Re: [LAD] Multiple JACK servers connected in one host?

On Fri, March 11, 2016 11:59 pm, Paul Davis wrote:
> On Fri, Mar 11, 2016 at 7:17 AM, Patrick Shirkey
> <pshirkey@email-addr-hidden
>> wrote:
>
>>
>> On Fri, March 11, 2016 6:58 pm, Robin Gareus wrote:
>> > On 03/11/2016 08:03 AM, Patrick Shirkey wrote:
>> >> If this cannot be fixed in JACK directly we should be able to spin up
>> >> multiple instances on the same machine and have them play nice with
>> each
>> >> other.
>> >
>> > and how would that be different from splitting the current graph in
>> JACK
>> > and not preform worse?
>>
>> Currently it seems that we cant do either so which method is preferable?
>>
>> According to Jonathan's results he is finding a bottle neck with JACK
>> DSP
>> with a single server. In the absense of a fix for JACK so that it is not
>> a
>> bottle neck his solution is to run multiple servers on the same machine.
>> However it seems that it is not possible to have more than 2 instances
>> of
>> JACK running on the same machine without using a virtual
>> machine/environment.
>>
>> According to Paul the issue is that we should not rely on JACK to create
>> a
>> processing graph like Jonathans.
>>
>
>
> Not quite what I said, but close enough.
>
> 20 context switches minimum per process() cycle. This isn't dramatic, but
> it is notable. Some of them might not be context switches if the "Mixer"
> stuff is actually an example of a multi-client process - I don't know.
>
>
>>
>> I don't see much difference between a single server with multiple graphs
>> or multiple servers
>>
>
>
> That isn't the choice. The choice is threeway:
>
> - reduce overhead caused by context switching between programs
> - reduce DSP load by running more in parallel (this is dependent on the
> graph; JACK2 will do
> the best possible already, so if Jonathan is already using JACK2,
> maximum parallelism
> is already in use)

Are we absolutely sure this is the case? That Jonathan has not found a
"bug" in JACK2 or the DSP load algorithm?

> - reduce the amount of work done by each client.

According to Jonathan his multiple cores are barely reaching 5% usage. How
can JACK_DSP be so high when there is so much room left to play with if
JACK2 is handling the parallelism correctly?

It seems similar to my car telling me that I am red lighting when I am
only going 20km/hr in second.

--
Patrick Shirkey
Boost Hardware Ltd
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