Messages in this thread | | | Date | Wed, 6 Nov 2019 10:58:10 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH 1/2] perf/core: Adding capability to disable PMUs event multiplexing |
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On Wed, Nov 06, 2019 at 10:40:32AM +0100, Peter Zijlstra wrote: > On Wed, Nov 06, 2019 at 01:01:40AM +0000, Ganapatrao Prabhakerrao Kulkarni wrote: > > When PMUs are registered, perf core enables event multiplexing > > support by default. There is no provision for PMUs to disable > > event multiplexing, if PMUs want to disable due to unavoidable > > circumstances like hardware errata etc. > > > > Adding PMU capability flag PERF_PMU_CAP_NO_MUX_EVENTS and support > > to allow PMUs to explicitly disable event multiplexing. > > This doesn't make sense, multiplexing relies on nothing that normal > event scheduling doesn't also rely on. > > Either you can schedule different sets of events, or you cannot.
More specifically, how is a reschedule due to rotation any different than a reschedule due to context switch?
Both cases we do a full reprogram of the PMU.
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