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IDProjectCategoryView StatusLast Update
0005845ardourbugspublic2014-01-30 11:34
Reporterjoaakive Assigned To 
Status newResolutionopen 
Product Version2.8.12 
Summary0005845: jack audio program with multiple outputs gives ardour huge cpu loads when connected
DescriptionI am creating a music software on linux using jack, that has multiple outputs (16). When running full dsp process in my program (many synths, samplers, etc..), the cpu load is little high but nothing near troubling. This is when jack client's outputs are unconnected or connected straight to sound card outputs.

So, then as I start Ardour and open empty template (no plugins or anything), cpu load stays down in 5% (monitoring with top) until I connect my program's outputs into Ardour inputs (mono tracks). After that, Ardour cpu usage jumps to 80-95% and causes everything to slow down into unusable, even if my prog is not processing much anything. This doesn't make any sense as puredata instances with the same or higher amount of jack outputs are not causing similar cpu loads to ardour (empty or even full with plugins). This does not happen when my program is connected to puredata or audacity with as many outputs as possible.
Additional InformationI'm using rt kernel linux test machine (running ubuntu studio 12.04 lts), program's very minimal gui is drawn with SDL 1.2. Program has multiple threads.
TagsNo tags attached.



2014-01-30 09:28

administrator   ~0015643

The most likely explanations for this is that your app produces or NaN


2014-01-30 09:29

reporter   ~0015644

as with any right mind, no sdl-drawing/memory allocation/io is made in the programs's jack callback function


2014-01-30 11:34

reporter   ~0015645

Thanks to x42. Disabling denormal floats at the code level solved the problem entirely.

Issue History

Date Modified Username Field Change
2014-01-30 09:11 joaakive New Issue
2014-01-30 09:28 x42 Note Added: 0015643
2014-01-30 09:29 joaakive Note Added: 0015644
2014-01-30 11:34 joaakive Note Added: 0015645