Date: Thu, 4 Feb 1999 11:45:51 -0500 From: "Lawrence Hughes" <Lawrence.Hughes@mindspring.com> To: <freebsd-questions@FreeBSD.ORG> Subject: Re: Pentium II install Message-ID: <06b101be505d$d2f9cf00$3a01010a@lhughes.secureit.com>
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hmmmm.... so many fascinating things to sort out.... where to begin...
1. The Pentium II does in fact have two internal processors, one for
Integer operations, one for Floating Point. These two units used
to be sold independently (e.g. 386/387) but converged about the
time of the i486.
2. Both the Integer unit and FP unit are used by most software today,
Windows or otherwise. Very old fossil software might emulate the
FP stuff in software, assuming no FP processor was present, but
most chips made in the last few years include FP hardware.
3. There may be some x86 variants with multiple internal integer
functional units, to pass the one instruction/clock cycle limit, I'm
not sure (haven't kept THAT close track of x86 lately). Even if
they do, this is completely internal, and appears to be a single
processor to the programmer (parallelism and scheduling is
handled by something called a "stunt box" - and first showed
up in Seymour Cray's CDC 6000 series computers.) Pretty
much transparent to software (ok, you can play a few games
to help out the stunt box for maximum parallelism - typically
done by ordering machine instructions in the last phase of
compiler optimization passes).
4. The PII can definitely be built in parallel configurations - with
multiple chips - dual PII boards are readily available, and
not even that outrageously expensive today. They can be
wired for "twice the bang" or fault tolerant "let's both do the
same thing, and recover if we don't agree" mode
5. With the traditional dual CPU (or quad, 6x, 8x, which takes
somewhat more complex motherboards/backplanes), you
can get fairly linear scaling of performance with added
CPUs. Maybe 3.5X a 1 CPU system with 4 CPUs.
6. To harvest the performance possible on a SMP (Symmetric
Multi Processor), your OS needs to support multi process
correctly (can schedule any process on any available CPU)
and/or multi-threading. Windows NT can do both. FreeBSD
3.0 supports allocating processes across multiple CPUs.
(anyone happen to know if the FreeBSD pThreads supports
SMP in 3.0, to spread threads in a single process across
multiple CPUs?)
7. Win9x (slightly rewarmed barely 32-bit DOS and Win3.1)
can't do much of anything with additional CPUs. Nor can
anything from MS prior to those.
Verstehe?
-----Original Message-----
From: gkaplan <gkaplan@castle.net>
To: freebsd-questions@FreeBSD.ORG <freebsd-questions@FreeBSD.ORG>
Date: Thursday, February 04, 1999 10:29 AM
Subject: Pentium II install
>I have been given to understand that the P II is inherently a dual
>processor, and that under most if not all (ms) operating systems the
>second processor will idle. The question is what if anything need to be
>done during or after an initial FreeBSD installation needs to be done to
>have a functioning dual processor system?
>
>
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