Date: Mon, 9 Jul 2001 12:44:32 -0700 (PDT) From: Matt Dillon <dillon@earth.backplane.com> To: Barney Wolff <barney@databus.com> Cc: Alfred Perlstein <bright@sneakerz.org>, Michal Mertl <mime@traveller.cz>, freebsd-smp@FreeBSD.ORG Subject: Re: Is SMP BETA in STABLE? Message-ID: <200107091944.f69JiW799011@earth.backplane.com> References: <Pine.BSO.4.21.0107091143430.3190-100000@prg.traveller.cz> <20010709104637.C1894@sneakerz.org> <20010709133904.A32043@tp.databus.com>
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: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.
'Single threaded' in Alfred's response simply meant that Apache can
only handle one connection per fork. It still forks a number of
processes and so can handle a number of connections in parallel.
Apache serializes connection accept()s but that would have no bearing
on what you are seeing.
-Matt
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