Re: suspend processes at load

[ebiederm@xmission.com (Eric W. Biederman)]

"James A. Sutherland" <jas88@cam.ac.uk> writes:

> On Mon, 19 Mar 2001 21:06:55 +0100, you wrote:
> 
> >What about this: give to process way how to tell kernel "it is not
> >good to suspend me, because there are process' that depend on me and
> >wouldn't be blocked." Syscall or /proc filesystem could be used.
> >
> >It is not the way how to say which process should be suspended but a
> >way how to say which could NOT - usefull for example for X server, may
> >be some daemons, aso.
> 
> Possibly; TBH, I don't think it's worth it. Remember, "suspending" X
> would just stop your mouse moving etc. for (e.g.) 5 seconds; in fact,
> that should block most graphical processes, which may well resolve the
> thrashing in itself!

Actually we should only apply suspension and the like to SCHED_OTHER.
The realtime scheduling classes should be left as is.  If an
application is safe to run realtime, it should be o.k. in the
thrashing situation. 

Also actually suspending a realtime process would be a violation of
the realtime scheduling guarantees, where with SCHED_OTHER you can be
expected to be suspended at any time.

Eric
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