modify the tracer output, to make it a bit easier to read
Change the output from:
> bash-3471 [003] 357.014755: [INCORRECT] sched_info_dequeued:sched_stats.h:177
> bash-3471 [003] 357.014756: [correct] update_curr:sched_fair.c:489
> bash-3471 [003] 357.014758: [correct] calc_delta_fair:sched_fair.c:411
to:
> bash-3471 [003] 357.014755: [ MISS ] sched_info_dequeued:sched_stats.h:177
> bash-3471 [003] 357.014756: [ .... ] update_curr:sched_fair.c:489
> bash-3471 [003] 357.014758: [ .... ] calc_delta_fair:sched_fair.c:411
it's good to have fields aligned vertically, and the only important
information is a prediction miss, so display only that information.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Impact: new likely/unlikely branch tracer
This patch adds a way to record the instances of the likely() and unlikely()
branch condition annotations.
When "unlikely" is set in /debugfs/tracing/iter_ctrl the unlikely conditions
will be added to any of the ftrace tracers. The change takes effect when
a new tracer is passed into the current_tracer file.
For example:
bash-3471 [003] 357.014755: [INCORRECT] sched_info_dequeued:sched_stats.h:177
bash-3471 [003] 357.014756: [correct] update_curr:sched_fair.c:489
bash-3471 [003] 357.014758: [correct] calc_delta_fair:sched_fair.c:411
bash-3471 [003] 357.014759: [correct] account_group_exec_runtime:sched_stats.h:356
bash-3471 [003] 357.014761: [correct] update_curr:sched_fair.c:489
bash-3471 [003] 357.014763: [INCORRECT] calc_delta_fair:sched_fair.c:411
bash-3471 [003] 357.014765: [correct] calc_delta_mine:sched.c:1279
Which shows the normal tracer heading, as well as whether the condition was
correct "[correct]" or was mistaken "[INCORRECT]", followed by the function,
file name and line number.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Impact: new unlikely/likely profiler
Andrew Morton recently suggested having an in-kernel way to profile
likely and unlikely macros. This patch achieves that goal.
When configured, every(*) likely and unlikely macro gets a counter attached
to it. When the condition is hit, the hit and misses of that condition
are recorded. These numbers can later be retrieved by:
/debugfs/tracing/profile_likely - All likely markers
/debugfs/tracing/profile_unlikely - All unlikely markers.
# cat /debug/tracing/profile_unlikely | head
correct incorrect % Function File Line
------- --------- - -------- ---- ----
2167 0 0 do_arch_prctl process_64.c 832
0 0 0 do_arch_prctl process_64.c 804
2670 0 0 IS_ERR err.h 34
71230 5693 7 __switch_to process_64.c 673
76919 0 0 __switch_to process_64.c 639
43184 33743 43 __switch_to process_64.c 624
12740 64181 83 __switch_to process_64.c 594
12740 64174 83 __switch_to process_64.c 590
# cat /debug/tracing/profile_unlikely | \
awk '{ if ($3 > 25) print $0; }' |head -20
44963 35259 43 __switch_to process_64.c 624
12762 67454 84 __switch_to process_64.c 594
12762 67447 84 __switch_to process_64.c 590
1478 595 28 syscall_get_error syscall.h 51
0 2821 100 syscall_trace_leave ptrace.c 1567
0 1 100 native_smp_prepare_cpus smpboot.c 1237
86338 265881 75 calc_delta_fair sched_fair.c 408
210410 108540 34 calc_delta_mine sched.c 1267
0 54550 100 sched_info_queued sched_stats.h 222
51899 66435 56 pick_next_task_fair sched_fair.c 1422
6 10 62 yield_task_fair sched_fair.c 982
7325 2692 26 rt_policy sched.c 144
0 1270 100 pre_schedule_rt sched_rt.c 1261
1268 48073 97 pick_next_task_rt sched_rt.c 884
0 45181 100 sched_info_dequeued sched_stats.h 177
