Re: [Jack-Devel] How can Jack run with less nperiods than ALSA?

right, so this output is what is confusing me:

/usr/local/bin/jackd -dalsa -n 4
jackd 0.124.0
Copyright 2001-2009 Paul Davis, Stephane Letz, Jack O'Quinn, Torben
Hohn and others.
jackd comes with ABSOLUTELY NO WARRANTY
This is free software, and you are welcome to redistribute it
under certain conditions; see the file COPYING for details

JACK compiled with System V SHM support.
loading driver ..
creating alsa driver ... hw:0|hw:0|1024|4|48000|0|0|nomon|swmeter|-|32bit
[14020.281368] tlv320aic3x-codec 1-001b: ASoC: Not enforcing
symmetric_rates due to race
configuring for 48000Hz, period = 1024 frames (21.3 ms), buffer = 4 periods
ALSA: final selected sample format for capture: 32bit integer little-endian
ALSA: use 16 periods for capture
ALSA: final selected sample format for playback: 32bit integer little-endian
ALSA: use 16 periods for playback

On 9 November 2013 17:55, Paul Davis <[hidden]> wrote:
>
>
>
> On Fri, Nov 8, 2013 at 6:18 AM, Kaspar Bumke <[hidden]> wrote:
>>
>> Hey,
>>
>> this is a question that is bothering me as I try and understand the Jack
>> architecture better.
>>
>> Say that ALSA is running at 48kHz 256samples with 4 periods. What happens
>> when I start jack with 2 periods? Where do the additional interrupts come
>> from?
>
>
> quite a bit of confusion here, it seems. JACK will not general work
> correctly when sharing a device. If it is sharing a device, then it is
> ALSA's job to generate the timingm, and it will use one of several possible
> timer sources.
>
> In general if JACK is using a particular PCM device, it is the *only* user
> of that device, and ALSA is doing what JACK tells it to do.
>

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