[computer-go] Library of Effective GO routines v 0.106

[Łukasz Lew]

A whole benchmark fits in L1 cache.

But maybe somehow hyperthreading is involved.
I will investigate.

Thanks,
Łukasz

On 2/22/07, Nick Apperson <apperson at gmail.com> wrote:
> if cache is your limiting factor that is usually shared.  Also, if you are
> using processors with hyperthreading, it is possible.  Or if bus bandwidth
> is your limiting factor... but if it is exactly 2x slower that is indeed
> very odd.  My money is on the fact that you have a bottleneck somewhere else
> and those processors were operating below capacity the whole time and that
> now that you added more, it is becoming more obvious.  If for instance, you
> had the following situation:
>
> thread A creates a queue of tasks for the rest of the threads to do.  If
> thread A isn't able to keep the queue full, then obviously more processors
> won't help.
>
> The only other though I have is that your compiler isn't writing code that
> allows for proper multithreading.  Can you be more specific on which
> processors are giving you a hard time?
>
> - Nick
>
>
> On 2/22/07, Łukasz Lew <lukasz.lew at gmail.com> wrote:
> > I do not understand it. Maybe someone does?
> > I've made some tests on 2 core processors, and I have strange results.
> > Some of 2 core processors got results exactly 2x times worse than they
> should.
> > Why?
> > I have no idea.
> > But 2.8 Ghz 2 core works exactly like my 1.4 laptop.
> >
> >
> > Also version of g++ does matter.
> > Łukasz
> >
> > On 2/21/07, Brian Slesinsky <brian at slesinsky.org> wrote:
> > > The only real change is to link against the Boost libraries I
> > > installed using DarwinPorts.  Here are the diffs:
> > >
> > > -CFLAGS += -Wall #-static #-Wno-long-long -Wextra -Wno-variadic-macros
> > > +CFLAGS += -Wall -I/opt/local/include -L/opt/local/lib
> > >
> > > It's a desktop and I don't see any options for power management.
> > > Maybe it's just a difference in processors?  It's a two core chip but
> > > perhaps not as fast at single-threaded apps.  Adding multithreading
> > > might help.
> > >
> > > - Brian
> > >
> > > On 2/21/07, Łukasz Lew <lukasz.lew at gmail.com> wrote:
> > > > On 2/21/07, Brian Slesinsky < brian at slesinsky.org> wrote:
> > > > > [resending; apologies if you get this twice.]
> > > > >
> > > > > Hi,
> > > >
> > > > Hi Brian,
> > > >
> > > > >
> > > > > This is my first post to the list, so I'll introduce myself:   I'm a
> > > > > software developer and just getting started with playing Go.  I read
> > > > > the article in the Economist and thought that the work on
> Monte-Carlo
> > > > > based Go programs sounds promising.  I'm not interested in writing
> my
> > > > > own Go program but would like to experiment with improving existing
> > > > > programs.
> > > >
> > > > Have fun ;)
> > > >
> > > > >
> > > > > I built and started libego on an iMac with a 2GHz Intel Core Duo.
> The
> > > > > initial benchmark reports these results:
> > > > >
> > > > > Performance:
> > > > >   100000 playouts
> > > > >   1.84255 seconds
> > > > >   54.2727 kpps
> > > > > Black wins = 43983
> > > > > White wins = 56017
> > > > > P(black win) = 0.43983
> > > > >
> > > > > Are these numbers to be expected?
> > > >
> > > > They are correct, except rather low performance.
> > > > It should be rather about 80 kpps (kilo playouts per second)
> > > >
> > > > There are few possible reasons for this:
> > > >  - You are using a laptop with power management
> > > >   - You changed Makefile or some source files to make it compile on
> Mac?
> > > >
> > > > Best Regards,
> > > > Łukasz Lew
> > > >
> > > > >
> > > > > - Brian
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