Messages in this thread Patch in this message | | | From | kosaki.motohiro@gmail ... | Subject | [PATCH 09/10] sched: task_sched_runtime introduce micro optimization | Date | Mon, 29 Apr 2013 23:17:17 -0400 |
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From: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
rq lock in task_sched_runtime() is necessary for two reasons. 1) accessing se.sum_exec_runtime is inatomic on 32bit and 2) do_task_delta_exec() require it.
And then, 64bit can avoid holds rq lock when add_delta is false.
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> --- kernel/sched/core.c | 6 ++++++ 1 files changed, 6 insertions(+), 0 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index b817e6d..24ba1c6 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -2657,6 +2657,12 @@ unsigned long long task_sched_runtime(struct task_struct *p, bool add_delta) struct rq *rq; u64 ns = 0; + /* Micro optimization. */ +#ifdef CONFIG_64BIT + if (!add_delta) + return p->se.sum_exec_runtime; +#endif + rq = task_rq_lock(p, &flags); ns = p->se.sum_exec_runtime; if (add_delta) -- 1.7.1
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