linux-kernel - Re: [External] Re: [PATCH] sched/core: Avoid selecting the task that is throttled to run when core-sched enable

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Date:   Tue, 21 Mar 2023 14:16:54 +0800
From:   Hao Jia <jiahao.os@...edance.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     mingo@...hat.com, mingo@...nel.org, juri.lelli@...hat.com,
        vincent.guittot@...aro.org, dietmar.eggemann@....com,
        rostedt@...dmis.org, bsegall@...gle.com, mgorman@...e.de,
        bristot@...hat.com, vschneid@...hat.com,
        mgorman@...hsingularity.net, linux-kernel@...r.kernel.org,
        Cruz Zhao <CruzZhao@...ux.alibaba.com>
Subject: Re: [External] Re: [PATCH] sched/core: Avoid selecting the task that
 is throttled to run when core-sched enable



On 2023/3/20 Peter Zijlstra wrote:
> On Thu, Mar 16, 2023 at 04:18:06PM +0800, Hao Jia wrote:
> 
>> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
>> index af017e038b48..27cb06e19b12 100644
>> --- a/kernel/sched/core.c
>> +++ b/kernel/sched/core.c
>> @@ -261,36 +261,51 @@ void sched_core_dequeue(struct rq *rq, struct task_struct *p, int flags)
>>   		resched_curr(rq);
>>   }
>>   
>> +static int sched_task_is_throttled(struct task_struct *p, int cpu)
>>   {
>> +	if (p->sched_class->task_is_throttled)
>> +		return p->sched_class->task_is_throttled(p, cpu);
>>   
>> +	return 0;
>>   }
>>   
>>   static struct task_struct *sched_core_next(struct task_struct *p, unsigned long cookie)
>>   {
>>   	struct rb_node *node = &p->core_node;
>> +	int cpu = task_cpu(p);
>> +
>> +	do {
>> +		node = rb_next(node);
>> +		if (!node)
>> +			return NULL;
>> +
>> +		p = container_of(node, struct task_struct, core_node);
> 
> I've changed this to __node_2_sc() to match the rest. It looks to have
> been randomly not using it.

OK, Thanks!
> 
>> +		if (p->core_cookie != cookie)
>> +			return NULL;
>> +	} while (sched_task_is_throttled(p, cpu));
>> +
>> +	return p;
>> +}
>>   
>> +/*
>> + * Find left-most (aka, highest priority) and unthrottled task matching @cookie.
>> + * If no suitable task is found, NULL will be returned.
>> + */
>> +static struct task_struct *sched_core_find(struct rq *rq, unsigned long cookie)
>> +{
>> +	struct task_struct *p;
>> +	struct rb_node *node;
>> +
>> +	node = rb_find_first((void *)cookie, &rq->core_tree, rb_sched_core_cmp);
>>   	if (!node)
>>   		return NULL;
>>   
>> +	p = __node_2_sc(node);
>> +	if (!sched_task_is_throttled(p, rq->cpu))
>> +		return p;
>> +
>> +	return sched_core_next(p, cookie);
>>   }
>>   
>>   /*
> 
> OK, fair enough.

Thanks for your review. Do I need to modify to send V2 patch?

Thanks,
Hao
> 
>