linux-kernel - Re: [PATCH] sched: Fix rq nr

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Message-ID: <Y/3B2CwI+RdoDt7T@debian.me>
Date:   Tue, 28 Feb 2023 15:56:56 +0700
From:   Bagas Sanjaya <bagasdotme@...il.com>
To:     zhenggy <zhenggy@...natelecom.cn>, mingo@...hat.com,
        peterz@...radead.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
Cc:     linux-kernel@...r.kernel.org
Subject: Re: [PATCH] sched: Fix rq nr_uninterruptible count

On Tue, Feb 28, 2023 at 03:08:58PM +0800, zhenggy wrote:
> When an uninterrptable task is queue to a differect cpu as where
> it is dequeued, the rq nr_uninterruptible will be incorrent, so
> fix it.

tl;dr (too much typos above). Would you like to "massage" the commit
mesage?

> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index 25b582b..cd5ef6e 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -4068,6 +4068,7 @@ bool ttwu_state_match(struct task_struct *p, unsigned int state, int *success)
>  {
>  	unsigned long flags;
>  	int cpu, success = 0;
> +	struct rq *src_rq, *dst_rq;
> 
>  	preempt_disable();
>  	if (p == current) {
> @@ -4205,6 +4206,16 @@ bool ttwu_state_match(struct task_struct *p, unsigned int state, int *success)
>  			atomic_dec(&task_rq(p)->nr_iowait);
>  		}
> 
> +		if (p->sched_contributes_to_load) {
> +			src_rq = cpu_rq(task_cpu(p));
> +			dst_rq = cpu_rq(cpu);
> +
> +			double_rq_lock(src_rq, dst_rq);
> +			src_rq->nr_uninterruptible--;
> +			dst_rq->nr_uninterruptible++;
> +			double_rq_unlock(src_rq, dst_rq);
> +		}
> +

Can you explain what the code above does to fix the problem you
mentioned above?

Thanks.

-- 
An old man doll... just what I always wanted! - Clara

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