Subject: Re: Slow Xeon Performance
To: Matthew Orgass <darkstar@city-net.com>
From: Bryan Vyhmeister <bsd@hub3.net>
List: port-i386
Date: 08/31/2003 01:16:10
> On 2003-08-30 bsd@hub3.net wrote:
> 
> > It makes a good bit of sense that it could be the issue. Now the
> > question is how does it get fixed? Thank you so much for your help.
> 
>   Did you check the BIOS for cache settings?

Thank you for reminding me. I forgot to go check that setting. The Cache
setting in the BIOS had the following options: Disabled, Write-Thru,
Write-Back, and Reserved. It was on Write-Thru. I just changed it to
Reserved and it is suddenly noticeably faster. I ran heapsort just to be
sure and here is the output:


   Heap Sort C Program
   Version 1.0, 04 Oct 1992

   Size of long (bytes): 4

   Array Size    RunTime      Scale    MIPS
    (bytes)       (sec)
         8000     0.0004     0.4202 1158.31
        16000     0.0008     0.9087 1170.32
        32000     0.0016     1.9536 1191.45
        64000     0.0035     4.1799 1193.44
       128000     0.0072     8.9025 1243.49
       256000     0.0151    18.8884 1249.20
       512000     0.0328    39.9503 1218.93
      1024000     0.0823    84.2432 1023.96
      2048000     0.2055   177.1721  862.13

   Runtime is the average for 1 iteration.
   High MIPS =  1249.20
   Low  MIPS =   862.13


I included the pre-Cache heapsort output below for reference:


   Heap Sort C Program
   Version 1.0, 04 Oct 1992

   Size of long (bytes): 4

   Array Size    RunTime      Scale    MIPS
    (bytes)       (sec)
         8000     0.0087     0.4202   48.19
        16000     0.0192     0.9087   47.23
        32000     0.0402     1.9536   48.62
        64000     0.0900     4.1799   46.46
       128000     0.1929     8.9025   46.15
       256000     0.4133    18.8884   45.70
       512000     0.8734    39.9503   45.74
      1024000     1.8513    84.2432   45.51
      2048000     3.8544   177.1721   45.97

   Runtime is the average for 1 iteration.
   High MIPS =    48.62
   Low  MIPS =    45.51


That is a huge difference. Thank you so much for your help. It is great
to have the machine functioning properly. Thanks again!!

Bryan