perf events: Dont report side-band events on each cpu for per-task-per-cpu events
Peter Zijlstra [Thu, 17 Dec 2009 12:16:32 +0000 (13:16 +0100)]
Acme noticed that his FORK/MMAP numbers were inflated by about
the same factor as his cpu-count.

This led to the discovery of a few more sites that need to
respect the event->cpu filter.

Reported-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <20091217121830.215333434@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

kernel/perf_event.c

index 8ab8698..03cc061 100644 (file)
@@ -1381,6 +1381,9 @@ static void perf_ctx_adjust_freq(struct perf_event_context *ctx)
                if (event->state != PERF_EVENT_STATE_ACTIVE)
                        continue;
 
+               if (event->cpu != -1 && event->cpu != smp_processor_id())
+                       continue;
+
                hwc = &event->hw;
 
                interrupts = hwc->interrupts;
@@ -3265,6 +3268,9 @@ static void perf_event_task_output(struct perf_event *event,
 
 static int perf_event_task_match(struct perf_event *event)
 {
+       if (event->cpu != -1 && event->cpu != smp_processor_id())
+               return 0;
+
        if (event->attr.comm || event->attr.mmap || event->attr.task)
                return 1;
 
@@ -3290,12 +3296,11 @@ static void perf_event_task_event(struct perf_task_event *task_event)
        rcu_read_lock();
        cpuctx = &get_cpu_var(perf_cpu_context);
        perf_event_task_ctx(&cpuctx->ctx, task_event);
-       put_cpu_var(perf_cpu_context);
-
        if (!ctx)
                ctx = rcu_dereference(task_event->task->perf_event_ctxp);
        if (ctx)
                perf_event_task_ctx(ctx, task_event);
+       put_cpu_var(perf_cpu_context);
        rcu_read_unlock();
 }
 
@@ -3372,6 +3377,9 @@ static void perf_event_comm_output(struct perf_event *event,
 
 static int perf_event_comm_match(struct perf_event *event)
 {
+       if (event->cpu != -1 && event->cpu != smp_processor_id())
+               return 0;
+
        if (event->attr.comm)
                return 1;
 
@@ -3408,15 +3416,10 @@ static void perf_event_comm_event(struct perf_comm_event *comm_event)
        rcu_read_lock();
        cpuctx = &get_cpu_var(perf_cpu_context);
        perf_event_comm_ctx(&cpuctx->ctx, comm_event);
-       put_cpu_var(perf_cpu_context);
-
-       /*
-        * doesn't really matter which of the child contexts the
-        * events ends up in.
-        */
        ctx = rcu_dereference(current->perf_event_ctxp);
        if (ctx)
                perf_event_comm_ctx(ctx, comm_event);
+       put_cpu_var(perf_cpu_context);
        rcu_read_unlock();
 }
 
@@ -3491,6 +3494,9 @@ static void perf_event_mmap_output(struct perf_event *event,
 static int perf_event_mmap_match(struct perf_event *event,
                                   struct perf_mmap_event *mmap_event)
 {
+       if (event->cpu != -1 && event->cpu != smp_processor_id())
+               return 0;
+
        if (event->attr.mmap)
                return 1;
 
@@ -3564,15 +3570,10 @@ got_name:
        rcu_read_lock();
        cpuctx = &get_cpu_var(perf_cpu_context);
        perf_event_mmap_ctx(&cpuctx->ctx, mmap_event);
-       put_cpu_var(perf_cpu_context);
-
-       /*
-        * doesn't really matter which of the child contexts the
-        * events ends up in.
-        */
        ctx = rcu_dereference(current->perf_event_ctxp);
        if (ctx)
                perf_event_mmap_ctx(ctx, mmap_event);
+       put_cpu_var(perf_cpu_context);
        rcu_read_unlock();
 
        kfree(buf);
@@ -3863,6 +3864,9 @@ static int perf_swevent_match(struct perf_event *event,
                                struct perf_sample_data *data,
                                struct pt_regs *regs)
 {
+       if (event->cpu != -1 && event->cpu != smp_processor_id())
+               return 0;
+
        if (!perf_swevent_is_counting(event))
                return 0;