The ability to utilize multiple cores in a single application to speed up
execution depends mainly on the design of the application.  If the
application was designed to consist of a "mother" process and multiple
"daughter" processes then you can multiprocess in hardware.  The mother
initializes the environment, manages memory heaps, and schedules daughter
tasks to execute.  In the mainframe world we say the mother "attaches"
sub-processes, in Unix-based OSes we say it "forks" its sub-processes.  The
idea is the same: you have multiple daughters that compete for processor
resources.  I might create an application that has a user component, a
database component, and some report generating process.  In theory my mother
task can fork off all three and pass work between them all.  When a mouse
click causes the user interface to fetch a new screen and there's a
processor available, then both the mother task and the daughter can each
execute on separate CPUs (assuming a duo-core).  Likewise, the DB and report
generator can both utilize the two processors.  In a single processor
environment all subtasks must single thread through the processor.  

Net result is that an application designed for multitasking can make great
use of a multiple CPU computer.  The reality is that most personal computer
applications were designed to single thread on a single CPU.  To answer your
question another way, if the application was designed in anticipation of
multiple hardware CPUs, you can see a significant speed up in throughput.
It all depends on the underlying application design.  
-Mike

__________________
Michel David Lowe
Purcellville, VA
-----Original Message-----
From: Computer Guys Announcements and Discussion List
[mailto:[EMAIL PROTECTED] On Behalf Of Wayne Dernoncourt
Sent: Monday, April 30, 2007 3:28 PM
To: [email protected]
Subject: [CGUYS] multi-core CPU's

Intel and AMD both have multi-core CPU's out now.  I'm
wondering how difficult it is to modify existing code
to use this ability?  We have some compute bound code
that seems to have multiple threads, the vendor says
that in their testing (from years ago) that multiple
processors didn't help much (for their code).  Now that
multiple core CPU's and multiple CPU systems are
becoming more common, are there applications which can
use multiple cores effectively?

-- 
Take care  | This clown speaks for himself, his job doesn't
Wayne D.   | supply this, at least not directly
When in doubt, form a committee


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