[LAU] macbook pro core 2 duo ubuntustudio configuration

5tefan st9fan at gmail.com
Thu Dec 6 00:19:13 UTC 2012


i've recently installed ubuntustudio in parallel with osx on my macbook pro.
ubuntu is basically running fine but i'm having troubles getting it to
perform equally well as in osx. i'm mainly using supercollider and i have an
edirol fa-101 firewire interface. ubuntu resp. the preinstalled
ffado-drivers detected the interface immediately and i could use it with
supercollider (via jackd(mp)) easily. however, the performance is by far not
as good as under osx. a simple test-patch in supercollider that was
consuming about 30% cpu max. in osx (tested withcoreaudio as well as jack,
started via jackrouter) was quickly using up to 100% in linux, producing
lots and lots of xruns.

after asking on the supercollider-mailinglist someone pointed me to this
where i found this test:

after executing the test i followed the recommended steps to tune my system.
this is the current state:
== GUI-enabled checks ==
Checking if you are root... no - good
Checking filesystem 'noatime' parameter... found - warning
/media/exchange does not have the 'noatime' parameter set
/media/satellite does not have the 'noatime' parameter set
/media/scratch does not have the 'noatime' parameter set
/media/burn does not have the 'noatime' parameter set
/media/G4 does not have the 'noatime' parameter set
/media/emergency does not have the 'noatime' parameter set
For more information, see
Checking CPU Governors... CPU 0: 'ondemand' CPU 1: 'ondemand'  - not good
Set CPU Governors to 'performance' with 'cpufreq-set -c <cpunr> -g
See also: http://linuxmusicians.com/viewtopic.php?f=27&t=844
Checking swappiness... 10 - good
Checking for resource-intensive background processes... none found - good
Checking checking sysctl inotify max_user_watches... >= 524288 - good
Checking access to the high precision event timer... readable - good
Checking access to the real-time clock... readable - good
Checking whether you're in the 'audio' group... yes - good
Checking for multiple 'audio' groups... no - good
yes - good.
Checking the ability to prioritize processes with chrt... yes - good
Checking kernel support for high resolution timers... found - good
Kernel with Real-Time Preemption... not found - not good
Kernel without real-time capabilities found
For more information, see
Checking if kernel system timer is set to 1000 hz... found - good
Checking kernel support for tickless timer... found - good
== Other checks ==
Checking filesystem types... ok.
not found.
** Warning: no tmpfs partition mounted on /tmp
   For more information, see:
   - http://wiki.linuxmusicians.com/doku.php?id=system_configuration#tmpfs
   - http://lowlatency.linuxaudio.org
** Set $SOUND_CARD_IRQ to the IRQ of your soundcard to enable more checks.
   Find your sound card's IRQ by looking at '/proc/interrupts' and lspci.

... i've even built a new kernel from the latest sources of the stable 3.2
branch (for some reason i wasn't successful building it "preemptive" though
the config says it is). however, with this configuration the performance is
just as bad as before or even worse. 

my startup-configuration for jackd(mp) is the following:

/usr/bin/jackd -P89 -p128 -t1000 -dfirewire -r96000 -p512 -n3 -i8 -o8

admittedly this may be tight but using a 128 sample buffer at 96 khz is no
problem on osx and i am interested in keeping latency as small as possible.
but even with a 1024 sample buffer i'm getting xruns and cpu-usage is really
high compared to osx.

has anyone on this list experience with my particular setup (ubuntustudio,
firewire soundcard, macbook pro core 2 duo)? 

any help highly appreciated,


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