Messages in this thread | | | Date | Sun, 27 Sep 2009 00:02:46 +0530 | From | "K.Prasad" <> | Subject | Re: [RFC PATCH] perf_core: provide a kernel-internal interface to get to performance counters |
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On Sat, Sep 26, 2009 at 12:03:28PM -0400, Frank Ch. Eigler wrote: > > Arjan van de Ven <arjan@infradead.org> 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.
Wouldn't SystemTap be another user that desires support for multiple/all CPU perf-counters (apart from hw-breakpoints as a potential user)? As Arjan pointed out, perf's present design would support only a per-CPU or per-task counter; not both.
Thanks, K.Prasad
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