Messages in this thread | | | Date | Thu, 1 Oct 2009 09:25:18 +0200 | From | Ingo Molnar <> | Subject | Re: [RFC PATCH] perf_core: provide a kernel-internal interface to get to performance counters |
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* Arjan van de Ven <arjan@infradead.org> wrote:
> On Sun, 27 Sep 2009 00:02:46 +0530 > "K.Prasad" <prasad@linux.vnet.ibm.com> wrote: > > > On Sat, Sep 26, 2009 at 12:03:28PM -0400, Frank Ch. Eigler wrote: > > > > 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. > > I'm sorry but I think I am missing your point. "all cpu counters" > would be one small helper wrapper away, a helper I'm sure the > SystemTap people are happy to submit as part of their patch series > when they submit SystemTap to the kernel.
Yes, and Frederic wrote that wrapper already for the hw-breakpoints patches. It's a non-issue and does not affect the design - we can always gang up an array of per cpu perf events, it's a straightforward use of the existing design.
User-space tools have been doing this for ages already, 'perf top' will open an array of per cpu events to monitor all events in the system.
Ingo
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