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Scheduler refactor Pt. 1

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* Simplifies scheduling logic, specifically regarding thread status. It should be much clearer which statuses are valid
for a thread at any given point in the system.
* Removes dead code from thread.cpp.
* Moves the implementation of resetting a ThreadContext to the corresponding core's implementation.

Other changes:
* Fixed comments in arm interfaces.
* Updated comments in thread.cpp
* Removed confusing, useless, functions like MakeReady() and ChangeStatus() from thread.cpp.
* Removed stack_size from Thread. In the CTR kernel, the thread's stack would be allocated before thread creation.
This commit is contained in:
Kevin Hartman 2015-01-25 22:56:17 -08:00
parent 848795f383
commit 5fcbfc06eb
7 changed files with 289 additions and 286 deletions
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364
src/core/hle/kernel/thread.cpp
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@ -21,8 +21,11 @@
namespace Kernel {
/// Event type for the thread wake up event
static int ThreadWakeupEventType = -1;
bool Thread::ShouldWait() {
return status != THREADSTATUS_DORMANT;
return status != THREADSTATUS_DEAD;
}
void Thread::Acquire() {
@ -33,12 +36,20 @@ void Thread::Acquire() {
static std::vector<SharedPtr<Thread>> thread_list;
// Lists only ready thread ids.
static Common::ThreadQueueList<Thread*, THREADPRIO_LOWEST+1> thread_ready_queue;
static Common::ThreadQueueList<Thread*, THREADPRIO_LOWEST+1> ready_queue;
static Thread* current_thread;
static const u32 INITIAL_THREAD_ID = 1; ///< The first available thread id at startup
static u32 next_thread_id; ///< The next available thread id
// The first available thread id at startup
static u32 next_thread_id = 1;
/**
* Creates a new thread ID
* @return The new thread ID
*/
inline static u32 const NewThreadId() {
return next_thread_id++;
}
Thread::Thread() {}
Thread::~Thread() {}
@ -47,86 +58,53 @@ Thread* GetCurrentThread() {
return current_thread;
}
/// Resets a thread
static void ResetThread(Thread* t, u32 arg, s32 lowest_priority) {
memset(&t->context, 0, sizeof(Core::ThreadContext));
t->context.cpu_registers[0] = arg;
t->context.pc = t->entry_point;
t->context.sp = t->stack_top;
t->context.cpsr = 0x1F; // Usermode
// TODO(bunnei): This instructs the CPU core to start the execution as if it is "resuming" a
// thread. This is somewhat Sky-Eye specific, and should be re-architected in the future to be
// agnostic of the CPU core.
t->context.mode = 8;
if (t->current_priority < lowest_priority) {
t->current_priority = t->initial_priority;
}
t->wait_objects.clear();
t->wait_address = 0;
}
/// Change a thread to "ready" state
static void ChangeReadyState(Thread* t, bool ready) {
if (t->IsReady()) {
if (!ready) {
thread_ready_queue.remove(t->current_priority, t);
}
} else if (ready) {
if (t->IsRunning()) {
thread_ready_queue.push_front(t->current_priority, t);
} else {
thread_ready_queue.push_back(t->current_priority, t);
}
t->status = THREADSTATUS_READY;
}
}
/// Check if a thread is waiting on a the specified wait object
/**
* Check if a thread is waiting on the specified wait object
* @param thread The thread to test
* @param wait_object The object to test against
* @return True if the thread is waiting, false otherwise
*/
static bool CheckWait_WaitObject(const Thread* thread, WaitObject* wait_object) {
if (thread->status != THREADSTATUS_WAIT_SYNCH)
return false;
auto itr = std::find(thread->wait_objects.begin(), thread->wait_objects.end(), wait_object);
if (itr != thread->wait_objects.end())
return thread->IsWaiting();
return false;
return itr != thread->wait_objects.end();
}
/// Check if the specified thread is waiting on the specified address to be arbitrated
/**
* Check if the specified thread is waiting on the specified address to be arbitrated
* @param thread The thread to test
* @param wait_address The address to test against
* @return True if the thread is waiting, false otherwise
*/
static bool CheckWait_AddressArbiter(const Thread* thread, VAddr wait_address) {
return thread->IsWaiting() && thread->wait_objects.empty() && wait_address == thread->wait_address;
return thread->status == THREADSTATUS_WAIT_ARB && wait_address == thread->wait_address;
}
/// Stops the current thread
void Thread::Stop(const char* reason) {
void Thread::Stop() {
// Release all the mutexes that this thread holds
ReleaseThreadMutexes(this);
ChangeReadyState(this, false);
status = THREADSTATUS_DORMANT;
// Cancel any outstanding wakeup events for this thread
CoreTiming::UnscheduleEvent(ThreadWakeupEventType, callback_handle);
// Clean up thread from ready queue
// This is only needed when the thread is termintated forcefully (SVC TerminateProcess)
if (status == THREADSTATUS_READY){
ready_queue.remove(current_priority, this);
}
status = THREADSTATUS_DEAD;
WakeupAllWaitingThreads();
// Stopped threads are never waiting.
