linux-kernel - Re: [RFC PATCH 1/5] numa: introduce per-cgroup numa balancing locality, statistic

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Message-ID: <b0148598-3a9c-d5d5-4c30-5bbb0f68145d@linux.alibaba.com>
Date:   Tue, 23 Apr 2019 17:14:53 +0800
From:   王贇 <yun.wang@...ux.alibaba.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     hannes@...xchg.org, mhocko@...nel.org, vdavydov.dev@...il.com,
        Ingo Molnar <mingo@...hat.com>, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org
Subject: Re: [RFC PATCH 1/5] numa: introduce per-cgroup numa balancing
 locality, statistic

On 2019/4/23 下午4:44, Peter Zijlstra wrote:
> 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.

Thanks for point out :-) not have to be 10, I think we can save first two
and make it PERCENT_0_29, already wrong enough if it drops below 30% and
it's helpless to know detail changes in this section.

Regards,
Michael Wang

>