Re: Comments on the KSE option

From: Daniel Eischen <deischen_at_freebsd.org>
Date: Fri, 27 Oct 2006 16:41:16 -0400 (EDT)
On Fri, 27 Oct 2006, Paul Allen wrote:

>> From Julian Elischer <julian_at_elischer.org>, Fri, Oct 27, 2006 at 12:27:14PM -0700:
>> The aim of the fair scheduling code is to ensure that if you, as a user,
>> make a process that starts 1000 threads, and I as a user, make an
>> unthreaded process, then I can still get to the CPU at somewhat similar
>> rates to you.  A naive scheduler would give you 1000 cpu slots and me 1.
> 
> Ah.  Let me be one of the first to take a crack at attacking this idea as
> a mistake.

No, it is POSIX.  You, the application, can write a program with
system scope or process scope threads and get whatever you behavior
you want, within rlimits of course.

If you want unfair scheduling, then create your threads with
system scope contention, otherwise use process scope.  The
kernel should be designed to allow both, and have adjustable
limits in place for (at least) system scope threads.

Noone is saying that you can't have as many system scope threads
as you want (and as allowed by limits), just that you must also
be able to have process scope threads (with probably higher limits
or possibly no limits).

-- 
DE
Received on Fri Oct 27 2006 - 18:41:21 UTC

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