linux-kernel - Re: [RFC 3/4] mm, page_alloc: move cpuset seqcount checking to slowpath

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Message-ID: <372726f9-3bc9-217f-3bf5-c40d3e52a6b6@suse.cz>
Date:   Wed, 18 Jan 2017 10:26:34 +0100
From:   Vlastimil Babka <vbabka@...e.cz>
To:     Hillf Danton <hillf.zj@...baba-inc.com>,
        'Mel Gorman' <mgorman@...hsingularity.net>,
        'Ganapatrao Kulkarni' <gpkulkarni@...il.com>
Cc:     'Michal Hocko' <mhocko@...nel.org>, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org
Subject: Re: [RFC 3/4] mm, page_alloc: move cpuset seqcount checking to
 slowpath

On 01/18/2017 08:22 AM, Hillf Danton wrote:
> On Wednesday, January 18, 2017 6:16 AM Vlastimil Babka wrote:
>>
>> This is a preparation for the following patch to make review simpler. While
>> the primary motivation is a bug fix, this could also save some cycles in the
>> fast path.
>>
> This also gets kswapd involved.
> Dunno how frequent cpuset is changed in real life.

I don't think the extra kswapd wakeups due to retry_cpuset would be noticeable. 
Such frequent cpuset changes would likely have their own associated overhead 
larger than the wakeups.

>
> Hillf
>