[Shootout-list] Re: Yes! Re: Dual CPU machine?

[Shae Matijs Erisson]

John Skaller <skaller@users.sourceforge.net> writes:

> So am I .. do you have ANY simplish C programs that benefit significantly?

Are simplish C programs important for a baseline?

> Semantically perhaps, but there is no way to 'simulate' a performance
> measurement based on a real time clock, without making the kind of
> assumptions which the benchmarks would actually be checking.

I wonder if valgrind or other lightweight cpu simulator could still simulate
multiple CPUs and also give a far more accurate profile of the benchmarks.

> Ocaml, for example, can spawn threads, but they cannot 
> be concurrent (there is a global lock to protect the garbage
> collector which isn't thread-safe).

Haskell's GHC is just gaining the ability for a single program to use multiple
processors, but I wouldn't expect a tremendous gain since the implementation
isn't finished, much less tuned. I am very interested in techniques to tune
data localization. For example, I wonder how much distributed garbage
collection affects speed in NUMA systems, that sort of stuff.

> OTOH many problems can easily be divided between processes and use message
> passing -- numerical problems are typical, where there is a very expensive
> calculation on a small amount of data.

I'm interested in exactly the opposite of that. 
I want to measure parallelization without manual labor.

> Indeed .. but you'll need a 32 CPU machine to test do the measurements .. the
> year after next we'll surely have 4 core CPUs .. :)

The STI Cell has 9 cores in a 'single core' design, and the roadmap goes up to
64 'single cores' on a chip. I look forward to 576 physical cores on a chip.
(Especially since I know I can afford to buy a two-socket motherboard every two
years or so.) Because of that, I want to know how a single program can scale.
-- 
It seems I've been living two lives. One life is a self-employed web developer
In the other life, I'm shapr, functional programmer.  | www.ScannedInAvian.com
One of these lives has futures (and subcontinuations!)|  --Shae Matijs Erisson