On 05/17/2010 05:20 AM, Stéphane Letz wrote:
What would be the different steps to follow to add realtime support to
libdispatch then ?
I would start by filing an RFE bug to the libdispatch tracker, since this is a complex request that may take some time to implement. Here's the link: http://libdispatch.macosforge.org/trac/newticket The dispatch_queue_create() function and the dispatch_queue_attr struct could be extended to specify a realtime queue [1]. The pthread_workqueue_attr struct could be extended to support a time_constraint_policy for the worker threads [2]. Each realtime dispatch_queue would use a separate pthread_workqueue whose threads would run with the desired time_constraint_policy. For additional context, take a look at the pthread_workqueue code I pulled from the xnu and darwin sources: http://mark.heily.com/src/libpthread_workqueue.tar Regards, - Mark [1] typedef struct dispatch_queue_attr { int thread_policy; struct thread_time_constraint_policy ttcpolicy; } dispatch_queue_attr_t; dispatch_queue_attr_t attr = { .thread_policy = THREAD_TIME_CONSTRAINT_POLICY, .ttcpolicy = { .period = ?, .computation = ?, .constraint = ?, .preemptible = 1, }, }; my_queue = dispatch_queue_create("org.jack.realtime.audio", &attr); [2] typedef struct { uint32_t sig; int queueprio; int overcommit; + int thread_policy; + struct thread_time_constraint_policy *ttcpolicy; unsigned int resv2[13]; } pthread_workqueue_attr_t; +int pthread_workqueue_attr_settimeconstraintpolicy_np( + pthread_workqueue_attr_t * attr, + struct thread_time_constraint_policy *ttcpolicy);