Comment 33 for bug 1259070

https://bugs.freedesktop.org/enter_bug.cgi?product=PulseAudio

as pulseaudio disable period wakeup when using timer scheduling

you can only use the following to find out whether the alsa period update properly if you are using tsched=0

http://www.alsa-project.org/main/index.php/XRUN_Debug

 8 Dump positions on each period update call

 echo 8 > /proc/asound/card0/pcm0c/xrun_debug