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Date: Mon, 29 Dec 2003 18:25:36 -0500
From: "David B. Stevens" <dsteven3@maine.rr.com>
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To: Thomas Molina <tmolina@cablespeed.com>
CC: Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: 2.6.0 performance problems
References: <Pine.LNX.4.58.0312291647410.5288@localhost.localdomain> <Pine.LNX.4.58.0312291420370.1586@home.osdl.org> <Pine.LNX.4.58.0312291755080.5835@localhost.localdomain>
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Thomas,

Have you tried lowering the read ahead in 2.6 to 8.

I don't know what you are doing with your workload but it is possible 
that you are transferring useless data and clogging the plumbing a bit.

Cheers,
  Dave



Thomas Molina wrote:

>It certainly looks like DMA is enabled.  Under 2.4 I get:
>
>[root@lap root]# hdparm /dev/hda
>
>/dev/hda:
> multcount    = 16 (on)
> IO_support   =  1 (32-bit)
> unmaskirq    =  1 (on)
> using_dma    =  1 (on)
> keepsettings =  0 (off)
> readonly     =  0 (off)
> readahead    =  8 (on)
> geometry     = 2584/240/63, sectors = 39070080, start = 0
>
>
>Under 2.6  I get:
>
>[root@lap root]# hdparm /dev/hda
>
>/dev/hda:
> multcount    = 16 (on)
> IO_support   =  1 (32-bit)
> unmaskirq    =  1 (on)
> using_dma    =  1 (on)
> keepsettings =  0 (off)
> readonly     =  0 (off)
> readahead    = 256 (on)
> geometry     = 38760/16/63, sectors = 39070080, start = 0
>  
>