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Date:   Thu, 11 Jul 2019 15:43:53 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     =?utf-8?B?546L6LSH?= <yun.wang@linux.alibaba.com>
Cc:     hannes@cmpxchg.org, mhocko@kernel.org, vdavydov.dev@gmail.com,
        Ingo Molnar <mingo@redhat.com>, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org, mcgrof@kernel.org, keescook@chromium.org,
        linux-fsdevel@vger.kernel.org, cgroups@vger.kernel.org,
        Mel Gorman <mgorman@suse.de>, riel@surriel.com
Subject: Re: [PATCH 1/4] numa: introduce per-cgroup numa balancing locality,
 statistic
Message-ID: <20190711134353.GB3402@hirez.programming.kicks-ass.net>
References: <209d247e-c1b2-3235-2722-dd7c1f896483@linux.alibaba.com>
 <60b59306-5e36-e587-9145-e90657daec41@linux.alibaba.com>
 <3ac9b43a-cc80-01be-0079-df008a71ce4b@linux.alibaba.com>
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On Wed, Jul 03, 2019 at 11:28:10AM +0800, 王贇 wrote:
> +#ifdef CONFIG_NUMA_BALANCING
> +
> +enum memcg_numa_locality_interval {
> +	PERCENT_0_29,
> +	PERCENT_30_39,
> +	PERCENT_40_49,
> +	PERCENT_50_59,
> +	PERCENT_60_69,
> +	PERCENT_70_79,
> +	PERCENT_80_89,
> +	PERCENT_90_100,
> +	NR_NL_INTERVAL,
> +};

That's just daft; why not make 8 equal sized buckets.

> +struct memcg_stat_numa {
> +	u64 locality[NR_NL_INTERVAL];
> +};

> +	if (remote || local) {
> +		idx = ((local * 10) / (remote + local)) - 2;

		idx = (NR_NL_INTERVAL * local) / (remote + local);

> +	}
> +
> +	rcu_read_lock();
> +	memcg = mem_cgroup_from_task(p);
> +	if (idx != -1)
> +		this_cpu_inc(memcg->stat_numa->locality[idx]);
> +	rcu_read_unlock();
> +}
> +#endif