rt kernel

ailo ailo.at at gmail.com
Wed Apr 6 13:36:46 UTC 2011

Well, if you get a chance, please try them. 2.6.38, that is.

Also, I'm hoping 2.6.39 will be even better, since it seems we will be
able to adjust irq priority.

Perhaps the midi problems are partly because of Alsa? Don't know much,
but from what I hear, alsa midi is not the most reliable.

On 04/06/2011 03:00 PM, Ralf Mardorf wrote:
> On Wed, 2011-04-06 at 14:40 +0200, ailo wrote:
>> On 04/06/2011 12:54 PM, Ralf Mardorf wrote:
>>>> How have you tested? What results have you obtained? If you want
>>>> convince someone else you should provide testing procedures and
>>>> numeric results.
>>> If I play a MIDI track with external MIDI equipment, DX7, Matrix-1000,
>>> D4, TG33 and others with 1000 Hz timer and record it to an audio track
>>> and watch the files by Audacity, I can see that there's more jitter,
>>> than when using the HR timer.
>>> I also recorded kick, hi hat and snare one after the other and the
>>> rhythm didn't groove anymore.
>>> On LAD, 64 Studio lists, perhaps JACK devel and others too I posted
>>> tests years ago. All regarding to this issue and other sync issues,
>>> because Linux lacks on sync.
>> How recently have you tested -generic and -lowlatency?
>> -- 
>> ailo
> I didn't really tested 'lowlatency', because even the RT-patch doesn't
> fit to my needs, hence I suspect that preemption only wouldn't be ok,
> even if it should be as good as preemption rt.
> I once used a preemption only kernel, had some issues, asked for help at
> JACK devel list or another list and they asked me to use a kernel
> preemption + rt. IIRC the issue had nothing to do with the preemption
> only kernel, it still was there when using a preemption + rt kernel,
> anyway, if you report async issues and xruns and stuff like that for
> jackd, resp. jackd clients and you aren't using a kernel-rt, the first
> hint you'll get, is to use a kernel-rt and depending to the kind of
> problem, nobody will take a look to your issues, before you do this.
> Default and vanilla kernels don't do what I do need. For this I don't
> need to do tests, resp. launching an audio app and just moving the ps2
> mouse will demonstrate the limitations of a default kernel(-desktop,
> -generic or what ever a distro does call the default kernel).
> Greetz,
> Ralf


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