linux-kernel - Re: [PATCH 1/3] slub: set a criteria for slub node partial adding

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Message-ID: <1322825802.2607.10.camel@edumazet-laptop>
Date:	Fri, 02 Dec 2011 12:36:42 +0100
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Alex Shi <alex.shi@...el.com>
Cc:	cl@...ux.com, penberg@...nel.org, linux-kernel@...r.kernel.org,
	linux-mm@...ck.org
Subject: Re: [PATCH 1/3] slub: set a criteria for slub node partial adding

Le vendredi 02 décembre 2011 à 16:23 +0800, Alex Shi a écrit :
> From: Alex Shi <alexs@...el.com>
> 
> Times performance regression were due to slub add to node partial head
> or tail. That inspired me to do tunning on the node partial adding, to
> set a criteria for head or tail position selection when do partial
> adding.
> My experiment show, when used objects is less than 1/4 total objects
> of slub performance will get about 1.5% improvement on netperf loopback
> testing with 2048 clients, wherever on our 4 or 2 sockets platforms,
> includes sandbridge or core2.
> 
> Signed-off-by: Alex Shi <alex.shi@...el.com>
> ---
>  mm/slub.c |   18 ++++++++----------
>  1 files changed, 8 insertions(+), 10 deletions(-)
> 

netperf (loopback or ethernet) is a known stress test for slub, and your
patch removes code that might hurt netperf, but benefit real workload.

Have you tried instead this far less intrusive solution ?

if (tail == DEACTIVATE_TO_TAIL ||
    page->inuse > page->objects / 4)
         list_add_tail(&page->lru, &n->partial);
else
         list_add(&page->lru, &n->partial);



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