Bug#633815: jackd2: High CPU usage following sleep (top reports 190% on quad-core)

[Adrian Knoth]

On 07/14/11 01:49, Joel Roth wrote:

Hi!

> Package: jackd2
> Version: 1.9.6~dfsg.1-2
> Severity: normal
> 
> Observed when running jackd with user privileges.
> 
> System is extremely sluggish until I kill jackd.

Can we have some numbers, please?

Many people run jackd2 with user privileges, that's actually the
recommended way, and none of them experiences a substantial slowdown.

So we need to find out what's wrong with your system or particular
setup.

I suggest a procedure like this:

   0. Update to the current package version
   1. Stop jackd (killall -9 jackd, if need be)
   2. Start top, htop or another CPU
   3. Start jackd -d dummy

This must not trigger an considerable increase in CPU usage. Then, stop
this jackd and start your real jackd. Which parameters do you use? Which
soundcard is it?

Increasing the buffer size will ease the timing and hence lower the CPU
load. Assuming you use ALSA:

   $ jackd -d alsa -p 2048  --> relaxed timing
   $ jackd -d alsa -p 128   --> stresses the CPU a bit more

In case of firewire audio interfaces, there has been made a fix recently
that triggered tons of error messages to be printed on the console, thus
making the entire system awfully slow. The newest package has the fix.


Cheers