Audio module CPU utilization

[jmiskovic]

With blank main.lua the lovr process consumes 12% of my CPU.

Turning off the t.modules.audio = false brings it under the 1%.

Here's the callgrind output showing how the ALSA miniaudio backend spends it's time:

Switching miniaudio backend to PulseAudio has a similar effect on CPU utilization to disabling the audio module.

I've tested the PulseAudio audio to work correctly in lovr, but this was with PipeWire which has interface for PulseAudio. I can re-test on actual PulseAudio in few days. @bjorn you mentioned some issues with PA you had before, let me know what so I can test that specifically.

Edit: above profiling is done with valgrind --tool=callgrind ./lovr . on the debug build, and visualized through kcachegrind.

[bjornbytes]

I'm getting roughly:

• 6-7% CPU usage with pulseaudio
• 8-9% CPU usage with ALSA
• 5% CPU usage with t.modules.audio = false

This was on an optimized build. If I change BUFFER_SIZE to 1024 in audio.h I get a little bit less overhead (presumably at the cost of latency).

If I disable the window, ALSA sits at 12% CPU and the other configurations are at 10%.

These are imprecise metrics, but it does seem like ALSA has a bit more overhead than pulseaudio. Maybe not as much as you're seeing though...

[bjornbytes]

• Wonder if t.audio.start should be false by default, or if that's too weird/annoying.
• Or maybe audio could lazily start the audio device once the first source is played.

[jmiskovic]

Strange that I'm the only one seeing this as it really heats up the laptop. I'm happy with using the PulseAudio backend, feel free to close the ticket.