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>

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 60b333a..71c2d44 100644 (file)
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -1763,8 +1763,9 @@ static void ctx_sched_out(struct perf_event_context *ctx,
                          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 @@ static void ctx_sched_out(struct perf_event_context *ctx,
                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 @@ ctx_sched_in(struct perf_event_context *ctx,
             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 @@ ctx_sched_in(struct perf_event_context *ctx,
         * 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);
 }