From: Brian Hurt <bhurt@spnz.org>
To: "Brandon J. Van Every" <vanevery@indiegamedesign.com>
Cc: caml <caml-list@inria.fr>
Subject: Re: [Caml-list] Bigarray is a pig
Date: Fri, 23 Jul 2004 16:05:16 -0500 (CDT) [thread overview]
Message-ID: <Pine.LNX.4.44.0407231554230.4202-100000@localhost.localdomain> (raw)
In-Reply-To: <OOEALCJCKEBJBIJHCNJDIEIOHFAB.vanevery@indiegamedesign.com>
On Fri, 23 Jul 2004, Brandon J. Van Every wrote:
> I have been looking at the sources of the Bigarray implementation. I am
> chagrined to discover that not only does Bigarray cost a function call
> per array element access, but a number of additional piggish things
> happen per access.
If memory serves, Ocaml can optimize the access if the size and type are
known, getting rid of the function call overhead and type specialization.
I don't think it gets rid of the bounds checking, tho- which is good.
Can someone who actually knows what is going on clarify this?
> To C/C++ programmers interested in performance, this
> defeats the purpose of using unboxed array elements. If I wanted to pay
> function call overhead per element, for instance when communicating with
> OpenGL, I'd simply call functions.
Function calls aren't that expensive. From comments in other forums:
http://groups.google.com/groups?hl=en&lr=&ie=UTF-8&selm=cdjsuj%24cs6%241%40wolfberry.srv.cs.cmu.edu
may I respectfully suggest that you are prematurely optimizing? A
function call to a known function takes 1-2 clock cycles. A cache miss,
on the other hand, can take hundreds of clock cycles:
http://groups.google.com/groups?dq=&hl=en&lr=&ie=UTF-8&threadm=45022fc8.0407221624.6fd81ad0%40posting.google.com&prev=/groups%3Fhl%3Den%26lr%3D%26ie%3DUTF-8%26group%3Dcomp.arch
--
"Usenet is like a herd of performing elephants with diarrhea -- massive,
difficult to redirect, awe-inspiring, entertaining, and a source of
mind-boggling amounts of excrement when you least expect it."
- Gene Spafford
Brian
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next prev parent reply other threads:[~2004-07-23 20:57 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-07-23 20:36 Brandon J. Van Every
2004-07-23 21:05 ` Brian Hurt [this message]
2004-07-24 9:49 ` Brandon J. Van Every
2004-07-23 21:05 ` Olivier Andrieu
2004-07-24 9:07 ` Brandon J. Van Every
2004-07-24 9:59 ` Marcin 'Qrczak' Kowalczyk
2004-07-25 9:09 ` David McClain
2004-07-24 10:39 ` Markus Mottl
2004-07-23 21:45 ` David McClain
2004-07-23 22:01 ` David McClain
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