Arch Linux

zabrielza

Member

Registered: 2015-03-02

Posts: 125

Why does Firefox performance slow down after starting Jack server?

Hello,

I started configuring my audio on my system. So, I want to have jack working (not jack2, to work with wineasio) with best sound quality with all sound routed through jack. When i start jack server with this command and settings:

killall jackd;killall pulseaudio;jackd -R -t 1000 -d alsa -P hw:0,0 -r 48000 -n2 -D

Firefox slows down, opens new pages slow and the scroll down is very very slow. I had this issue with other distros too. I suspect that it has to do with realtime ( which i need for my audio related apps like traktor through wine, ardour, ableton through wine etc) without being sure about it. Any idea why this is happening?

ooo

Member

Registered: 2013-04-10

Posts: 1,638

Re: Why does Firefox performance slow down after starting Jack server?

Jack really shouldn't have such effect by itself, unless it was using a lot of cpu for some reason. Did you check that cpu usage of jack isn't over the top?

I'd imagine using heavy applications through wine would more likely be the cause of this issue. Does this happen if you only use linux native applications through jack?

zabrielza

Member

Registered: 2015-03-02

Posts: 125

Re: Why does Firefox performance slow down after starting Jack server?

Jack really shouldn't have such effect by itself, unless it was using a lot of cpu for some reason. Did you check that cpu usage of jack isn't over the top?

I'd imagine using heavy applications through wine would more likely be the cause of this issue. Does this happen if you only use linux native applications through jack?

Well, Take a look here. Actually, one time firefox scrolls down, opens pages etc as normal as before and the other time it slows a lot. But this is happening when I have jack open. Also, This is whether I open wine apps or not. Has this something to do with realtime kernel or not?

ooo

Member

Registered: 2013-04-10

Posts: 1,638

Re: Why does Firefox performance slow down after starting Jack server?

Has this something to do with realtime kernel or not?

sorry I didn't understand you were talking about realtime kernel.
If you suspect the rt-patches is causing your issues, it should be easy enough to test: Just boot into arch kernel and try to reproduce the issue there.

zabrielza

Member

Registered: 2015-03-02

Posts: 125

Re: Why does Firefox performance slow down after starting Jack server?

Has this something to do with realtime kernel or not?

sorry I didn't understand you were talking about realtime kernel.
If you suspect the rt-patches is causing your issues, it should be easy enough to test: Just boot into arch kernel and try to reproduce the issue there.

Oh, Sorry, I meant I don't have realtime kernel ( I am downloading it now to test it).  But maybe, even without a realtime kernel, jack takes a priority better than firefox or other apps. I imagine We want this for better sound quality without xruns etc. Am I in the right direction?

ooo

Member

Registered: 2013-04-10

Posts: 1,638

Re: Why does Firefox performance slow down after starting Jack server?

Yes, since you used -R flag with jackd, it will use realtime priority (and yes, usually you want that for low latency without xruns, it doesn't really matter for audio quality though). So jack will be priorized over other applications, but you still shouldn't see any major slowdowns unless jackd was actually utilizing the cpu to some degree. You could try starting jackd without '-R' to see if that makes any difference.

Instead of the rt-kernel, I'd suggest testing the ck-patched kernel. It should provide better overall desktop performance, and in my experience also helps with realtime audio applications. rt-kernel could be useful if you really need as low audio latency as possible (e.g. for playing live etc.)

I also noticed that you've reniced your X to -1. Something like that could also cause unexpected slowdowns as X takes priority over other applications.

Last edited by ooo (2015-04-25 18:57:46)

schivmeister

Developer/TU

From: Singapore

Registered: 2007-05-17

Posts: 971

Website

Re: Why does Firefox performance slow down after starting Jack server?

I had this issue with other distros too.

This smells like hardware problem. Do this:

1. Kill pulseaudio, jack, and make sure they are killed
2. Make sure you do not renice anything or apply other such tweaks
3. Run jackd -d alsa
4. Use your system
5. If unsatisfactory, try jackd -d alsa -p 1024 -n 3
6. Use your system

Jack runs with realtime priority by default (no flag required), and we still use the audio group to provide that privilege. I also do not advocate the realtime kernel, but you may try it. Jack not functioning well (i.e. hampering other tasks significantly) on a standard kernel is cause for concern.

You can read/grep your dmesg and systemd journal for suspicious messages. You may try running real-time audio tasks in another operating system with your hardware, and upon success may proceed to debug the problem on Linux, possibly with the help of the alsa developers.

Or better yet, grab a supported semi-pro external audio device if jack is important for you. However, this may not help if the problem is somewhere deeper, e.g. at the hardware interrupt level.

Last edited by schivmeister (2015-04-30 18:21:56)

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I need real, proper pen and paper for this.