// Clean up any dangling references in objects that this thread was waiting for
for (auto& wait_object : wait_objects) {
wait_object->RemoveWaitingThread(this);
}
wait_objects.clear();
wait_address = 0;
}
/// Changes a threads state
static void ChangeThreadState(Thread* t, ThreadStatus new_status) {
if (!t || t->status == new_status) {
return;
}
ChangeReadyState(t, (new_status & THREADSTATUS_READY) != 0);
t->status = new_status;
}
/// Arbitrate the highest priority thread that is waiting
Thread* ArbitrateHighestPriorityThread(u32 address) {
Thread* highest_priority_thread = nullptr;
s32 priority = THREADPRIO_LOWEST;
@ -153,108 +131,113 @@ Thread* ArbitrateHighestPriorityThread(u32 address) {
return highest_priority_thread;
}
/// Arbitrate all threads currently waiting
void ArbitrateAllThreads(u32 address) {
// Iterate through threads, find highest priority thread that is waiting to be arbitrated...
// Resume all threads found to be waiting on the address
for (auto& thread : thread_list) {
if (CheckWait_AddressArbiter(thread.get(), address))
thread->ResumeFromWait();
}
}
/// Calls a thread by marking it as "ready" (note: will not actually execute until current thread yields)
static void CallThread(Thread* t) {
// Stop waiting
ChangeThreadState(t, THREADSTATUS_READY);
}
/**
* Switches the CPU's active thread context to that of the specified thread
* @param new_thread The thread to switch to
*/
static void SwitchContext(Thread* new_thread) {
_dbg_assert_msg_(Kernel, new_thread->status == THREADSTATUS_READY, "Thread must be ready to become running.");
/// Switches CPU context to that of the specified thread
static void SwitchContext(Thread* t) {
Thread* cur = GetCurrentThread();
Thread* previous_thread = GetCurrentThread();
// Save context for current thread
if (cur) {
Core::g_app_core->SaveContext(cur->context);
// Save context for previous thread
if (previous_thread) {
Core::g_app_core->SaveContext(previous_thread->context);
if (cur->IsRunning()) {
ChangeReadyState(cur, true);
if (previous_thread->status == THREADSTATUS_RUNNING) {
// This is only the case when a reschedule is triggered without the current thread
// yielding execution (i.e. an event triggered, system core time-sliced, etc)
ready_queue.push_front(previous_thread->current_priority, previous_thread);
previous_thread->status = THREADSTATUS_READY;
}
}
// Load context of new thread
if (t) {
current_thread = t;
ChangeReadyState(t, false);
t->status = (t->status | THREADSTATUS_RUNNING) & ~THREADSTATUS_READY;
Core::g_app_core->LoadContext(t->context);
if (new_thread) {
current_thread = new_thread;
ready_queue.remove(new_thread->current_priority, new_thread);
new_thread->status = THREADSTATUS_RUNNING;
Core::g_app_core->LoadContext(new_thread->context);
} else {
current_thread = nullptr;
}
}
/// Gets the next thread that is ready to be run by priority
static Thread* NextThread() {
/**
* Pops and returns the next thread from the thread queue
* @return A pointer to the next ready thread
*/
static Thread* PopNextReadyThread() {
Thread* next;
Thread* cur = GetCurrentThread();
Thread* thread = GetCurrentThread();
if (cur && cur->IsRunning()) {
next = thread_ready_queue.pop_first_better(cur->current_priority);
if (thread && thread->status == THREADSTATUS_RUNNING) {
// We have to do better than the current thread.
