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From: Kumar Gala <galak@kernel.crashing.org>
Subject: Re: [PATCH] ppc44x: support for 256K PAGE_SIZE
Date: Fri, 19 Oct 2007 10:48:01 -0500
To: Yuri Tikhonov <yur@emcraft.com>
Cc: linuxppc-dev@ozlabs.org, Paul Mackerras <paulus@samba.org>
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On Oct 19, 2007, at 10:37 AM, Yuri Tikhonov wrote:

> On Friday 19 October 2007 03:21, Paul Mackerras wrote:
>> Have you measured the performance using a 64kB page size?  If so, how
>> does it compare with the 256kB page size?
>
>  I measured the performance of the sequential full-stripe write  
> operations to
> a RAID-5 array (P values below are in MB per second) using the h/w  
> accelerated
> RAID-5 driver.
>
>  Here are the comparative results for the different PAGE_SIZE values:
>
> PAGE_SIZE = 4K:
>  P = 66 MBps;
>
> PAGE_SIZE = 16K:
>  P = 145 MBps;
>
> PAGE_SIZE = 64K:
>  P = 196 MBps;
>
> PAGE_SIZE = 256K:
>  P = 217 MBps.

Is this all in kernel space? or is there a user space aspect to the  
benchmark?

>> The 64kB page size has the attraction that no binutils changes are
>> required.
>
>  That's true, but the additional performance is an attractive thing  
> too.

- k