linux-kernel - Re: [PATCH v2] sched/numa: do not balance tasks onto isolated cpus

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Message-ID: <20180727074851.GY2494@hirez.programming.kicks-ass.net>
Date:   Fri, 27 Jul 2018 09:48:51 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Cheng Lin <cheng.lin130@....com.cn>
Cc:     mingo@...hat.com, linux-kernel@...r.kernel.org,
        jiang.biao2@....com.cn, zhong.weidong@....com.cn,
        tan.hu@....com.cn.cn
Subject: Re: [PATCH v2] sched/numa: do not balance tasks onto isolated cpus

On Thu, Jul 26, 2018 at 04:19:08PM +0800, Cheng Lin wrote:
> -	if (!cpumask_test_cpu(arg.dst_cpu, &arg.src_task->cpus_allowed))
> +	if ((!cpumask_test_cpu(arg.dst_cpu, &arg.src_task->cpus_allowed))
> +		|| !housekeeping_test_cpu(arg.dst_cpu, HK_FLAG_DOMAIN))
>  		goto out;

You did not read the comment I provided last time. Using isolcpus (and
thus it's renamed houskeeping thing) is the wrong thing to do. Load
balancing should be limited to it's root domain.