Re: Tuning the system for jackd
> Hello!
>
>> I'm re-styling the demudi tasks packages, which I'd like to upload to
>> Debian in the near future. One of them it's called demudi-config and
>> it's haevily based on the debian-edu-config package. It uses cfengine
>> to customize configuration files in a consistent manner.
>>
>> As already discussed, we are going to drop the demudi specific version
>> of the jack package, and rely on the debian one.
>>
>> I was wandering about which tunings are needed to the enhance the
>> performance of jackd, and whether they should be accomplished through
>> the demudi-config task or directly with jackd.
>>
>> The ones that come to my mind are:
>>
>> 1) Turn on low latency:
>>
>> echo 1 > /proc/sys/kernel/lowlatency
>
> using /etc/sysctl.conf is nicer than this.
>
Perfect, thank for the hint.
>> This assumes a patched 2.4 kernel, which AFAIK is not the case of
>> the official Debian kernel.
>
> True. Are you going to upload the DeMuDi Kernel to Debian?
>
Yes I'd be glad to do it, but I'm not sure whether once I become a Debian
maintaner I'm allowed to upload kernel-image packages..
>> I don't know whether the 2.6 series need such tuning too..
>
> There are now lowlatency patches (in this form) for 2.6. There is
> PREEMPT and in the ck-patches there is a very interesting isochronous
> scheduling mode.
>
Ok. Shall we start writing a list of all the patches we apply over the
standard 2.6 kernel source package?
>> 2) Setuid the jackstart binary. This can be accomplished via
>> dpkg-statoverride (as suggested in the README.Debian of jackd), but
>> I'm not sure whether the best solution is:
>
> Why don't you all subscribe to the jack-audio-connection-kit package on
> <http://packages.qa.debian.org/j/jack-audio-connection-kit.html>?
>
Sure, I just did it.
> JACK (>= 0.94.0-2) does contain jackstart setuid root, executable by
> group audio.
>
> dpkg-statoverride is only if you want to _override_ permissions.
>
Sorry I really didn't notice this. Well done! :)
ù>>
>> 3) Mount /tmp as a tmpfs, adding the line
>>
>> none /tmp tmpfs defaults 0 0
>>
>> to fstab. Again this can be accomplished both inside demudi-config
>> and inside jackd and I'm not sure which place is better.
>
> Also done. libc6 >= something-ds11 mounts a shmfs onto /dev/shm. JACK
> (>= 0.94.0-2) puts its files there.
>
Really great.
>> 4) Write a ~/.asoundrc file (for users in the audio group). I don't
>> know if this is really necessary, but it can be accomplished by
>> demudi-config.
>
> No. I don't think it's necessary. jackd defaults to hw:0, which makes
> sense.
>
Ok so let's drop it.
Free
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