On Tue, 2 Nov 1999, Daniel M. Eischen wrote:
> Julian Elischer wrote:
> > Here is an updated version of the rather simplistic requirements for a
> > threads model for freeBSD.
> > 1/ Multiple independent 'threads of control' within a single process
> > at user level. The most basic quality of threads.
> > 2/ Ability to simultaneously schedule M threads over N Processors,
> > and have min(M,N) threads simultaneously executing.
> Shouldn't this be M threads over N [lightweight] Processes?
well, not until we decide that we are going to HAVE LWPs. :-)
this is teh really highest level requirement.
> > 6/ (contentious) multiple theads should be bound to within the resource
> > limits of the single process.
> Disagree. I want lightweight processes to have their own quantum
> not limited (in total) to the parent process quantum.
Most people disagree with you on this one, so if you want what you
describe, you will have to thik of a way of decribing it as an optional
characteristic. We discussed this and the overwhelming majority decided
that a threaded program has no real scheduling advantage over a non
threaded program, oth that what it get's by teh nature of blockin gless
and being on multiple CPUs. Having said that, it is possible that you want
your threaded proggram to hog the system (the sysadmin may disagree, in
which case you must still be bound by your process limits). Should this be
the case, you should be able to specify some optional (non
default) characteristic that allows this.. If you can thinkk of a good way
of describing this, we can include it.. (but it can't be the default
behaviour as far as I can see.)
> > -------------
> > Meta-goals
> > -----------
> > We should keep our eyes on:
> > *) scalability
> > *) performance
> > *) ability to support features required by standards based threads.
> > *) ability to support features of those therad packages we select as
> > needed.
> How about [from the "scheduler activations" paper] Flexibility?
* define 'flexibility' ? :-) I think the 4th point covers what we
need in that regard?
> > refs:
> > http://www.freebsd.org/~deischen/p95-anderson.pdf
> > http://www.freebsd.org/cgi/getmsg.cgi?fetch=25000+30231+/usr/local/www/db/text/1
> > 999/freebsd-current/19990321.freebsd-current
> > http://lt.tar.com/
> Do you want other references? I know there are several available papers on
> Solaris multi-threading. There are also papers on locking mechanisms.
yes. references are good.
> Dan Eischen
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