Re: [linux-audio-dev] Re: [announce] [patch] Voluntary KernelPreemption Patch

From: Andrew Morton
Date: Mon Jul 12 2004 - 19:13:44 EST


Paul Davis <paul@xxxxxxxxxxxxxxxxxxxxx> wrote:
>
> >OK, thanks. The problem areas there are the timer-based route cache
> >flushing and reiserfs.
> >
> >We can probably fix the route caceh thing by rescheduling the timer after
> >having handled 1000 routes or whatever, although I do wonder if this is a
> >thing we really need to bother about - what else was that machine up to?
>
> i have one concern about this that i talked to takashi about when we
> were in bordeaux. it seems to me that the ALSA xrun debug stuff is
> measuring things when the interrupt handler for the ALSA device
> executes and detects an xrun. if the handler itself was delayed, then
> the stack trace for its execution doesn't or might not show what
> caused the delay. this means, perhaps, that we need to be rather
> careful interpreting these traces.
>

We can usually tell that from the trace. If it points up into a busy piece
of code then it's pretty obvious what's happening. If the trace is due to
a long irq-off time then it will point up into the offending
local_irq_enable().

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/