Optimize Scheduler/IPC/HID + Fix Various Bugs

* Optimize Scheduler With Per-Thread Scheduler Conditions
* Optimize IPC by yielding
* Optimize HID Vibration
* Fix Priority Inheritance
* Fix `KThread` Start/Kill/Signal Races 
* Fix `YieldPending` Races in `StartThread` & `SvcHandler` 
* Fix POSIX Time -> NN CalendarTime Conversion 
* Fix HID `TouchScreen`/`NPad` Activation

app/src/main/cpp/skyline/input/npad.cpp

@@ -11,7 +11,7 @@ namespace skyline::input {
          {*this, hid->npad[4], NpadId::Player5}, {*this, hid->npad[5], NpadId::Player6},
          {*this, hid->npad[6], NpadId::Player7}, {*this, hid->npad[7], NpadId::Player8},
          {*this, hid->npad[8], NpadId::Handheld}, {*this, hid->npad[9], NpadId::Unknown},
-        } {}
+        } { Activate(); /* NPads are activated by default, certain homebrew is reliant on this behavior */ }
 
     void NpadManager::Update() {
         std::lock_guard guard(mutex);
@@ -83,25 +83,27 @@ namespace skyline::input {
 
     void NpadManager::Activate() {
         std::lock_guard guard(mutex);
+        if (!activated) {
+            supportedIds = {NpadId::Handheld, NpadId::Player1, NpadId::Player2, NpadId::Player3, NpadId::Player4, NpadId::Player5, NpadId::Player6, NpadId::Player7, NpadId::Player8};
+            styles = {.proController = true, .joyconHandheld = true, .joyconDual = true, .joyconLeft = true, .joyconRight = true};
+            activated = true;
 
-        supportedIds = {NpadId::Handheld, NpadId::Player1, NpadId::Player2, NpadId::Player3, NpadId::Player4, NpadId::Player5, NpadId::Player6, NpadId::Player7, NpadId::Player8};
-        styles = {.proController = true, .joyconHandheld = true, .joyconDual = true, .joyconLeft = true, .joyconRight = true};
-        activated = true;
-
-        Update();
+            Update();
+        }
     }
 
     void NpadManager::Deactivate() {
         std::lock_guard guard(mutex);
+        if (activated) {
+            supportedIds = {};
+            styles = {};
+            activated = false;
 
-        supportedIds = {};
-        styles = {};
-        activated = false;
+            for (auto &npad : npads)
+                npad.Disconnect();
 
-        for (auto &npad : npads)
-            npad.Disconnect();
-
-        for (auto &controller : controllers)
-            controller.device = nullptr;
+            for (auto &controller : controllers)
+                controller.device = nullptr;
+        }
     }
 }

app/src/main/cpp/skyline/input/npad.h

@@ -21,7 +21,7 @@ namespace skyline::input {
     class NpadManager {
       private:
         const DeviceState &state;
-        bool activated{false}; //!< If this NpadManager is activated or not
+        bool activated{};
 
         friend NpadDevice;
 

app/src/main/cpp/skyline/input/npad_device.cpp

@@ -425,10 +425,15 @@ namespace skyline::input {
     }
 
     void NpadDevice::Vibrate(bool isRight, const NpadVibrationValue &value) {
-        if (isRight)
+        if (isRight) {
+            if (vibrationRight && (*vibrationRight) == value)
+                return;
             vibrationRight = value;
-        else
+        } else {
+            if (vibrationLeft == value)
+                return;
             vibrationLeft = value;
+        }
 
         if (vibrationRight)
             Vibrate(vibrationLeft, *vibrationRight);
@@ -437,6 +442,12 @@ namespace skyline::input {
     }
 
     void NpadDevice::Vibrate(const NpadVibrationValue &left, const NpadVibrationValue &right) {
+        if (vibrationLeft == left && vibrationRight && (*vibrationRight) == right)
+            return;
+
+        vibrationLeft = left;
+        vibrationRight = right;
+
         if (partnerIndex == constant::NullIndex) {
             std::array<VibrationInfo, 4> vibrations{
                 VibrationInfo{left.frequencyLow, left.amplitudeLow * (constant::AmplitudeMax / 4)},

