Date: Tue, 10 Jul 2001 10:00:39 +0200 (CEST) From: Michal Mertl <mime@traveller.cz> To: Matt Dillon <dillon@earth.backplane.com> Cc: freebsd-smp@FreeBSD.ORG Subject: Re: Is SMP BETA in STABLE? Message-ID: <Pine.BSO.4.21.0107100847070.14739-100000@prg.traveller.cz> In-Reply-To: <200107091944.f69JiW799011@earth.backplane.com>
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On Mon, 9 Jul 2001, Matt Dillon wrote: > > :Er, then what are the 8 httpd processes I see running on my machine? > :It may well be that Apache handles all requests from a single client > :in one process, to avoid unfairness, so you might try hitting it > :from multiple clients. > : > :Oh yes - I've been running smp on two machines since 4.0, with > :absolutely zero problems. But they're lightly loaded, except > :during make buildworld. > : > :Barney Wolff > : > :On Mon, Jul 09, 2001 at 10:46:37AM -0500, Alfred Perlstein wrote: > :> > :> Apache is a single threaded program, each instance should only be able > :> to take up one cpu on a mp system, so what you're seeing looks like > :> it makes sense. > > On -stable, only one cpu can be running in the kernel at any given time. > The cpu's can only run in parallel when running in userland (or one in the > kernel and the other in userland). So if your web server is basically > just copying bits, it will be running mostly in the kernel. If your > web server is doing significant userland processing, you will see both > cpu's in use - that is assuming that you have a significant enough > web load. > Thanks. That clarifies the thing. The consequence of this is that as I assume a lot of web server processing is quite simple this 'one kernel at a time' seems quite limiting for serving apache on stable. Do you know if the people telling SMP in Linux kernel (say 2.2 and 2.4) is better (I mean better performing) right? I won't switch to Linux anyway :-). The page I tested on was in perl - I bechmarked once with mod-perl and once without (got interesting results - on dual p3-600 with mod-perl I got 17 pages/second and without 1.6) and resulting html was about 1.5Kb. Both cases showed a little more than 50% cpu utilization. This could mean than (even with a bit more complicated page) the overhead of connection setup (may be mostly Apache's fault) and data transfer (even on loopback) is crucial. I'll do some more benchmarking because I thing it's not correct setup to benchmark on localhost. I'll also look at ApacheBench. It's implementation may quite easily affect the results too. This is getting quite off-topic, but I think that lot of people interested in FreeBSD on SMP machines do on their servers webserving so they might be a bit interested. -- Michal Mertl mime@traveller.cz To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-smp" in the body of the message
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