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 Developers <linux-audio-dev@...>
Date: Sunday, July 11, 2010 - 3:21 pm

On Sun, Jul 11, 2010 at 04:53:14PM +0200, Ralf Mardorf wrote:

OK, so the proprietary driver seems to yield better 'worst latency' values
compared to nouveau. That's kind of odd, anything X-related would have a much
lower priority than the MIDI threads.

> Note that for Ubuntu Studio 2 tests failed because of time out errors

What exactly timed out?

> even the tests that were passed with success are significantly less good,

> ------------------------------------------------------------------------

> ------------------------------------------------------------------------

2 differences jump out:

- the frequency scaling is set to 'performance' on your suse install and to
'?' on your ubuntu install.
- The kernel options for your suse install has the options 'SMP PREEMPT RT',
while your ubuntu install has the options 'SMP PREEMPT'. In other words, it
looks like your ubuntu kernel has 'normal' preemption, but not the -rt

The latter looks like a good candidate for explaining the difference. Could
you test with the kernel from the linux-image-2.6.31-10-rt package instead of
the kernel from the linux-image-2.6.32-21-preempt package which you seem to be
using now?

Kind regards,

Linux-audio-dev mailing list

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Re: [LAD] PCI MIDI jitter - comparison Ubuntu (bad) and Suse..., Arnout Engelen, (Sun Jul 11, 3:21 pm)