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.
