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-rw-r--r--include/linux/perf_event.h10
-rw-r--r--kernel/perf_event.c42
2 files changed, 44 insertions, 8 deletions
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 057bf22..40150f3 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -747,6 +747,16 @@ struct perf_event {
u64 tstamp_running;
u64 tstamp_stopped;
+ /*
+ * timestamp shadows the actual context timing but it can
+ * be safely used in NMI interrupt context. It reflects the
+ * context time as it was when the event was last scheduled in.
+ *
+ * ctx_time already accounts for ctx->timestamp. Therefore to
+ * compute ctx_time for a sample, simply add perf_clock().
+ */
+ u64 shadow_ctx_time;
+
struct perf_event_attr attr;
struct hw_perf_event hw;
diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 517d827..cb6c0d2 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -674,6 +674,8 @@ event_sched_in(struct perf_event *event,
event->tstamp_running += ctx->time - event->tstamp_stopped;
+ event->shadow_ctx_time = ctx->time - ctx->timestamp;
+
if (!is_software_event(event))
cpuctx->active_oncpu++;
ctx->nr_active++;
@@ -3396,7 +3398,8 @@ static u32 perf_event_tid(struct perf_event *event, struct task_struct *p)
}
static void perf_output_read_one(struct perf_output_handle *handle,
- struct perf_event *event)
+ struct perf_event *event,
+ u64 enabled, u64 running)
{
u64 read_format = event->attr.read_format;
u64 values[4];
@@ -3404,11 +3407,11 @@ static void perf_output_read_one(struct perf_output_handle *handle,
values[n++] = perf_event_count(event);
if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED) {
- values[n++] = event->total_time_enabled +
+ values[n++] = enabled +
atomic64_read(&event->child_total_time_enabled);
}
if (read_format & PERF_FORMAT_TOTAL_TIME_RUNNING) {
- values[n++] = event->total_time_running +
+ values[n++] = running +
atomic64_read(&event->child_total_time_running);
}
if (read_format & PERF_FORMAT_ID)
@@ -3421,7 +3424,8 @@ static void perf_output_read_one(struct perf_output_handle *handle,
* XXX PERF_FORMAT_GROUP vs inherited events seems difficult.
*/
static void perf_output_read_group(struct perf_output_handle *handle,
- struct perf_event *event)
+ struct perf_event *event,
+ u64 enabled, u64 running)
{
struct perf_event *leader = event->group_leader, *sub;
u64 read_format = event->attr.read_format;
@@ -3431,10 +3435,10 @@ static void perf_output_read_group(struct perf_output_handle *handle,
values[n++] = 1 + leader->nr_siblings;
if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED)
- values[n++] = leader->total_time_enabled;
+ values[n++] = enabled;
if (read_format & PERF_FORMAT_TOTAL_TIME_RUNNING)
- values[n++] = leader->total_time_running;
+ values[n++] = running;
if (leader != event)
leader->pmu->read(leader);
@@ -3459,13 +3463,35 @@ static void perf_output_read_group(struct perf_output_handle *handle,
}
}
+#define PERF_FORMAT_TOTAL_TIMES (PERF_FORMAT_TOTAL_TIME_ENABLED|\
+ PERF_FORMAT_TOTAL_TIME_RUNNING)
+
static void perf_output_read(struct perf_output_handle *handle,
struct perf_event *event)
{
+ u64 enabled = 0, running = 0, now, ctx_time;
+ u64 read_format = event->attr.read_format;
+
+ /*
+ * compute total_time_enabled, total_time_running
+ * based on snapshot values taken when the event
+ * was last scheduled in.
+ *
+ * we cannot simply called update_context_time()
+ * because of locking issue as we are called in
+ * NMI context
+ */
+ if (read_format & PERF_FORMAT_TOTAL_TIMES) {
+ now = perf_clock();
+ ctx_time = event->shadow_ctx_time + now;
+ enabled = ctx_time - event->tstamp_enabled;
+ running = ctx_time - event->tstamp_running;
+ }
+
if (event->attr.read_format & PERF_FORMAT_GROUP)
- perf_output_read_group(handle, event);
+ perf_output_read_group(handle, event, enabled, running);
else
- perf_output_read_one(handle, event);
+ perf_output_read_one(handle, event, enabled, running);
}
void perf_output_sample(struct perf_output_handle *handle,
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