* Con Kolivas <[email protected]> wrote:
> On Wednesday 22 March 2006 01:17, Mike Galbraith wrote:
> > On Wed, 2006-03-22 at 00:53 +1100, Con Kolivas wrote:
> > > The yardstick for changes is now the speed of 'ls' scrolling in the
> > > console. Where exactly are those extra cycles going I wonder? Do you
> > > think the scheduler somehow makes the cpu idle doing nothing in that
> > > timespace? Clearly that's not true, and userspace is making something
> > > spin unnecessarily, but we're gonna fix that by modifying the
> > > scheduler.... sigh
> >
> > *Blink*
> >
> > Are you having a bad hair day??
>
> My hair is approximately 3mm long so it's kinda hard for that to happen.
>
> What you're fixing with unfairness is worth pursuing. The 'ls' issue
> just blows my mind though for reasons I've just said. Where are the
> magic cycles going when nothing else is running that make it take ten
> times longer?
i believe such artifacts are due to array switches not happening (due to
the workload getting queued back to rq->active, not rq->expired), and
'ls' only gets a timeslice once in a while, every STARVATION_LIMIT
times. I.e. such workloads penalize the CPU-bound 'ls' process quite
heavily.
Ingo
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