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

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Message-ID: <201807311112492239674@zte.com.cn>
Date:   Tue, 31 Jul 2018 11:12:49 +0800 (CST)
From:   <cheng.lin130@....com.cn>
To:     <peterz@...radead.org>
Cc:     <mingo@...hat.com>, <linux-kernel@...r.kernel.org>,
        <jiang.biao2@....com.cn>, <zhong.weidong@....com.cn>,
        <tan.hu@....com.cn>
Subject: 答复: 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.

"isolcpus" is "[Deprecated - use cpusets instead]" in the lastest kernel(4.18).

Before 4.15, the option "isolcpus" is "the preferred way to isolate CPUs". 

Although it is "Deprecated",  but we also can use it in the lastest kernel. 

And now a large number of “isolcpus” are using in the old way. Whether NUMA-balancing 

should consider the “isolcpus” for forward compatibility? Or in some branches?
<div class="zcontentRow"><p>&gt;On&nbsp;Thu,&nbsp;Jul&nbsp;26,&nbsp;2018&nbsp;at&nbsp;04:19:08PM&nbsp;+0800,&nbsp;Cheng&nbsp;Lin&nbsp;wrote:<br></p><div><div class="zhistoryRow" style="display:block"><div id="zwriteHistoryContainer"><div class="control-group zhistoryPanel"><div class="zhistoryContent">&gt;&gt;&nbsp;-&nbsp;&nbsp;&nbsp;&nbsp;if&nbsp;(!cpumask_test_cpu(arg.dst_cpu,&nbsp;&amp;arg.src_task-&gt;cpus_allowed))<br>&gt;&gt;&nbsp;+&nbsp;&nbsp;&nbsp;&nbsp;if&nbsp;((!cpumask_test_cpu(arg.dst_cpu,&nbsp;&amp;arg.src_task-&gt;cpus_allowed))<br>&gt;&gt;&nbsp;+&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;||&nbsp;!housekeeping_test_cpu(arg.dst_cpu,&nbsp;HK_FLAG_DOMAIN))<br>&gt;&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;goto&nbsp;out;<br>&gt;<br>&gt;You&nbsp;did&nbsp;not&nbsp;read&nbsp;the&nbsp;comment&nbsp;I&nbsp;provided&nbsp;last&nbsp;time.&nbsp;Using&nbsp;isolcpus&nbsp;(and<br>&gt;thus&nbsp;it's&nbsp;renamed&nbsp;houskeeping&nbsp;thing)&nbsp;is&nbsp;the&nbsp;wrong&nbsp;thing&nbsp;to&nbsp;do.&nbsp;Load<br>&gt;balancing&nbsp;should&nbsp;be&nbsp;limited&nbsp;to&nbsp;it's&nbsp;root&nbsp;domain.</div></div></div></div></div><p style="line-height: 21px; white-space: normal;"><br></p><p style="line-height: 21px; white-space: normal;">"isolcpus" is "[Deprecated - use cpusets instead]" in the lastest kernel(4.18).</p><p style="line-height: 21px; white-space: normal;">Before 4.15, the option "isolcpus" is "the preferred way to isolate CPUs".&nbsp;</p><p style="line-height: 21px; white-space: normal;"><br></p><p style="line-height: 21px; white-space: normal;">Although it is "Deprecated", &nbsp;but we also can use it in the lastest kernel.&nbsp;</p><p style="line-height: 21px; white-space: normal;">And now a large number of “isolcpus” are using in the old way. Whether NUMA-balancing&nbsp;</p><p style="line-height: 21px; white-space: normal;">should consider the “isolcpus” for forward compatibility? Or in some branches?</p><p><br></p></div>