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| author | Li Zefan <lizf@cn.fujitsu.com> | 2010-07-02 11:07:32 +0800 |
|---|---|---|
| committer | Steven Rostedt <rostedt@goodmis.org> | 2010-07-20 21:52:33 -0400 |
| commit | e870e9a1240bcef1157ffaaf71dac63362e71904 (patch) | |
| tree | b8f57a68ff45b35dab8cdfa474e17622d275bdc6 /kernel/trace/ring_buffer.c | |
| parent | cc5edb0eb9ce892b530e34a5d110382483587942 (diff) | |
| download | linux-e870e9a1240bcef1157ffaaf71dac63362e71904.tar.gz linux-e870e9a1240bcef1157ffaaf71dac63362e71904.tar.bz2 linux-e870e9a1240bcef1157ffaaf71dac63362e71904.zip | |
tracing: Allow to disable cmdline recording
We found that even enabling a single trace event that will rarely be
triggered can add big overhead to context switch.
(lmbench context switch test)
-------------------------------------------------
2p/0K 2p/16K 2p/64K 8p/16K 8p/64K 16p/16K 16p/64K
ctxsw ctxsw ctxsw ctxsw ctxsw ctxsw ctxsw
------ ------ ------ ------ ------ ------- -------
2.19 2.3 2.21 2.56 2.13 2.54 2.07
2.39 2.51 2.35 2.75 2.27 2.81 2.24
The overhead is 6% ~ 11%.
It's because when a trace event is enabled 3 tracepoints (sched_switch,
sched_wakeup, sched_wakeup_new) will be activated to map pid to cmdname.
We'd like to avoid this overhead, so add a trace option '(no)record-cmd'
to allow to disable cmdline recording.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
LKML-Reference: <4C2D57F4.2050204@cn.fujitsu.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'kernel/trace/ring_buffer.c')
0 files changed, 0 insertions, 0 deletions