HEADS UP: ULE is the default scheduler now

Marc G. Fournier scrappy at hub.org
Sun Jan 25 16:16:57 PST 2004

Jeff, were you able to clear up the use of ULE on a single CPU machine
with SMP enabled?

On Sat, 24 Jan 2004, Jeff Roberson wrote:

> On Sat, 24 Jan 2004, Jeff Roberson wrote:
> > ULE has entered into its probationary period as the default scheduler.
> > This is intended to give it wider exposure to work out the last few kinks.
> > If all goes well it will remain the default through the rest of the 5.x
> > series.  If you aren't running it now, please switch over.
> >
> > I have been out of town or very busy over the last few months.  I should
> > be more available to address things as they come up now.  If anyone is
> > aware of any current issues, please contact me with any details you may
> > have.
> I was asked to follow up with a summary of why you might want to use ULE.
> For the average user, interactivity is reported to be better in many
> cases.  This means less skipping, jerking, etc. in interactive
> applications while the machine is very busy.  This will not prevent
> problems due to overload disk subsystems, but it does help with overloaded
> CPUs.
> On SMP machines ULE has per cpu run queues which allow for CPU
> affinity, CPU binding, advanced HyperThreading support, as well as
> providing a framework for more optimizations in the future.  This means
> that as our kernel is locked better the scheduler will be able to make
> more efficient use of the available parallel resources.
> ULE has been stable for some time.  The only problems that are likely to
> remain are corner cases where interactivity is not as good or where
> performance is not as good as with the old scheduler.
> Cheers,
> Jeff
> >
> > Thanks,
> > Jeff
> >
> >
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Marc G. Fournier           Hub.Org Networking Services (http://www.hub.org)
Email: scrappy at hub.org           Yahoo!: yscrappy              ICQ: 7615664

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