Messages in this thread | | | Date | Mon, 07 Dec 2009 16:38:03 +0800 | From | Xiao Guangrong <> | Subject | Re: [PATCH 2/2] perf lock: New subcommand "lock" to perf for analyzing lock statistics |
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Ingo Molnar wrote:
> Also, i agree that the performance aspect is probably the most pressing > issue. Note that 'perf bench sched messaging' is very locking intense so > a 10x slowdown is not entirely unexpected - we still ought to optimize > it all some more. 'perf lock' is an excellent testcase for this in any > case. >
Here are some test results to show the overhead of lockdep trace events:
select pagefault mmap Memory par Cont_SW latency latency latency R/W BD latency
disable ftrace 0 0 0 0 0
enable all ftrace -16.65% -109.80% -93.62% 0.14% -6.94%
enable all ftrace -2.67% 1.08% -3.65% -0.52% -0.68% except lockdep
We also found big overhead when using kernbench and fio, but we haven't verified whether it's caused by lockdep events.
Thanks, Xiao
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