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

[XeCycle]

Tom Gundersen <teg at jklm.no> writes:

> 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.

I'll have a look.

> And also checking if
>
> for dev in /proc/asound/card*/pcm*/sub*/prealloc; do
> echo 64 > $dev
> done
>
> solves the problem.

Thanks, this solves it.  Curious about what is this?

> 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.

I believed I did every step in the guide (on the arch wiki), also no
programs showed any error --- but they can't produce any sound.

-- 
Carl Lei (XeCycle)
Department of Physics, Shanghai Jiao Tong University
OpenPGP public key: 7795E591
Fingerprint: 1FB6 7F1F D45D F681 C845 27F7 8D71 8EC4 7795 E591
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