0 15 100 sched_move_task sched.c 8700
0 15 100 sched_move_task sched.c 8690
53167 33217 38 schedule sched.c 4457
0 80208 100 sched_info_switch sched_stats.h 270
30585 49631 61 context_switch sched.c 2619
# cat /debug/tracing/profile_likely | awk '{ if ($3 > 25) print $0; }'
39900 36577 47 pick_next_task sched.c 4397
20824 15233 42 switch_mm mmu_context_64.h 18
0 7 100 __cancel_work_timer workqueue.c 560
617 66484 99 clocksource_adjust timekeeping.c 456
0 346340 100 audit_syscall_exit auditsc.c 1570
38 347350 99 audit_get_context auditsc.c 732
0 345244 100 audit_syscall_entry auditsc.c 1541
38 1017 96 audit_free auditsc.c 1446
0 1090 100 audit_alloc auditsc.c 862
2618 1090 29 audit_alloc auditsc.c 858
0 6 100 move_masked_irq migration.c 9
1 198 99 probe_sched_wakeup trace_sched_switch.c 58
2 2 50 probe_wakeup trace_sched_wakeup.c 227
0 2 100 probe_wakeup_sched_switch trace_sched_wakeup.c 144
4514 2090 31 __grab_cache_page filemap.c 2149
12882 228786 94 mapping_unevictable pagemap.h 50
4 11 73 __flush_cpu_slab slub.c 1466
627757 330451 34 slab_free slub.c 1731
2959 61245 95 dentry_lru_del_init dcache.c 153
946 1217 56 load_elf_binary binfmt_elf.c 904
102 82 44 disk_put_part genhd.h 206
1 1 50 dst_gc_task dst.c 82
0 19 100 tcp_mss_split_point tcp_output.c 1126
As you can see by the above, there's a bit of work to do in rethinking
the use of some unlikelys and likelys. Note: the unlikely case had 71 hits
that were more than 25%.
Note: After submitting my first version of this patch, Andrew Morton
showed me a version written by Daniel Walker, where I picked up
the following ideas from:
1) Using __builtin_constant_p to avoid profiling fixed values.
2) Using __FILE__ instead of instruction pointers.
3) Using the preprocessor to stop all profiling of likely
annotations from vsyscall_64.c.
Thanks to Andrew Morton, Arjan van de Ven, Theodore Tso and Ingo Molnar
for their feed back on this patch.
(*) Not ever unlikely is recorded, those that are used by vsyscalls
(a few of them) had to have profiling disabled.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Theodore Tso <tytso@mit.edu>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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'tracing/ring-buffer' into tracing/core
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Impact: deadlock fix in ring_buffer_read_start
The ring_buffer_iter_reset was called from ring_buffer_read_start
where both grabbed the reader_lock.
This patch separates out the internals of ring_buffer_iter_reset
to its own function so that both APIs may grab the reader_lock.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Impact: disable preemption when calling sched_clock()
The ring_buffer_time_stamp still uses sched_clock as its counter.
But it is a bug to call it with preemption enabled. This requirement
should not be pushed to the ring_buffer_time_stamp callers, so
the ring_buffer_time_stamp needs to disable preemption when calling
sched_clock.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Impact: Split the boot tracer entries in two parts: call and return
Now that we are using the sched tracer from the boot tracer, we want
to use the same timestamp than the ring-buffer to have consistent time
captures between sched events and initcall events.
So we get rid of the old time capture by the boot tracer and split the
initcall events in two parts: call and return. This way we have the
ring buffer timestamp of both.
