From owner-freebsd-questions Sat May 10 15:01:48 1997 Return-Path: Received: (from root@localhost) by hub.freebsd.org (8.8.5/8.8.5) id PAA25711 for questions-outgoing; Sat, 10 May 1997 15:01:48 -0700 (PDT) Received: from luke.cpl.net ([206.85.245.131]) by hub.freebsd.org (8.8.5/8.8.5) with ESMTP id PAA25703 for ; Sat, 10 May 1997 15:01:45 -0700 (PDT) Received: from localhost (shawn@localhost) by luke.cpl.net (8.8.5/8.7.3) with SMTP id PAA01287; Sat, 10 May 1997 15:01:33 -0700 (PDT) Date: Sat, 10 May 1997 15:01:33 -0700 (PDT) From: Shawn Ramsey To: Michael Alwan cc: questions@FreeBSD.ORG Subject: Re: advantages of symmetric processing In-Reply-To: <3.0.1.32.19970510172546.006d5f78@rma.edu> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-questions@FreeBSD.ORG X-Loop: FreeBSD.org Precedence: bulk > To anyone interested: > > I'm interested in a dual processor motherboard (i.e. Tyan Tomcat III Dual > [original Pentium]) and symmetric multiprocessing as a way of a) increasing > speed of apps under FreeBSD or WinNT b) taking advantage of falling Pentium > prices (original socket 7 Pentiums without MMX) c) using my present 120 MHZ > Pentium and d) allowing a relatively inexpensive upgrade path for a few > years to come. > > On the other hand, there are other socket 7 processors like the AMD K6 with > all the 32 bit optimizations, faster clock speeds, and lower prices than > newer Intel stuff. The upgrade path (beyond 266 MHZ) seems unpredictable, > and as far as I know, it can't be multiprocessed. > > Here's my question. All other things being equal (version of operating > system, system bus speed, amount of ram, kernel configuration, disk speed, > etc.) which runs a given app faster--symmetric multiprocessing or faster > clock speeds with one processor? > > Compare, say, two 120 MHZ Pentiums to one 200 MHZ Pentium Pro. Do > something CPU-intensive in a database. Which will come out ahead? What is > the break-even point? I'm less likely to be networking or using my machine > as a server and more likely to be image-processing or DTP or using a database. > > I haven't been researching this for long, but everything I've read seems to > suggest adding a second processor doesn't increase the speed of a given > operation more than 50%. There is a lot more information about the impact > of cpu clock speeds, obviously because most people have one cpu. I also > realize that at the rate new hardware and software is coming out, any > prediction now might make no sense in 2 months. I'm just looking for the > most bang for the bucks I have now. > > If anyone has any answers experience, or opinions, I'd be really > interested. It's hard to get a straight answer from a vendor. Im no expert, and have never even used a dual processor system. But one thing I have heard a lot about them, is you can start one program/process, such as compiling a huge program. You could then continue to use the system with no slowdown because it will use the second processor. But I would think a single 200 would be faster than 2 120's, unless you are doing somehting like what I just described.