Re: [ON TOPIC] HELP: Getting lousy memory throughput from Abit KD7

From: Dave Jones <davej@codemonkey.org.uk>
To: Timothy Miller <miller@techsource.com>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [ON TOPIC] HELP:  Getting lousy memory throughput from Abit KD7
Date: Tue, 22 Jul 2003 22:04:01 +0100	[thread overview]
Message-ID: <20030722210401.GA6952@suse.de> (raw)
In-Reply-To: <3F1D8EAB.6020801@techsource.com>

On Tue, Jul 22, 2003 at 03:21:15PM -0400, Timothy Miller wrote:
 > This suggests to me that there is one of these possibilities which is 
 > contributing to the poor performance under Linux:
 > 
 > 1) Linux is not programming the KT400 chipset properly and is thus not 
 > getting the throughput it could.

Linux doesn't do any chipset specific tuning.

 > 2) SANDRA uses instructions (SSE, etc) which are able to access memory 
 > more efficiently than whatever STREAM is using.

very likely. its the only way to really saturate the bus.

 > 3) SANDRA inflates its scores to make people feel better.

unlikely.

 > 4) Linux has not properly set up the CPU caches.

Linux doesn't do anything with CPU caches.

 > What I want to know is this:
 > Am I getting realistic throughput for what STREAM does?

I'm unfamiliar with STREAM, so cannot comment

 > What is SANDRA doing that lets it get such high scores when STREAM does not?

Is this even an apples to apples comparison? If not, it's irrelevant.

		Dave