An example trace:
[ 27.904149584] calling net_ns_init+0x0/0x1c0 @ 1
[ 27.904429624] initcall net_ns_init+0x0/0x1c0 returned 0 after 0 msecs
[ 27.904575926] calling reboot_init+0x0/0x20 @ 1
[ 27.904655399] initcall reboot_init+0x0/0x20 returned 0 after 0 msecs
[ 27.904800228] calling sysctl_init+0x0/0x30 @ 1
[ 27.905142914] initcall sysctl_init+0x0/0x30 returned 0 after 0 msecs
[ 27.905287211] calling ksysfs_init+0x0/0xb0 @ 1
##### CPU 0 buffer started ####
init-1 [000] 27.905395: 1:120:R + [001] 11:115:S
##### CPU 1 buffer started ####
<idle>-0 [001] 27.905425: 0:140:R ==> [001] 11:115:R
init-1 [000] 27.905426: 1:120:D ==> [000] 0:140:R
<idle>-0 [000] 27.905431: 0:140:R + [000] 4:115:S
<idle>-0 [000] 27.905451: 0:140:R ==> [000] 4:115:R
ksoftirqd/0-4 [000] 27.905456: 4:115:S ==> [000] 0:140:R
udevd-11 [001] 27.905458: 11:115:R + [001] 14:115:R
<idle>-0 [000] 27.905459: 0:140:R + [000] 4:115:S
<idle>-0 [000] 27.905462: 0:140:R ==> [000] 4:115:R
udevd-11 [001] 27.905462: 11:115:R ==> [001] 14:115:R
ksoftirqd/0-4 [000] 27.905467: 4:115:S ==> [000] 0:140:R
<idle>-0 [000] 27.905470: 0:140:R + [000] 4:115:S
<idle>-0 [000] 27.905473: 0:140:R ==> [000] 4:115:R
ksoftirqd/0-4 [000] 27.905476: 4:115:S ==> [000] 0:140:R
<idle>-0 [000] 27.905479: 0:140:R + [000] 4:115:S
<idle>-0 [000] 27.905482: 0:140:R ==> [000] 4:115:R
ksoftirqd/0-4 [000] 27.905486: 4:115:S ==> [000] 0:140:R
udevd-14 [001] 27.905499: 14:120:X ==> [001] 11:115:R
udevd-11 [001] 27.905506: 11:115:R + [000] 1:120:D
<idle>-0 [000] 27.905515: 0:140:R ==> [000] 1:120:R
udevd-11 [001] 27.905517: 11:115:S ==> [001] 0:140:R
[ 27.905557107] initcall ksysfs_init+0x0/0xb0 returned 0 after 3906 msecs
[ 27.905705736] calling init_jiffies_clocksource+0x0/0x10 @ 1
[ 27.905779239] initcall init_jiffies_clocksource+0x0/0x10 returned 0 after 0 msecs
[ 27.906769814] calling pm_init+0x0/0x30 @ 1
[ 27.906853627] initcall pm_init+0x0/0x30 returned 0 after 0 msecs
[ 27.906997803] calling pm_disk_init+0x0/0x20 @ 1
[ 27.907076946] initcall pm_disk_init+0x0/0x20 returned 0 after 0 msecs
[ 27.907222556] calling swsusp_header_init+0x0/0x30 @ 1
[ 27.907294325] initcall swsusp_header_init+0x0/0x30 returned 0 after 0 msecs
[ 27.907439620] calling stop_machine_init+0x0/0x50 @ 1
init-1 [000] 27.907485: 1:120:R + [000] 2:115:S
init-1 [000] 27.907490: 1:120:D ==> [000] 2:115:R
kthreadd-2 [000] 27.907507: 2:115:R + [001] 15:115:R
<idle>-0 [001] 27.907517: 0:140:R ==> [001] 15:115:R
kthreadd-2 [000] 27.907517: 2:115:D ==> [000] 0:140:R
<idle>-0 [000] 27.907521: 0:140:R + [000] 4:115:S
<idle>-0 [000] 27.907524: 0:140:R ==> [000] 4:115:R
udevd-15 [001] 27.907527: 15:115:D + [000] 2:115:D
ksoftirqd/0-4 [000] 27.907537: 4:115:S ==> [000] 2:115:R
udevd-15 [001] 27.907537: 15:115:D ==> [001] 0:140:R
kthreadd-2 [000] 27.907546: 2:115:R + [000] 1:120:D
kthreadd-2 [000] 27.907550: 2:115:S ==> [000] 1:120:R
init-1 [000] 27.907584: 1:120:R + [000] 15: 0:D
init-1 [000] 27.907589: 1:120:R + [000] 2:115:S
init-1 [000] 27.907593: 1:120:D ==> [000] 15: 0:R
udevd-15 [000] 27.907601: 15: 0:S ==> [000] 2:115:R
##### CPU 0 buffer started ####
kthreadd-2 [000] 27.907616: 2:115:R + [001] 16:115:R
##### CPU 1 buffer started ####
<idle>-0 [001] 27.907620: 0:140:R ==> [001] 16:115:R
kthreadd-2 [000] 27.907621: 2:115:D ==> [000] 0:140:R
udevd-16 [001] 27.907625: 16:115:D + [000] 2:115:D
<idle>-0 [000] 27.907628: 0:140:R + [000] 4:115:S
udevd-16 [001] 27.907629: 16:115:D ==> [001] 0:140:R
