linux-kernel - Re: [PATCH v3] sched/numa: add per-process numa

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Message-ID: <cf52d7d3-e7f8-2b4e-a752-8be8d95b31fb@bytedance.com>
Date:   Thu, 6 Jan 2022 16:08:35 +0800
From:   Gang Li <ligang.bdlg@...edance.com>
To:     Mel Gorman <mgorman@...e.de>
Cc:     linux-api@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-fsdevel@...r.kernel.org, linux-doc@...r.kernel.org,
        songmuchun@...edance.com, zhengqi.arch@...edance.com
Subject: Re: [PATCH v3] sched/numa: add per-process numa_balancing

Hi,
Any comments please?

;)

On 2021/12/6 10:45, Gang Li wrote:
> This patch add a new api PR_NUMA_BALANCING in prctl.
> 
> A large number of page faults will cause performance loss when numa
> balancing is performing. Thus those processes which care about worst-case
> performance need numa balancing disabled. Others, on the contrary, allow a
> temporary performance loss in exchange for higher average performance, so
> enable numa balancing is better for them.
> 
> Numa balancing can only be controlled globally by
> /proc/sys/kernel/numa_balancing. Due to the above case, we want to
> disable/enable numa_balancing per-process instead.
> 
> Add numa_balancing under mm_struct. Then use it in task_tick_fair.
> 
> Set per-process numa balancing:
> 	prctl(PR_NUMA_BALANCING, PR_SET_NUMAB_DISABLE); //disable
> 	prctl(PR_NUMA_BALANCING, PR_SET_NUMAB_ENABLE);  //enable
> 	prctl(PR_NUMA_BALANCING, PR_SET_NUMAB_DEFAULT); //follow global
> Get numa_balancing state:
> 	prctl(PR_NUMA_BALANCING, PR_GET_NUMAB, &ret);
> 	cat /proc/<pid>/status | grep NumaB_enabled
> 
> Cc: linux-api@...r.kernel.org
> Signed-off-by: Gang Li <ligang.bdlg@...edance.com>
> ---
> 
> Changes in v3:
> - Fix compile error.
> 
> Changes in v2:
> - Now PR_NUMA_BALANCING support three states: enabled, disabled, default.
>    enabled and disabled will ignore global setting, and default will follow
>    global setting.
-- 
Thanks
Gang Li