linux-kernel - Re: [PATCH v4 00/22] slab: replace cpu (partial) slabs with sheaves

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Message-ID: <imzzlzuzjmlkhxc7hszxh5ba7jksvqcieg5rzyryijkkdhai5q@l2t4ye5quozb>
Date: Thu, 29 Jan 2026 23:18:54 +0800
From: Hao Li <hao.li@...ux.dev>
To: Vlastimil Babka <vbabka@...e.cz>
Cc: Harry Yoo <harry.yoo@...cle.com>, Petr Tesarik <ptesarik@...e.com>, 
	Christoph Lameter <cl@...two.org>, David Rientjes <rientjes@...gle.com>, 
	Roman Gushchin <roman.gushchin@...ux.dev>, Andrew Morton <akpm@...ux-foundation.org>, 
	Uladzislau Rezki <urezki@...il.com>, "Liam R. Howlett" <Liam.Howlett@...cle.com>, 
	Suren Baghdasaryan <surenb@...gle.com>, Sebastian Andrzej Siewior <bigeasy@...utronix.de>, 
	Alexei Starovoitov <ast@...nel.org>, linux-mm@...ck.org, linux-kernel@...r.kernel.org, 
	linux-rt-devel@...ts.linux.dev, bpf@...r.kernel.org, kasan-dev@...glegroups.com, 
	kernel test robot <oliver.sang@...el.com>, stable@...r.kernel.org, "Paul E. McKenney" <paulmck@...nel.org>
Subject: Re: [PATCH v4 00/22] slab: replace cpu (partial) slabs with sheaves

Hi Vlastimil,

I conducted a detailed performance evaluation of the each patch on my setup.

During my tests, I observed two points in the series where performance
regressions occurred:

    Patch 10: I noticed a ~16% regression in my environment. My hypothesis is
    that with this patch, the allocation fast path bypasses the percpu partial
    list, leading to increased contention on the node list.

    Patch 12: This patch seems to introduce an additional ~9.7% regression. I
    suspect this might be because the free path also loses buffering from the
    percpu partial list, further exacerbating node list contention.

These are the only two patches in the series where I observed noticeable
regressions. The rest of the patches did not show significant performance
changes in my tests.

I hope these test results are helpful.

-- 
Thanks,
Hao