<idle>-0 [000] 27.907631: 0:140:R ==> [000] 4:115:R
ksoftirqd/0-4 [000] 27.907636: 4:115:S ==> [000] 2:115:R
kthreadd-2 [000] 27.907644: 2:115:R + [000] 1:120:D
kthreadd-2 [000] 27.907647: 2:115:S ==> [000] 1:120:R
init-1 [000] 27.907657: 1:120:R + [001] 16: 0:D
<idle>-0 [001] 27.907666: 0:140:R ==> [001] 16: 0:R
[ 27.907703862] initcall stop_machine_init+0x0/0x50 returned 0 after 0 msecs
[ 27.907850704] calling filelock_init+0x0/0x30 @ 1
[ 27.907926573] initcall filelock_init+0x0/0x30 returned 0 after 0 msecs
[ 27.908071327] calling init_script_binfmt+0x0/0x10 @ 1
[ 27.908165195] initcall init_script_binfmt+0x0/0x10 returned 0 after 0 msecs
[ 27.908309461] calling init_elf_binfmt+0x0/0x10 @ 1
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Impact: Cleanups on the boot tracer and ftrace
This patch bring some cleanups about the boot tracer headers. The
functions and structures of this tracer have nothing related to ftrace
and should have so their own header file.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Conflicts:
kernel/trace/ring_buffer.c
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Impact: Restructure WARN_ONs in ring_buffer.c
The current WARN_ON macros in ring_buffer.c are quite ugly.
This patch cleans them up and uses a single RB_WARN_ON that returns
the value of the condition. This allows the caller to abort the
function if the condition is true.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-2.6-trace into tracing/urgent
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Impact: enable/disable ring buffer recording API added
Several kernel developers have requested that there be a way to stop
recording into the ring buffers with a simple switch that can also
be enabled from userspace. This patch addes a new kernel API to the
ring buffers called:
tracing_on()
tracing_off()
When tracing_off() is called, all ring buffers will not be able to record
into their buffers.
tracing_on() will enable the ring buffers again.
These two act like an on/off switch. That is, there is no counting of the
number of times tracing_off or tracing_on has been called.
A new file is added to the debugfs/tracing directory called
tracing_on
This allows for userspace applications to also flip the switch.
echo 0 > debugfs/tracing/tracing_on
disables the tracing.
echo 1 > /debugfs/tracing/tracing_on
enables it.
Note, this does not disable or enable any tracers. It only sets or clears
a flag that needs to be set in order for the ring buffers to write to
their buffers. It is a global flag, and affects all ring buffers.
The buffers start out with tracing_on enabled.
There are now three flags that control recording into the buffers:
tracing_on: which affects all ring buffer tracers.
buffer->record_disabled: which affects an allocated buffer, which may be set
if an anomaly is detected, and tracing is disabled.
cpu_buffer->record_disabled: which is set by tracing_stop() or if an
anomaly is detected. tracing_start can not reenable this if
an anomaly occurred.
The userspace debugfs/tracing/tracing_enabled is implemented with
tracing_stop() but the user space code can not enable it if the kernel
called tracing_stop().
Userspace can enable the tracing_on even if the kernel disabled it.
It is just a switch used to stop tracing if a condition was hit.
tracing_on is not for protecting critical areas in the kernel nor is
it for stopping tracing if an anomaly occurred. This is because userspace
can reenable it at any time.
