Date: Sun, 29 Oct 2006 00:53:08 -0400 (EDT) From: Daniel Eischen <deischen@freebsd.org> To: Matthew Dillon <dillon@apollo.backplane.com> Cc: Paul Allen <nospam@ugcs.caltech.edu>, Robert Watson <rwatson@freebsd.org>, Julian Elischer <julian@elischer.org>, freebsd-current@freebsd.org, David Xu <davidxu@freebsd.org> Subject: Re: Comments on the KSE option Message-ID: <Pine.GSO.4.64.0610290048530.15683@sea.ntplx.net> In-Reply-To: <200610290344.k9T3itAw054920@apollo.backplane.com> References: <45425D92.8060205@elischer.org> <200610281132.21466.davidxu@freebsd.org> <20061028105454.S69980@fledge.watson.org> <20061028194125.GL30707@riyal.ugcs.caltech.edu> <20061028204357.A83519@fledge.watson.org> <200610290344.k9T3itAw054920@apollo.backplane.com>
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On Sat, 28 Oct 2006, Matthew Dillon wrote: > > (2) Just because the POSIX scheduler implements all sorts of different > scopes and priority schemes says NOTHING AT ALL about how programs > operating under such a scheduler should be apportioned cpu relative > to OTHER PROGRAMS WHICH ARE INDEPENDANTLY RUNNING ON THE SYSTEM. POSIX > is an abstraction (or virtualization out of available resources), > just like everything else. If you try to treat it as a hard requirement > the only result will be a broken system that might happily run everything > else into the ground and stop allowing root ssh logins in order to > accomodate a badly written POSIX program. There are many third party > applications that set POSIX priorities, in particular realtime > priorities, that I'd rather they not actually use. Most of these > programs set these priorities based on the author's attempt to tune > them on a single operating system (e.g. linux) and in a single operating > environment. > > All a program can ever really do when requesting POSIX scheduling > resources is compete against itself. It is the system operator, at a > higher level, that must control how those resources compete with > other programs. That should be clear to everyone it is so obvious. Actually, that's not quite true. I assume you know the thing you left out: system scope threads compete against all the other system scope threads in the system (from all applications, not just within one application). -- DE
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