Re: [RFC PATCH] perf_core: provide a kernel-internal interface to get to performance counters

From: Frank Ch. Eigler
Date: Sat Sep 26 2009 - 12:04:06 EST



Arjan van de Ven <arjan@xxxxxxxxxxxxx> writes:

> [...]
> There are reasons for kernel code to ask for, and use, performance counters.
> For example, in CPU freq governors this tends to be a good idea, but there
> are other examples possible as well of course.
>
> This patch adds the needed bits to do enable this functionality; they have been
> tested in an experimental cpufreq driver that I'm working on, and the changes
> are all that I needed to access counters properly.
> [...]

For what it's worth, this sort of thing also looks useful from
systemtap's point of view.

It appears that the patch assumes that a perf counter instance is to
be associated with the "current" task. How do you use this from your
prototype scheduler? Do you create/attach a new one for each thread?


- FChE
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