Messages in this thread | | | From | xiaoggchen(陈小光) <> | Subject | 答复: [PATCH] sched: don't check rq after new idle balance return positive(Internet mail) | Date | Wed, 16 Dec 2020 09:44:32 +0000 |
| |
-----邮件原件----- 发件人: Peter Zijlstra <peterz@infradead.org> 发送时间: 2020年12月15日 16:33 收件人: chenxg1x@gmail.com 抄送: linux-kernel@vger.kernel.org; mingo@redhat.com; juri.lelli@redhat.com; vincent.guittot@linaro.org; dietmar.eggemann@arm.com; rostedt@goodmis.org; bsegall@google.com; mgorman@suse.de; bristot@redhat.com; heddchen(陈贺) <heddchen@tencent.com>; xiaoggchen(陈小光) <xiaoggchen@tencent.com> 主题: Re: [PATCH] sched: don't check rq after newidle_balance return positive(Internet mail)
On Tue, Dec 15, 2020 at 02:48:50PM +0800, chenxg1x@gmail.com wrote: >> From: Chen Xiaoguang <xiaoggchen@tencent.com> >> >> In pick_next_task_fair, if CPU is going to idle newidle_balance is >> called first trying to pull some tasks. >> When newidle_balance returns positive which means it does pulls tasks >> or some tasks enqueued then there is no need to check >> sched_fair_runnable again.
> No, I think it actually does need to, because while it counts the number of tasks it pulled, it doesn't verify it still has them after it re-acquires rq->lock. That is, someone could've come along and stolen them > right from under our noses. Ah, yes, our change only make sense when pulling nothing in load_balance but some tasks enqueued this rq during the lock of this rq is released. Thanks.
>> >> Signed-off-by: He Chen <heddchen@tencent.com> >> Signed-off-by: Xiaoguang Chen <xiaoggchen@tencent.com>
> This SoB chain is broken. The first SoB should be the author, but From does not match. We will fix this next time.
| |