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SubjectRe: 2.5.69 Interrupt Latency
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On Thu, 2003-05-08 at 14:22, Andrew Morton wrote:
> Paul Fulghum <paulkf@microgate.com> wrote:
> >
> > On Wed, 2003-05-07 at 17:28, Andrew Morton wrote:
> > > Paul Fulghum <paulkf@microgate.com> wrote:
> > > >
> > > > 2.5.69
> > > > Latency 100-110usec (5x increase)
> > > > Spikes from 5-10 milliseconds
> > > >

> > I'm going to try your suggestion of doing a stack dump
> > when the driver encounters the large spikes in IRQ latency,
> > to determine if something is leaving interrupts disabled.
>
> I wasn't very informative, alas.

Yeah, I've been reading through the 2.5.69 patch again and
could not really see anything that related to the
stack dump.

> > That will not address the fact that the minimum
> > latency has jumped from 20usec (2.4.20 - 2.5.68) to 100usec
> > (2.5.69). This may actually be two separate problems
> > introduced with 2.5.69
>
> Can you pinpoint a kernel version at which it started to happen?

Exactly with 2.5.69

2.5.68 works fine as do earlier versions back to 2.4.20-8
(earliest tested for this problem). All these versions have
very consistant latencies as described above.

The problem definately started with the 2.5.69

--
Paul Fulghum, paulkf@microgate.com
Microgate Corporation, http://www.microgate.com


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