Re: [PATCH] ia64: disable preemption in udelay()

Lee Revell
2005-12-16T03:19:11Z

On Thu, 2005-12-15 at 18:12 -0800, John Hawkes wrote:
> From: "Lee Revell" <rlrevell@joe-job.com>
> > There are 10 drivers that udelay(10000) or more and a TON that
> > udelay(1000). Turning those all into 1ms+ non preemptible sections will
> > be very bad.
>
> What about 100usec non-preemptible sections?

That will disappear into the noise, in normal usage these happen all the
time. 500usec non preemptible regions are rare (~1 hour to show up) and
1ms very rare (24 hours). My tests show that 300 usec or so is a good
place to draw the line if you don't want it to show up in latency tests.

Lee