schedstat: consolidate per-task cpu runtime stats

Impact: simplify code

When we turn on CONFIG_SCHEDSTATS, per-task cpu runtime is accumulated
twice. Once in task->se.sum_exec_runtime and once in sched_info.cpu_time.
These two stats are exactly the same.

Given that task->se.sum_exec_runtime is always accumulated by the core
scheduler, sched_info can reuse that data instead of duplicate the accounting.

Signed-off-by: Ken Chen <kenchen@google.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 2 insertions, 0 deletions

diff --git a/kernel/sched.c b/kernel/sched.c
index f53e2b8ef521..fd835fc320b8 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -596,6 +596,8 @@ struct rq {
 #ifdef CONFIG_SCHEDSTATS
         /* latency stats */
         struct sched_info rq_sched_info;
+        unsigned long long rq_cpu_time;
+        /* could above be rq->cfs_rq.exec_clock + rq->rt_rq.rt_runtime ? */
 
         /* sys_sched_yield() stats */
         unsigned int yld_exp_empty;