On Mon, Feb 06, 2017 at 02:11:36PM -0500, Leeder, Neil wrote: > Hi Mark, > Thanks for those comments - I'll add the fixes. Cheers! > On 2/6/2017 10:48 AM, Mark Rutland wrote: > >I'm still concerned by this use of the filter_match callback, because it > >depends on the set of other active events, and can change as other > >events are scheduled in and out. > > > >When we schedule in two conflicting events A and B in order, B will fail > >its filter match. When we scheduled out A and B in order, B will succeed > >its filter match. > > > >The perf core does not expect this inconsistency, and this appears to > >break the timing update logic in event_sched_out(), when unconditionally > >called from ctx_sched_out() as part of perf_rotate_context(). > > > >I would feel much happier if we dropped l2_cache_filter_match(), at > >least for the timebeing, and handled this as we do for other cases of > >intra-pmu resource contention. > > > >We can then consider the filter_match addition on its own at a later > >point. > > So could this be detected in get_event_idx, the same way we handle > counter resource contention? That would eliminate filter_match, and > it's the same way its done in armv7 > (arch/arm/kernel/perf_event_v7.c:krait_pmu_get_event_idx()). Returning -EAGAIN from event_get_ixd() in that case sounds good to me. Thanks, Mark. -- To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
