Messages in this thread | | | Date | Tue, 23 Nov 2010 12:33:59 +0100 | Subject | Re: [PATCH] perf: add support for per-event sampling period or frequency in perf record | From | Stephane Eranian <> |
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On Tue, Nov 23, 2010 at 12:33 PM, Stephane Eranian <eranian@google.com> wrote: > On Tue, Nov 23, 2010 at 12:11 PM, Peter Zijlstra <peterz@infradead.org> wrote: >> On Tue, 2010-11-23 at 11:45 +0200, Stephane Eranian wrote: >>> This patch allows specifying a per event sampling period or frequency. >>> Up until now, the same sampling period or frequency was applied to all >>> the events specified on the command line of perf record. A sampling >>> period depends on the event, thus it is necessary to specify it per event. >>> >>> With this patch, both the -F and -c options now take a comma separated >>> list of values. If a value is omitted for an event, it defaults to 1000Hz >>> frequency mode as before. >>> >>> $ perf record -e cycles,instructions -c 100000,200000 -a -- sleep 5 >> >> >> I remember an email not too long ago where people proposed to change the >> syntax so that: >> >> -e evnt1,evnt2 -- create a group containing both events >> -e evnt1 -e evnt2 -- create two separate events >> > Yes, that would be nice too especially for people interested in event ratios. > >> It would be nice to make sure these two proposals will not interfere. >> >> Alternatively we extend the event syntax to include the period, >> something like: >> >> -e evnt1:period=1234 >> > Yes, that's the other approach. It may be more readable when you > have more events. I have that working with libpfm4, i.e., the full > event string is processed by the library. But for now, we could try > and do this in the tool as well, something like: > > -e evtnt1:period=1234 -e evnt2:freq=100 > Forgot to say, that the reason I did it thru -c and -F was to maintain backward compatibility. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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