Messages in this thread | | | Date | Mon, 28 Jun 2010 15:21:04 +0200 | From | Frederic Weisbecker <> | Subject | Re: [RFC][PATCH 05/11] perf: register pmu implementations |
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On Thu, Jun 24, 2010 at 04:28:09PM +0200, Peter Zijlstra wrote: > + if (bp->attr.type != PERF_TYPE_BREAKPOINT) > + return -ENOENT; > + > + err = register_perf_hw_breakpoint(bp); > + if (err) > + return err; > + > + bp->destroy = bp_perf_event_destroy;
Seems it would make sense to also have destroy in the pmu, it's the same along every events in the same class right?
But this can be for later.
> +static LIST_HEAD(pmus); > +static DEFINE_MUTEX(pmus_lock); > +static struct srcu_struct pmus_srcu; > + > +int perf_pmu_register(struct pmu *pmu) > +{ > + mutex_lock(&pmus_lock); > + list_add_rcu(&pmu->entry, &pmus); > + mutex_unlock(&pmus_lock); > + > + return 0; > +} > + > +void perf_pmu_unregister(struct pmu *pmu) > +{ > + mutex_lock(&pmus_lock); > + list_del_rcu(&pmu->entry); > + mutex_unlock(&pmus_lock); > > - atomic_inc(&perf_swevent_enabled[event_id]); > - event->destroy = sw_perf_event_destroy; > + synchronize_srcu(&pmus_srcu); > +} > + > +struct pmu *perf_init_event(struct perf_event *event) > +{ > + struct pmu *pmu = NULL; > + int idx; > + > + idx = srcu_read_lock(&pmus_srcu); > + list_for_each_entry_rcu(pmu, &pmus, entry) { > + int ret = pmu->event_init(event); > + if (!ret) > + break; > + if (ret != -ENOENT) { > + pmu = ERR_PTR(ret); > + break; > } > - pmu = &perf_ops_generic; > - break; > } > + srcu_read_unlock(&pmus_srcu, idx); > > return pmu; > }
I'm still not sure why all this locking is needed. We don't even support pmus in modules.
Is there something coming soon that will use this? I remember something about KVM.
And who will have to use srcu? It seems the event fastpath would be concerned, right? Will that have an impact on the performances?
> @@ -5743,15 +5742,15 @@ perf_cpu_notify(struct notifier_block *s > { > unsigned int cpu = (long)hcpu; > > - switch (action) { > + switch (action & ~CPU_TASKS_FROZEN) { > > case CPU_UP_PREPARE: > - case CPU_UP_PREPARE_FROZEN: > + case CPU_DOWN_FAILED: > perf_event_init_cpu(cpu); > break; > > + case CPU_UP_CANCELED: > case CPU_DOWN_PREPARE: > - case CPU_DOWN_PREPARE_FROZEN: > perf_event_exit_cpu(cpu); > break;
That doesn't seem to be related to this patch initial topic.
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