Andrea Arcangeli wrote:
>
> ...
> >
> > The difference is unlikely to be noticed by many. (But it should be
> > _better_ than stock 2.4)
>
> it can't be better in SMP because due its scalability feature we
> completely lose track of the global smp and we only can keep track of
> the single per-cpu queue. Was it on SMP or UP?
The problem with the "interactivity estimator" was observed on
dual CPU. It has almost vanished in 2.4.20aa1 and I don't think
it needs any more attention.
(BTW: it is not possible to trigger this problem when the background
load is just one or more busywaits. It has to be a compilation. It
could be something to do with all the short-lived processes, or gcc -pipe)
> ...
> > With a `make -j1' running:
> >
> > - Normal O(1) behaviour in StarOffice 5.2 is 15-30 second delays between
> > actions.
> >
> > - With 2.4.20aa1, typing into a text document typically had a 2-3 character
> > delay.
> >
> > - With the standard 2.4 scheduler the delay is zero characters.
>
> again, I guess that's SMP and that's quite a pain to fix it to be 100%
> equivalent to 2.4 without hurting scalability.
This problem is the "changed sched_yield semantics". It was actually
tested on uniprocessor. The difference between 2.4 and 2.4-aa is
still noticeable here, but it is not a terrible problem now.
> ..
>
> Overall I don't see any showstopper with openoffice (or staroffice) on
> my version of the o1 scheduler.
I'd agree that it's not a showstopper. It's in the "could be improved
a bit sometime" department.
Post-2.4, well, spinning on sched_yield() is a silly way to implement
a graphical application and I don't believe we need to struggle to
support such a thing.
The Open Group say
The sched_yield() function shall force the running thread to relinquish
the processor until it again becomes the head of its thread list. It
takes no arguments.
That's a bit vague, but it does tend to imply that a yield could
relinquish the CPU for a very long time.
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This archive was generated by hypermail 2b29 : Sat Dec 07 2002 - 22:00:17 EST