Date: Wed, 10 Aug 2005 16:38:25 -0400 From: John Baldwin <jhb@FreeBSD.org> To: frank@exit.com Cc: Andre Oppermann <andre@freebsd.org>, freebsd-arch@freebsd.org Subject: Re: Special schedulers, one CPU only kernel, one only userland Message-ID: <200508101638.27087.jhb@FreeBSD.org> In-Reply-To: <1123704605.54957.8.camel@realtime.exit.com> References: <42F9ECF2.8080809@freebsd.org> <200508100911.50004.jhb@FreeBSD.org> <1123704605.54957.8.camel@realtime.exit.com>
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On Wednesday 10 August 2005 04:10 pm, Frank Mayhar wrote: > On Wed, 2005-08-10 at 09:11 -0400, John Baldwin wrote: > > I think this is the model that BSD/OS employed > > for SMP in its 4.x series before they did their version of SMPng. > > I didn't grunge around in the scheduler (much), but as far as I'm aware > BSD/OS 4.x used the Big Giant Lock mechanism just as FreeBSD did, and > for the same reason. I believe that at some point during the 4.x series they added a scheduler lock that covered just enough to allow threads that weren't asleep in the kernel to be switched to without require the big giant lock and that it was a pretty decent performance win over the earlier single BGL ala FreeBSD 4.x. -- John Baldwin <jhb@FreeBSD.org> <>< http://www.FreeBSD.org/~jhb/ "Power Users Use the Power to Serve" = http://www.FreeBSD.org
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