[SOLVED] TSC on Atom CPU and downscaling CPU frequency

[agent_kith]

My cyclic test comes out around the 32000 mark give  or take, it doesnt seem that anything I have done since I started fiddling with snakeoil has made much difference, although not 100% sure on that.

I don't think it's going to do much difference regardless of the meddling. In theory changing the timer to pit/hpet/tsc etc will affect this. As is overclocking/underclockingi, or faster RAM. This test is mostly down to hardware speed.

Anyway your mark gives about 32 us (microseconds) which is relatively good. Not the best, but it's relatively responsive enough. I think my atom also yields similar results.

Using this as an example, that single number alone is not informative enough. What one should be interested to know is looking at the average of say 30 us, with a min of 1 us, and a max of 500 us. How many times did the computer's latency fall between > 30 us and < 500 us? Is there a pattern to it?

For audio playback, my theory is any latency less than 100 us is ok. In Snakeoil's cyclic test, that will show up as 100000 (because Snakeoil uses nanoseconds). Why is this enough? 100 us is actually 0.0001 seconds. Now when you run your applications in real time, and your computer can respond to the code in 0.0001 seconds, I reckon it's OK.
 

I think I can probably make an incremental benefit if I can separate the roon service from the rest of the processes but still not clear how this may do this, If I startup with a roon service and then try to separate tasks to other cores snakeoil doesnt seem to "see" roon as a task.

I cannot explain this but yes separation of tasks into cores does appear to work. I am thinking Roon takes too long to start, and my script to isolate the processes is run before that. .. Will have to add more code to check for that. This will hopefully be fixed in Blind Testing update 1.
 

Cyclicsope looks interesting, look forward to trying it. 

Me too. You can actually run this now from VNC. But my aim is to add this into the web app.
 

the 100hz idea also sounds interesting, is there a precedent or are you  lone wolf on this, 

I would hope not. Anybody who has a passing grade in Computer Operating Systems would know this.

There are many meanings to latencies. One of the more common one is lag. as an example, when you type a key on the keyboard, and the time it takes when that happen till the character appears on screen is called a lag. For this use case, using a 1000 Hz kernel will be better than a 100 Hz one. For just audio you don't need this.

So when do you need 1000 Hz kernels? When user interaction is important, or for syncing. Example:

1. When playing a movie, where video and audio has to sync up (lip sync)
   
2. Playing a game, when you fire a gun, the audio need to sound immediately
   
3. specific applications like voice over IP (VoIP), music mixing, video editing, etc
   

Long story short, if you need to 'line up multiple' inputs, then a higher timing is desirable.

Having said that, that's the theory. Does not necessarily mean 1000 Hz is bad. In some cases using something worse in theory actually yields better results. Over the next few days I'd build a 1000 Hz kernel, and you can try it and let me know how it goes. As always I will not recommend people what settings to use, it is important for people to find 'their own way' and tune Snakeoil to what they like, then share their results.

 

There seem to be multiple strategies and these may be split up further depending on whether you are running a server/renderer box or separate boxes, low Hz, low power(arm or detuned more powerful processors) . I note the pi release is live so look forward to giving it a go but just trying to figure out what the best hardware might be to try, assuming not pi but that will probably be first cab off the rank.

Personally I like to stay on a platform for years, study it and tweak the hell out of it. That focus is important because it means I am always clear when there is an improvement. Hence unlike a lot of people I havn't churn my audio gear. I am still using the same pre/amp and speakers for the past 10 years, the same DAC for the past 2 to 3. Using the same system for long periods gives me a stable reference. Unfortunately it also means I'm slow to adapt to big changes.

But I cannot force everybody to be on my pace. Pi is just the start, I think I will work on expressiobin in the next year. To be honest the software is well designed and will port to almost any architecture that has a debian OS. As requests come in, I will fill them in, but for myself I will still stick to my Atom.

Again thanks and appreciate your hard work!

My pleasure!
 

Another question is what is your preferred server/player. Clearly not Roon. would like to try it   

My system is simple. So I prefer LMS/Squeezelite. Music are WAV files and served over NAS (via CIFS).

If you want the best quality, I think MPD v20 so far is probably the best. Unfortunately that player is too good and it doesn't ease me into the music (too revealing?).. Sometimes I can feel my energy drained after a long MPD session. Squeezelite on the other hand, makes me feels recharged.

As for Roon, I think there's something wrong with it? See this thread.