Yes very dissappointing bandwidth.
Probably the simple logics is that in a dual machine, 2 memory controllers
is always
faster than 1.
http://www.cs.virginia.edu/stream/stream_mail/2005/0020.html
2x 2.8Ghz opteron
-------------------------------------------------------------
Function Rate (MB/s) Avg time Min time Max time
Copy: 9368.0362 0.0039 0.0043 0.0043
Scale: 9206.1106 0.0040 0.0043 0.0047
Add: 9457.6361 0.0057 0.0063 0.0064
Triad: 9499.4051 0.0057 0.0063 0.0064
----- Original Message -----
From: "Mark Hahn" <[EMAIL PROTECTED]>
To: "Jason Holmes" <[EMAIL PROTECTED]>
Cc: <beowulf@beowulf.org>
Sent: Monday, August 14, 2006 8:04 PM
Subject: Re: [Beowulf] Woodcrest Memory bandwidth
Here's a 4 core Woodcrest system with 4 sticks of 2 GB 667 MHz FB-dimms:
Function Rate (MB/s) Avg time Min time Max time
Copy: 4813.2590 0.2663 0.2659 0.2675
Scale: 4826.2181 0.2656 0.2652 0.2662
Add: 5244.0135 0.3664 0.3661 0.3669
Triad: 5244.3106 0.3665 0.3661 0.3671
This was a pathscale compiled stream executable with openmp using 4
threads.
kinda sucks, doesn't it? here's what I get for a not-new dual-275 with
8x1G PC3200 (I think):
Function Rate (MB/s) RMS time Min time Max time
Copy: 5714.6837 0.0840 0.0840 0.0841
Scale: 5821.0766 0.0825 0.0825 0.0826
Add: 6437.8226 0.1119 0.1118 0.1120
Triad: 6414.2079 0.1123 0.1123 0.1124
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