/*
* Set the thread's requested mode and recompute priority
* Called with thread mutex and thread locked
*
* TODO: Mitigate potential problems caused by moving thread to end of runq
* whenever its priority is recomputed
* Only remove when it actually changes? Attempt to re-insert at appropriate location?
*/
static void
thread_set_user_sched_mode_and_recompute_pri(thread_t thread, sched_mode_t mode)
{
if (thread->policy_reset)
return;
boolean_t removed = thread_run_queue_remove(thread);
/*
* TODO: Instead of having saved mode, have 'user mode' and 'true mode'.
* That way there's zero confusion over which the user wants
* and which the kernel wants.
*/
if (thread->sched_flags & TH_SFLAG_DEMOTED_MASK)
thread->saved_mode = mode;
else
sched_set_thread_mode(thread, mode);
thread_recompute_priority(thread);
if (removed)
thread_run_queue_reinsert(thread, SCHED_TAILQ);
}
/*
* thread_set_mode_and_absolute_pri:
*
* Set scheduling policy & absolute priority for thread, for deprecated
* thread_set_policy and thread_policy interfaces.
*
* Note that there is no implemented difference between POLICY_RR and POLICY_FIFO.
* Both result in FIXED mode scheduling.
*
* Called with thread mutex locked.
*/
kern_return_t
thread_set_mode_and_absolute_pri(
thread_t thread,
integer_t policy,
integer_t priority)
{
spl_t s;
sched_mode_t mode;
kern_return_t kr = KERN_SUCCESS;
if (thread_is_static_param(thread))
return (KERN_POLICY_STATIC);
if (thread->policy_reset)
return (KERN_SUCCESS);
/* Setting legacy policies on threads kills the current QoS */
if (thread->requested_policy.thrp_qos != THREAD_QOS_UNSPECIFIED) {
thread_mtx_unlock(thread);
kr = thread_remove_qos_policy(thread);
thread_mtx_lock(thread);
if (!thread->active) {
return (KERN_TERMINATED);
}
}
switch (policy) {
case POLICY_TIMESHARE:
mode = TH_MODE_TIMESHARE;
break;
case POLICY_RR:
case POLICY_FIFO:
mode = TH_MODE_FIXED;
break;
default:
panic("unexpected sched policy: %d", policy);
break;
}
s = splsched();
thread_lock(thread);
/* This path isn't allowed to change a thread out of realtime. */
if ((thread->sched_mode != TH_MODE_REALTIME) &&
(thread->saved_mode != TH_MODE_REALTIME)) {
/*
* Reverse engineer and apply the correct importance value
* from the requested absolute priority value.
*/
if (priority >= thread->max_priority)
priority = thread->max_priority - thread->task_priority;
else if (priority >= MINPRI_KERNEL)
priority -= MINPRI_KERNEL;
else if (priority >= MINPRI_RESERVED)
priority -= MINPRI_RESERVED;
else
priority -= BASEPRI_DEFAULT;
priority += thread->task_priority;
if (priority > thread->max_priority)
priority = thread->max_priority;
else if (priority < MINPRI)
priority = MINPRI;
thread->importance = priority - thread->task_priority;
boolean_t removed = thread_run_queue_remove(thread);
thread_set_user_sched_mode(thread, mode);
thread_recompute_priority(thread);
if (removed)
thread_setrun(thread, SCHED_TAILQ);
}
thread_unlock(thread);
splx(s);
sfi_reevaluate(thread);
return (kr);
}
kern_return_t
thread_policy_set_internal(
thread_t thread,
thread_policy_flavor_t flavor,
thread_policy_t policy_info,
mach_msg_type_number_t count)
{
kern_return_t result = KERN_SUCCESS;
spl_t s;
thread_mtx_lock(thread);
if (!thread->active) {
thread_mtx_unlock(thread);
return (KERN_TERMINATED);
}
switch (flavor) {
case THREAD_EXTENDED_POLICY:
{
boolean_t timeshare = TRUE;
if (count >= THREAD_EXTENDED_POLICY_COUNT) {
thread_extended_policy_t info;
info = (thread_extended_policy_t)policy_info;
timeshare = info->timeshare;
}
sched_mode_t mode = (timeshare == TRUE) ? TH_MODE_TIMESHARE : TH_MODE_FIXED;
s = splsched();
thread_lock(thread);
boolean_t removed = thread_run_queue_remove(thread);
thread_set_user_sched_mode(thread, mode);
thread_recompute_priority(thread);
if (removed)
thread_setrun(thread, SCHED_TAILQ);
thread_unlock(thread);
splx(s);
sfi_reevaluate(thread);
break;
}
case THREAD_TIME_CONSTRAINT_POLICY:
{
thread_time_constraint_policy_t info;
if (count < THREAD_TIME_CONSTRAINT_POLICY_COUNT) {
result = KERN_INVALID_ARGUMENT;
break;
}
info = (thread_time_constraint_policy_t)policy_info;
if ( info->constraint < info->computation ||
info->computation > max_rt_quantum ||
info->computation < min_rt_quantum ) {
result = KERN_INVALID_ARGUMENT;
break;
}
s = splsched();
thread_lock(thread);
boolean_t removed = thread_run_queue_remove(thread);
thread->realtime.period = info->period;
thread->realtime.computation = info->computation;
thread->realtime.constraint = info->constraint;
thread->realtime.preemptible = info->preemptible;
thread_set_user_sched_mode(thread, TH_MODE_REALTIME);
thread_recompute_priority(thread);
if (removed)
thread_setrun(thread, SCHED_TAILQ);
thread_unlock(thread);
splx(s);
sfi_reevaluate(thread);
break;
}
case THREAD_PRECEDENCE_POLICY:
{
thread_precedence_policy_t info;
if (count < THREAD_PRECEDENCE_POLICY_COUNT) {
result = KERN_INVALID_ARGUMENT;
break;
}
info = (thread_precedence_policy_t)policy_info;
s = splsched();
thread_lock(thread);
thread->importance = info->importance;
thread_recompute_priority(thread);
thread_unlock(thread);
splx(s);
break;
}
case THREAD_AFFINITY_POLICY:
{
thread_affinity_policy_t info;
if (!thread_affinity_is_supported()) {
result = KERN_NOT_SUPPORTED;
break;
}
if (count < THREAD_AFFINITY_POLICY_COUNT) {
result = KERN_INVALID_ARGUMENT;
break;
}
info = (thread_affinity_policy_t) policy_info;
/*
* Unlock the thread mutex here and
* return directly after calling thread_affinity_set().
