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Subject: Re: [PATCH v2 2/3] sched/numa: expose per-task
 pages-migration-failure
From:   =?UTF-8?B?546L6LSH?= <yun.wang@linux.alibaba.com>
To:     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>,
        Luis Chamberlain <mcgrof@kernel.org>,
        Kees Cook <keescook@chromium.org>,
        Iurii Zaikin <yzaikin@google.com>,
        =?UTF-8?Q?Michal_Koutn=c3=bd?= <mkoutny@suse.com>,
        linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-doc@vger.kernel.org,
        "Paul E. McKenney" <paulmck@linux.ibm.com>
References: <743eecad-9556-a241-546b-c8a66339840e@linux.alibaba.com>
 <207ef46c-672c-27c8-2012-735bd692a6de@linux.alibaba.com>
 <3931bf05-2939-0499-7660-8cc9a6f71c9a@linux.alibaba.com>
Message-ID: <c63e9e2c-ea9e-3f61-734c-afa3b92cd5bb@linux.alibaba.com>
Date:   Mon, 2 Dec 2019 10:22:15 +0800
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Hi, Peter,

This has been acked by Mel Gorman, since it is not much related
with the rest patches, would you like to pick this one now?

Regards,
Michael Wang

On 2019/11/27 上午9:50, 王贇 wrote:
> NUMA balancing will try to migrate pages between nodes, which
> could caused by memory policy or numa group aggregation, while
> the page migration could failed too for eg when the target node
> run out of memory.
> 
> Since this is critical to the performance, admin should know
> how serious the problem is, and take actions before it causing
> too much performance damage, thus this patch expose the counter
> as 'migfailed' in '/proc/PID/sched'.
> 
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Michal Koutný <mkoutny@suse.com>
> Suggested-by: Mel Gorman <mgorman@suse.de>
> Signed-off-by: Michael Wang <yun.wang@linux.alibaba.com>
> ---
>  kernel/sched/debug.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
> index f7e4579e746c..73c4809c8f37 100644
> --- a/kernel/sched/debug.c
> +++ b/kernel/sched/debug.c
> @@ -848,6 +848,7 @@ static void sched_show_numa(struct task_struct *p, struct seq_file *m)
>  	P(total_numa_faults);
>  	SEQ_printf(m, "current_node=%d, numa_group_id=%d\n",
>  			task_node(p), task_numa_group_id(p));
> +	SEQ_printf(m, "migfailed=%lu\n", p->numa_faults_locality[2]);
>  	show_numa_stats(p, m);
>  	mpol_put(pol);
>  #endif
>