One problem is that on SMPs "average" doesn't really make sense. Statistically, "average" (mean()) only really makes sense when you have a Gaussian distribution of results. The benchmark results for SMPs tend to be stongly modal, i.e. very tight clusters around a few values. In this environment "average" is generally meaningless.
That being said, the '-P' flag exists on most lmbench version 3 benchmarks and allows one to have a given number of jobs running in parallel. It is intended to measure performance under load. However, even in this case one may see modal results. Please see the recent lmbench paper [2] for an example. Cheers, Carl References [1] Larry McVoy and Carl Staelin. lmbench: Portable tools for performance analysis. Proceedings 1996 USENIX Annual Technical Conference (San Diego, CA), pages 279--284. January 1996. http://www.usenix.org/publications/library/proceedings/sd96/mcvoy.html [2] Carl Staelin. lmbench --- an extensible micro- benchmark suite. HPL-2004-213. December 2004. Also to appear in Software Practice and Experience. http://www.hpl.hp.com/techreports/2004/HPL-2004-213.pdf _________________________________________________ [(hp)] Carl Staelin Senior Research Scientist Hewlett-Packard Laboratories Technion City Haifa, 32000 ISRAEL +972(4)823-1237x305 +972(4)822-0407 fax [EMAIL PROTECTED] ______ http://www.hpl.hp.com/personal/Carl_Staelin ______ -----Original Message----- From: Luck, Tony [mailto:[EMAIL PROTECTED] Sent: Wednesday, January 19, 2005 8:35 AM To: Zou, Nanhai; Larry McVoy; Linus Torvalds Cc: Mosberger, David; Staelin, Carl; [EMAIL PROTECTED]; linux-ia64@vger.kernel.org; Kernel Mailing List Subject: RE: [Lmbench-users] Re: pipe performance regression on ia64 >Maybe lmbench could add a feature that bw_pipe will fork CPU number of >children to measure the average throughput. > >This will give a much reasonable result when running bw_pipe on a SMP >Box, at least for Linux. bw_pipe (along with most/all of the lmbench tools already has a "-P" argument to specify the degree of parallelism). -Tony - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/