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sched/deadline: Make update_curr_dl() more accurate 

rq->clock_task may be updated between the two calls of
rq_clock_task() in update_curr_dl(). Calling rq_clock_task() only
once makes it more accurate and efficient, taking update_curr() as
reference.

Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Wen Yang <wen.yang99@zte.com.cn>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Jiang Biao <jiang.biao2@zte.com.cn>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: zhong.weidong@zte.com.cn
Link: http://lkml.kernel.org/r/1517882148-44599-1-git-send-email-wen.yang99@zte.com.cn
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Wen Yang 2018-02-06 09:55:48 +08:00 committed by Ingo Molnar
parent 6a546c7e69
commit 6fe0ce1eb0
1 changed files with 4 additions and 2 deletions
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6
kernel/sched/deadline.c
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@ -1153,6 +1153,7 @@ static void update_curr_dl(struct rq *rq)
struct sched_dl_entity *dl_se = &curr->dl;
u64 delta_exec, scaled_delta_exec;
int cpu = cpu_of(rq);
u64 now;
if (!dl_task(curr) || !on_dl_rq(dl_se))
return;
@ -1165,7 +1166,8 @@ static void update_curr_dl(struct rq *rq)
* natural solution, but the full ramifications of this
* approach need further study.
*/
delta_exec = rq_clock_task(rq) - curr->se.exec_start;
now = rq_clock_task(rq);
delta_exec = now - curr->se.exec_start;
if (unlikely((s64)delta_exec <= 0)) {
if (unlikely(dl_se->dl_yielded))
goto throttle;
@ -1178,7 +1180,7 @@ static void update_curr_dl(struct rq *rq)
curr->se.sum_exec_runtime += delta_exec;
account_group_exec_runtime(curr, delta_exec);
curr->se.exec_start = rq_clock_task(rq);
curr->se.exec_start = now;
cgroup_account_cputime(curr, delta_exec);
sched_rt_avg_update(rq, delta_exec);