Commit b1d4f7f4 authored Feb 10, 2011 by Clemens Ladisch Committed by Takashi Iwai Feb 10, 2011

ALSA: hrtimer: handle delayed timer interrupts



If a timer interrupt was delayed too much, hrtimer_forward_now() will
forward the timer expiry more than once.  When this happens, the
additional number of elapsed ALSA timer ticks must be passed to
snd_timer_interrupt() to prevent the ALSA timer from falling behind.

This mostly fixes MIDI slowdown problems on highly-loaded systems with
badly behaved interrupt handlers.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Reported-and-tested-by: Arthur Marsh <arthur.marsh@internode.on.net>
Cc: <stable@kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

parent a6c47a85

sound/core/hrtimer.c

+3 −2

Original line number	Diff line number	Diff line
		@@ -45,12 +45,13 @@ static enum hrtimer_restart snd_hrtimer_callback(struct hrtimer *hrt)
		{
		struct snd_hrtimer *stime = container_of(hrt, struct snd_hrtimer, hrt);
		struct snd_timer *t = stime->timer;
		unsigned long oruns;

		if (!atomic_read(&stime->running))
		return HRTIMER_NORESTART;

		hrtimer_forward_now(hrt, ns_to_ktime(t->sticks * resolution));
		snd_timer_interrupt(stime->timer, t->sticks);
		oruns = hrtimer_forward_now(hrt, ns_to_ktime(t->sticks * resolution));
		snd_timer_interrupt(stime->timer, t->sticks * oruns);

		if (!atomic_read(&stime->running))
		return HRTIMER_NORESTART;

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