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authorStephane Eranian <eranian@google.com>2010-10-20 15:25:01 +0200
committerIngo Molnar <mingo@elte.hu>2010-10-22 14:18:27 +0200
commitd7842da470f244d258f21c5f72cd8388b3541d04 (patch)
tree02196f905f3c27ab9dfc85b26dbb32348d943d60 /kernel/perf_event.c
parent9ffcfa6f1f63eeac15555b745c292eb9f59130f6 (diff)
downloadop-kernel-dev-d7842da470f244d258f21c5f72cd8388b3541d04.zip
op-kernel-dev-d7842da470f244d258f21c5f72cd8388b3541d04.tar.gz
perf_events: Fix for transaction recovery in group_sched_in()
This new version (see commit 8e5fc1a) is much simpler and ensures that in case of error in group_sched_in() during event_sched_in(), the events up to the failed event go through regular event_sched_out(). But the failed event and the remaining events in the group have their timings adjusted as if they had also gone through event_sched_in() and event_sched_out(). This ensures timing uniformity across all events in a group. This also takes care of the tstamp_stopped problem in case the group could never be scheduled. The tstamp_stopped is updated as if the event had actually run. With this patch, the following now reports correct time_enabled, in case the NMI watchdog is active: $ task -e unhalted_core_cycles,instructions_retired,baclears,baclears noploop 1 noploop for 1 seconds 0 unhalted_core_cycles (100.00% scaling, ena=997,552,872, run=0) 0 instructions_retired (100.00% scaling, ena=997,552,872, run=0) 0 baclears (100.00% scaling, ena=997,552,872, run=0) 0 baclears (100.00% scaling, ena=997,552,872, run=0) And the older test case also works: $ task -einstructions_retired,baclears,baclears -e unhalted_core_cycles,baclears,baclears sleep 5 1680885 instructions_retired (69.39% scaling, ena=950756, run=291006) 10735 baclears (69.39% scaling, ena=950756, run=291006) 10735 baclears (69.39% scaling, ena=950756, run=291006) 0 unhalted_core_cycles (100.00% scaling, ena=817932, run=0) 0 baclears (100.00% scaling, ena=817932, run=0) 0 baclears (100.00% scaling, ena=817932, run=0) Signed-off-by: Stephane Eranian <eranian@google.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <4cbeeebc.8ee7d80a.5a28.0d5f@mx.google.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/perf_event.c')
-rw-r--r--kernel/perf_event.c22
1 files changed, 20 insertions, 2 deletions
diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 39afdb0..517d827 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -691,6 +691,8 @@ group_sched_in(struct perf_event *group_event,
{
struct perf_event *event, *partial_group = NULL;
struct pmu *pmu = group_event->pmu;
+ u64 now = ctx->time;
+ bool simulate = false;
if (group_event->state == PERF_EVENT_STATE_OFF)
return 0;
@@ -719,11 +721,27 @@ group_error:
/*
* Groups can be scheduled in as one unit only, so undo any
* partial group before returning:
+ * The events up to the failed event are scheduled out normally,
+ * tstamp_stopped will be updated.
+ *
+ * The failed events and the remaining siblings need to have
+ * their timings updated as if they had gone thru event_sched_in()
+ * and event_sched_out(). This is required to get consistent timings
+ * across the group. This also takes care of the case where the group
+ * could never be scheduled by ensuring tstamp_stopped is set to mark
+ * the time the event was actually stopped, such that time delta
+ * calculation in update_event_times() is correct.
*/
list_for_each_entry(event, &group_event->sibling_list, group_entry) {
if (event == partial_group)
- break;
- event_sched_out(event, cpuctx, ctx);
+ simulate = true;
+
+ if (simulate) {
+ event->tstamp_running += now - event->tstamp_stopped;
+ event->tstamp_stopped = now;
+ } else {
+ event_sched_out(event, cpuctx, ctx);
+ }
}
event_sched_out(group_event, cpuctx, ctx);
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