boolean_t
swtch_pri(
__unused struct swtch_pri_args *args)
{
register processor_t myprocessor;
boolean_t result;
disable_preemption();
myprocessor = current_processor();
if (SCHED(processor_queue_empty)(myprocessor) && rt_runq.count == 0) {
mp_enable_preemption();
return (FALSE);
}
enable_preemption();
counter(c_swtch_pri_block++);
thread_depress_abstime(thread_depress_time);
thread_block_reason((thread_continue_t)swtch_pri_continue, NULL, AST_YIELD);
thread_depress_abort_internal(current_thread());
disable_preemption();
myprocessor = current_processor();
result = !SCHED(processor_queue_empty)(myprocessor) || rt_runq.count > 0;
enable_preemption();
return (result);
}
static void
swtch_pri_continue(void)
{
register processor_t myprocessor;
boolean_t result;
thread_depress_abort_internal(current_thread());
disable_preemption();
myprocessor = current_processor();
result = !SCHED(processor_queue_empty)(myprocessor) || rt_runq.count > 0;
mp_enable_preemption();
thread_syscall_return(result);
/*NOTREACHED*/
}
static void
thread_switch_continue(void)
{
register thread_t self = current_thread();
int option = self->saved.swtch.option;
boolean_t reenable_workq_callback = self->saved.swtch.reenable_workq_callback;
if (option == SWITCH_OPTION_DEPRESS || option == SWITCH_OPTION_OSLOCK_DEPRESS)
thread_depress_abort_internal(self);
if (reenable_workq_callback)
thread_switch_enable_workqueue_sched_callback();
thread_syscall_return(KERN_SUCCESS);
/*NOTREACHED*/
}
/*
* thread_depress_abort:
*
* Prematurely abort priority depression if there is one.
*/
kern_return_t
thread_depress_abort(
register thread_t thread)
{
kern_return_t result;
if (thread == THREAD_NULL)
return (KERN_INVALID_ARGUMENT);
thread_mtx_lock(thread);
if (thread->active)
result = thread_depress_abort_internal(thread);
else
result = KERN_TERMINATED;
thread_mtx_unlock(thread);
return (result);
}
/*
* thread_switch:
*
* Context switch. User may supply thread hint.
*/
kern_return_t
thread_switch(
struct thread_switch_args *args)
{
thread_t thread = THREAD_NULL;
thread_t self = current_thread();
mach_port_name_t thread_name = args->thread_name;
int option = args->option;
mach_msg_timeout_t option_time = args->option_time;
uint32_t scale_factor = NSEC_PER_MSEC;
boolean_t reenable_workq_callback = FALSE;
boolean_t depress_option = FALSE;
boolean_t wait_option = FALSE;
/*
* Validate and process option.
*/
switch (option) {
case SWITCH_OPTION_NONE:
workqueue_thread_yielded();
break;
case SWITCH_OPTION_WAIT:
wait_option = TRUE;
workqueue_thread_yielded();
break;
case SWITCH_OPTION_DEPRESS:
depress_option = TRUE;
workqueue_thread_yielded();
break;
case SWITCH_OPTION_DISPATCH_CONTENTION:
scale_factor = NSEC_PER_USEC;
wait_option = TRUE;
if (thread_switch_disable_workqueue_sched_callback())
reenable_workq_callback = TRUE;
break;
case SWITCH_OPTION_OSLOCK_DEPRESS:
depress_option = TRUE;
if (thread_switch_disable_workqueue_sched_callback())
reenable_workq_callback = TRUE;
break;
case SWITCH_OPTION_OSLOCK_WAIT:
wait_option = TRUE;
if (thread_switch_disable_workqueue_sched_callback())
reenable_workq_callback = TRUE;
break;
default:
return (KERN_INVALID_ARGUMENT);
}
/*
* Translate the port name if supplied.
*/
if (thread_name != MACH_PORT_NULL) {
ipc_port_t port;
if (ipc_port_translate_send(self->task->itk_space,
thread_name, &port) == KERN_SUCCESS) {
ip_reference(port);
ip_unlock(port);
thread = convert_port_to_thread(port);
ip_release(port);
if (thread == self) {
thread_deallocate(thread);
thread = THREAD_NULL;
}
}
}
if (option == SWITCH_OPTION_OSLOCK_DEPRESS || option == SWITCH_OPTION_OSLOCK_WAIT) {
if (thread != THREAD_NULL) {
if (thread->task != self->task) {
/*
* OSLock boosting only applies to other threads
* in your same task (even if you have a port for
* a thread in another task)
*/
thread_deallocate(thread);
thread = THREAD_NULL;
} else {
/*
* Attempt to kick the lock owner up to our same IO throttling tier.
* If the thread is currently blocked in throttle_lowpri_io(),
* it will immediately break out.
*
* TODO: SFI break out?
*/
int new_policy = proc_get_effective_thread_policy(self, TASK_POLICY_IO);
set_thread_iotier_override(thread, new_policy);
}
}
}
/*
* Try to handoff if supplied.
*/
if (thread != THREAD_NULL) {
spl_t s = splsched();
/* This may return a different thread if the target is pushing on something */
thread_t pulled_thread = thread_run_queue_remove_for_handoff(thread);
KERNEL_DEBUG_CONSTANT(MACHDBG_CODE(DBG_MACH_SCHED,MACH_SCHED_THREAD_SWITCH)|DBG_FUNC_NONE,
thread_tid(thread), thread->state,
pulled_thread ? TRUE : FALSE, 0, 0);
if (pulled_thread != THREAD_NULL) {
/* We can't be dropping the last ref here */
thread_deallocate_safe(thread);
if (wait_option)
assert_wait_timeout((event_t)assert_wait_timeout, THREAD_ABORTSAFE,
option_time, scale_factor);
else if (depress_option)
thread_depress_ms(option_time);
self->saved.swtch.option = option;
self->saved.swtch.reenable_workq_callback = reenable_workq_callback;
thread_run(self, (thread_continue_t)thread_switch_continue, NULL, pulled_thread);
/* NOTREACHED */
panic("returned from thread_run!");
}
splx(s);
thread_deallocate(thread);
}
if (wait_option)
assert_wait_timeout((event_t)assert_wait_timeout, THREAD_ABORTSAFE, option_time, scale_factor);
else if (depress_option)
thread_depress_ms(option_time);
self->saved.swtch.option = option;
self->saved.swtch.reenable_workq_callback = reenable_workq_callback;
thread_block_reason((thread_continue_t)thread_switch_continue, NULL, AST_YIELD);
if (depress_option)
thread_depress_abort_internal(self);
if (reenable_workq_callback)
thread_switch_enable_workqueue_sched_callback();
return (KERN_SUCCESS);
}