app/src/main/cpp/skyline/input/npad_device.h

@@ -105,6 +105,13 @@ namespace skyline::input {
         float frequencyLow;
         float amplitudeHigh;
         float frequencyHigh;
+
+        bool operator==(const NpadVibrationValue &other) const {
+            return (amplitudeLow == other.amplitudeLow) &&
+                (frequencyLow == other.frequencyLow) &&
+                (amplitudeHigh == other.amplitudeHigh) &&
+                (frequencyHigh == other.frequencyHigh);
+        }
     };
     static_assert(sizeof(NpadVibrationValue) == 0x10);
 

app/src/main/cpp/skyline/input/touch.cpp

@@ -5,12 +5,14 @@
 
 namespace skyline::input {
     TouchManager::TouchManager(const DeviceState &state, input::HidSharedMemory *hid) : state(state), section(hid->touchScreen) {
-        Activate();
+        Activate(); // The touch screen is expected to be activated by default, commercial games are reliant on this behavior
     }
 
     void TouchManager::Activate() {
-        activated = true;
-        SetState({});
+        if (!activated) {
+            activated = true;
+            SetState({});
+        }
     }
 
     void TouchManager::SetState(const span<TouchScreenPoint> &points) {
@@ -37,7 +39,7 @@ namespace skyline::input {
 
         section.header.timestamp = util::GetTimeTicks();
         section.header.entryCount = std::min(static_cast<u8>(section.header.entryCount + 1), constant::HidEntryCount);
-        section.header.maxEntry = constant::HidEntryCount - 1;
+        section.header.maxEntry = section.header.entryCount;
         section.header.currentEntry = entryIndex;
     }
 }

app/src/main/cpp/skyline/kernel/scheduler.cpp

@@ -15,8 +15,8 @@ namespace skyline::kernel {
         if (*tls) {
             const auto &state{*reinterpret_cast<nce::ThreadContext *>(*tls)->state};
             state.scheduler->Rotate(false);
-            state.scheduler->WaitSchedule();
             YieldPending = false;
+            state.scheduler->WaitSchedule();
         } else {
             YieldPending = true;
         }
@@ -59,7 +59,10 @@ namespace skyline::kernel {
             }
 
             if (optimalCore != currentCore) {
-                RemoveThread();
+                if (!alwaysInsert && thread == state.thread)
+                    RemoveThread();
+                else if (!alwaysInsert && thread != state.thread)
+                    throw exception("Migrating an external thread (T{}) without 'alwaysInsert' isn't supported", thread->id);
                 thread->coreId = optimalCore->id;
                 InsertThread(thread);
                 state.logger->Debug("Load Balancing T{}: C{} -> C{}", thread->id, currentCore->id, optimalCore->id);
@@ -81,27 +84,6 @@ namespace skyline::kernel {
 
     void Scheduler::InsertThread(const std::shared_ptr<type::KThread> &thread) {
         auto &core{cores.at(thread->coreId)};
-
-        thread_local bool signalHandlerSetup{};
-        if (!signalHandlerSetup) {
-            signal::SetSignalHandler({YieldSignal}, SignalHandler);
-            signalHandlerSetup = true;
-        }
-
-        if (!thread->preemptionTimer) {
-            struct sigevent event{
-                .sigev_signo = YieldSignal,
-                .sigev_notify = SIGEV_THREAD_ID,
-                ._sigev_un = {
-                    ._tid = gettid(),
-                },
-            };
-            timer_t timer;
-            if (timer_create(CLOCK_THREAD_CPUTIME_ID, &event, &timer))
-                throw exception("timer_create has failed with '{}'", strerror(errno));
-            thread->preemptionTimer.emplace(timer);
-        }
-
         std::unique_lock lock(core.mutex);
         auto nextThread{std::upper_bound(core.queue.begin(), core.queue.end(), thread->priority.load(), type::KThread::IsHigherPriority)};
         if (nextThread == core.queue.begin()) {
@@ -116,10 +98,8 @@ namespace skyline::kernel {
             } else {
                 core.queue.push_front(thread);
             }
-            if (thread != state.thread) {
-                lock.unlock(); // We should unlock this prior to waking all threads to not cause contention on the core lock
-                core.frontCondition.notify_all(); // We only want to trigger the conditional variable if the current thread isn't inserting itself
-            }
+            if (thread != state.thread)
+                thread->wakeCondition.notify_one(); // We only want to trigger the conditional variable if the current thread isn't inserting itself
         } else {
             core.queue.insert(nextThread, thread);
         }
@@ -132,7 +112,7 @@ namespace skyline::kernel {
         std::shared_lock lock(core->mutex);
         if (loadBalance && thread->affinityMask.count() > 1) {
             std::chrono::milliseconds loadBalanceThreshold{PreemptiveTimeslice * 2}; //!< The amount of time that needs to pass unscheduled for a thread to attempt load balancing
-            while (!core->frontCondition.wait_for(lock, loadBalanceThreshold, [&]() { return !core->queue.empty() && core->queue.front() == thread; })) {
+            while (!thread->wakeCondition.wait_for(lock, loadBalanceThreshold, [&]() { return !core->queue.empty() && core->queue.front() == thread; })) {
                 lock.unlock();
                 LoadBalance(state.thread);
                 if (thread->coreId == core->id) {
@@ -145,12 +125,12 @@ namespace skyline::kernel {
                 loadBalanceThreshold *= 2; // We double the duration required for future load balancing for this invocation to minimize pointless load balancing
             }
         } else {
-            core->frontCondition.wait(lock, [&]() { return !core->queue.empty() && core->queue.front() == thread; });
+            thread->wakeCondition.wait(lock, [&]() { return !core->queue.empty() && core->queue.front() == thread; });
         }
 
