perf events: Allow per-task-per-cpu counters
In order to allow for per-task-per-cpu counters, useful for
scalability when profiling task hierarchies, we allow installing
events with event->cpu != -1 in task contexts.
__perf_event_sched_in() already skips events where ->cpu
mis-matches the current cpu, fix up __perf_install_in_context()
and __perf_event_enable() to also respect this filter.
This does lead to vary hard to interpret enabled/running times
for such counters, but I don't see a simple solution for that.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: fweisbec@gmail.com
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <20091216165904.831451147@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 0dd8e5d..2e0aaa3 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -782,6 +782,9 @@
add_event_to_ctx(event, ctx);
+ if (event->cpu != -1 && event->cpu != smp_processor_id())
+ goto unlock;
+
/*
* Don't put the event on if it is disabled or if
* it is in a group and the group isn't on.
@@ -925,6 +928,9 @@
goto unlock;
__perf_event_mark_enabled(event, ctx);
+ if (event->cpu != -1 && event->cpu != smp_processor_id())
+ goto unlock;
+
/*
* If the event is in a group and isn't the group leader,
* then don't put it on unless the group is on.
@@ -1595,10 +1601,7 @@
unsigned long flags;
int err;
- /*
- * If cpu is not a wildcard then this is a percpu event:
- */
- if (cpu != -1) {
+ if (pid == -1 && cpu != -1) {
/* Must be root to operate on a CPU event: */
if (perf_paranoid_cpu() && !capable(CAP_SYS_ADMIN))
return ERR_PTR(-EACCES);