ALSA module: tsched=0 causes skipping on nVidia HDMI output under QEMU-KVM
Submitted by Daniel Edgecumbe
Assigned to pul..@..op.org
Description
bool pa_alsa_may_tsched [modules/alsa/alsa-util.c] disables tsched if PA determines that it is running within a VM.
This causes awful skipping audio on my system. Removing the check enables the use of tsched and PA functions without a hitch.
Details
Guest VM running under QEMU-KVM. Arch Linux current 4.4.5-1-ARCH as of 2016/03/31 pulseaudio-git commit 0f48b7c82378c32194b625d1fd886eee7f1e5928 Date: Sun Mar 13 23:56:54 2016 +0200 NVIDIA proprietary driver on nVidia GeForce 960GTX - using nVidia HDMI audio.
git blame appears to stem from 2009 - has support for tsched improved since then?
53b046d5 src/modules/alsa/alsa-util.c (Lennart Poettering 2009-11-05 03:23:08 +0100 1482) /* We cannot depend on being woken up when we ask for in a VM, 53b046d5 src/modules/alsa/alsa-util.c (Lennart Poettering 2009-11-05 03:23:08 +0100 1483) * so let's fallback to classic IO based playback then. */
I would go ahead and submit a pull request to disable this check but I'm unsure of the ramifications across different virtualization solutions.