Re: [linux-audio-dev] Re: 2.4.0-test low-latency mini-HOWTO

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Subject: Re: [linux-audio-dev] Re: 2.4.0-test low-latency mini-HOWTO
From: Tommi Ilmonen (tilmonen_AT_cc.hut.fi)
Date: Sat Sep 23 2000 - 18:12:31 EEST

Hi.

After long struggle with kernel patching, disk corruption, Linux
reinstalls and the other usual goodies I managed to get a kernel with
low-latency patches in place and hard disk tuned (2.4.0-test8 with
Andrew's patches).

I then benchmarked the system with my audio app and got latencies in range
of 10-30 milliseconds. Not very promising. I then found and fixed a few
bugs in my software. Latencies are now down to less than 5 milliseconds.
The system works reliably when handling dull-duplex stereo IO and
running DSP and streaming two stereo streams to the disk and running GUI
and even sometimes using memory management (I do not (yet) fear little
mallocing in RT-apps). Yes, there are many threads...

I am running Mustajuuri which is a real application, not a minimal
benchmark. It is not really ready for prime time, but it seems there is
hope :-)

So I can confirm what others have also said: Things are looking good.

If someone else wants to test it the source is at (not a small package):

http://www.tml.hut.fi/~tilmonen/mustajuuri/download/index.html

The command line looks more or less like this:

./mj/Linux-2.4.0-test8/dmain examples/simple_filer.mj

You need to set the latencies manually each time you run the app
(Mustajuuri->Setup->Latency->Maximum buffer).

Tommi Ilmonen Researcher
>=> http://www.hut.fi/u/tilmonen/
  Linux/IRIX audio: Mustajuuri
>=> http://www.tml.hut.fi/~tilmonen/mustajuuri/
    3D audio: DIVA
>=> http://www.tml.hut.fi/Research/DIVA/

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