* This is necessary for correct lock ordering because
* thread_affinity_set() takes the task lock.
*/
thread_mtx_unlock(thread);
return thread_affinity_set(thread, info->affinity_tag);
}
case THREAD_THROUGHPUT_QOS_POLICY:
{
thread_throughput_qos_policy_t info = (thread_throughput_qos_policy_t) policy_info;
int tqos;
if (count < THREAD_LATENCY_QOS_POLICY_COUNT) {
result = KERN_INVALID_ARGUMENT;
break;
}
if ((result = qos_throughput_policy_validate(info->thread_throughput_qos_tier)) !=
KERN_SUCCESS) {
break;
}
tqos = qos_extract(info->thread_throughput_qos_tier);
thread->effective_policy.t_through_qos = tqos;
}
break;
case THREAD_LATENCY_QOS_POLICY:
{
thread_latency_qos_policy_t info = (thread_latency_qos_policy_t) policy_info;
int lqos;
if (count < THREAD_THROUGHPUT_QOS_POLICY_COUNT) {
result = KERN_INVALID_ARGUMENT;
break;
}
if ((result = qos_latency_policy_validate(info->thread_latency_qos_tier)) !=
KERN_SUCCESS) {
break;
}
lqos = qos_extract(info->thread_latency_qos_tier);
/* The expected use cases (opt-in) of per-thread latency QoS would seem to
* preclude any requirement at present to re-evaluate timers on a thread level
* latency QoS change.
*/
thread->effective_policy.t_latency_qos = lqos;
}
break;
case THREAD_QOS_POLICY:
case THREAD_QOS_POLICY_OVERRIDE:
{
thread_qos_policy_t info = (thread_qos_policy_t)policy_info;
if (count < THREAD_QOS_POLICY_COUNT) {
result = KERN_INVALID_ARGUMENT;
break;
}
if (info->qos_tier < 0 || info->qos_tier >= THREAD_QOS_LAST) {
result = KERN_INVALID_ARGUMENT;
break;
}
if (info->tier_importance > 0 || info->tier_importance < THREAD_QOS_MIN_TIER_IMPORTANCE) {
result = KERN_INVALID_ARGUMENT;
break;
}
if (info->qos_tier == THREAD_QOS_UNSPECIFIED && info->tier_importance != 0) {
result = KERN_INVALID_ARGUMENT;
break;
}
/*
* Going into task policy requires the task mutex,
* because of the way synchronization against the IO policy
* subsystem works.
*
* We need to move thread policy to the thread mutex instead.
* <rdar://problem/15831652> separate thread policy from task policy
*/
if (flavor == THREAD_QOS_POLICY_OVERRIDE) {
int strongest_override = info->qos_tier;
if (info->qos_tier != THREAD_QOS_UNSPECIFIED &&
thread->requested_policy.thrp_qos_override != THREAD_QOS_UNSPECIFIED)
strongest_override = MAX(thread->requested_policy.thrp_qos_override, info->qos_tier);
thread_mtx_unlock(thread);
/* There is a race here. To be closed in <rdar://problem/15831652> separate thread policy from task policy */
proc_set_task_policy(thread->task, thread, TASK_POLICY_ATTRIBUTE, TASK_POLICY_QOS_OVERRIDE, strongest_override);
return (result);
}
thread_mtx_unlock(thread);
proc_set_task_policy2(thread->task, thread, TASK_POLICY_ATTRIBUTE, TASK_POLICY_QOS_AND_RELPRIO, info->qos_tier, -info->tier_importance);
thread_mtx_lock(thread);
if (!thread->active) {
thread_mtx_unlock(thread);
return (KERN_TERMINATED);
}
break;
}
default:
result = KERN_INVALID_ARGUMENT;
break;
}
thread_mtx_unlock(thread);
return (result);
}
