From mboxrd@z Thu Jan  1 00:00:00 1970
From: Andi Kleen <andi@firstfloor.org>
Subject: Re: Sampling hardware counter values with timers
Date: Fri, 13 May 2016 06:40:41 -0700
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	(Keno Fischer's message of "Fri, 13 May 2016 00:00:16 -0400")
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To: Keno Fischer <kfischer@college.harvard.edu>
Cc: linux-perf-users@vger.kernel.org

Keno Fischer <kfischer@college.harvard.edu> writes:

> Hello everyone,
>
> I was wondering if it is possible (either using the `perf` user space
> tool or using the perf_events API) to periodically sample the value of
> a hardware counter (in my particular case I'd like to sample the
> retired-branch-counter). I know it is possible to do the opposite
> (i.e. sample a timestamp every specified number of branches), but I
> wasn't able to see an easy way to sample the hardware counter at a
> specified frequency. Is this possible?

perf record works this way by default. The counter period is dynamically
adjusted for a given frequency. The default frequency is 1000.
You can set it with -F.

Another alternative is to use perf stat -I ... if you only need the counts.

-Andi