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Thread: Implement priority boost for starved threads.

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SVC: Return correct error code on invalid CreateThread processor ID.

SVC: Assert when creating a thread with an invalid userland priority.
This commit is contained in:
bunnei 2015-03-23 23:55:21 -04:00
parent ee3377b67d
commit 7b9f428b23
5 changed files with 92 additions and 28 deletions
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48
src/core/hle/kernel/thread.cpp
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@ -140,6 +140,29 @@ void ArbitrateAllThreads(u32 address) {
}
}
/// Boost low priority threads (temporarily) that have been starved
static void PriorityBoostStarvedThreads() {
u64 current_ticks = CoreTiming::GetTicks();
for (auto& thread : thread_list) {
// TODO(bunnei): Threads that have been waiting to be scheduled for `boost_ticks` (or
// longer) will have their priority temporarily adjusted to 1 higher than the highest
// priority thread to prevent thread starvation. This general behavior has been verified
// on hardware. However, this is almost certainly not perfect, and the real CTR OS scheduler
// should probably be reversed to verify this.
const u64 boost_timeout = 2000000; // Boost threads that have been ready for > this long
u64 delta = current_ticks - thread->last_running_ticks;
if (thread->status == THREADSTATUS_READY && delta > boost_timeout && !thread->idle) {
const s32 boost_priority = std::max(ready_queue.get_first()->current_priority - 1, 0);
ready_queue.move(thread, thread->current_priority, boost_priority);
thread->current_priority = boost_priority;
}
}
}
/**
* Switches the CPU's active thread context to that of the specified thread
* @param new_thread The thread to switch to
@ -151,6 +174,7 @@ static void SwitchContext(Thread* new_thread) {
// Save context for previous thread
if (previous_thread) {
previous_thread->last_running_ticks = CoreTiming::GetTicks();
Core::g_app_core->SaveContext(previous_thread->context);
if (previous_thread->status == THREADSTATUS_RUNNING) {
@ -168,6 +192,9 @@ static void SwitchContext(Thread* new_thread) {
ready_queue.remove(new_thread->current_priority, new_thread);
new_thread->status = THREADSTATUS_RUNNING;
// Restores thread to its nominal priority if it has been temporarily changed
new_thread->current_priority = new_thread->nominal_priority;
Core::g_app_core->LoadContext(new_thread->context);
} else {
current_thread = nullptr;
@ -364,7 +391,8 @@ ResultVal<SharedPtr<Thread>> Thread::Create(std::string name, VAddr entry_point,
thread->status = THREADSTATUS_DORMANT;
thread->entry_point = entry_point;
thread->stack_top = stack_top;
thread->initial_priority = thread->current_priority = priority;
thread->nominal_priority = thread->current_priority = priority;
thread->last_running_ticks = CoreTiming::GetTicks();
thread->processor_id = processor_id;
thread->wait_set_output = false;
thread->wait_all = false;
@ -400,18 +428,11 @@ static void ClampPriority(const Thread* thread, s32* priority) {
void Thread::SetPriority(s32 priority) {
ClampPriority(this, &priority);
if (current_priority == priority) {
return;
}
// If thread was ready, adjust queues
if (status == THREADSTATUS_READY)
ready_queue.move(this, current_priority, priority);
if (status == THREADSTATUS_READY) {
// If thread was ready, adjust queues
ready_queue.remove(current_priority, this);
ready_queue.prepare(priority);
ready_queue.push_back(priority, this);
}
current_priority = priority;
nominal_priority = current_priority = priority;
}
SharedPtr<Thread> SetupIdleThread() {
@ -440,6 +461,9 @@ SharedPtr<Thread> SetupMainThread(u32 stack_size, u32 entry_point, s32 priority)
void Reschedule() {
Thread* prev = GetCurrentThread();
PriorityBoostStarvedThreads();
Thread* next = PopNextReadyThread();
HLE::g_reschedule = false;