Re: [PATCH] sched: don't check rq after newidle_balance return positive

[Peter Zijlstra]

On Tue, Dec 15, 2020 at 02:48:50PM +0800, chenxg1x@xxxxxxxxx wrote:
> From: Chen Xiaoguang <xiaoggchen@xxxxxxxxxxx>
> 
> 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.

> 
> Signed-off-by: He Chen <heddchen@xxxxxxxxxxx>
> Signed-off-by: Xiaoguang Chen <xiaoggchen@xxxxxxxxxxx>

This SoB chain is broken. The first SoB should be the author, but From
does not match.