perf_events: Add perf_event_time()

Adds perf_event_time() to try and centralize access to event
timing and in particular ctx->time. Prepares for cgroup support.

Signed-off-by: Stephane Eranian <eranian@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <4d22059c.122ae30a.5e0e.ffff8b8b@mx.google.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 24 insertions, 14 deletions

diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index dcdb19ed83a6..b782b7a79f00 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -268,6 +268,12 @@ static void update_context_time(struct perf_event_context *ctx)
         ctx->timestamp = now;
 }
 
+static u64 perf_event_time(struct perf_event *event)
+{
+        struct perf_event_context *ctx = event->ctx;
+        return ctx ? ctx->time : 0;
+}
+
 /*
  * Update the total_time_enabled and total_time_running fields for a event.
  */
@@ -281,7 +287,7 @@ static void update_event_times(struct perf_event *event)
                 return;
 
         if (ctx->is_active)
-                run_end = ctx->time;
+                run_end = perf_event_time(event);
         else
                 run_end = event->tstamp_stopped;
 
@@ -290,7 +296,7 @@ static void update_event_times(struct perf_event *event)
         if (event->state == PERF_EVENT_STATE_INACTIVE)
                 run_end = event->tstamp_stopped;
         else
-                run_end = ctx->time;
+                run_end = perf_event_time(event);
 
         event->total_time_running = run_end - event->tstamp_running;
 }
@@ -546,6 +552,7 @@ event_sched_out(struct perf_event *event,
                   struct perf_cpu_context *cpuctx,
                   struct perf_event_context *ctx)
 {
+        u64 tstamp = perf_event_time(event);
         u64 delta;
         /*
          * An event which could not be activated because of
@@ -557,7 +564,7 @@ event_sched_out(struct perf_event *event,
             && !event_filter_match(event)) {
                 delta = ctx->time - event->tstamp_stopped;
                 event->tstamp_running += delta;
-                event->tstamp_stopped = ctx->time;
+                event->tstamp_stopped = tstamp;
         }
 
         if (event->state != PERF_EVENT_STATE_ACTIVE)
@@ -568,7 +575,7 @@ event_sched_out(struct perf_event *event,
                 event->pending_disable = 0;
                 event->state = PERF_EVENT_STATE_OFF;
         }
-        event->tstamp_stopped = ctx->time;
+        event->tstamp_stopped = tstamp;
         event->pmu->del(event, 0);
         event->oncpu = -1;
 
@@ -780,6 +787,8 @@ event_sched_in(struct perf_event *event,
                  struct perf_cpu_context *cpuctx,
                  struct perf_event_context *ctx)
 {
+        u64 tstamp = perf_event_time(event);
+
         if (event->state <= PERF_EVENT_STATE_OFF)
                 return 0;
 
@@ -796,9 +805,9 @@ event_sched_in(struct perf_event *event,
                 return -EAGAIN;
         }
 
-        event->tstamp_running += ctx->time - event->tstamp_stopped;
+        event->tstamp_running += tstamp - event->tstamp_stopped;
 
-        event->shadow_ctx_time = ctx->time - ctx->timestamp;
+        event->shadow_ctx_time = tstamp - ctx->timestamp;
 
         if (!is_software_event(event))
                 cpuctx->active_oncpu++;
@@ -910,11 +919,13 @@ static int group_can_go_on(struct perf_event *event,
 static void add_event_to_ctx(struct perf_event *event,
                                struct perf_event_context *ctx)
 {
+        u64 tstamp = perf_event_time(event);
+
         list_add_event(event, ctx);
         perf_group_attach(event);
-        event->tstamp_enabled = ctx->time;
-        event->tstamp_running = ctx->time;
-        event->tstamp_stopped = ctx->time;
+        event->tstamp_enabled = tstamp;
+        event->tstamp_running = tstamp;
+        event->tstamp_stopped = tstamp;
 }
 
 /*
@@ -1054,14 +1065,13 @@ static void __perf_event_mark_enabled(struct perf_event *event,
                                         struct perf_event_context *ctx)
 {
         struct perf_event *sub;
+        u64 tstamp = perf_event_time(event);
 
         event->state = PERF_EVENT_STATE_INACTIVE;
-        event->tstamp_enabled = ctx->time - event->total_time_enabled;
+        event->tstamp_enabled = tstamp - event->total_time_enabled;
         list_for_each_entry(sub, &event->sibling_list, group_entry) {
-                if (sub->state >= PERF_EVENT_STATE_INACTIVE) {
-                        sub->tstamp_enabled =
-                                ctx->time - sub->total_time_enabled;
-                }
+                if (sub->state >= PERF_EVENT_STATE_INACTIVE)
+                        sub->tstamp_enabled = tstamp - sub->total_time_enabled;
         }
 }