linux-kernel - Re: linux+glibc memory allocator, poor performance

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Date:	Wed, 12 Mar 2008 21:32:55 +0000
From:	Al Viro <viro@...IV.linux.org.uk>
To:	Rik van Riel <riel@...hat.com>
Cc:	"J.C. Pizarro" <jcpiza@...il.com>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: linux+glibc memory allocator, poor performance

On Wed, Mar 12, 2008 at 05:22:21PM -0400, Rik van Riel wrote:
> On Wed, 12 Mar 2008 21:09:04 +0100
> "J.C. Pizarro" <jcpiza@...il.com> wrote:
> 
> > Assume a SMP system that has 8 CPUs. The main problem of requesting
> > pages is the BKL (Big Kernel Lock) in this SMP system used for mutual
> > exclusion of the shared resource (the memory).
> > 
> > To solve this major problem, i propose you freely to allocate 8 local caches
> > of (e.g.) 2 MiB each CPU (total 2MiB x 8 CPUs = 16 MiB) acting as
> > 8 producer buffers for globally many consumer tasks (e.g. >= 20).
> > 
> > When the some producer buffer is empty then it does unfrequently BKL to
> > allocate another 2 MiB more from the shared resource (the memory).
> 
> You really should read the source code before proposing ideas.
> 
> The kernel has done roughly what you describe since a little before
> 2.6.0.

ITYM a little before 2.4.0, and even prior to that it hadn't been under BKL.
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