Re: [Caml-list] Slow GC problem

[Shivkumar Chandrasekaran <shiv@ece.ucsb.edu>]

This seems to be confirmed by some modifications I did to the code. I 
was able to reduce a whole lot of temporary bigarray allocations and 
got a 30% speed improvement. However any further reduction of bigarray 
creation will require a major "add-on" modification to my entire 
library design, or, memory re-use hacks all over the place. So I would 
like to be reasonably sure that this is worth-while before I proceed.

On Tuesday, April 8, 2003, at 03:28 AM, Damien Doligez wrote:

> On Monday, April 7, 2003, at 07:53 PM, Shivkumar Chandrasekaran wrote:
>
>> Pursuing my earlier enquiry: I noticed that module Bigarray allocated 
>> its arrays using "malloc" rather than on the ocaml heap. My problem 
>> allocates a lot (say 100,000) bigarrays of rather small size (say 30 
>> x 30). Can this potentially increase the cost of gc? (I have this 
>> mental picture of the ocaml heap fragmented by these immovable 
>> malloc'd bigarrays.) Any help will be appreciated. Thanks,
>
> It doesn't matter.  The ocaml heap is allocated in big chunks from 
> malloc,
> and other malloc blocks cannot interfere with its fragmentation.
>
> If your program is allocating lots of temporary bigarrays and leaves 
> them
> to be collected by the GC, then I would say it's using bigarrays in an
> inefficient way.  Bigarrays are mostly designed to be long-lived 
> objects.
> If you can find a way to re-use your bigarrays instead of allocating 
> new
> ones, you should get better performance.
>
> -- Damien
>
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--shiv--

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