linux-kernel - Re: [PATCH 1/3] mm/slub: fix the race between validate_slab and slab

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Message-ID: <alpine.DEB.2.22.394.2206131548420.295113@gentwo.de>
Date:   Mon, 13 Jun 2022 15:50:46 +0200 (CEST)
From:   Christoph Lameter <cl@...two.de>
To:     Rongwei Wang <rongwei.wang@...ux.alibaba.com>
cc:     David Rientjes <rientjes@...gle.com>, songmuchun@...edance.com,
        Hyeonggon Yoo <42.hyeyoo@...il.com>, akpm@...ux-foundation.org,
        vbabka@...e.cz, roman.gushchin@...ux.dev, iamjoonsoo.kim@....com,
        penberg@...nel.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/3] mm/slub: fix the race between validate_slab and
 slab_free

On Sat, 11 Jun 2022, Rongwei Wang wrote:

> > Ok so the idea is to take the lock only if kmem_cache_debug. That looks
> > ok. But it still adds a number of new branches etc to the free loop.
> >
> > Some performance tests would be useful.
> Hi Christoph
>
> Thanks for your time!
> Do you have some advice in benchmarks that need me to test? And I find that
> hackbench and lkp was used frequently in mm/slub.c commits[1,2]. But I have no
> idea how to use these two benchmarks test to cover the above changes. Can you
> give some examples? Thanks very much!


Hi Rongwei,

Well run hackbench with an without the change.

There are also synthetic benchmarks available  at
https://gentwo.org/christoph/slub/tests/

These measure the cycles that slab operations take. However, they are a
bit old and I think Pekka may have a newer version of these
patches.

Greetings,
	Christoph