Side effect: With this patch, I discovered a dead variable in ftrace.c
called tracing_on. This patch removes it.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'timers-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
timers: handle HRTIMER_CB_IRQSAFE_UNLOCKED correctly from softirq context
nohz: disable tick_nohz_kick_tick() for now
irq: call __irq_enter() before calling the tick_idle_check
x86: HPET: enter hpet_interrupt_handler with interrupts disabled
x86: HPET: read from HPET_Tn_CMP() not HPET_T0_CMP
x86: HPET: convert WARN_ON to WARN_ON_ONCE
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
sched: release buddies on yield
fix for account_group_exec_runtime(), make sure ->signal can't be freed under rq->lock
sched: clean up debug info
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'tracing-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
ring-buffer: prevent infinite looping on time stamping
ftrace: disable tracing on resize
ftrace: fix breakage in bin_fmt results
ftrace: ftrace.txt version update
ftrace: update txt document
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Impact: serialize reader accesses to individual CPU ring buffers
The code in the ring buffer expects only one reader at a time, but currently
it puts that requirement on the caller. This is not strong enough, and this
patch adds a "reader_lock" that serializes the access to the reader API
of the ring buffer.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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* 'for-linus' of git://oss.sgi.com/xfs/xfs:
[XFS] XFS: Check for valid transaction headers in recovery
[XFS] handle memory allocation failures during log initialisation
[XFS] Account for allocated blocks when expanding directories
[XFS] Wait for all I/O on truncate to zero file size
[XFS] Fix use-after-free with log and quotas
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git://git.kernel.org/pub/scm/linux/kernel/git/mfasheh/ocfs2
* 'upstream-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mfasheh/ocfs2: (21 commits)
ocfs2: Check search result in ocfs2_xattr_block_get()
ocfs2: fix printk related build warnings in xattr.c
ocfs2: truncate outstanding block after direct io failure
ocfs2/xattr: Proper hash collision handle in bucket division
ocfs2: return 0 in page_mkwrite to let VFS retry.
ocfs2: Set journal descriptor to NULL after journal shutdown
ocfs2: Fix check of return value of ocfs2_start_trans() in xattr.c.
ocfs2: Let inode be really deleted when ocfs2_mknod_locked() fails
ocfs2: Fix checking of return value of new_inode()
ocfs2: Fix check of return value of ocfs2_start_trans()
ocfs2: Fix some typos in xattr annotations.
ocfs2: Remove unused ocfs2_restore_xattr_block().
ocfs2: Don't repeat ocfs2_xattr_block_find()
ocfs2: Specify appropriate journal access for new xattr buckets.
ocfs2: Check errors from ocfs2_xattr_update_xattr_search()
ocfs2: Don't return -EFAULT from a corrupt xattr entry.
ocfs2: Check xattr block signatures properly.
ocfs2: add handler_map array bounds checking
ocfs2: remove duplicate definition in xattr
ocfs2: fix function declaration and definition in xattr
...
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Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-2.6
* 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-2.6: (35 commits)
V4L/DVB (9516): cx18: Move DVB buffer transfer handling from irq handler to work_queue
V4L/DVB (9557): gspca: Small changes for the sensor HV7131B in zc3xx.
V4L/DVB (9556): gspca: Bad init sequence for sensor HV7131B in zc3xx.
V4L/DVB (9549): gspca: Fix a typo in one of gspca chips name.
V4L/DVB (9515): cx18: Use correct Mailbox IRQ Ack values and misc IRQ handling cleanup
V4L/DVB (9493): kconfig patch
V4L/DVB (9527): af9015: fix compile warnings
V4L/DVB (9524): af9013: fix bug in status reading
V4L/DVB (9511): cx18: Mark CX18_CPU_DE_RELEASE_MDL as a slow API call
V4L/DVB (9510): cx18: Fix write retries for registers that always change - part 2.
V4L/DVB (9506): ivtv/cx18: fix test whether modules should be loaded or not.
V4L/DVB (9499): cx88-mpeg: final fix for analogue only compilation + de-alloc fix
V4L/DVB (9496): cx88-blackbird: bugfix: cx88-blackbird-mpeg-users
V4L/DVB (9495): cx88-blackbird: bugfix: cx88-blackbird-poll-fix
V4L/DVB (9494): anysee: initialize anysee_usb_mutex statically
V4L/DVB (9492): unplug oops from dvb_frontend_init...
V4L/DVB (9486): ivtv/ivtvfb: no longer experimental
V4L/DVB (9485): ivtv: remove incorrect V4L1 & tvaudio dependency
V4L/DVB (9482): Documentation, especially regarding audio and informational links
V4L/DVB (9475): cx18: Disable write retries for registers that always change - part 1.
...
