Re: [Jack-Devel] JACK thread priorities on different OSes

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DateFri, 13 May 2011 10:17:27 -0700
From Devin Anderson <[hidden] at charityfinders dot com>
ToStéphane Letz <[hidden] at grame dot fr>
CcJack Developers <[hidden] at lists dot jackaudio dot org>
In-Reply-ToStéphane Letz Re: [Jack-Devel] JACK thread priorities on different OSes
On Thu, May 12, 2011 at 2:10 PM, Stéphane Letz <[hidden]> wrote:

>>> Any GUI thread, disk access, main thread... Think about any standard
>>> audio application (Reason, Live....) that the user start using JackRouter
>>> ASIO/JACK bridge. If this process get REALTIME_PRIORITY_CLASS,
>>> then it will certainly cause problem for any other running application.
>>
>> Oh!  I see where there's a miscommunication.
>>
>> I'm not saying that JACK 2 should set the process priority of client
>> processes; I'm saying that JACK 2 should allow its *own* process
>> priority to be set via a command line argument.
>
> OK this could make more sense, and would help for the audio/MIDI
> threads.
>
> But then I guess all other threads of JACK server (like the server/client
> communication one) should be lowered, possibly to
> THREAD_PRIORITY_IDLE ( which is finally still 16, that is again... over
> THREAD_PRIORITY_TIME_CRITICAL thread of any other process...)
> Hum... (1)

How much processing does the server do?  How much would it get in the
way of other JACK clients?  Maybe this question is dependent on a
person's particular usage of JACK, such that REALTIME_PRIORITY_CLASS
might work for some people and not for others.

> Then the Audio RT thread of clients should be handled in another
> process class,... hum (2)

Maybe.  Other client processes can potentially gain higher process
priorities too.  JACK 2 can't really control what happens in this
case, which makes it more important for the process priority of JACK 2
to be configurable.

> and we also have the issue that internal JACK clients running in the
> server process would be "boosted" so possibly behave differently
> than other out of process JACK clients Hum (3)...

How might they behave differently?

-- 
Devin Anderson
devin (at) charityfinders (dot) com

CharityFinders - http://www.charityfinders.com/
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