// This call returns null when that's not possible.
next = ready_queue.pop_first_better(thread->current_priority);
} else {
next = thread_ready_queue.pop_first();
}
if (next == 0) {
return nullptr;
next = ready_queue.pop_first();
}
return next;
}
void WaitCurrentThread_Sleep() {
Thread* thread = GetCurrentThread();
ChangeThreadState(thread, ThreadStatus(THREADSTATUS_WAIT | (thread->status & THREADSTATUS_SUSPEND)));
thread->status = THREADSTATUS_WAIT_SLEEP;
}
void WaitCurrentThread_WaitSynchronization(SharedPtr<WaitObject> wait_object, bool wait_set_output, bool wait_all) {
void WaitCurrentThread_WaitSynchronization(std::vector<SharedPtr<WaitObject>> wait_objects, bool wait_set_output, bool wait_all) {
Thread* thread = GetCurrentThread();
thread->wait_set_output = wait_set_output;
thread->wait_all = wait_all;
// It's possible to call WaitSynchronizationN without any objects passed in...
if (wait_object != nullptr)
thread->wait_objects.push_back(wait_object);
ChangeThreadState(thread, ThreadStatus(THREADSTATUS_WAIT | (thread->status & THREADSTATUS_SUSPEND)));
thread->wait_objects = std::move(wait_objects);
thread->status = THREADSTATUS_WAIT_SYNCH;
}
void WaitCurrentThread_ArbitrateAddress(VAddr wait_address) {
Thread* thread = GetCurrentThread();
thread->wait_address = wait_address;
ChangeThreadState(thread, ThreadStatus(THREADSTATUS_WAIT | (thread->status & THREADSTATUS_SUSPEND)));
thread->status = THREADSTATUS_WAIT_ARB;
}
/// Event type for the thread wake up event
static int ThreadWakeupEventType = -1;
// TODO(yuriks): This can be removed if Thread objects are explicitly pooled in the future, allowing
// us to simply use a pool index or similar.
static Kernel::HandleTable wakeup_callback_handle_table;
/// Callback that will wake up the thread it was scheduled for
/**
* Callback that will wake up the thread it was scheduled for
* @param thread_handle The handle of the thread that's been awoken
* @param cycles_late The number of CPU cycles that have passed since the desired wakeup time
*/
static void ThreadWakeupCallback(u64 thread_handle, int cycles_late) {
SharedPtr<Thread> thread = wakeup_callback_handle_table.Get<Thread>((Handle)thread_handle);
if (thread == nullptr) {
LOG_CRITICAL(Kernel, "Callback fired for invalid thread %08X", thread_handle);
LOG_CRITICAL(Kernel, "Callback fired for invalid thread %08X", (Handle)thread_handle);
return;
}
thread->SetWaitSynchronizationResult(ResultCode(ErrorDescription::Timeout, ErrorModule::OS,
ErrorSummary::StatusChanged, ErrorLevel::Info));
if (thread->status == THREADSTATUS_WAIT_SYNCH) {
thread->SetWaitSynchronizationResult(ResultCode(ErrorDescription::Timeout, ErrorModule::OS,
ErrorSummary::StatusChanged, ErrorLevel::Info));
if (thread->wait_set_output)
thread->SetWaitSynchronizationOutput(-1);
if (thread->wait_set_output)
thread->SetWaitSynchronizationOutput(-1);
}
thread->ResumeFromWait();
}
void Thread::WakeAfterDelay(s64 nanoseconds) {
// Don't schedule a wakeup if the thread wants to wait forever
if (nanoseconds == -1)
@ -265,7 +248,7 @@ void Thread::WakeAfterDelay(s64 nanoseconds) {
}
void Thread::ReleaseWaitObject(WaitObject* wait_object) {
if (wait_objects.empty()) {
if (status != THREADSTATUS_WAIT_SYNCH || wait_objects.empty()) {
LOG_CRITICAL(Kernel, "thread is not waiting on any objects!");
return;
}
@ -307,34 +290,48 @@ void Thread::ReleaseWaitObject(WaitObject* wait_object) {
}
void Thread::ResumeFromWait() {
// Cancel any outstanding wakeup events
// Cancel any outstanding wakeup events for this thread
CoreTiming::UnscheduleEvent(ThreadWakeupEventType, callback_handle);
status &= ~THREADSTATUS_WAIT;
// Remove this thread from all other WaitObjects
for (auto wait_object : wait_objects)
wait_object->RemoveWaitingThread(this);
wait_objects.clear();
wait_set_output = false;
wait_all = false;
wait_address = 0;
if (!(status & (THREADSTATUS_WAITSUSPEND | THREADSTATUS_DORMANT | THREADSTATUS_DEAD))) {
ChangeReadyState(this, true);
switch (status) {
case THREADSTATUS_WAIT_SYNCH:
// Remove this thread from all other WaitObjects
for (auto wait_object : wait_objects)
wait_object->RemoveWaitingThread(this);
break;
case THREADSTATUS_WAIT_ARB:
case THREADSTATUS_WAIT_SLEEP:
break;
case THREADSTATUS_RUNNING:
case THREADSTATUS_READY:
LOG_ERROR(Kernel, "Thread with object id %u has already resumed.", GetObjectId());
_dbg_assert_(Kernel, false);
return;
case THREADSTATUS_DEAD:
// This should never happen, as threads must complete before being stopped.
