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SubjectRe: quad ppro Compaq proliant 5000 problems with 2.1.106-ac4 was: Re: Any SMP people out there with SCSI CD ROMs?

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
if I recall correctly...

that benchmark is very memory-intensive not using cache very well at
all. I ran one copy, then two copies, etc... each extra copy added
about 7 seconds of cpu time, caused by memory bandwidth limits. This
machine uses 4-way interleaving, and seems to scale quite well. I
have a threaded application that can smoke all 4 cpus for hours and
it gets enough hash hits that I don't see any degradation at all when
I run 4 copies of this program, vs 1 copy, vs 1 copy with 4 threads...

So it appears to work quite well for me. I do have gross problems
with the pthread mutex stuff, so I don't use them, having resorted to
spinlocks for better performance.


Robert Hyatt Computer and Information Sciences
hyatt@cis.uab.edu University of Alabama at Birmingham
(205) 934-2213 115A Campbell Hall, UAB Station
(205) 934-5473 FAX Birmingham, AL 35294-1170

On Thu, 25 Jun 1998 linker@nightshade.ml.org wrote:

>
>
> On Wed, 24 Jun 1998, Arnaldo Carvalho de Melo wrote:
> [snip]
> > [mike@sckott mike]$ uname -a
> > Linux sckott 2.1.106 #1 SMP Tue Jan 19 03:14:07 2038 i686 unknown
> >
> >
> > - Arnaldo
>
> Were you having fun with the date or is something wrong?
>
> Think you could so some bencharks on how well linux does on a 4 cpu
> system? Few people use Linux on 4 cpu boxen, so performance numbers are
> hard to find. Linux performs very well on two cpu boxen.
>
> Because of this lack of data, there is more ammo for the FUD bringers.
> Several times I've heard that 'Linux only supports 2 cpus' or 'Linux
> doesnt scale well past two cpus'.
>
>


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