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Re: tools to convert debian sarge to 16K page size

To: Fuxin Zhang <fxzhang@ict.ac.cn>
Subject: Re: tools to convert debian sarge to 16K page size
From: Ralf Baechle <ralf@linux-mips.org>
Date: Fri, 10 Mar 2006 16:38:36 +0000
Cc: Thiemo Seufer <ths@networkno.de>, Linux/MIPS Development <linux-mips@linux-mips.org>
In-reply-to: <44118268.5030109@ict.ac.cn>
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On Fri, Mar 10, 2006 at 09:43:04PM +0800, Fuxin Zhang wrote:

> Thiemo Seufer 写道:
> > Can you provide information about the performance impact? That is,
> > what system(s) you use, and some basic benchmark numbers. Did you also
> > try 64k pages?
> The system is running debian sarge,with a mips like Chinese 4-way
> superscalar CPU and marvell 64240 system bridge, 256M sdram.Maybe
> related information: this CPU has 64K 4-way dcache/icache,so cache
> alias exists with 4K configuration.
> 
> Big page size helps a bit with at least computational programs, such as
> SPEC CPU2000 benchmarks. The attached jpg is a graph showing the results
> of some SPEC programs under different page sizes. But we have not
> benchmarked other workloads. 16K page size is used mainly to avoid cache
> alias, which caused us too much time.
> 
> Yes, with 64k more patches needed(some "short" field overflow?I don't
> remember the exact modifications,other guys did it)

There is more to large pages than just improved performance.  They'll
also save 75% memory for mem_map, will eleminate cache aliases in a
bulletproof way.  And will make allocation of memory larger than 4kB
reliable - this especially is a big bonus with ethernet jumboframes with
some NICs.

  Ralf

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