Re: [2.4.17/18pre] VM and swap - it's really unusable

Peter Wächtler
2002-01-21T16:30:42Z

yodaiken@fsmlabs.com schrieb:
>
> On Mon, Jan 21, 2002 at 05:05:01PM +0100, Daniel Phillips wrote:
> > > I think of "benefit", perhaps naiively, in terms of something that can
> > > be measured or demonstrated rather than just announced.
> >
> > But you see why asap scheduling improves latency/throughput *in theory*,
>
> Nope. And I don't even see a relationship between preemption and asap I/O
> schedulding. What make you think that I/O threads won't be preempted by
> other threads?
>

I/O intensive threads block early voluntarily - while CPU hogs don't.
Statistically there is a higher chance, that a CPU hog gets preempted
instead of an IO bound (that gives up the CPU in some useconds anyway)

The next IO request is hitting the device "earlier" - instead of waiting
for the next schedule() - that makes sense to me.

With this scenario the system CPU utilization gets "bigger" for the benefit
of "faster" IO. OTOH, seti@home needs longer to run.