[arch-general] Time delay problem with latest [core] kernel

[Tom Gundersen]

On Sun, Nov 13, 2011 at 10:00 PM, XeCycle <xecycle at gmail.com> wrote:
> Hi, I'm using the latest kernel from [core] (linux 3.1-4), and
> experienced a terrible delay of software MIDI synthesizers.
>
> I'm using fluidsynth, using ALSA as the output driver (I simply can't
> get jack working), and VMPK as a keyboard MIDI event generator.  The
> delay used to be fine, but with the latest kernel, it's longer than 0.5
> secs --- that's unusable.  I believe this should be kernel-related,
> could you please suggest some solutions or workarounds?

Some more data would be needed. I suggest trying out latencytop. And
also checking if

for dev in /proc/asound/card*/pcm*/sub*/prealloc; do
echo 64 > $dev
done

solves the problem.

I think the first step should be to figure out why Jack does not work,
that's supposed to deal with low-latency situations, so using ALSA
directly might not have been tested very much for this use.