+int
+pbd_absolute_rt_priority (int policy, int priority)
+{
+ /* POSIX requires a spread of at least 32 steps between min..max */
+ const int p_min = sched_get_priority_min (policy); // Linux: 1
+ const int p_max = sched_get_priority_max (policy); // Linux: 99
+
+ if (priority == 0) {
+ /* use default. XXX this should be relative to audio (JACK) thread,
+ * internal backends use -20 (Audio), -21 (MIDI), -22 (compuation)
+ */
+ priority = 7; // BaseUI backwards compat.
+ }
+
+ if (priority > 0) {
+ priority += p_min;
+ } else {
+ priority += p_max;
+ }
+ if (priority > p_max) priority = p_max;
+ if (priority < p_min) priority = p_min;
+ return priority;
+}
+
+
+
+int
+pbd_realtime_pthread_create (
+ const int policy, int priority, const size_t stacksize,
+ pthread_t *thread,
+ void *(*start_routine) (void *),
+ void *arg)
+{
+ int rv;
+
+ pthread_attr_t attr;
+ struct sched_param parm;
+
+ parm.sched_priority = pbd_absolute_rt_priority (policy, priority);
+
+ pthread_attr_init (&attr);
+ pthread_attr_setschedpolicy (&attr, policy);
+ pthread_attr_setschedparam (&attr, &parm);
+ pthread_attr_setscope (&attr, PTHREAD_SCOPE_SYSTEM);
+ pthread_attr_setinheritsched (&attr, PTHREAD_EXPLICIT_SCHED);
+ pthread_attr_setstacksize (&attr, stacksize);
+ rv = pthread_create (thread, &attr, start_routine, arg);
+ pthread_attr_destroy (&attr);
+ return rv;
+}
+int
+pbd_set_thread_priority (pthread_t thread, const int policy, int priority)
+{
+ struct sched_param param;
+ memset (¶m, 0, sizeof (param));
+ param.sched_priority = pbd_absolute_rt_priority (policy, priority);
+
+ return pthread_setschedparam (thread, SCHED_FIFO, ¶m);
+}
+
+bool
+pbd_mach_set_realtime_policy (pthread_t thread_id, double period_ns)
+{
+#ifdef _APPLE_
+ thread_time_constraint_policy_data_t policy;
+#ifndef NDEBUG
+ mach_msg_type_number_t msgt = 4;
+ boolean_t dflt = false;
+ kern_return_t rv = thread_policy_get (pthread_mach_thread_np (_main_thread),
+ THREAD_TIME_CONSTRAINT_POLICY, (thread_policy_t) &policy,
+ &msgt, &dflt);
+ printf ("Mach Thread(%p) %d %d %d %d DFLT %d OK: %d\n", _main_thread, policy.period, policy.computation, policy.constraint, policy.preemptible, dflt, rv == KERN_SUCCESS);
+#endif
+
+ mach_timebase_info_data_t timebase_info;
+ mach_timebase_info(&timebase_info);
+ const double period_clk = period_ns * (double)timebase_info.denom / (double)timebase_info.numer;
+
+ policy.period = period_clk;
+ policy.computation = period_clk * .9;
+ policy.constraint = period_clk * .95;
+ policy.preemptible = true;
+ kern_return_t res = thread_policy_set (pthread_mach_thread_np (thread_id),
+ THREAD_TIME_CONSTRAINT_POLICY, (thread_policy_t) &policy,
+ THREAD_TIME_CONSTRAINT_POLICY_COUNT);
+
+#ifndef NDEBUG
+ printf ("Mach Thread(%p) %d %d %d %d OK: %d\n", thread_id, policy.period, policy.computation, policy.constraint, policy.preemptible, res == KERN_SUCCESS);
+#endif
+ return res != KERN_SUCCESS;
+#endif
+ return false; // OK
+}