         if (thread->priority == core->preemptionPriority) {
             struct itimerspec spec{.it_value = {.tv_nsec = std::chrono::duration_cast<std::chrono::nanoseconds>(PreemptiveTimeslice).count()}};
-            timer_settime(*thread->preemptionTimer, 0, &spec, nullptr);
+            timer_settime(thread->preemptionTimer, 0, &spec, nullptr);
             thread->isPreempted = true;
         }
 
@@ -162,10 +142,10 @@ namespace skyline::kernel {
         auto *core{&cores.at(thread->coreId)};
 
         std::shared_lock lock(core->mutex);
-        if (core->frontCondition.wait_for(lock, timeout, [&]() { return !core->queue.empty() && core->queue.front() == thread; })) {
+        if (thread->wakeCondition.wait_for(lock, timeout, [&]() { return !core->queue.empty() && core->queue.front() == thread; })) {
             if (thread->priority == core->preemptionPriority) {
                 struct itimerspec spec{.it_value = {.tv_nsec = std::chrono::duration_cast<std::chrono::nanoseconds>(PreemptiveTimeslice).count()}};
-                timer_settime(*thread->preemptionTimer, 0, &spec, nullptr);
+                timer_settime(thread->preemptionTimer, 0, &spec, nullptr);
                 thread->isPreempted = true;
             }
 
@@ -188,18 +168,18 @@ namespace skyline::kernel {
             // Splice the linked element from the beginning of the queue to where it's priority is present
             core.queue.splice(std::upper_bound(core.queue.begin(), core.queue.end(), thread->priority.load(), type::KThread::IsHigherPriority), core.queue, core.queue.begin());
 
-            if (core.queue.front() != thread) {
-                // If we aren't at the front of the queue, only then should we notify other threads that the front of the queue has changed
-                lock.unlock();
-                core.frontCondition.notify_all();
-            }
+            auto front{core.queue.front()};
+            if (front != thread)
+                front->wakeCondition.notify_one(); // If we aren't at the front of the queue, only then should we wake the thread at the front up
 
             if (cooperative && thread->isPreempted) {
                 // If a preemptive thread did a cooperative yield then we need to disarm the preemptive timer
                 struct itimerspec spec{};
-                timer_settime(*thread->preemptionTimer, 0, &spec, nullptr);
+                timer_settime(thread->preemptionTimer, 0, &spec, nullptr);
             }
             thread->isPreempted = false;
+        } else {
+            throw exception("T{} called Rotate while not being at the front of C{}'s queue", thread->id, thread->coreId);
         }
     }
 
@@ -213,11 +193,14 @@ namespace skyline::kernel {
             // If the thread isn't in the queue then the new priority will be handled automatically on insertion
             return;
         if (currentIt == core->queue.begin()) {
-            // Alternatively, if it's currently running then we'd just want to reorder after it rotates
-            if (!thread->isPreempted && thread->priority == core->preemptionPriority) {
+            // Alternatively, if it's currently running then we'd just want to cause it to yield if it's priority is lower than the the thread behind it
+            auto nextIt{std::next(currentIt)};
+            if (nextIt != core->queue.end() && (*nextIt)->priority < thread->priority) {
+                thread->SendSignal(YieldSignal);
+            } else if (!thread->isPreempted && thread->priority == core->preemptionPriority) {
                 // If the thread needs to be preempted due to the new priority then arm it's preemption timer
                 struct itimerspec spec{.it_value = {.tv_nsec = std::chrono::duration_cast<std::chrono::nanoseconds>(PreemptiveTimeslice).count()}};
-                timer_settime(*thread->preemptionTimer, 0, &spec, nullptr);
+                timer_settime(thread->preemptionTimer, 0, &spec, nullptr);
                 thread->isPreempted = true;
             }
             return;
@@ -232,7 +215,7 @@ namespace skyline::kernel {
 
