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Regarding SMP computing
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Date: 2006-09-25 (19:42)
From: Richard Jones <rich@a...>
Subject: Re: [Caml-list] Regarding SMP computing
On Mon, Sep 25, 2006 at 08:13:50AM -0400, Jacques Carette wrote:
> Over on Haskell-cafe, Simon Peyton-Jones says:
> "GHC 6.6 (release candidate available) supports parallel execution on 
> SMP machines.
> Garbage collection is not parallelised yet, something we plan to fix
> this autumn."
> A bit of competition is a good thing, isn't it?

Can someone explain how/if this is better than using MPI for
parallelism?  The reason I ask is that we are starting to use MPI for
real on SMP machines to process our larger datasets.

On a related note, is/could there be a way in OCaml to tell the GC not
to bother going "into" a particular data structure to check if it part
of it has become unreachable?  Our Weblogs library[1] loads a whole
set of log files into memory (multiple gigabytes of memory), basically
stored in a big linked list with lots of smaller structures hanging
off each element, and I *know* that the hanging elements will never
become unreachable unless the main linked list does so.  I'd like to
be able to tell the runtime that.  Otherwise every time we do a major
collection it's going to be uselessly iterating over the whole lot,
and that appears to have particularly bad consequences as soon as we
start to go into swap.



Richard Jones, CTO Merjis Ltd.
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