Re: Transport problem

Hello,

> the
ALSA documentation is incomplete and in many cases incorrect

Do you happen to remember off hand which parts are incorrect? I think we
should report them to the ALSA project.

- PM

On Sun, 19 Feb 2023, 13:53 Ted Felix, <ted-Ll1PANez7xxWk0Htik3J/[email protected]> wrote:

>    We rely completely on ALSA for timer stuff.  The key routine for
> setting the timer in RG is:
>
> AlsaDriver::setCurrentTimer()
>
>    Unless there is a bug in there (which there may very well be, the
> ALSA documentation is incomplete and in many cases incorrect), the
> problems tend to be due to bugs in ALSA or the kernel.  They usually get
> sorted over time by the ALSA folks.  If they notice them.  This one
> seems like an interesting combination of requirements to reproduce and
> thus might fly under their radar.
>
>    I recommend building the latest kernel and seeing if that fixes the
> issue.  My three-year-old Debian/Ubuntu oriented notes are here if you
> need:
>
> http://www.tedfelix.com/linux/kernel-build.html
>
>    In general, it's really easy to do.
>
>    If it's still there, a bug report for the ALSA folks seems like the
> way to go.  They can help find the issue in ALSA, or even in Rosegarden
> if that's where the problem is.
>
> Ted.
>
> On 2/11/23 4:42 AM, Will Godfrey wrote:
> > Recently I found Rosegarden was losing the timer source, and the
> transport was
> > freezing - sometimes for nearly a second after which it would send a
> bunch of
> > notes, then carry on as normal.
> >
> > It was some time before I realised it only happened on my Ryzen 5
> machine (the
> > one I use for music) and not on my office Intel one. I hadn't made any
> changes
> > to the system and got sidetracked into thinking maybe I'd somehow
> managed to
> > get infected with some malware. However I eventually remembered I'd done
> a
> > normal devuan update. The only significant change was the Linux kernel
> V5.10 to
> > V 6.1. Rolling that back cured the problem.
> >
> > Asking some questions on-line identified the problem.
> >
> > First off, I use the RT-Preemt kernel - the 'normal' one doesn't have
> the issue
> > at all.
> >
> > Secondly, the Ryzen has the AMD equivalent of hyper-threading, my older
> Intel
> > doesn't.
> >
> > Finally, since Linux V5.12 the scheduler has been modified to allow
> dynamic
> > preemption. Disabling this in the BIOS cures the problem, albeit with a
> very
> > small loss of performance.
> >
> > I wonder if there should be another look at how Rosegarden does it's
> timing. I
> > did try to set the timing source to the audio hardware. It seemed to
> recognise
> > it, but actually totally ignored it. Saving and reloading showed no time
> source
> > at all, yet still ran as if it was on System Timer.
> >
>
>
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