Date: Thu, 27 Nov 2003 15:28:18 -0800 From: Kent Stewart <kstewart@owt.com> To: JacobRhoden <jrhoden@unimelb.edu.au>, Uwe Doering <gemini@geminix.org>, freebsd-questions@freebsd.org Subject: Re: Multiple CPU Performance Message-ID: <200311271528.18216.kstewart@owt.com> In-Reply-To: <200311281010.01899.jrhoden@unimelb.edu.au> References: <200311261658.34693.fbsd-questions@trini0.org> <3FC672EC.1000904@geminix.org> <200311281010.01899.jrhoden@unimelb.edu.au>
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On Thursday 27 November 2003 03:10 pm, JacobRhoden wrote: > > Gerard Samuel wrote: > > > I was fortunate to acquire a dual Slot one motherboard. > > > I currently only have one PIII 450 in there, and its working without > > > any problems so far. > > > This box is primarily for www/samba/cvs. > > > I was wondering if my PHP apps would benefit (run faster) if I > > > introduced a 2nd CPU. > > I am no expert on this sort of thing, but I thought I should add one thing, > in case you havent thought of it... What is the load on your cpu? It can > be found by doing a top.. if it never reaches 1.0 while running php apps, > then an extra cpu is not going to make much difference. In general I have > found that the bottleneck in older computers tends to be the hard drive, > not the CPU. > I saw a comment recently that stood out. It was to the effect that SMP lets you run more applications at the same speed. On buildworlds, for example, the suggestion is to use -j4 on single cpu systems. I find the -j4 runs a buildworld 20-30% slower than no -j at all. The -j8 ran faster on SMP. The process of running multiple makes has a process switching overhead that costs me time. I also have IDE HDs and suspect that the tagged queuing built into good scsi HDs gets around some of the HD bottle neck. Kent -- Kent Stewart Richland, WA http://users.owt.com/kstewart/index.html
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