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Date:      Wed, 21 Nov 2001 18:41:55 -0800
From:      Peter Wemm <peter@wemm.org>
To:        Alfred Perlstein <bright@mu.org>
Cc:        Julian Elischer <julian@elischer.org>, arch@FreeBSD.ORG
Subject:   Re: Kernel Thread scheduler 
Message-ID:  <20011122024155.868CF3811@overcee.netplex.com.au>
In-Reply-To: <20011121184508.T13393@elvis.mu.org> 

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Alfred Perlstein wrote:
> * Julian Elischer <julian@elischer.org> [011121 18:40] wrote:
> > 
> > 
> > Peter, John (Baldwin) and I got to gether yesterday and thrashed
> > out the mechanisms behind the KSE/thread scheduler.
> > This allows us to go ahead and start coding again, now that we know what
> > we are aiming at.
> > 
> > Here is the basic mechanism.
> [snip]
> 
> Since my request is about one one thousandth as complex as this I'm
> just going to ask:
> 
> Will this stuff be usable as a lightweight mechanism inside the kernel?

We talked doing a "raw" implemetation first without the userland
glue (like rfork is "raw" with no sync mechanisms etc).  If we have this
basic functionality first then we should be able to glue it onto kthread
pretty easily.

> Case in point, could nfsd be changed to only have one process (instead
> of many) while still being able to block and get an upcall?

In theory yes.  The thing is though that nfsd doesn't really run in
userland so it doesn't really buy us much.  It just gives us a slightly
less overhead way of popping new contexts into and out of existence.

What's really needed is for nfsd to self manage.  All the userland process
is needed for is creating and binding the listen sockets, and holding them
open while the kernel has fun with them.  It shouldn't have to create $n
processes in advance "in case" they are needed.  The kernel side should
be able to add/remove nfsd contexts in response to load (and some limits).

Cheers,
-Peter
--
Peter Wemm - peter@FreeBSD.org; peter@yahoo-inc.com; peter@netplex.com.au
"All of this is for nothing if we don't go to the stars" - JMS/B5


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