Re: [PATCH 1/3] mm/slub: fix the race between validate_slab and slab_free

From: Christoph Lameter <cl@gentwo.de>
To: Rongwei Wang <rongwei.wang@linux.alibaba.com>
Cc: David Rientjes <rientjes@google.com>,
	songmuchun@bytedance.com, Hyeonggon Yoo <42.hyeyoo@gmail.com>,
	akpm@linux-foundation.org, vbabka@suse.cz,
	roman.gushchin@linux.dev, iamjoonsoo.kim@lge.com,
	penberg@kernel.org, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/3] mm/slub: fix the race between validate_slab and slab_free
Date: Mon, 13 Jun 2022 15:50:46 +0200 (CEST)	[thread overview]
Message-ID: <alpine.DEB.2.22.394.2206131548420.295113@gentwo.de> (raw)
In-Reply-To: <02298c0e-3293-9deb-f1ed-6d8862f7c349@linux.alibaba.com>

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