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AW: [Caml-list] The tag bit
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Date: 2004-08-13 (15:44)
From: Christophe Raffalli <christophe.raffalli@u...>
Subject: Re: AW: [Caml-list] The tag bit
skaller wrote:
> On Fri, 2004-08-13 at 22:58, Christophe Raffalli wrote:
>>Does anyone have  a comparison between two identical GC except one 
>>should have a tag bit and the other be conservative ?
> The Boehm collector is quite efficient: if you compare it
> to hand written encodings such as reference counting
> for example.
> The main problem with it is that it has to 'stop the world'
> whilst it is doing its thing, and so isn't useful for
> real time applications such as a game where you can easily
> pay 20% of all CPU for the GC -- but you simply can't freeze
> up the game for 10 seconds every few minutes.
> The Ocaml generational collector is likely to be much better
> at this -- some of the workload is spread over time, and
> the remaining major collection when needed will also be
> faster, and can be called manually at appropriate points.
> A second point is -- Boehm cannot defragment memory.
> Ocaml can (although the compaction is 'world stop').
> So .. i don't think the 'overall CPU use' of the two collector
> kinds is actually what you need to compare: the real time
> performance and/or ability to operate with C/C++ code
> are the likely issues.
It is not true, on some configuration (including intel I think) Boehm's 
GC can be incremental. At least the documentation say so.
Christophe Raffalli
Université de Savoie
Batiment Le Chablais, bureau 21
73376 Le Bourget-du-Lac Cedex

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