Re: [Caml-list] custom mmap modeled on bigarray

[Eric Stokes <eric.stokes@csun.edu>]

Even if it isn't it can be distributed as a GODI patch fairly easily. I 
think a patch such as this, if architected well
would allow me to improve performance of some of my C bindings even 
more, and that is a good thing.

On Aug 9, 2004, at 10:06 PM, Jack Andrews wrote:

> i know the argument for developing first, optimizing later.  i also 
> know
> the arguments for not caring about fine-grain performance and to look
> at the big picture.  i've argued both and seen where these arguments 
> fail.
>
> consider compressed data as a bit stream from disk.
> say it has simple encoding:
>  phrase :=
>   byte:<number-of-bits>, byte:<number-of-values>, int[]:<bit-stream>
> eg:
>   0x03 0x0a 0b1110 0011 1001 0100   1110 0101 1101 1100
>   |    |    +<bit-stream>
>   |    +number-of-values
>   +number-of-bits
>
> represents the sequence of 10 3-bit numbers:
>
>  111,000,111,001,010,011,100,101,110,111
>
> now consider a sentence as
>   sentence := <empty> | phrase, sentence
>
> without an enhanced FFI, ocaml will be considerably slower than C for
> uncompressing (and compressing).
>
> in my previous post, i suggest that some language primitives similar to
> %bigarray_ref_1 could be introduced to make ocaml comparable to C.  i
> have investigated this possibility, and my suggestion is that
> %bigarray_ref is replaced by a primitive %ffi_ref and made public.
> then bigarray can be built on the more general %ffi_ref and developers
> have a fast means of accessing C arrays like mmap regions.
>
> if i spend time implementing %ffi_ref/set, is there any chance of it 
> being
> incorporated into ocaml?
>
> thanks,
>
>
>
> jack
>
>
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