Re: Tree based scheduling

Erik Corry (
Fri, 23 Jan 1998 11:31:30 +0100 (MET)

Rauli Ruohonen wrote:
> Rik van Riel wrote:

> >Excellent idea... But what do you do when a SCHED_BATCH
> >process blocks because of a pagefault?
> >You wouldn't want to bring in another SCHED_BATCH process
> >then, would you?

> Something else (not SCHED_BATCH process) could be run, if possible. If not..
> :/ This needs more thought, too..

> >Maybe a normal (ie: as found in other unices) swap daemon
> >(ie: true swapping) solve this problem far better?

> What does the swap daemon do? I haven't used other unices much..

Most Unixes differentiate between paging (where individual
pages are sent to backing store) and swapping (where the
entire process is sent to backing store). Swapping can
be good when the machine is thrashing, or when you want
to start several jobs simultanously that are big enough
to cause thrashing, and just want the scheduler to handle
it. I've often wondered why Linux doesn't have this. Has
technology moved on in such a way that swapping isn't
worth it any more, or is it just that noone had the time?

Erik Corry