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Date:   Tue, 23 Apr 2019 10:44:44 +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
Subject: Re: [RFC PATCH 1/5] numa: introduce per-cgroup numa balancing
 locality, statistic
Message-ID: <20190423084444.GB11158@hirez.programming.kicks-ass.net>
References: <209d247e-c1b2-3235-2722-dd7c1f896483@linux.alibaba.com>
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On Mon, Apr 22, 2019 at 10:11:24AM +0800, 王贇 wrote:
> +#ifdef CONFIG_NUMA_BALANCING
> +
> +enum memcg_numa_locality_interval {
> +	PERCENT_0_9,
> +	PERCENT_10_19,
> +	PERCENT_20_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,
> +};
> +
> +struct memcg_stat_numa {
> +	u64 locality[NR_NL_INTERVAL];
> +};

If you make that 8 it fits a single cacheline. Do you really need the
additional resolution? If so, then 16 would be the next logical amount
of buckets. 10 otoh makes no sense what so ever.