Re: [2.4.17/18pre] VM and swap - it's really unusable

george anzinger
2002-01-15T03:09:01Z

Daniel Phillips wrote:
>
> On January 14, 2002 10:09 am, yodaiken@fsmlabs.com wrote:
> > UNIX generally tries to ensure liveness. So you know that
> > cat lkarchive | grep feel | wc
> > will complete and not just that, it will run pretty reasonably because
> > for UNIX _every_ process is important and gets cpu and IO time.
> > When you start trying to add special low latency tasks, you endanger
> > liveness. And preempt is especially corrosive because one of the
> > mechanisms UNIX uses to assure liveness is to make sure that once a
> > process starts it can do a significant chunk of work.
>
If I read this right, your complaint is not with preemption but with
scheduler policy. Clearly both are needed to "assure liveness".
Another way of looking at preemption is that is enables a more
responsive and nimble scheduler policy (afterall it is the scheduler
that decided that task A should give way to task B. All preemption does
is to allow that to happen with greater dispatch.) Given that, we can
then discuss what scheduler policy should be.
--
George george@mvista.com
High-res-timers: http://sourceforge.net/projects/high-res-timers/
Real time sched: http://sourceforge.net/projects/rtsched/