perf/core: Update cgroup time with descendants

From: "leilei.lin" <[email protected]>

This fix updating cgroup time when event is being scheduled in by cgroup descendants

Signed-off-by leilei.lin <[email protected]>

---
 kernel/events/core.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

kernel/events/core.c +3 -2

index 3e691b7..6f6bd1e 100644
@@ -662,7 +662,9 @@ static inline void update_cgrp_time_from_event(struct perf_event *event)
        /*
         * Do not update time when cgroup is not active
         */
-       if (cgrp == event->cgrp)
+       if (cgrp == event->cgrp ||
+               cgroup_is_descendant(cgrp->css.cgroup,
+                       event->cgrp->css.cgroup))
                __update_cgrp_time(event->cgrp);
 }
 
--

2.8.4.31.g9ed660f

Add steps of reproducing

1

```
mkdir /sys/fs/cgroup/perf_event/root1
mkdir /sys/fs/cgroup/perf_event/root1/leaf1
```
2  $pid is any running process
```
echo $pid > /sys/fs/cgroup/perf_event/root1/cgroup.procs
```

3

```
perf stat -e cycles -G root1 -a -I 1000
```

You shall get 0 cycles from it, which should have been cycles of $pid

2017-09-14 15:03 GMT+08:00 <[email protected]>:

Quoted 10 lines

From: "leilei.lin" <[email protected]>

This fix updating cgroup time when event is being scheduled in by cgroup descendants

Signed-off-by leilei.lin <[email protected]>

---
 kernel/events/core.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

kernel/events/core.c static inline void update_cgrp_time_from_event(struct perf_event *event) · line 668

Quoted 13 lines

kernel/events/core.c +3 -1

index 3e691b7..6f6bd1e 100644
@@ -662,7 +662,9 @@ static inline void update_cgrp_time_from_event(struct perf_event *event)
        /*
         * Do not update time when cgroup is not active
         */
-       if (cgrp == event->cgrp)
+       if (cgrp == event->cgrp ||
+               cgroup_is_descendant(cgrp->css.cgroup,
+                       event->cgrp->css.cgroup))
                __update_cgrp_time(event->cgrp);