* Re: 答复: Re: [RFC PATCH V5 5/5] workqueue: introduce a way to setworkqueue's scheduler
[not found] <201801291350022080675@zte.com.cn>
@ 2018-01-29 6:31 ` Mike Galbraith
0 siblings, 0 replies; only message in thread
From: Mike Galbraith @ 2018-01-29 6:31 UTC (permalink / raw)
To: wen.yang99
Cc: tj, zhong.weidong, jiang.biao2, tan.hu, jiangshanlai, xiaolong.ye,
linux-kernel
On Mon, 2018-01-29 at 13:50 +0800, wen.yang99@zte.com.cn wrote:
>
> > What happens when a new kworker needs to be spawned?
> create_worker -> worker_attach_to_pool, in the function
> worker_attach_to_pool， we add this chunk:
>
> --- a/kernel/workqueue.c
> +++ b/kernel/workqueue.c
> @@ -1699,6 +1699,7 @@ static void worker_attach_to_pool(struct worker *worker,
> * online CPUs. It'll be re-applied when any of the CPUs come up.
> */
> set_cpus_allowed_ptr(worker->task, pool->attrs->cpumask);
> + sched_setattr(worker->task, &pool->attrs->sched_attr);
>
> /*
> * The pool->attach_mutex ensures %POOL_DISASSOCIATED remains
>
> pool->attach_mutex may guarante it, add sched_setattr may apply the
> wq's sched_attr to the spawned kworer.
That doesn't help kthreadd get to a CPU in a box being saturated by RT.
As long as you are careful, it's not a problem, I just mentioned it
because it's a hole.
-Mike
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