[PlanetCCRMA] Best performance?

Mark Knecht Mark Knecht <markknecht@gmail.com>
Tue Nov 16 07:11:01 2004

On Tue, 16 Nov 2004 22:24:10 +0800, Timo Sivula <timo.sivula@luukku.com> wrote:
> Dear Jack, Linux and Planet CCRMA addicts,
> I propose a contest of who can run his or her home studio in realtime
> with a latency less than 10 ms for the longest consecutive time without
> a single xrun. Minimum software running has to be Rosegarden and Qsynth
> with at least one soundfont.
> My system generates a couple of xruns at 4 am every night, but stays
> stable for the rest of the day, so my record is 24 h with latency of
> 8.71 ms.
> br, Timo

There is a test we do in the Pro Tools LE forums that involves
recording the largest number of tracks at the same time using plugins,
the idea being to test both CPU power and disk access. Under Ardour
something close would be done like this:

Pretest setup - setup Jack for a specific known amount of latency,
such as <10mS.

1) Set up a new Ardour session
2) Add a new track
3) Add to that track 5 plugins. (The Pro Tools tested used a strange
set of plugins - one EQ - 3 different delays and a limiter. I would
suggest choosing a more useful set, such as:

a) All pass delay line, linear interpolation
b) Auto phaser
c) DJ EQ (mono)
d) Multivoice Chorus
e) SC1

Enable all 5 plugins and record enable that track. 

4) With this one track record enabled, enable Ardour to record and
record audio from your sound card for 3 minutes without xruns. If you
can't do that then back off on latency in Jack and try again until you
find the most aggressive setting you can that will record xrun free
for 3 minutes.

5) Noting DSP Load on the system duplicate the above 5-plugin track
until DSP usage reaches but does not go above 80%. Ensure taht all
tracks added are record enabled. While I haven't done it on my laptop
this looks like it might be about 25 mono tracks.

6) When the multi-track test setup is complete (maximum number of
tracks, all tracks have 5 identical sets of enabled plugins, DSP usage
is not above 80%) then start recording and record for at least 3
minutes without xruns.

7) If you cannot record for 3 minutes without xruns then remove tracks
until you can.

8) Report the results - your CPU, system info, distro, disk speeds
using hdparm -tT on your audio drive, Ardour and Jack revisions, etc.

Beyond this Ardour/Jack only test I'd like to see a similar test done
using VST plugins but I think it's 3-6 months early for that on a
global basis.

What do you think of this sort of test? 

- Mark