Decreased performance and higher DSP load with JACK .116.1 + Ardour 2.7.1


I have been working for the last few months on a Ubuntu 7.10 based downloadable “Snapshot” of a working Linux A/V setup with Ardour 2.7.1 pre builtwith LV2 FREESOUND WIIMOTE also the latest DSSI-VST, Hydrogen, Rosegarden, QSynth, also with the PAM mods preconfigured and an rtirq script as well as OOTB FFado firewire and Tascam US-122,224,428 support and the ALSA GUI’s for RME, Envy24 etc. It will also include all current development libs for advanced users to build their own Ardours and simplify that “Arduous” task as well. lastly the correct version of WINE for stable VST performance and Window rendering.

I am now ready to upload for distribution however I am not at all happy with the performance of JACK .116.1 and Ardour 2.7.1. Playing existing arrangements I am experiencing numerous xruns and DSP loads up to 20% higher than with JACK 109.2, I built JACK .116.1 from source and have included the necessary mods to fstab, I am using the Ubuntu 7.10 Gutsy -rt kernel which benchmarks significantly higher than the Hardy Kernel and supposedly the Intrepid -rt kernel is currently very poor. Using JACK 109.2 has solved the instability and Xruns, however using Ardour 2.7.1 with JACK 109.2 is requiring me to double my frames per period figures on both my Tascam US-122 and MAudio 1010LT in order to get smooth performance over previous versions, Any Ideas?

In laymans terms what performance benefits should be expected from JACK .116.1 over 109.2 for “normal” DAW use?

The whole purpose of this “Snapshot” is to simplify and get the most recent Linux Audio Apps to new users in as “Ready to Roll” fashion as possible, I am happy with everything except Ardour’s performance and Ardour is what I am most eager to get into the hands of new users!

0.116 has no planned “performance” benefits over 0.109, although it has slightly less chance of clicking if clients do things like asking for the current graph (ports & connections). 0.116 is primarily about correct behaviour when clients misbehave. 0.109 was easy to crash or leave in an indeterminate state if you killed a client, or started too many clients or used a misbehaving client. there were other improvements, but most of them subtle details that most users would not notice.

there have been no other reports of performance degradation with 0.116 that i have seen.


As always thanks for your time in replying, I forgot to mention another issue with 0.116.1 was the dreaded “JACK has been disconnected because Ardour wasn’t fast enough” errors every time Ardour was launched, Since it was a consistent error I will file it as a bug, this also went away with 0.109.2. Sorry I didn’t put this in my first post but I am unable to edit the first post, I will proceed with 0.109.2 (in the Snapshot) for now and continue testing 0.116.1.