Re: perf, x86: Provide a PEBS capable cycle event

From: Ingo Molnar
Date: Wed Jan 26 2011 - 06:37:57 EST

* Linux Kernel Mailing List <linux-kernel@xxxxxxxxxxxxxxx> wrote:

> Gitweb:
> Commit: 7639dae0ca11038286bbbcda05f2bef601c1eb8d
> Parent: abe43400579d5de0078c2d3a760e6598e183f871
> Author: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
> AuthorDate: Tue Dec 14 21:26:40 2010 +0100
> Committer: Ingo Molnar <mingo@xxxxxxx>
> CommitDate: Thu Dec 16 11:36:44 2010 +0100
> perf, x86: Provide a PEBS capable cycle event
> Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
> LKML-Reference: <new-submission>
> Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
> ---
> arch/x86/kernel/cpu/perf_event_intel.c | 26 ++++++++++++++++++++++++++
> 1 files changed, 26 insertions(+), 0 deletions(-)

btw., precise profiling via PEBS:

perf record -e cycles:p ...

works pretty nicely now on Nehalem CPUs and later.

Could we perhaps make perf record and perf top default to cycles:p on x86, and
silently fall back to regular cycles events if the CPU does not support this event

That would make our profiles more precise by default - without users having to do
anything funky.


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