Date: Thu, 23 Oct 1997 19:14:48 -0500 (EST) From: "John S. Dyson" <toor@dyson.iquest.net> To: shieyuan@eecs.harvard.edu (ShieYuan Wang) Cc: freebsd-smp@freebsd.org Subject: Re: SMP is slower when two processors are enabled Message-ID: <199710240014.TAA01451@dyson.iquest.net> In-Reply-To: <199710232354.TAA27809@steward.eecs.harvard.edu> from ShieYuan Wang at "Oct 23, 97 07:54:21 pm"
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ShieYuan Wang said: > protocol stack to transfer unlimited data on the same local host. If I > only enable one processor, the throughput can be 35 MB/sec. However if > I enable the other processor hoping to get better throughput, I only get > 12 MB/sec. > > I know that locking overhead between multiple processors may be a lot. But > I never thought that it could be so high. Could anyone give me some clues > about this bad performance? My SMP 3.0 was installed about 6 months ago. > Does the more recent SMP have better performance and have solved the > performance problem? Your suggestion will be highly appriciated. > Most likely it is the overhead of moving data between CPUs. Could be cache effects also. -- John dyson@freebsd.org jdyson@nc.com
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