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perf trace: Exclude the kernel part of the callchain leading to a syscall

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The kernel parts are not that useful:

  # trace -m 512 -e nanosleep --call dwarf  usleep 1
     0.065 ( 0.065 ms): usleep/18732 nanosleep(rqtp: 0x7ffc4ee4e200) = 0
                                       syscall_slow_exit_work ([kernel.kallsyms])
                                       do_syscall_64 ([kernel.kallsyms])
                                       return_from_SYSCALL_64 ([kernel.kallsyms])
                                       __nanosleep (/usr/lib64/libc-2.22.so)
                                       usleep (/usr/lib64/libc-2.22.so)
                                       main (/usr/bin/usleep)
                                       __libc_start_main (/usr/lib64/libc-2.22.so)
                                       _start (/usr/bin/usleep)
  #

So lets just use perf_event_attr.exclude_callchain_kernel to avoid
collecting it in the ring buffer:

  # trace -m 512 -e nanosleep --call dwarf  usleep 1
     0.063 ( 0.063 ms): usleep/19212 nanosleep(rqtp: 0x7ffc3df10fb0) = 0
                                       __nanosleep (/usr/lib64/libc-2.22.so)
                                       usleep (/usr/lib64/libc-2.22.so)
                                       main (/usr/bin/usleep)
                                       __libc_start_main (/usr/lib64/libc-2.22.so)
                                       _start (/usr/bin/usleep)
  #

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Milian Wolff <milian.wolff@kdab.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-qctu3gqhpim0dfbcp9d86c91@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Arnaldo Carvalho de Melo
2016-04-11 15:49:11 -03:00
parent ea4539652e
commit 44621819dd
2 changed files with 16 additions and 0 deletions
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3
tools/perf/Documentation/perf-trace.txt
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@@ -123,6 +123,9 @@ the thread executes on the designated CPUs. Default is to monitor all CPUs.
man pages for details. The ones that are most useful in 'perf trace'
are 'dwarf' and 'lbr', where available, try: 'perf trace --call-graph dwarf'.
--kernel-syscall-graph::
Show the kernel callchains on the syscall exit path.
--event::
Trace other events, see 'perf list' for a complete list.