Re: [9fans] plan9 finished

[David Presotto <presotto@closedmind.org>]

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Of course not...

The normal scheduler was rewritten by rsc.  There are two
changes.  The first is a sort of ganging or processes.  If
a process wakes up another one, and the first process blocks
without using its quanta, the second gets to run.  This is to
help out processes piping to each other.

The other change was to make our scheduler to look more like
a BSD style fair share scheduler.  It was done to be nicer
to cpu hogs.

Also, sape rewrote the real time edf support to make it just
run as the top two scheduler priorities rather than a totally
different mechanism.  If there are edf processes waiting to run,
rsc's gang stuff doesn't happen, i.e., the real time processes
have priority over ganging.

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From: andrey mirtchovski <mirtchov@cpsc.ucalgary.ca>
To: 9fans@cse.psu.edu
Subject: Re: [9fans] plan9 finished
Date: Sat, 28 Feb 2004 08:11:46 -0700
Message-ID: <2e1022d55d7fb8547701ea3c5212d28e@plan9.ucalgary.ca>


> Except we've had two major rewrites of the scheduler in the last 6 months...

Is there a writeup on the changes anywhere?  I know it was mentioned
on 9fans but thought somehow that there'll be a document detailing why
the changes were made, what they were and what improvements they
resulted into, once they were complete.

andrey