>>> In some of the powerpc platforms, event group testcase fails as below: >>> >>> # perf test -v 'Event groups' >>> 69: Event groups : >>> --- start --- >>> test child forked, pid 9765 >>> Using CPUID 0x00820200 >>> Using hv_24x7 for uncore pmu event >>> 0x0 0x0, 0x0 0x0, 0x0 0x0: Fail >>> 0x0 0x0, 0x0 0x0, 0x1 0x3: Pass >>> >>> The testcase creates various combinations of hw, sw and uncore >>> PMU events and verify group creation succeeds or fails as expected. >>> This tests one of the limitation in perf where it doesn't allow >>> creating a group of events from different hw PMUs. >>> >>> The testcase starts a leader event and opens two sibling events. >>> The combination the fails is three hardware events in a group. >>> "0x0 0x0, 0x0 0x0, 0x0 0x0: Fail" >>> >>> Type zero and config zero which translates to PERF_TYPE_HARDWARE >>> and PERF_COUNT_HW_CPU_CYCLE. There is event constraint in powerpc >>> that events using same counter cannot be programmed in a group. >>> Here there is one alternative event for cycles, hence one leader >>> and only one sibling event can go in as a group. >> >> For power9, cycles seems to map to PM_CYC event: >> >> GENERIC_EVENT_ATTR(cpu-cycles, PM_CYC); >> >> However, I don't see PM_CYC in power9_event_alternatives[]. Is PM_RUN_CYC >> and PM_CYC are same? > > Hi Ravi > > They are not the same. PM_CYC count irrespective of the run latch state (idle > state) > whereas PM_RUN_CYC doesn’t do that. > > This test runs fine in power9. The event code for PM_CYC is > EVENT(PM_CYC, 0x0001e) > > Here it is not specifically meant to be run a particular counter and even if > no alternative event is defined, it can pick available counters and go in as > a group.
Got it. > But there are cases like other PMU (which is used in absence of platform > specific PMU) , where alternative event is specified to run a particular > counter. > Example: arch/powerpc/perf/generic-compat-pmu.c > > EVENT(PM_CYC_ALT, 0x100f0) > EVENT(PM_CYC, 0x600f4) > > In this case, we can have only two cycles events to go in a group. So with > our testcase events, one leader and only one sibling event > can go in a group (checked other PMU’s to confirm two is possible). So added > this fix to consider instructions as one of the sibling event. Thanks for the explanation. Reviewed-by: Ravi Bangoria <ravi.bango...@amd.com> Thanks, Ravi