LOG_CRITICAL(Kernel, "Thread with object id %u cannot be resumed because it's DEAD.",
GetObjectId());
_dbg_assert_(Kernel, false);
return;
}
ready_queue.push_back(current_priority, this);
status = THREADSTATUS_READY;
}
/// Prints the thread queue for debugging purposes
/**
* Prints the thread queue for debugging purposes
*/
static void DebugThreadQueue() {
Thread* thread = GetCurrentThread();
if (!thread) {
return;
LOG_DEBUG(Kernel, "Current: NO CURRENT THREAD");
} else {
LOG_DEBUG(Kernel, "0x%02X %u (current)", thread->current_priority, GetCurrentThread()->GetObjectId());
}
LOG_DEBUG(Kernel, "0x%02X %u (current)", thread->current_priority, GetCurrentThread()->GetObjectId());
for (auto& t : thread_list) {
s32 priority = thread_ready_queue.contains(t.get());
s32 priority = ready_queue.contains(t.get());
if (priority != -1) {
LOG_DEBUG(Kernel, "0x%02X %u", priority, t->GetObjectId());
}
@ -342,14 +339,7 @@ static void DebugThreadQueue() {
}
ResultVal<SharedPtr<Thread>> Thread::Create(std::string name, VAddr entry_point, s32 priority,
u32 arg, s32 processor_id, VAddr stack_top, u32 stack_size) {
if (stack_size < 0x200) {
LOG_ERROR(Kernel, "(name=%s): invalid stack_size=0x%08X", name.c_str(), stack_size);
// TODO: Verify error
return ResultCode(ErrorDescription::InvalidSize, ErrorModule::Kernel,
ErrorSummary::InvalidArgument, ErrorLevel::Permanent);
}
u32 arg, s32 processor_id, VAddr stack_top) {
if (priority < THREADPRIO_HIGHEST || priority > THREADPRIO_LOWEST) {
s32 new_priority = CLAMP(priority, THREADPRIO_HIGHEST, THREADPRIO_LOWEST);
LOG_WARNING(Kernel_SVC, "(name=%s): invalid priority=%d, clamping to %d",
@ -369,13 +359,12 @@ ResultVal<SharedPtr<Thread>> Thread::Create(std::string name, VAddr entry_point,
SharedPtr<Thread> thread(new Thread);
thread_list.push_back(thread);
thread_ready_queue.prepare(priority);
ready_queue.prepare(priority);
thread->thread_id = next_thread_id++;
thread->thread_id = NewThreadId();
thread->status = THREADSTATUS_DORMANT;
thread->entry_point = entry_point;
thread->stack_top = stack_top;
thread->stack_size = stack_size;
thread->initial_priority = thread->current_priority = priority;
thread->processor_id = processor_id;
thread->wait_set_output = false;
@ -385,75 +374,74 @@ ResultVal<SharedPtr<Thread>> Thread::Create(std::string name, VAddr entry_point,
thread->name = std::move(name);
thread->callback_handle = wakeup_callback_handle_table.Create(thread).MoveFrom();
ResetThread(thread.get(), arg, 0);
CallThread(thread.get());
// TODO(peachum): move to ScheduleThread() when scheduler is added so selected core is used
// to initialize the context
Core::g_app_core->ResetContext(thread->context, stack_top, entry_point, arg);
ready_queue.push_back(thread->current_priority, thread.get());
thread->status = THREADSTATUS_READY;
return MakeResult<SharedPtr<Thread>>(std::move(thread));
}
/// Set the priority of the thread specified by handle
void Thread::SetPriority(s32 priority) {
// If priority is invalid, clamp to valid range
if (priority < THREADPRIO_HIGHEST || priority > THREADPRIO_LOWEST) {
s32 new_priority = CLAMP(priority, THREADPRIO_HIGHEST, THREADPRIO_LOWEST);
LOG_WARNING(Kernel_SVC, "invalid priority=%d, clamping to %d", priority, new_priority);
// TODO(peachum): Remove this. Range checking should be done, and an appropriate error should be returned.
