linux-kernel - Re: Re: Re: Re: Re: Re: Re: Re: [PATCH v1] sched/numa: add per-process numa

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Message-ID: <20211118085819.GD3301@suse.de>
Date:   Thu, 18 Nov 2021 08:58:20 +0000
From:   Mel Gorman <mgorman@...e.de>
To:     Gang Li <ligang.bdlg@...edance.com>
Cc:     Jonathan Corbet <corbet@....net>, Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Juri Lelli <juri.lelli@...hat.com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Ben Segall <bsegall@...gle.com>,
        Daniel Bristot de Oliveira <bristot@...hat.com>,
        linux-api@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
        linux-fsdevel@...r.kernel.org, linux-doc@...r.kernel.org
Subject: Re: Re: Re: Re: Re: Re: Re: Re: [PATCH v1] sched/numa: add
 per-process numa_balancing

On Thu, Nov 18, 2021 at 11:26:30AM +0800, Gang Li wrote:
> On 11/17/21 6:10 PM, Mel Gorman wrote:
> > On Wed, Nov 17, 2021 at 05:38:28PM +0800, Gang Li wrote:
> > > If those APIs are ok with you, I will send v2 soon.
> > > 
> > > 1. prctl(PR_NUMA_BALANCING, PR_SET_THP_DISABLE);
> > 
> > It would be (PR_SET_NUMAB_DISABLE, 1)
> > 
> > > 2. prctl(PR_NUMA_BALANCING, PR_SET_THP_ENABLE);
> > 
> > An enable prctl will have the same problems as
> > prctl(PR_NUMA_BALANCING, PR_SET_NUMA_BALANCING, 0/1) -- it should have
> > meaning if the numa_balancing sysctl is disabled.
> > 
> > > 3. prctl(PR_NUMA_BALANCING, PR_GET_THP);
> > > 
> > 
> > PR_GET_NUMAB_DISABLE
> > 
> 
> How about this:
> 
> 1. prctl(PR_NUMA_BALANCING, PR_SET_NUMAB_DEFAULT); //follow global
> 2. prctl(PR_NUMA_BALANCING, PR_SET_NUMAB_DISABLE); //disable
> 3. prctl(PR_NUMA_BALANCING, PR_SET_NUMAB_ENABLE);  //enable

If PR_SET_NUMAB_ENABLE enables numa balancing for a task when
kernel.numa_balancing == 0 instead of returning an error then sure.

> 4. prctl(PR_NUMA_BALANCING, PR_GET_NUMAB);
> 
> PR_SET_NUMAB_DISABLE/ENABLE can always have meaning whether the
> numa_balancing sysctl is disabled or not,
> 
> -- 
> Thanks,
> Gang Li
> 

-- 
Mel Gorman
SUSE Labs