linux-kernel - Re: [PATCH sched_ext/for-6.11] sched_ext: Reverting @p->sched

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Message-ID: <cd3fa16d-5a70-4c85-a591-fa4fa481f50b@huawei.com>
Date: Wed, 17 Jul 2024 10:01:13 +0800
From: "Zhangqiao (2012 lab)" <zhangqiao22@...wei.com>
To: Tejun Heo <tj@...nel.org>
CC: <void@...ifault.com>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH sched_ext/for-6.11] sched_ext: Reverting @p->sched_class
 if @p->disallow is set



在 2024/7/17 4:48, Tejun Heo 写道:
> Hello,
>
> On Tue, Jul 16, 2024 at 07:32:09PM +0800, Zhangqiao (2012 lab) wrote:
>> 在 2024/7/12 2:57, Tejun Heo 写道:
>>> On Thu, Jul 11, 2024 at 07:07:20PM +0800, Zhangqiao (2012 lab) wrote:
>>> ...
>>>>    		if (p->policy == SCHED_EXT) {
>>>>    			p->policy = SCHED_NORMAL;
>>>> +			p->sched_class = &fair_sched_class;
>>>>    			atomic_long_inc(&scx_nr_rejected);
>>> Did you see any issues with the existing implementation? The policy is set
>>> before the task is attached, so it should work fine. Also, you can't change
>>> sched_class by just assigning to it.
>> What does "attach" mean? I'm not sure. p->sched_class is assigned in
>> __sched_fork() which is performed before scx_ops_init_task().
> Ah, I see what you mean. I was referring to the classs switching operations
> in scx_ops_enable(). You're looking at the fork path. I don't think we can

Yes, i was referring to the fork path.

> switch sched_class at that point and the .disallow mechanism is there to
> allow the scheduler to filter out tasks on scheduler start. I'll update the
> code so that .disallow is only allowed during the initial attach.
>
> Thanks.
>