perf: Store active software events in a hashlist
in [Kernel]
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From: Eric Dumazet on 8 Apr 2010 16:10 Le jeudi 08 avril 2010 à 21:39 +0200, Frederic Weisbecker a écrit : .... > @@ -5401,6 +5507,16 @@ static void __cpuinit perf_event_init_cpu(int cpu) > spin_lock(&perf_resource_lock); > cpuctx->max_pertask = perf_max_events - perf_reserved_percpu; > spin_unlock(&perf_resource_lock); > + > + mutex_lock(&cpuctx->hlist_mutex); > + if (&cpuctx->hlist_refcount > 0) { if (cpuctx->hlist_refcount > 0) > + struct swevent_hlist *hlist; > + > + hlist = kzalloc(sizeof(*hlist), GFP_KERNEL); > + WARN_ON_ONCE(!hlist); > + rcu_assign_pointer(cpuctx->swevent_hlist, hlist); > + } > + mutex_unlock(&cpuctx->hlist_mutex); > } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Frederic Weisbecker on 8 Apr 2010 16:20 On Thu, Apr 08, 2010 at 10:04:41PM +0200, Eric Dumazet wrote: > Le jeudi 08 avril 2010 � 21:39 +0200, Frederic Weisbecker a �crit : > > ... > > > @@ -5401,6 +5507,16 @@ static void __cpuinit perf_event_init_cpu(int cpu) > > spin_lock(&perf_resource_lock); > > cpuctx->max_pertask = perf_max_events - perf_reserved_percpu; > > spin_unlock(&perf_resource_lock); > > + > > + mutex_lock(&cpuctx->hlist_mutex); > > + if (&cpuctx->hlist_refcount > 0) { > > > if (cpuctx->hlist_refcount > 0) Doh! Thanks, will fix. > > > + struct swevent_hlist *hlist; > > + > > + hlist = kzalloc(sizeof(*hlist), GFP_KERNEL); > > + WARN_ON_ONCE(!hlist); > > + rcu_assign_pointer(cpuctx->swevent_hlist, hlist); > > + } > > + mutex_unlock(&cpuctx->hlist_mutex); > > } > > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Peter Zijlstra on 16 Apr 2010 07:00
On Wed, 2010-04-14 at 02:53 +0200, Frederic Weisbecker wrote: > > Each time a software event triggers, we need to walk through > the entire list of events from the current cpu and task contexts > to retrieve a running perf event that matches. > We also need to check a matching perf event is actually counting. > > This walk is wasteful and makes the event fast path scaling > down with a growing number of events running on the same > contexts. > > To solve this, we store the running perf events in a hashlist to > get an immediate access to them against their type:event_id when > they trigger. Looks good, thanks Frederic! -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |