Re: recomended way to check longest period that interupts aredisabled ?

From: Peter Zijlstra
Date: Thu Apr 26 2007 - 05:54:23 EST

On Thu, 2007-04-26 at 02:13 -0700, Mike Mattie wrote:
> Hello,
> I am still struggling to track down problems with audio playback. I get intermittent:
> Apr 26 02:01:40 reforged [13230.947879] cannot submit sync urb (err = -45)
> I have tackled the scheduler issues to where I really don't think the
> driver is being starved at all. I am running audacious like so:
> schedtool -R -p 50 -n 1 -e audacious
> At this point the strongest correlation I can get is that starting
> programs seems to trigger the stutter. I have suspected IO for
> some time.
> My system image , / & /usr are on a libata (VIA PATA) driver.
> I have disabled the write-cache , but I also have noatime set
> on mount, for /usr
> My big suspicion is that one of my drivers, likely IO is
> disabling interrupts for too long.
> I have looked but not found a tool for measuring the longest
> period interrupts are disabled and pointing the finger at
> the culprit, could anyone on this list recommend tools that
> might help me pinpoint what is going on ?
> I would also be delighted for any sort of recommended latency
> testing tools.
> pin-pointing this is going to be a "learning experience" but
> every time I think I am about to have a bonding moment with
> the kernel audio skips; I am highly motivated.

The -rt kernel contains a full latency tracer.

Some hardware just isn't up to the job though...

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