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Date:   Tue, 3 Dec 2019 08:16:15 +0100
From:   Ingo Molnar <mingo@kernel.org>
To:     =?utf-8?B?546L6LSH?= <yun.wang@linux.alibaba.com>
Cc:     Ingo Molnar <mingo@redhat.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Juri Lelli <juri.lelli@redhat.com>,
        Michal =?iso-8859-1?Q?Koutn=FD?= <mkoutny@suse.com>,
        Mel Gorman <mgorman@suse.de>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH RESEND] sched/numa: expose per-task
 pages-migration-failure
Message-ID: <20191203071615.GD115767@gmail.com>
References: <7038afda-dd08-f01f-5da0-afadf76f5533@linux.alibaba.com>
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* 王贇 <yun.wang@linux.alibaba.com> 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>
> Acked-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]);

Any reason not to expose the other 2 fields of this array as well, which 
show remote/local migrations?

Thanks,

	Ingo