static void ClampPriority(const Thread* thread, s32* priority) {
if (*priority < THREADPRIO_HIGHEST || *priority > THREADPRIO_LOWEST) {
_dbg_assert_msg_(Kernel, false, "Application passed an out of range priority. An error should be returned.");
s32 new_priority = CLAMP(*priority, THREADPRIO_HIGHEST, THREADPRIO_LOWEST);
LOG_WARNING(Kernel_SVC, "(name=%s): invalid priority=%d, clamping to %d",
thread->name.c_str(), *priority, new_priority);
// TODO(bunnei): Clamping to a valid priority is not necessarily correct behavior... Confirm
// validity of this
priority = new_priority;
*priority = new_priority;
}
}
void Thread::SetPriority(s32 priority) {
ClampPriority(this, &priority);
if (current_priority == priority) {
return;
}
// Change thread priority
s32 old = current_priority;
thread_ready_queue.remove(old, this);
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;
thread_ready_queue.prepare(current_priority);
// Change thread status to "ready" and push to ready queue
if (IsRunning()) {
status = (status & ~THREADSTATUS_RUNNING) | THREADSTATUS_READY;
}
if (IsReady()) {
thread_ready_queue.push_back(current_priority, this);
}
}
SharedPtr<Thread> SetupIdleThread() {
// We need to pass a few valid values to get around parameter checking in Thread::Create.
auto thread = Thread::Create("idle", Memory::KERNEL_MEMORY_VADDR, THREADPRIO_LOWEST, 0,
THREADPROCESSORID_0, 0, Kernel::DEFAULT_STACK_SIZE).MoveFrom();
THREADPROCESSORID_0, 0).MoveFrom();
thread->idle = true;
CallThread(thread.get());
return thread;
}
SharedPtr<Thread> SetupMainThread(s32 priority, u32 stack_size) {
// Initialize new "main" thread
auto thread_res = Thread::Create("main", Core::g_app_core->GetPC(), priority, 0,
THREADPROCESSORID_0, Memory::SCRATCHPAD_VADDR_END, stack_size);
// TODO(yuriks): Propagate error
_dbg_assert_(Kernel, thread_res.Succeeded());
SharedPtr<Thread> thread = std::move(*thread_res);
SharedPtr<Thread> SetupMainThread(u32 stack_size, u32 entry_point, s32 priority) {
_dbg_assert_(Kernel, !GetCurrentThread());
// If running another thread already, set it to "ready" state
Thread* cur = GetCurrentThread();
if (cur && cur->IsRunning()) {
ChangeReadyState(cur, true);
}
// Initialize new "main" thread
auto thread_res = Thread::Create("main", entry_point, priority, 0,
THREADPROCESSORID_0, Memory::SCRATCHPAD_VADDR_END);
SharedPtr<Thread> thread = thread_res.MoveFrom();
// Run new "main" thread
current_thread = thread.get();
thread->status = THREADSTATUS_RUNNING;
Core::g_app_core->LoadContext(thread->context);
SwitchContext(thread.get());
return thread;
}
/// Reschedules to the next available thread (call after current thread is suspended)
void Reschedule() {
Thread* prev = GetCurrentThread();
Thread* next = NextThread();
Thread* next = PopNextReadyThread();
HLE::g_reschedule = false;
if (next != nullptr) {
@ -480,8 +468,10 @@ void Thread::SetWaitSynchronizationOutput(s32 output) {
////////////////////////////////////////////////////////////////////////////////////////////////////
void ThreadingInit() {
next_thread_id = INITIAL_THREAD_ID;
ThreadWakeupEventType = CoreTiming::RegisterEvent("ThreadWakeupCallback", ThreadWakeupCallback);
// Setup the idle thread
SetupIdleThread();
}
void ThreadingShutdown() {