Using sound thread quadruples CPU usage

Questions
1

Not sure if anyone else noticed this, but I’ve always had an issue with Defold using so much more CPU than I’d expect it to. Today I was playing around with game.project and found out that disabling sound threading lowered average CPU usage from ~40% to ~10%.

Using sound thread

yes thread
yes thread1115×710 68.4 KB

Not using sound thread

no thread
no thread1266×773 86.2 KB

This is an HP Elitebook 840r G4 with Intel Core i5-7300U @ 2.60Gz running Windows 10.
I don’t necessarily need the threading, but this is interesting considering that thread on is default. I’ve been experiencing a lot of audio cracking and with this project from CPU issues (entire computer lags) and this had been a contributing to it.
Not sure what category to put this one in, but any thoughts?

2

Interesting. On macOS I see more or less the same CPU usage with and without the Sound Thread.

Can you share a bit more info about your project? How many sounds are you playing? Which format? Which sample rate? What does the engine show on startup?

INFO:SOUND:   DSP backend: Fallback
INFO:SOUND: Sound
INFO:SOUND:   nSamplesPerSec:   48000
3 
INFO:SOUND: Mix format:
INFO:SOUND:   wFormatTag:       fffe  IEEE_FLOAT/PCM/EXTENSIBLE: 3 / 1 / fffe
INFO:SOUND:   nChannels:        2
INFO:SOUND:   nSamplesPerSec:   48000
INFO:SOUND:   nAvgBytesPerSec:  384000
INFO:SOUND:   nBlockAlign:      8
INFO:SOUND:   wBitsPerSample:   32
INFO:SOUND:   -> Format:        3  IEEE_FLOAT/PCM/EXTENSIBLE: 3 / 1 / fffe
INFO:SOUND:   DSP backend: SSE
INFO:SOUND: Sound
INFO:SOUND:   nSamplesPerSec:   48000

The game contains multiple sound files and components, but at the time it was only playing 1 song, an ogg file (loaded from disk and resource.set_sound’d onto a sound component) with a 44.1k sample rate.

4

Are you able to share this as an isolated project for us to test (you can email me at bjorn@defold.se) if you prefer.

5

battle test barebones.zip (6.6 MB)

Here’s a version of it with all the content removed. I checked whether it had the same effect, and it did.

6

Thanks. I’m still not able to reproduce the CPU usage difference. I’m seeing the same usage (~28-30%) with and without using sound threads. I stripped down the project further:

Archive.zip (3.3 MB)

Can you please check that this version behaves the same on your machine?

Note: I also did a change and set Update Frequency in game.project Display section from hardcoded 60 to 0 (variable).

7

I’d also like you to test the CPU usage with other tools, such as Process Explorer.
(The reason for that is that I’ve heard Windows’ CPU measurements may a little bit misleading sometimes)

8

This was again on macOS.

I’ve now also tested on Windows 10 on a fairly low end PC and when measuring with the Windows task Manager I barely reach 2% CPU usage with and without threads. It is very strange that we are getting so very different results.

INFO:SOUND: Mix format:
INFO:SOUND:   wFormatTag:       fffe  IEEE_FLOAT/PCM/EXTENSIBLE: 3 / 1 / fffe
INFO:SOUND:   nChannels:        2
INFO:SOUND:   nSamplesPerSec:   44100
INFO:SOUND:   nAvgBytesPerSec:  352800
INFO:SOUND:   nBlockAlign:      8
INFO:SOUND:   wBitsPerSample:   32
INFO:SOUND:   -> Format:        3  IEEE_FLOAT/PCM/EXTENSIBLE: 3 / 1 / fffe
INFO:SOUND:   DSP backend: SSE
INFO:SOUND: Sound
INFO:SOUND:   nSamplesPerSec:   44100

We do have different samples per second though…

Edit:

> file sound/mus_forest.ogg 
sound/mus_forest.ogg: Ogg data, Vorbis audio, stereo, 44100 Hz, ~224000 bps, created by: Xiph.Org libVorbis I

I wonder if it is upsampling from 44 to 48 which is the reason?

9

I still see the same effect, though Process Explorer does show it running with 66-80% of what task manager says, there is still a significant increase shown by it (without → 1-2%, with → 20-30%). I’ll now create a 48k version of the file to see if that’s the issue. But I am confused why the system is 48k instead of 44.1k? What is Defold reading when it prints these messages?

10

Just ran it with a 48k file, it does the exact same thing

11

It gets the devices from the WASAPI api, which gets it from your system.