Date: Fri, 24 Nov 2006 13:33:31 +0000
From: Alan <alan@lxorguk.ukuu.org.uk>
To: "Martin A. Fink" <fink@mpe.mpg.de>
Cc: linux-kernel@vger.kernel.org
Subject: Re: SATA Performance with Intel ICH6
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In-Reply-To: <200611241407.01210.fink@mpe.mpg.de>
References: <200611241407.01210.fink@mpe.mpg.de>
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On Fri, 24 Nov 2006 14:07:01 +0100
"Martin A. Fink" <fink@mpe.mpg.de> wrote:

> If I understand the design of this chipset correctly, then I would have
> expected, that the CPU needs to do only few work, instead I found out, that
> writing to disk seems to be really hard work for the CPU.

It has some work to do - the amount in question depends upon the file
system and device drivers in use. For very high throughput read up on
the O_DIRECT feature.

> My final aim is to get around 140MB/s of data from 3 different Gigabit
> Ethernet cards and store it on 3 harddisk drives that perform 50MB/s.
> >From the SATA bus side there should be no problem. Each of the 4 SATAs on
> this ICH6 chipset are capable of 150MB/s.

I doubt an ICH6 has the total memory bandwidth to achieve that to be
honest, but with PCI-E maybe you can.
 
> So what makes my CPU that slow? Is it a hardware problem or a problem of
> SATA driver of my operating system?

You don't give anything like enough information to even guess this. What
controller, what disks, what driver, what kernel version ?

> By the way: I'm working with SuSE Linux 9.2 on a Dell Desktop PC, 1GB RAM

For vendor kernels, especially older ones it is probably best to ask the
vendor first.

Alan

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