11 Jul
2010
11 Jul
'10
6:07 p.m.
On 07/11/2010 05:18 PM, Ralf Mardorf wrote:
Hi Robin :)
On Sun, 2010-07-11 at 17:11 +0200, Robin Gareus wrote:
The whole output of 'ps -eo...' will be tooooooo long. Just have a look
and check for high priority processes that are different on both systems.
If you have rtirq installed: '/etc/init.d/rtirq status' will show the
same list but only display processes with RTPRIO set.
Oh and I missed that the Ubuntu's 2.6.32.XX is actually not a rt-preemt
kernel. many thanks to Arnout to spot that.
If there's still a difference between SuSe & Ubuntu using the identical
kernel, with no significant high-priority processes: please post the
version of the alsa-libs for both systems.
Not sure if it has been mentioned before, but you should set your
soundcard's IRQ handler priority to sth "high" (eg 90) and use '-P
89'
with alsa-midi-latency-test.
With the default of "-P 99" the kernel will always end up inverting
priorities to run it (the overhead for doing so is low but it may still
be relevant).
Thanks for being persistent on the Midi Jitter issue. Some of that info
is bound to come in handy..
ciao,
robin
Hi Ralf,
You are comparing a banana and an orange to find out which one is
sweeter. Given the nature of the problem it would help a lot to have as
little differences between the systems under test, otherwise it's
impossible to track it down.
I hazard a guess that it's Ubuntu's 2.6.32 realtime-preemt-kernel.
There are no official 2.6.32 rt-patches and it's likely that some of the
back/forward ports have screwed things up.
Good argument! OTOH an audio distro shouldn't use a kernel that will
increase latency. I'll build 2.6.31.6-rt19 for Ubuntu Studio, btw. I had
this kernel for 64 Studio too, but only in combination with USB MIDI.
Is 'cat /proc/interrupts' identical on
both systems?
what about 'ps ax | wc -l' and
'ps -eo pid,class,rtprio,ni,pri,pcpu,stat,comm --sort -rtprio'
Are there high-priority jobs present on Ubuntu which are not on SuSE?
I dunno, I'll run those commands and post them later, building a kernel
will take some time.