Messages in this thread Patch in this message | | | Date | Sat, 09 Apr 2011 21:17:47 +0200 | From | Peter Zijlstra <> | Subject | [RFC][PATCH 8/9] perf: Change close() semantics for group events |
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In order to always call list_del_event() on the correct cpu if the event is part of an active context and avoid having to do two IPIs, change the close() semantics slightly.
The current perf_event_disable() call would disable a whole group if the event that's being closed is the group leader, whereas the new code keeps the group siblings enabled.
People should not rely on this behaviour and I don't think they do, but in case we find they do, the fix is easy and we have to take the double IPI cost.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> --- kernel/perf_event.c | 8 +------- 1 file changed, 1 insertion(+), 7 deletions(-)
Index: linux-2.6/kernel/perf_event.c =================================================================== --- linux-2.6.orig/kernel/perf_event.c +++ linux-2.6/kernel/perf_event.c @@ -2920,12 +2920,6 @@ int perf_event_release_kernel(struct per { struct perf_event_context *ctx = event->ctx; - /* - * Remove from the PMU, can't get re-enabled since we got - * here because the last ref went. - */ - perf_event_disable(event); - WARN_ON_ONCE(ctx->parent_ctx); /* * There are two ways this annotation is useful: @@ -2942,8 +2936,8 @@ int perf_event_release_kernel(struct per mutex_lock_nested(&ctx->mutex, SINGLE_DEPTH_NESTING); raw_spin_lock_irq(&ctx->lock); perf_group_detach(event); - list_del_event(event, ctx); raw_spin_unlock_irq(&ctx->lock); + perf_remove_from_context(event); mutex_unlock(&ctx->mutex); free_event(event);
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