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From: Jon Harrop <jonathandeanharrop@googlemail.com>
To: "'Fabrice Le Fessant'" <Fabrice.Le_fessant@inria.fr>
Cc: <caml-list@inria.fr>
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Date: Tue, 19 Apr 2011 23:47:48 +0100
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Subject: RE: [Caml-list] Efficient OCaml multicore -- roadmap?

Fabrice wrote:
> Well, Java has fully multi-threaded garbage collection, so there is no point that it
> is possible to do it.
> 
> The problem is that it has a cost, and the cost is a huge slowdown on mono-
> threaded programs.

Lucas says "zero". You say "huge". Can we do a better job of quantifying this? Where do you believe the slowdown would come from? Given that GC intensive OCaml programs can spend 30% of their time in the GC, do you not think it might be possible to improve performance by exploiting more cores? Can you give example code that you would expect to be adversely affected the most by a multi-threaded runtime?

Cheers,
Jon.