commit db24d33e08b88e990991760a44d72006a5dc6102
author Peter Zijlstra <a.p.zijlstra@chello.nl> Sat Apr 09 21:17:45 2011 +0200
committer Ingo Molnar <mingo@elte.hu> Sat May 28 18:01:17 2011 +0200
tree a36c4aba0e221e5833b15432971e526959a3aff1
parent 2c29ef0fef8aaff1f91263fc75c749d659da6972

perf: Change and simplify ctx::is_active semantics

Instead of tracking if a context is active or not, track which events
of the context are active. By making it a bitmask of
EVENT_PINNED|EVENT_FLEXIBLE we can simplify some of the scheduling
routines since it can avoid adding events that are already active.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20110409192141.930282378@chello.nl
Signed-off-by: Ingo Molnar <mingo@elte.hu>

kernel/events/core.c

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 60b333a..71c2d44 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -1763,8 +1763,9 @@
 			  enum event_type_t event_type)
 {
 	struct perf_event *event;
+	int is_active = ctx->is_active;
 
-	ctx->is_active = 0;
+	ctx->is_active &= ~event_type;
 	if (likely(!ctx->nr_events))
 		return;
 
@@ -1774,12 +1775,12 @@
 		return;
 
 	perf_pmu_disable(ctx->pmu);
-	if (event_type & EVENT_PINNED) {
+	if ((is_active & EVENT_PINNED) && (event_type & EVENT_PINNED)) {
 		list_for_each_entry(event, &ctx->pinned_groups, group_entry)
 			group_sched_out(event, cpuctx, ctx);
 	}
 
-	if (event_type & EVENT_FLEXIBLE) {
+	if ((is_active & EVENT_FLEXIBLE) && (event_type & EVENT_FLEXIBLE)) {
 		list_for_each_entry(event, &ctx->flexible_groups, group_entry)
 			group_sched_out(event, cpuctx, ctx);
 	}
@@ -2058,8 +2059,9 @@
 	     struct task_struct *task)
 {
 	u64 now;
+	int is_active = ctx->is_active;
 
-	ctx->is_active = 1;
+	ctx->is_active |= event_type;
 	if (likely(!ctx->nr_events))
 		return;
 
@@ -2070,11 +2072,11 @@
 	 * First go through the list and put on any pinned groups
 	 * in order to give them the best chance of going on.
 	 */
-	if (event_type & EVENT_PINNED)
+	if (!(is_active & EVENT_PINNED) && (event_type & EVENT_PINNED))
 		ctx_pinned_sched_in(ctx, cpuctx);
 
 	/* Then walk through the lower prio flexible groups */
-	if (event_type & EVENT_FLEXIBLE)
+	if (!(is_active & EVENT_FLEXIBLE) && (event_type & EVENT_FLEXIBLE))
 		ctx_flexible_sched_in(ctx, cpuctx);
 }