On Wed, 2012-09-05 at 16:03 +0200, Stephane Eranian wrote: > Hi, > > I was looking at the rotation code and I found out that when > I monitor a SW event (in my case a probe), I end up having > two PMUs on the rotation list on Intel Core: cpu and software. > > I thought there was no multiplexing needed for SW events.
Correct, since programming of swevents should always succeed. > So why is the SW PMU on the rotation list causing extra > iterations through the rotation code? Because... uhm.. someone (probably me) didn't think to exclude swevents. > Shouldn't we do something like: > > --- a/kernel/events/core.c > +++ b/kernel/events/core.c > @@ -771,6 +780,9 @@ static void perf_pmu_rotate_start(struct pmu *pmu) > struct perf_cpu_context *cpuctx = this_cpu_ptr(pmu->pmu_cpu_context); > struct list_head *head = &__get_cpu_var(rotation_list); > > + if (pmu->type == PERF_TYPE_SOFTWARE) > + return; > + > WARN_ON(!irqs_disabled()); > > if (list_empty(&cpuctx->rotation_list)) Yeah, I guess that'll do, although I guess something like: pmu->task_ctx_nr == perf_sw_context would be even better, since that would also work for TYPE_TRACEPOINT and possibly any other swevent like things. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
