Messages in this thread | | | Date | Fri, 22 Mar 2013 10:33:26 -0700 | From | Andi Kleen <> | Subject | Re: [PATCH v5 0/2] perf: use hrtimer for event multiplexing |
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On Fri, Mar 22, 2013 at 11:51:37AM +0100, Stephane Eranian wrote: > The current scheme of using the timer tick was fine > for per-thread events. However, it was causing > bias issues in system-wide mode (including for > uncore PMUs). Event groups would not get their > fair share of runtime on the PMU. With tickless > kernels, if a core is idle there is no timer tick, > and thus no event rotation (multiplexing). However, > there are events (especially uncore events) which do > count even though cores are asleep.
Would it be possible to only do this when uncore events are active? Otherwise it may have a large power cost and actually change results, as the core counters will tick more.
-Andi
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