From owner-freebsd-arch  Sun Oct  6 17:16:30 2002
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Date: Sun, 06 Oct 2002 17:15:09 -0700
From: Terry Lambert <tlambert2@mindspring.com>
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To: Antony T Curtis <antony.t.curtis@ntlworld.com>
Cc: Nate Lawson <nate@root.org>,
	David Francheski <davidf@caymas.com>, freebsd-arch@FreeBSD.ORG,
	freebsd-smp@FreeBSD.org
Subject: Re: Running independent kernel instances on dual-Xeon/E7500 system
References: <Pine.BSF.4.21.0210041721250.96201-100000@root.org> <3D9EB0A4.4CD09E20@mindspring.com> <3D9EF6E9.9040700@ntlworld.com>
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Nathan Hawkins wrote:
> Each approach has advantages and disadvantages, depending on what you're
> trying to accomplish.

I think in this case, it's that benchmarked performance actually
goes down in FreeBSD 4.6 when you run SMP, as opposed to running
UP, and FreeBSD -current is even worse, even if you disable the
debugging that's on by default.

Tools like "netperf" aren't really capable of taking advantage
of additional processors, but they are excellent at showing the
incremental slowdown that results from lack of CPU affinity (if
applicable), as well as any additional locking overhead (if
applicable).

Tools that run against web servers, where the web server has
been written to run with multiple processes (or mutithreaded, if
the threads system on the platform is SMP scalable) show less
improvement than expected; e.g.:

	http://www.softwareqatest.com/qatweb1.html#LOAD

...but they will at least show some small improvement with SMP.

-- Terry

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