Re: [uPATCH] SMP scheduling fix (?)

Robert M. Hyatt (hyatt@cis.uab.edu)
Fri, 15 Jan 1999 07:17:12 -0600 (CST)


On Fri, 15 Jan 1999, Rik van Riel wrote:

> On Thu, 14 Jan 1999, Robert M. Hyatt wrote:
>
> > This would make a good discussion point, since it is a topic I am
> > highly interested in. Take a process whose nice value is 0. And
> > a process that has been niced to +10. What is the expectation there?
>
> The expectation is that the +10 niced program gets half the
> CPU time from the 'normal' process.

ok... then '20'??? IE it would seem that that might be 1/4th using
the same 'what number is next in this series?' :) That's not bad,
but what about the one last case of '0%'??? IE I want to run
something that is going to take days to run, but I don't want it to
slow down my compiles at all, and I don't want it to interfere with
Crafty when it is playing on a chess server. I just want this
'ultra-low-priority' job to run when one or more cpus are completely
idle...

>
> > I'd _really_ like to have a nice value that says "don't run unless
> > you are twiddling your thumbs". Ie a nice 20 perhaps, that says I
> > don't want this to run unless there is _nothing_ else to schedule.
>
> I have a patch that does this. But since the patch can trigger
> a known race condition (hardly ever happens, I've seen it once
> in 4 months) and since I want people to test vanilla 2.2.0-pre*
> as much as possible I haven't updated the patch since -132.
>
> Once 2.2.0 stabilizes I'll continue to work on the patch,
> in the meantime please ignore my patchlet and forget about
> it :)
>
> > But I'd also like to be able to pick a nice value that means
> > 'something'. Anybody interested in trying to make something like
> > this work? IE at present nice 1, nice 2, etc don't seem to make
> > much difference, and would be about as useful as just nice xxx to
> > run at +10.
>
> I'll work on this as soon as 2.2 stabilizes. If you really
> really want it I might even be persuadable to make a version
> for kernel 2.2.0-preWhatever, but don't count on that...
>

it's not something that is critical, just something that would give us
all 'more control.' I'm in no rush, but am willing to test most anything
(if nothing else, I've become quite adept at applying patches, building
kernels and rebooting. :) )

Bob

> cheers,
>
> Rik -- If a Microsoft product fails, who do you sue?
> +-------------------------------------------------------------------+
> | Linux memory management tour guide. riel@nl.linux.org |
> | Scouting Vries cubscout leader. http://www.nl.linux.org/~riel |
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>
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