On Fri, Jun 10, 2016 at 11:13 AM, Marcin Lewandowski <marcin@saepia.net> wrote:

Hello,

if MAX_SHM_ID is an OS constant, why is it defined in JACK source code then?

oops, my mistake ... misread my own grep output. sorry about that.

I understand issues with context switching. But I am designing system that can easily split into multiple machines, so instead of having 1 huge JACK with 100 clients I can have 10 x 10 etc.

that won't help.

But still, I need to know what is the limit, and it seem to be quite unknown… I can obviously do crash testing, but I would prefer to rely on certain design principles, no luck that I won’t encounter some hardcoded limits...

well, as mentioned, you can't put things on the command line that have be constant across the server and library. so there are some constants that are going to be hard-coded whether you like it or not.

there is no "hard limit". the number of clients before there is so little time left for the process cycle() depends on (a) what each client does (b) how much time each client takes for its context switch (which is partially a function of what it does) (c) the period size

Any advice how to compute max number of clients?

as noted above, you cannot compute this number. it will vary dramatically depending on the condition.