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Date: Fri, 25 Jun 2004 10:54:43 +0200
From: Helge Hafting <helge.hafting@hist.no>
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To: Yaroslav Halchenko <yoh@psychology.rutgers.edu>
CC: linux kernel mailing list <linux-kernel@vger.kernel.org>
Subject: Re: alienware hardware - memory problem?
References: <20040624191026.GP728@washoe.rutgers.edu> <200406242315.56213.vda@port.imtp.ilyichevsk.odessa.ua> <20040624202626.GS728@washoe.rutgers.edu> <200406242358.55782.vda@port.imtp.ilyichevsk.odessa.ua> <20040624212600.GW728@washoe.rutgers.edu> <20040624215856.GA728@washoe.rutgers.edu> <20040625000102.GI728@washoe.rutgers.edu>
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Yaroslav Halchenko wrote:

>because slow down seems to be linked to memory: brk(0) takes on average
>0.5-1.5 second, I've decided to run silly memtest...
>I have around 1GB total on that beast, I turned off swap and did memtest
>1G
>  
>
Memory.  Could it be the good old MTRR problem?
Try "cat /proc/mtrr" and check that _all_ ordinary memory
is covered by a write-back mtrr.

Having most of the memory covered lacking a little at the top only
is not good enough - you'll see a major slowdown as linux tend to
use the topmost memory most and that will be very slow without
a MTRR.

If it indeed is a mtrr problem, confirm it by booting with mem=<low number>
and see that the machine is faster when not using the "slow" memory.
After that, get a bios upgrade or echo something useable
into /proc/mtrr

Helge Hafting
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