Q: Proper use of CPU pinning? How to make Mopidy3 container play always smooth?

[b0m541]

I am experiencing chopped-up replay with Mopidy3 sometimes. Sometimes restarting the Mopidy3 container helps, sometimes it does not help to get clear playback. (Restarting Snapcast does not help.)

 

The first thing I tried was to increase the --cpu-shares to 10240 for the Mopidy3 container and the Snapcast container.

That did not help, so I rolled this change back.

 

Next, I though, lets set 1 CPU aside for real-time applications, such as media servers (Mopidy, Snapcast, Plex, Owntone).

So I isolated one CPU and pinned the media servers to this CPU.

 

This actually led to bigger problems with Mopidy3, as the WebUI became unusable. Anything you do that actually influences the playing stream would not be executed, or much much later.

 

What am I missing here? Why did my move not improve the performance of Mopidy3? Does it need to use several CPUs?

 

What else can I try to improve the real-time performace of the media server containers?

(So far never had Problems with Plex and Owntone, though.)

 

[Squid]

CPU shares only makes a difference if there are multiple docker container all running full tilt.  Only then does it make a difference

 

When does it become choppy?  Most hard drive controllers will actually pause all I/O if a drive winds up spinning up.  See if it makes a difference with drive spindown disabled.

[b0m541]

The machine has 8 cores and was not Running full tilt in the situations when the sound was chopchopchop. So that explains why CPU shares did not help.

The bad sound did not have anything to do with drives spining up.

 

To be honest I have no idea what the root cause is. It does not sound like somethign is running out of buffers, then the music would just bause for a short time and then resume.

 

The stream sounds like a helicopter is chopping it up with its blades, don't know how to better describe this.

 

Maybe this is not related to performance?

 

Still I am left wondering why assigning an isolated core to Mopidy makes it basically unusable? Any ideas about that?