RE: [Bug-gnubg] Re: Getting gnubg to use all available cores

[Ingo Macherius]

Do you use the calibrate command or a batch analysis of matchfiles? The
former was shown to be of no value for benchmarks, see here:
http://lists.gnu.org/archive/html/bug-gnubg/2009-08/msg00006.html

With calibrate I had the very same effect of high idle times during
benchmarks, unless I used at least 8 threads per physical core.

I am doing benchmark on a 4 core machine which iterates over #thread (1..6)
and cache size (2^1 .. 2^27). Should be posted in say 3 hours, it literally
is still running :)

Ingo

> -----Original Message-----
> From: address@hidden 
> [mailto:address@hidden On 
> Behalf Of Louis Zulli
> Sent: Thursday, August 06, 2009 3:21 PM
> To: Michael Petch
> Cc: address@hidden
> Subject: [Bug-gnubg] Re: Getting gnubg to use all available cores
> 
> 
> 
> On Aug 5, 2009, at 4:02 PM, Michael Petch wrote:
> 
> > I'm unsure how the architecture is deployed and how OS/X 
> handles the 
> > physical cores, but it almost sounds like one Physical core is being
> > used
> > (Using Hyperthreads to run 2 threads simultaneously). I wonder if  
> > the memory
> > is shared across all the cores? A friend of mine was 
> suggesting that  
> > people
> > may have to wait for Snow Lapard to come out before OS/X properly  
> > utilizes
> > the Nehalem architecture (whetehr that si true or not, I 
> don't know).
> >
> > Anyway, as an experiment. If you run 2 copies of Gnubg at the same
> > time
> > (using multiple threads) do you get 400% CPU usage?
> >
> 
> 
> Hi Mike,
> 
> Sorry for the delay. I just had two copies of gnubg analyze the same  
> game, using 3 ply analysis. Each instance of gnubg used 200% 
> CPU. Each  
> copy was set to use 4 evaluation threads.
> 
> So what's the verdict here? Is Leopard simply not directing threads  
> correctly?
> 
> Louis
> 
> 
> 
> 
> 
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