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From: Terry Lambert <terry@lambert.org>
Newsgroups: comp.unix.bsd.freebsd.misc,comp.unix.solaris,comp.os.linux.misc
Subject: Re: Benchmarking different Unix Operating Systems
Date: Tue, 17 Sep 1996 18:39:03 -0700
Organization: Me
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Message-ID: <323F52B7.716C5364@lambert.org>
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Xref: euryale.cc.adfa.oz.au comp.unix.bsd.freebsd.misc:27410 comp.unix.solaris:82810 comp.os.linux.misc:129690
Brian Somers wrote:
] : Probably the correct way (as opposed to the Solaris/SVR4 suggested
] : method of implementing a new scheduling class) would be to have
] : a cooperative scheduler in user space an convert all blocking
] : kernel calls to non-blocking calls plus a user space thread
] : context switch.
]
] But what's the difference ? Even if I lose my chance at running 'cos
] I do a "kernel" thing, I end up w/ a higher priority than the guy that
] gets his whole quantum..... don't I ?
Sure you do.
And you get to eat context switching overhead you wouldn't have
had to otherwise, and your priority is not scalar relative to
the user-thread/kernel-thread ratio.
I've actually been engaged in a nice email discussion with Ingo
Molnar (of the Linux camp) since making this post.
It seems the best place to put the conversion for the
blocking-call -> non-blocking-call+contest-switch is in
trampoline code in the system call, and let the system appear
from user space as if each user thread context is a kernel
thread, and from kernel space as if each runnable context
is something to schedule available CPU resources against.
Terry Lambert
terry@lambert.org
---
Any opinions in this posting are my own and not those of my present
or previous employers.