[LAU] [Jack-Devel] zombification behaviour...

[torbenh]

hi... i thought i take this to lau to get an impression on users
feelings.

here is the story. i basically wanted to improve the heuristics for
client zombification. i wanted jack to only kick clients which take a
whole cpu slice. the result would be that you can overload the cpu
with well behaving clients, and jack would not act on it.

the result in a synchronous jackd (jackd1/tschack or jackd2 -S)
would be continuous xruns, and probably bad noise.

the problem is that its not 100% possible to identify the bad client,
and its always possible, that we might kick an inocent client.

so many people on jack-dev advocate not kicking any client (this is what
jack2 does) jack2 users probably have an SMP system, so jack RT load at
100% doesnt mean their system is unresponsive.

for UP users it might make sense to stop processing after a continous
series of timeouts, so that the user can fix things up.



On Wed, Nov 17, 2010 at 02:50:02PM -0500, Paul Davis wrote:
> 
>  [ ... ]
> 
> there are really 3 possible policies:
> 
>    1) ignore all client behaviour (jack2)
>    2) try to zombify the misbehaving client(s) (jack1)
>    3) stop running the process() cycle if there is misbehaviour, and
> restart whenever
>          the graph is rechained (indicating that a client has been removed, or
>          added, or connections where changed)
> 
> torben has been experimenting with an improved version of (2) and with (3)

my argumentation is that if i make the rules for (2) less agressive,
jack might not act up when you overload the cpu.
so i would basically like to protect the user by implementing (3)

after testing the overload situation i think the noise is not so bad.
and i would probably prefer this over silence, if i was on stage.

but UP people might want their cpu freed so they can fix the situation
quickly.

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-- 
torben Hohn