I have done similar testing of EM prediction codes, but G5 versus Xeon.
It is interesting to see your Opteron numbers because I'd been wondering
how it would perform. By the way, which Opteron chip (speed) are you
using?
One part of the codes I used is a large-matrix inversion. The 2 GHz G5
always out-performed the 3 GHz Xeon. Additionally, the G5 took a
smaller memory-bandwidth-hit than the Xeons. The inversion on a matrix
about 1.3 Gb in size required 78% longer (per process) with two large
processes running on two processors for the G5. The Xeon was 85% slower
in dual-processor mode. This really was a worst-case scenario, but
there is an obvious memory-bandwidth limitation (especially trying to
shove a > Gb data-set through the 6.5 GB/s memory pipe (for both
processors).
As far as the opteron goes... I wouldn't be surprised if there is a
slow-down depending on how the board is built, but on the AMD site, it
says the Opteron has a 19.2 GB/s bandwidth PER PROCESSOR.
-----Original Message-----
From: email@hidden
[mailto:email@hidden] On Behalf Of Sean C. Garrick
Sent: Thursday, January 22, 2004 6:46 PM
To: email@hidden
Subject: G5 bandwidth
I've been doing some more benchmarking using two homegrown CFD codes,
this time with Opterons and PPC-970s (G5).
Here is a typical single processor result :
Small memory code (110 MB): Time Opteron / Time G5 = 2.3
Opteron: 85 seconds
G5: 36 seconds
Large memory code (450MB) Time Opteron / Time G5 = 1.9
Opteron: 454 seconds
G5: 237 seconds
While the G5 is faster, the Opteron seems to have a better memory
access/bandwidth.
Also, I ran a job one job on the G5 using 1 processor and another
using 2 processors. The speed-up was only 50%. I did the same thing on
the Opteron and the speed-up was 83%!!!
I'm not sure what type of board the Opteron was built on but this is
very surprising as Apple was touting its motherboard as having the most
bandwidth. I think the performance is quite poor and I'm wondering its
worth getting 2 CPUs per board or just go with one?
Any ideas?
Thanks,
Sean
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References:
>G5 bandwidth (From: "Sean C. Garrick" <email@hidden>)
