Messages in this thread | | | Date | Tue, 21 Jun 2011 20:48:20 +0400 | From | Cyrill Gorcunov <> | Subject | Re: [RFC -tip] perf, x86: Add PERF_COUNT_HW_NMI_WATCHDOG event v2 |
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On Tue, Jun 21, 2011 at 06:20:56PM +0200, Stephane Eranian wrote: > Cyrill, > [repost because of MIME crap]
I saw first as well, sorry for delay, my isp is broken today :/
> > I admit I don't quite understand how this patch works around > the limitation. In the end you are still going to program some cycle > event into a P4 PMU register. So how it is going to free more counters > for regular users? > >
The key here is that we use that named non-sleeping ticks (as oprofile did) for nmi-watchdog and it allows us to free "cpu-cycles" counter for user needs. Of course we pick up one counter for this but it doesn't intersect with "cpu-cycles" counter (because counters are grouped and can count only specified events in each group). Stepane, should I post more details?
Cyrill
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