Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Subject: Re: Re: Re: Re: [PATCH v1] sched/numa: add per-process numa_balancing
To:     Mel Gorman <mgorman@suse.de>
Cc:     Jonathan Corbet <corbet@lwn.net>, Ingo Molnar <mingo@redhat.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Juri Lelli <juri.lelli@redhat.com>,
        Vincent Guittot <vincent.guittot@linaro.org>,
        Dietmar Eggemann <dietmar.eggemann@arm.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Ben Segall <bsegall@google.com>,
        Daniel Bristot de Oliveira <bristot@redhat.com>,
        linux-api@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>,
        linux-fsdevel@vger.kernel.org, linux-doc@vger.kernel.org
References: <20211027132633.86653-1-ligang.bdlg@bytedance.com>
 <20211028153028.GP3891@suse.de>
 <b884ad7d-48d3-fcc8-d199-9e7643552a9a@bytedance.com>
 <20211029083751.GR3891@suse.de>
 <CAMx52ARF1fVH9=YLQMjE=8ckKJ=q3X2-ovtKuQcoTyo564mQnQ@mail.gmail.com>
 <20211109091951.GW3891@suse.de>
From:   Gang Li <ligang.bdlg@bytedance.com>
Message-ID: <7de25e1b-e548-b8b5-dda5-6a2e001f3c1a@bytedance.com>
Date:   Tue, 9 Nov 2021 18:40:43 +0800
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0)
 Gecko/20100101 Thunderbird/78.14.0
MIME-Version: 1.0
In-Reply-To: <20211109091951.GW3891@suse.de>
Content-Type: text/plain; charset=iso-8859-15; format=flowed
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Precedence: bulk

On 11/9/21 5:19 PM, Mel Gorman wrote:
> On Tue, Nov 09, 2021 at 04:28:28PM +0800, Gang Li wrote:
>> If the global tuning affects default behaviour and the prctl
>> affects specific behaviour.  Then when prctl specifies
>> numa_balancing for a process, there is no way for the
>> global tuning to affect that process.
> 
> While I think it's very likely that the common case will be to disable
> NUMA balancing for specific processes,
> prctl(PR_NUMA_BALANCING,PR_SET_NUMA_BALANCING,1) should still be
> meaningful.
> 

I'm still a bit confused.

If we really want to enable/disable numa_balancing for all processes, 
but some of them override the global numa_balancing using prctl, what 
should we do?

Do we iterate through these processes to enable/disable them individually?