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From: "Jeffrey R. Carter" <spam.not.jrcarter@acm.not.spam.org>
Subject: Re: question about tasks, multithreading and multi-cpu machines
Date: Fri, 17 Mar 2006 19:42:17 GMT
Date: 2006-03-17T19:42:17+00:00	[thread overview]
Message-ID: <tiESf.626472$084.467989@attbi_s22> (raw)
In-Reply-To: <dvdrjt$3rb$1@sunnews.cern.ch>

Maciej Sobczak wrote:
> 
> Consider a simple example of two long vectors that need to be added. In 
> the simplest case you do this:
> 
>    for I in Vector'Range loop
>       V3(I) := V1(I) + V2(I);
>    end loop;
> 
> and you're done.

No, in all cases you should do

V3 := V1 + V2;

with an appropriate definition of "+" (which may be similar to your example).

> Now, assume that you want to target dual-CPU machine and you *know* that 
> you could greatly benefit from making things in paraller.

Then this is part of your requirements, and should be reflected in your design 
and implementation.

Incidentally, the English word is "parallel".

The interesting problem is writing portable code that takes advantage of N 
processors (N = 1, 2, 3, ...), with N unknown until run time.

-- 
Jeff Carter
"The time has come to act, and act fast. I'm leaving."
Blazing Saddles
36



  parent reply	other threads:[~2006-03-17 19:42 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-03-14 16:26 question about tasks, multithreading and multi-cpu machines Norbert Caspari
2006-03-14 16:51 ` Pascal Obry
2006-03-16  4:27   ` Norbert Caspari
2006-03-16 10:04     ` Alex R. Mosteo
2006-03-14 17:18 ` Jean-Pierre Rosen
2006-03-16  4:22   ` Norbert Caspari
2006-03-16  6:58     ` Jean-Pierre Rosen
2006-03-14 18:49 ` Martin Krischik
2006-03-14 18:56 ` tmoran
2006-03-14 23:01 ` Jeffrey Creem
2006-03-15  1:15   ` Jeffrey R. Carter
2006-03-16  8:06   ` Maciej Sobczak
2006-03-16 10:23     ` Ole-Hjalmar Kristensen
2006-03-16 12:59     ` Dmitry A. Kazakov
2006-03-16 15:11       ` Larry Kilgallen
2006-03-16 15:50       ` Maciej Sobczak
2006-03-16 18:03         ` Jean-Pierre Rosen
2006-03-16 20:06           ` Dr. Adrian Wrigley
2006-03-17  3:26       ` Randy Brukardt
2006-03-16 20:06     ` Jeffrey R. Carter
2006-03-17  8:22       ` Maciej Sobczak
2006-03-17 11:36         ` Dmitry A. Kazakov
2006-03-17 14:23           ` Maciej Sobczak
2006-03-17 19:10             ` Dmitry A. Kazakov
2006-03-17 19:42         ` Jeffrey R. Carter [this message]
2006-03-18  0:27           ` tmoran
2006-03-25 21:28     ` Robert A Duff
     [not found]       ` <43gb22h4811ojjh308r2lqf5qqrujijjok@4ax.com>
2006-03-26  0:44         ` Robert A Duff
2006-03-15  6:46 ` Simon Wright
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