On Thu, 17 Dec 1998, Linus Torvalds wrote:
> On Fri, 18 Dec 1998, Neil Conway wrote:
> >
> > Two little patches (~ one active line apiece). These are relative to
> > 131ac13 btw.
>
> Both look sane. The proc change penalty is just a random number, and I
> agree that 20 is likely to be excessive. I changed it to 15 as per your
> suggestion - being a random fudge-factor really means that the value
> should be determined by either real thought or testing, and your input
> counts as testing to me.
The real fix for this one is to try rescheduling the previous
processor of the task in question instead of blindly trying
current.
All it takes is one pointer per processor, so it can be done
(very) cheaply.
> > The second patch addresses one specific problem, namely the delays that
> > happen when you hit "ENTER" in a tcsh on a loaded SMP box. I don't like
> > this patch at all, it's as ugly as hell, so perhaps it will be obvious
> > to some guru or other how to fix the underlying problem:
>
> The underlying problem is that playing around with "current->counter" was
> just wrong, and deleting the line is the right thing to do. The counter
> thing seems to be entirely historical, with no real reason for it any
> more. Line deleted, no need to use #ifdef's and fancy comments. The only
> reason it was there was probably that nobody had noticed it before.
No real fix for that particular problem is needed -- the
process that does a timeout will leave the runqueue and
call schedule() anyway...
I'll try to code up a fix for the first problem later
today -- Linus, would you accept some (by now well-tested)
scheduler changes at this time?
regards,
Rik -- the flu hits, the flu hits, the flu hits -- MORE
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