Date: Mon, 16 Sep 1996 20:32:05 +0200 (MET DST) From: Stefan Esser <se@zpr.uni-koeln.de> To: Gilles BRUNO <Gilles.Bruno@ujf-grenoble.fr> Cc: freebsd-platforms@freebsd.org Subject: Re: Multi processor question Message-ID: <199609161832.UAA01621@x14.mi.uni-koeln.de> In-Reply-To: <1.5.4.16.19960916085352.2f8f515a@ujf-grenoble.fr> References: <1.5.4.16.19960916085352.2f8f515a@ujf-grenoble.fr>
next in thread | previous in thread | raw e-mail | index | archive | help
Gilles BRUNO writes: > Hi happy BSD'ers ! > > We're currently planning to purchase a Bi-Pentium Pro > based computer and installing FreeBSD on it : > I'd like to know if there's a *REAL* advantage to purchase > a BI processor box instead of a single P.Pro ? Don't think this is a good choice. Multi-processor systems always pay a price for having the CPU's work on common data structures, and the locking overhead can be very high. (Some primitives may run a factor of ten slower than in the single processor case.) I've seen dual P5 boards starting at $300, but most cost $500 or more. With the P133 costing $200 each, you end up at $700 to $900 for a 2*P5/133 system. The ASUS P6NP5 with a P6/150 can be had for some $800, too, with prices going down rapidly. And this is IMHO the far better choice ... > More especially, is FreeBSD optimized for dual processor > PCs ? Is there a real advantage to purchase such a box ? No, I don't think so. A P5/200 is not that much faster than the P5/166 since memory bandwidth is a limiting factor. And with two 133MHz P5 you'll see a much worse effect, because of the synchronization issues. FreeBSD doesn't support fine-grained kernel locking, and thus is not (yet) optimally supporting SMP systems. I've seen quite impressive performance numbers from those working on the SMP code, but if you want a reliable system just to get your work done, the single processor P6 can't be beaten :) Regards, STefan
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?199609161832.UAA01621>