[Rd] Some timings for 64 bit Opteron (ATLAS, GOTO, std)

[Liaw, Andy]

My understanding is far below `imperfect'!  However, our box has all 8 slots
filled with 2GB PC2100s...  Not a whole lot of room for change.

Best,
Andy

> From: rossini at blindglobe.net [mailto:rossini at blindglobe.net] 
> 
> And my understanding is completely imperfect, but note that
> organization (and selection) of memory modules on the motherboard can
> be critical for speed with the opterons; well known issue on the
> beowulf lists.
> 
> best,
> -tony
> 
> Peter Dalgaard <p.dalgaard at biostat.ku.dk> writes:
> 
> > "Liaw, Andy" <andy_liaw at merck.com> writes:
> >
> >> Hi Martin,
> >> 
> >> When I attended the LinuxWorld Expo in NYC back in 
> January, I chatted with
> >> some folks at the AMD booth, as well as guys from Penguin 
> Computing (where
> >> we bought our Opteron box).  I was told that the Operton 
> has this somewhat
> >> strange setup that the memory is controlled by one CPU.  
> The net effect of
> >> this being that when both CPUs are running, one might only 
> be running at
> >> around 90% instead of 99%.  The `NUMA' kernel is supposed 
> to fix this
> >> problem.  I wonder if this is related to the performance 
> of the threaded
> >> GOTO lib that you saw.  Has anyone tried the NUMA kernel?
> >> 
> >> Best,
> >> Andy
> >
> > My understanding is slightly different (I could be wrong though, I'm
> > hardly a hardware engineer): Each CPU controls one block of memory,
> > and only some motherboard have memory slots for both CPUs. If CPU2
> > wants to talk to CPU1's memory it has to ask CPU1 for it, with the
> > obvious potential for a performance hit.
> >
> > I'll see if I can get around to redoing my Opteron builds and trying
> > Martin's benchmarks in the next couple of days.
> >
> >         -p
> >
> > -- 
> >    O__  ---- Peter Dalgaard             Blegdamsvej 3  
> >   c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
> >  (*) \(*) -- University of Copenhagen   Denmark      Ph: 
> (+45) 35327918
> > ~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)             FAX: 
> (+45) 35327907
> >
> -- 
> rossini at u.washington.edu            
> http://www.analytics.washington.edu/ 
> Biomedical and Health 
> Informatics   University of Washington
> Biostatistics, SCHARP/HVTN          Fred Hutchinson Cancer 
> Research Center
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