Clemens Ladisch wrote, on 08/02/11 22:23:
Arthur Marsh wrote:
Arthur Marsh wrote, on 05/02/11 17:30:
MIDI playback either through xmms or aplaymidi won't keep regular time, sounding weird going faster and slower under any kind of system load except when nothing else is running.
I've tried setting "options snd-timer timer_limit=x" where x is anywhere from 5 down to 0, and seeing either:
$ cat /proc/asound/seq/timer Timer for queue 0 : HR timer Period time : 0.004000250 Skew : 65536 / 65536
or "system timer" in place of "HR timer".
In all cases, under sufficient load (which might be just running aptitude -u), the tempo of the MIDI file play-back slows right down.
The ALSA interfaces of both the system timer and the HR timer do not handle delayed interrupts correctly. Please try the patch below, and if it fixes the HR timer, tell me if you're OK with the published tag Reported-and-tested-by: Arthur Marsharthur.marsh@internode.on.net.
Regards, Clemens
--- a/sound/core/hrtimer.c +++ b/sound/core/hrtimer.c @@ -45,12 +45,13 @@ static enum hrtimer_restart snd_hrtimer_ { 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;
OK, I applied this patch.
When the MIDI file was playing:
$ cat /proc/asound/seq/timer Timer for queue 0 : HR timer Period time : 0.004000250 Skew : 65536 / 65536
I still experienced some slow-down and speed-up under heavy load.
Thanks for the patch. I'm happy to do any further testing you can suggest.
Regards,
Arthur.