[PD-dev] Re: [PD] pthread_setschedparam problem on OSX + fix

[Miller Puckette]

OK.. I've added an "nrt" flag so that on Mac the default ("rt") acts
as it did before...  When I get started on 0.38 I can make linux
choose "rt" automatically if it's setuid.

cheers
Miller

On Sun, Nov 23, 2003 at 03:18:21PM -0600, cgc wrote:
> I've been meaning to post this change for a long time, and have been 
> negligent about it.   
> 
> The pthread_setschedparam() hack that helps pd's audio not drop on OSX 
> is absolutely fatal when used with GEM.  The reason for this is that 
> OSX uses OpenGL for the entire UI and GL requires context switches to 
> handle multiple applications sharing the hardware.  When Pd sets it's 
> pthread priority higher than the UI, this context switch can be blocked 
> resulting in a complete lockout of UI events as GEM grabs all the CPU 
> resources and refuses to relinquish the context. 
> 
> The fix is to add the -rt option as prerequisite and not make this the 
> default action (a check to make sure GEM is not loaded would be good to 
> have as well): 
> 
> #ifdef MACOSX 
> 
>     if (sys_hipriority) 
>     { 
> 	struct sched_param param; 
> 	int policy = SCHED_RR; 
> 	int err; 
> 	param.sched_priority = 80; // adjust 0 : 100 
>         post("pd: real-time mode - using pthread_setschedparam\n"); 
> 	err = pthread_setschedparam(pthread_self(), policy, &param); 
> 	if (err) 
> 	    post("warning: high priority scheduling failed\n"); 
>     } 
> #endif /* MACOSX */ 
> 
> 
>