linux-kernel - Re: [PATCH v5 6/9] slub: Delay freezing of partial slabs

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Date:   Wed, 22 Nov 2023 15:32:50 +0100
From:   Vlastimil Babka <vbabka@...e.cz>
To:     Chengming Zhou <chengming.zhou@...ux.dev>,
        Mark Brown <broonie@...nel.org>
Cc:     cl@...ux.com, penberg@...nel.org, rientjes@...gle.com,
        iamjoonsoo.kim@....com, akpm@...ux-foundation.org,
        roman.gushchin@...ux.dev, 42.hyeyoo@...il.com, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org,
        Chengming Zhou <zhouchengming@...edance.com>,
        Matthew Wilcox <willy@...radead.org>
Subject: Re: [PATCH v5 6/9] slub: Delay freezing of partial slabs

On 11/22/23 15:28, Chengming Zhou wrote:
> 
> Yes, it looks so. There are some background services on the 128 CPUs machine.
> Although "stress-ng --rawpkt 128 --rawpkt-ops 100000000" has so much regression,
> I tried other less contented testcases:
> 
> 1. stress-ng --rawpkt 64 --rawpkt-ops 100000000
> 2. perf bench sched messaging -g 5 -t -l 100000
> 
> The performance numbers of this atomic version are pretty much the same.
> 
> So this atomic version should be good in most cases IMHO.

OK will fold the fix using full atomic version.

>>> And I also tested the atomic-optional version like below, found the
>>> performance numbers are much stable.
>> 
>> This gets rather ugly and fragile so I'd maybe rather go back to the
>> __unused field approach :/
>> 
> 
> Agree. If we don't want this atomic version, the __unused field approach
> seems better.
> 
> Thanks!
>