Messages in this thread |  | | | Date | Mon, 3 May 2010 13:53:19 -0700 | | Subject | Re: [PATCH] perf: implement recording/reporting per-cpu samples | | From | Arun Sharma <> |
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On Mon, May 3, 2010 at 1:42 PM, Peter Zijlstra <peterz@infradead.org> wrote: > > On Mon, 2010-05-03 at 13:38 -0700, Arun Sharma wrote: > > Enable PERF_SAMPLE_CPU by default. Implement --sort cpu. > > Why? The downside is that you unconditionally grow each sample and thus > increase the overhead for something that doesn't make sense for the > normal (task-inherit) case.
In a shared multi-core environment, users want to analyze why their program was slow. In particular, if the code ran slower only on certain CPUs due to interference from other programs or kernel threads, they want to know that.
But that's just our use case. The patch is mostly about --sort cpu option. If you want to drop the part that enables PERF_SAMPLE_CPU by default, that's fine by me.
-Arun
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