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git://git.kernel.org/pub/scm/linux/kernel/git/paulus/powerpc
* 'merge' of git://git.kernel.org/pub/scm/linux/kernel/git/paulus/powerpc:
powerpc: Update desktop/server defconfigs
powerpc: Fix msr check in compat_sys_swapcontext
powerpc: Repair device bindings documentation
powerpc: Updated Freescale PPC related defconfigs
powerpc: Update QE/CPM2 usb_ctlr structures for USB support
powerpc/86xx: Correct SOC bus-frequency in GE Fanuc SBC610 DTS
powerpc: Fix Book-E watchdog timer interval setting
powerpc/fsl-booke: Fix synchronization bug w/local tlb invalidates
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git://git.kernel.org/pub/scm/linux/kernel/git/airlied/drm-2.6
* 'drm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/airlied/drm-2.6:
drm/i915: Move legacy breadcrumb out of the reserved status page area
drm/i915: Filter pci devices based on PCI_CLASS_DISPLAY_VGA
drm/radeon: map registers at load time
drm: Remove infrastructure for supporting i915's vblank swapping.
i915: Remove racy delayed vblank swap ioctl.
i915: Don't whine when pci_enable_msi() fails.
i915: Don't attempt to short-circuit object_wait_rendering by checking domains.
i915: Clean up sarea pointers on leavevt
i915: Save/restore MCHBAR_RENDER_STANDBY on GM965/GM45
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git://git.kernel.org/pub/scm/linux/kernel/git/jgarzik/libata-dev
* 'upstream-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jgarzik/libata-dev:
libata: fix last_reset timestamp handling
libata: Avoid overflow in ata_tf_read_block() when tf->hba_lbal > 127
[libata] pata_pcmcia: another memory card support
[libata] pata_sch: notice attached slave devices
[libata] pata_cs553*.c: cleanup kernel-doc
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* git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc-2.6:
sparc64: Update defconfig.
Revert "sparc: correct section of current_pc()"
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* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6:
dsa: fix master interface allmulti/promisc handling
dsa: fix skb->pkt_type when mac address of slave interface differs
net: fix setting of skb->tail in skb_recycle_check()
net: fix /proc/net/snmp as memory corruptor
mac80211: fix a buffer overrun in station debug code
netfilter: payload_len is be16, add size of struct rather than size of pointer
ipv6: fix ip6_mr_init error path
[4/4] dca: fixup initialization dependency
[3/4] I/OAT: fix async_tx.callback checking
[2/4] I/OAT: fix dma_pin_iovec_pages() error handling
[1/4] I/OAT: fix channel resources free for not allocated channels
ssb: Fix DMA-API compilation for non-PCI systems
SSB: hide empty sub menu
vlan: Fix typos in proc output string
[netdrvr] usb/hso: Cleanup rfkill error handling
sfc: Correct address of gPXE boot configuration in EEPROM
el3_common_init() should be __devinit, not __init
hso: rfkill type should be WWAN
mlx4_en: Start port error flow bug fix
af_key: mark policy as dead before destroying
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fix:
arch/x86/kernel/ftrace.c: In function 'ftrace_return_to_handler':
arch/x86/kernel/ftrace.c:112: error: implicit declaration of function 'cpu_clock'
cpu_clock() is implicitly included via a number of ways, but its real
location is sched.h. (Build failure is triggerable if enough other
kernel components are turned off.)
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Clear buddies on yield, so that the buddy rules don't schedule them
despite them being placed right-most.
This fixed a performance regression with yield-happy binary JVMs.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Tested-by: Lin Ming <ming.m.lin@intel.com>
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fix:
arch/x86/kernel/ftrace.c: Assembler messages:
arch/x86/kernel/ftrace.c:140: Error: missing ')'
arch/x86/kernel/ftrace.c:140: Error: junk `(%ebp))' after expression
arch/x86/kernel/ftrace.c:141: Error: missing ')'
arch/x86/kernel/ftrace.c:141: Error: junk `(%ebp))' after expression
the [parent_replaced] is used in an =rm fashion, so that constraint
is correct in isolation - but [parent_old] aliases register %0 and uses
it in an addressing mode that is only valid with registers - so change
the constraint from =rm to =r.
This fixes the build failure.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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