Message-ID: <15bbfed1-5b7c-e6ff-07e9-9de3a0ee4728@bytedance.com>
Date:   Mon, 13 Dec 2021 14:49:48 +0800
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Subject: Re: [PATCH v3] sched/numa: add per-process numa_balancing
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To:     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>, Mel Gorman <mgorman@suse.de>,
        Daniel Bristot de Oliveira <bristot@redhat.com>
Cc:     linux-api@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-fsdevel@vger.kernel.org, linux-doc@vger.kernel.org
References: <20211206024530.11336-1-ligang.bdlg@bytedance.com>
From:   Gang Li <ligang.bdlg@bytedance.com>
In-Reply-To: <20211206024530.11336-1-ligang.bdlg@bytedance.com>
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Hi,
Any comments plz ;)

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@vger.kernel.org
> Signed-off-by: Gang Li <ligang.bdlg@bytedance.com>