Messages in this thread | | | Date | Thu, 25 Jun 1998 17:10:17 -0500 (CDT) | From | Robert HYATT <> | Subject | Re: quad ppro Compaq proliant 5000 problems with 2.1.106-ac4 was: Re: Any SMP people out there with SCSI CD ROMs? |
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On Thu, 25 Jun 1998, Scott Lampert wrote:
> > Robert HYATT wrote: > > > > > > I ran the matrix multiply benchmark... with 1, 2, 3 and 4 > > > processors. > > > > > > The numbers I got were 52 seconds, 59 seconds, 66 seconds and 73 seconds > > > > Hmmm... with four cpus the benchmark took 11 sec more then with 1 cpu ?? > > > > One might suppose you meant the times to be : > > > > 52/1 1 cpu > > 59/2 2 cpu > > 66/3 3 cpu > > 73/4 4 cpu > > > > Cheers... > > Umm.. I believe the difference is 23 seconds and I would imagine it to > be: > > 52 4 cpu > 59 3 cpu > 66 2 cpu > 73 1 cpu > > But I could be wrong. ;) >
No... the intent is to measure memory conflicts between the processors, since the PC bus is not exactly blazingly fast. I ran the same identical program one time, and it took 52 seconds. I ran two copies at the same time, and the time went up, reflecting the memory bottleneck. It gives a good idea of worst-case scaling for non-cache-friendly applications.
reasonable programs (which don't use 40mb arrays without a good blocking algorithm) don't see this degradation...
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