Re: How many hardware threads?

["Egil Høvik" <egilhovik@hotmail.com>]

On Jul 12, 2:47 am, "Peter C. Chapin" <pcc482...@gmail.com> wrote:
> As we all know there is currently a lot of "buzz" about parallel
> programming and about the "crisis in software development" that is
> associated with it. People using languages with weak support for
> concurrency are now wondering how they will use multi-core systems
> effectively and reliably. Of course Ada already has decent support for
> concurrency so part of the problem is solved for those of us using Ada.
>
> But not all of the problem...
>
> I see a couple of difficulties with writing effective parallel programs
> for "ordinary" applications (that is, applications that are not
> embarrassingly parallel). One difficulty is load balancing: how can one
> decompose a problem to keep all processors reasonably busy? The other
> difficulty is scalability: how can one design a single program that can
> use 2, 4, 16, 128, or more processors effectively without knowing ahead
> of time exactly how many processors there will be? I'm not an expert in
> Ada tasking but it seems like these questions are as big a problem for
> Ada as they are for any other language environment.
>
> I'm not looking for a solution to all tasking problems here. But there
> is one feature that seems like a necessary prerequisite to such a
> solution. The language (or its standard library) needs to provide a
> portable way for the program to determine how many hardware threads are
> available.
>
> I'm about to write a simple program that decomposes into parallel,
> compute-bound tasks quite nicely. How many such tasks should I create? I
> could ask the user to provide the number as a command line argument or
> in a configuration file. Yet it seems like the program should just be
> able to figure it out. Does Ada have a standard way of doing that? I
> didn't see anything in my (admittedly short) review.
>
> Thanks!
>
> Peter


Have a look at this proposal for Ada 2012:
http://www.ada-auth.org/cgi-bin/cvsweb.cgi/ai05s/ai05-0167-1.txt?rev=1.4

--
~egilhh