Re: [Jack-Devel] jack dsp load calculation

On 12/26/2015 04:10 PM, John Emmas wrote:
> On 26/12/2015 14:41, Robin Gareus wrote:
>> I like Nedko's idea: Allow to query all: min, average, max  over a long
>> time compared to the process-cycle (think second or seconds).
>>
> 
> Hmm...  I didn't get that email for some reason.  But yes - as a feature
> update, that sounds promising.  I'm just pointing out that (a) the
> averaging mechanism / hybrid approach is NOT the underlying cause of the
> problem you described - and (b) in Mixbus and Ardour, we can already
> make a solution which wouldn't need us to tinker with Jack.  i.e. the
> following strategy instead of our current one:-
> 
>       if ( the_client->got_notified_about_an_xrun() ) {
>             //  We know that an xrun occurred since we last checked
>             //  the CPU load - so do something to accommodate that.

Why are x-runs (100% usage not) included in the statistics?

>             //  and then reset the notification flag
>             reset_the_xrun_notification_flag ();
>       } else {
>             //  No xrun was encountered - so we can update normally...
>             update_cpu_load ();

What does "update_cpu_load ();" do?

>       }
> 
> That would be very simple to implement and I honestly think we should
> try that first, before tinkering too much with Jack.

Ardour/Mixbus has an explicit x-run counter since April 2015. Except the
x-run counter is user-resettable (in the toolbar). But the problem goes
back further. We've been pushing it off because it's mainly a detail and
I expected longer discussions...


My criticism is that jack's currently algorithm does not satisfy the
criteria: "an x-run implies 100% reported load".

How can we justify buffer over/under-runs if there is time left to
process the buffer?

best,
robin

1451144317.3107_0.ltw:2,a <567EB474.4030205 at gareus dot org>