[TriLUG] Questions about Threading

[John F Davis]

Apache typically runs more than one process.  With multiple cpu's you most
certainly get a benefit since
the different process's can be distributed across the different cpu's.

0.02

BTW, nice table of process vs thread.


"M. Mueller at Signalnetware.com" <mmueller at signalnetware.com>@trilug.org
on 03/26/2002 12:55:36 PM

Please respond to trilug at trilug.org

Sent by:    trilug-admin at trilug.org


To:    trilug at trilug.org
cc:
Subject:    Re: [TriLUG] Questions about Threading



On Tuesday 26 March 2002 12:08 pm, you wrote:
> I'm not a programmer, but I am curious about threading and the advantage
> to having a multi-processor linux box (I guess running an smp kernel).
> Do programs have to be written to take advantage of a dual-processor, or
> will cycles be distributed evenly during a process?  How do you know if
> your program will support multiple processors?

The kernel can use multiple processors to run more than one single threaded
program.

A program can be composed of:
process     threads
---------------------------
single            single
single            multiple
mutiple           single || multiple

Programs that are multi-process, multi-threaded might run faster in a
multi-processor environment.  A programmer could write a multi-process,
multi-thread operation that passes a semephore that allows execution only
with possesion of the semaphore, thus rendering multi-processors to be of
less value to such an application.

In general, it pays to understand the kernel scheduling function and design
a
program to take advantage of that algorithm.

Running a web server with multiple processes could probably be improved
using
a multiple processor server.

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