The problem is that when SAMPLE_PERIOD is not set, the kernel generates
a number of samples in proportion to an event's period. Number of these
samples may be too big and the kernel throttles all samples above a
defined limit.
E.g.: I want to trace when a process sleeps. I created a process which
sleeps for 1ms and for 4ms. perf got 100 events in both cases.
swapper 0 [000] 1141.371830: sched_stat_sleep: comm=foo pid=1801 delay=1386750 [ns]
swapper 0 [000] 1141.369444: sched_stat_sleep: comm=foo pid=1801 delay=4499585 [ns]
In the first case a kernel want to send 4499585 events and in the second
case it wants to send 1386750 events. perf-reports shows that process
sleeps in both places equal time.
Instead of this we can get only one sample with an attribute period. As
result we have less data transferring between kernel and user-space and
we avoid throttling of samples.
The patch "events: Don't divide events if it has field period" added a
kernel part of this functionality.
Acked-by: Arun Sharma <asharma@fb.com>
Cc: Arun Sharma <asharma@fb.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: devel@openvz.org
Link: http://lkml.kernel.org/r/1324391565-1369947-1-git-send-email-avagin@openvz.org
Signed-off-by: Andrew Vagin <avagin@openvz.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
The option is documented in man perf-script but was not yet implemented:
-a
Force system-wide collection. Scripts run without a
<command> normally use -a by default, while scripts run
with a <command> normally don't - this option allows the
latter to be run in system-wide mode.
As with perf record you now can profile in system-wide mode for the
runtime of a given command, e.g.:
# perf script -a syscall-counts sleep 2
Cc: Ingo Molnar <mingo@elte.hu>
Link: http://lkml.kernel.org/r/1322229925-10075-1-git-send-email-robert.richter@amd.com
Signed-off-by: Robert Richter <robert.richter@amd.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
A update is made to the sched:sched_switch event that adds some
logic to the first parameter of the __print_flags() that shows the
state of tasks. This change cause perf to fail parsing the flags.
A simple fix is needed to have the parser be able to process ops
within the argument.
Cc: stable@vger.kernel.org
Reported-by: Andrew Vagin <avagin@openvz.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
perf stat is failing on PowerPC:
Error: open_counter returned with 95 (Operation not supported). /bin/dmesg may provide additional information.
Fatal: Not all events could be opened.
commit 370faf1dd0 (perf stat: Fail softly on unsupported events)
added a check for failure returning ENOENT, but the POWER backend
returns EOPNOTSUPP. It looks like alpha, blackfin and mips do the
same.
With the patch applied, things work as expected:
Performance counter stats for '/bin/true':
0.362176 task-clock # 0.623 CPUs utilized
0 context-switches # 0.000 M/sec
0 CPU-migrations # 0.000 M/sec
28 page-faults # 0.077 M/sec
1,677,020 cycles # 4.630 GHz
<not supported> stalled-cycles-frontend
<not supported> stalled-cycles-backend
431,220 instructions # 0.26 insns per cycle
101,889 branches # 281.325 M/sec
4,145 branch-misses # 4.07% of all branches
0.000581361 seconds time elapsed
Cc: <stable@kernel.org> # 3.0+
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20111202093833.5fef7226@kryten
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This new test will validate these new routines extracted from 'perf
record':
- perf_evlist__config_attrs
- perf_evlist__prepare_workload
- perf_evlist__start_workload
In addition to several other perf_evlist methods.
It consists of starting a simple workload, setting up just one event to
monitor ("cycles") requesting that several PERF_SAMPLE_ fields be
present in all events.
It then will check that the expected PERF_RECORD_ events are produced
and will sanity check all its fields.
Some checks performed:
. PERF_SAMPLE_TIME monotonically increases.
. PERF_SAMPLE_CPU is the one requested with sched_setaffinity
. PERF_SAMPLE_TID and PERF_SAMPLE_PID matches the one we forked
in perf_evlist__prepare_workload and that is stored in
evlist->workload.pid
. For the events where these fields are also present in its
pre-sample_id_all fields (e.g. event->mmap.pid), that they are what
is expected too.
. That we get a bunch of mmaps:
PATH/libcSUFFIX
PATH/ldSUFFIX
[vdso]
PATH/sleep
Example:
[root@emilia ~]# taskset -c 3,4 perf test -v1 perf_sample
6: Validate PERF_RECORD_* events & perf_sample fields:
--- start ---
7159480799825 3 PERF_RECORD_SAMPLE
7159480805584 3 PERF_RECORD_SAMPLE
7159480807814 3 PERF_RECORD_SAMPLE
7159480810430 3 PERF_RECORD_SAMPLE
7159480861511 3 PERF_RECORD_MMAP 8086/8086: [0x7fffffffd000(0x2000) @ 0x7fffffffd000]: //anon
7159481052516 3 PERF_RECORD_COMM: sleep:8086
7159481070188 3 PERF_RECORD_MMAP 8086/8086: [0x400000(0x6000) @ 0]: /bin/sleep
7159481077104 3 PERF_RECORD_MMAP 8086/8086: [0x3d06400000(0x221000) @ 0]: /lib64/ld-2.12.so
7159481092912 3 PERF_RECORD_MMAP 8086/8086: [0x7fff1adff000(0x1000) @ 0x7fff1adff000]: [vdso]
7159481196779 3 PERF_RECORD_MMAP 8086/8086: [0x3d06800000(0x37f000) @ 0]: /lib64/libc-2.12.so
7160481558435 3 PERF_RECORD_EXIT(8086:8086):(8086:8086)
---- end ----
Validate PERF_RECORD_* events & perf_sample fields: Ok
[root@emilia ~]#
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-svag18v2z4idas0dyz3umjpq@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
To obtain a list of available tests:
[root@emilia linux]# perf test list
1: vmlinux symtab matches kallsyms
2: detect open syscall event
3: detect open syscall event on all cpus
4: read samples using the mmap interface
5: parse events tests
[root@emilia linux]#
To list just a subset:
[root@emilia linux]# perf test list syscall
2: detect open syscall event
3: detect open syscall event on all cpus
[root@emilia linux]#
To run a subset:
[root@emilia linux]# perf test detect
2: detect open syscall event: Ok
3: detect open syscall event on all cpus: Ok
[root@emilia linux]#
Specific tests can be chosen by number:
[root@emilia linux]# perf test 1 3 parse
1: vmlinux symtab matches kallsyms: Ok
3: detect open syscall event on all cpus: Ok
5: parse events tests: Ok
[root@emilia linux]#
Now to write more tests!
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-nqec2145qfxdgimux28aw7v8@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Stephane Eranian
Ingo Molnar
Jiri Olsa
Namhyung Kim
Nelson Elhage
Robert Richter
Andrew Vagin
Steven Rostedt
Anton Blanchard
Arnaldo Carvalho de Melo