[ale] Dual Processor Boards & Linux...

[jeff_hubbs at mcgraw-hill.com]

To add my two cents, when Vernard says "single threaded applications such
as most traditional process based applications will not run faster simply
by running them on an SMP machine," I think he's talking about the app *by
itself* as opposed to the same app running more than once, or a whole bunch
of different apps at once.

This is why at the DOE a year or more ago I specced out an NT machine that
was going to be spending the first part of its life running a DOS database
app.  I specced a two-CPU board but only popped for one CPU because NT's
VDM wasn't multithreaded and the second CPU wasn't going to be much help.
On the other hand, when the Oracle-based software comes down the pike and
replaces the DOS app, then it will be time to stuff in the second PII.
Multiple processors are good for things where you have several different
and not necessarily related things going on at once and if you're running
apps that are actually multithreaded.

Out of curiousity:  does anyone know what happens if you put Linux on the
6-Pentium-Pro ALR Revolution 6x6?  I used to have one at the DOE and I miss
it.

- Jeff






vernard at cc.gatech.edu (Vernard Martin) on 12/28/98 02:48:44 PM

To:   horus at larp.com (Jay Finch)
cc:   ale at cc.gatech.edu (bcc: Jeff Hubbs/Tower)

Subject:  Re: [ale] Dual Processor Boards & Linux...




> How hard is it to get Linux to support 2 processors?  (I know you have to
> enable the support when you compile the kernel, but is there more?)

The basic SMP support in the Linux kernel is in the scheduling of
processes. It
will automatically schedule tasks to run on both processes. However, by
default, single threaded applications such as most traditional process
based
applications will not run faster simply by running them on an SMP machine.
The
apps must either be multi-process so that one can be on each process or
they
must be multi-threaded so that you can split the threads over the two
processes
to get any speedup.

V
---
Vernard Martin (vernard at cc.gatech.edu)  http://www.cc.gatech.edu/~vernard/