linux-kernel - Re: [RFC Patch 3/3] mm/slub: setup maxim per-node partial according to cpu numbers

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Message-ID: <ZQPmFcmaRSrbK45H@feng-clx>
Date:   Fri, 15 Sep 2023 13:05:25 +0800
From:   Feng Tang <feng.tang@...el.com>
To:     "Lameter, Christopher" <cl@...amperecomputing.com>
CC:     Hyeonggon Yoo <42.hyeyoo@...il.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Pekka Enberg <penberg@...nel.org>,
        David Rientjes <rientjes@...gle.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Roman Gushchin <roman.gushchin@...ux.dev>,
        <linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [RFC Patch 3/3] mm/slub: setup maxim per-node partial according
 to cpu numbers

On Thu, Sep 14, 2023 at 07:40:22PM -0700, Lameter, Christopher wrote:
> On Thu, 14 Sep 2023, Feng Tang wrote:
> 
> > One reason I wanted to revisit the MIN_PARTIAL is, it was changed from
> > 2 to 5 in 2007 by Christoph, in commit 76be895001f2 ("SLUB: Improve
> > hackbench speed"), the system has been much huger since then.
> > Currently while a per-cpu partial can already have 5 or more slabs,
> > the limit for a node with possible 100+ CPU could be reconsidered.
> 
> Well the trick that I keep using in large systems with lots of memory is to
> use huge page sized page allocation. The applications on those already are
> using the same page size. Doing so usually removes a lot of overhead and
> speeds up things significantly.
> 
> Try booting with "slab_min_order=9"

Thanks for sharing the trick! I tried and it works here. But this is
kind of extreme and fit for some special use case, and these patches
try to be useful for generic usage.

Thanks,
Feng