25 Oct
2006
25 Oct
'06
1:09 p.m.
Clemens:
Most sound cards don't have an internal timer that
could be used for
MIDI timing. ALSA uses whatever timer is configured, the default for
this is the RTC timer.
It is? For ALSA sequencer queues? I thought the
default was system timer. Maybe it just depends on
the modules you have loaded.
My impression from Rosegarden users' reports has
been that trying to use the ALSA sequencer with the
RTC timer (something I've never bothered with myself:
I always use a 1000Hz system timer) is a reliable way
to lock up your system completely, with most kernels
from about 2.6.13 or so onwards.
I've been meaning to investigate with the latest ALSA
source and at least make a decent bug report for
ages, but you know the way it is, there are only
sixty hours in the day. It would be wonderful if some
excellent person had fixed it in the meantime.
Chris
25 Oct
25 Oct
1:17 p.m.
New subject: [linux-audio-dev] about MIDI timing...
On Wed, 2006-10-25 at 15:05 +0000, Chris Cannam wrote:
Clemens:
This is/was a bug or multiple bugs in the kernel's RTC driver. It
started to appear around 2.6.13 because that was the kernel release
where they regressed the default timer granularity from 1ms to 2.5ms,
forcing apps like Rosegarden to switch to RTC based timing.
Should be fixed in the latest kernels.
Lee
Most sound cards don't have an internal timer
that could be used for
MIDI timing. ALSA uses whatever timer is configured, the default for
this is the RTC timer.
It is? For ALSA sequencer queues? I thought the
default was system timer. Maybe it just depends on
the modules you have loaded.
My impression from Rosegarden users' reports has
been that trying to use the ALSA sequencer with the
RTC timer (something I've never bothered with myself:
I always use a 1000Hz system timer) is a reliable way
to lock up your system completely, with most kernels
from about 2.6.13 or so onwards.
I've been meaning to investigate with the latest ALSA
source and at least make a decent bug report for
ages, but you know the way it is, there are only
sixty hours in the day. It would be wonderful if some
excellent person had fixed it in the meantime. 
1:27 p.m.
New subject: [linux-audio-dev] about MIDI timing...
Chris Cannam wrote:
Clemens:
Since 1.0.11, the RTC timer is used, if available.
Most sound cards don't have an internal timer
that could be used for
MIDI timing. ALSA uses whatever timer is configured, the default for
this is the RTC timer.
It is? For ALSA sequencer queues? I thought the
default was system timer. Maybe it just depends on the modules you have loaded.
Timer modules are loaded automatically.
My impression from Rosegarden users' reports has
been that trying to use the ALSA sequencer with the
RTC timer (something I've never bothered with myself:
I always use a 1000Hz system timer) is a reliable way
to lock up your system completely, with most kernels
from about 2.6.13 or so onwards.
Kernels >= 2.6.15 work. The configure script checks for older kernels.
HTH
Clemens
6663
days inactive
6663
days old
linux-audio-dev@lists.linuxaudio.org
2 comments
3 participants
participants (3)
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Chris Cannam -
Clemens Ladisch -
Lee Revell