Re: [LAD] PCI MIDI jitter - comparison Ubuntu (bad) and Suse (might be ok)

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To: Ralf Mardorf <ralf.mardorf@...>
Cc: <linux-audio-dev@...>
Date: Sunday, July 11, 2010 - 4:07 pm

On 07/11/2010 05:18 PM, Ralf Mardorf 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..

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Re: [LAD] PCI MIDI jitter - comparison Ubuntu (bad) and Suse..., Robin Gareus, (Sun Jul 11, 4:07 pm)