         if (thread->isPreempted && thread->priority != core->preemptionPriority) {
             struct itimerspec spec{};
-            timer_settime(*thread->preemptionTimer, 0, &spec, nullptr);
+            timer_settime(thread->preemptionTimer, 0, &spec, nullptr);
             thread->isPreempted = false;
         }
 
@@ -247,13 +230,21 @@ namespace skyline::kernel {
 
     void Scheduler::ParkThread() {
         auto &thread{state.thread};
+        std::lock_guard migrationLock(thread->coreMigrationMutex);
         RemoveThread();
-        {
+
+        auto originalCoreId{thread->coreId};
+        thread->coreId = constant::ParkedCoreId;
+        for (auto &core : cores)
+            if (originalCoreId != core.id && thread->affinityMask.test(core.id) && (core.queue.empty() || core.queue.front()->priority > thread->priority))
+                thread->coreId = core.id;
+
+        if (thread->coreId == constant::ParkedCoreId) {
             std::unique_lock lock(parkedMutex);
             parkedQueue.insert(std::upper_bound(parkedQueue.begin(), parkedQueue.end(), thread->priority.load(), type::KThread::IsHigherPriority), thread);
-            thread->coreId = constant::ParkedCoreId;
-            parkedFrontCondition.wait(lock, [&]() { return parkedCore.queue.front() == thread && thread->coreId != constant::ParkedCoreId; });
+            thread->wakeCondition.wait(lock, [&]() { return parkedQueue.front() == thread && thread->coreId != constant::ParkedCoreId; });
         }
+
         InsertThread(thread);
     }
 
@@ -272,7 +263,7 @@ namespace skyline::kernel {
             if (parkedThread->priority < thread->priority || (parkedThread->priority == thread->priority && (!nextThread || parkedThread->timesliceStart < nextThread->timesliceStart))) {
                 parkedThread->coreId = thread->coreId;
                 parkedLock.unlock();
-                parkedFrontCondition.notify_all();
+                thread->wakeCondition.notify_one();
             }
         }
     }
@@ -290,16 +281,15 @@ namespace skyline::kernel {
                     if (thread->timesliceStart)
                         thread->averageTimeslice = (thread->averageTimeslice / 4) + (3 * (util::GetTimeTicks() - thread->timesliceStart / 4));
 
-                    // We need to notify that the front was changed, if we were at the front previously
-                    lock.unlock();
-                    core.frontCondition.notify_all();
+                    if (it != core.queue.end())
+                        (*it)->wakeCondition.notify_one(); // We need to wake the thread at the front of the queue, if we were at the front previously
                 }
             }
         }
 
         if (thread->isPreempted) {
             struct itimerspec spec{};
-            timer_settime(*thread->preemptionTimer, 0, &spec, nullptr);
+            timer_settime(thread->preemptionTimer, 0, &spec, nullptr);
             thread->isPreempted = false;
         }
 

app/src/main/cpp/skyline/kernel/scheduler.h

@@ -30,7 +30,7 @@ namespace skyline {
                 return (std::numeric_limits<u64>::max() >> ((std::numeric_limits<u64>::digits - 1 + min) - max)) << min;
             }
 
-            constexpr bool Valid(i8 value) const {
+            constexpr bool Valid(u8 value) const {
                 return (value >= min) && (value <= max);
             }
         };
@@ -47,7 +47,6 @@ namespace skyline {
                 u8 id;
                 u8 preemptionPriority; //!< The priority at which this core becomes preemptive as opposed to cooperative
                 std::shared_mutex mutex; //!< Synchronizes all operations on the queue
-                std::condition_variable_any frontCondition; //!< A conditional variable which is signalled when the front of the queue has changed
                 std::list<std::shared_ptr<type::KThread>> queue; //!< A queue of threads which are running or to be run on this core
 
                 CoreContext(u8 id, u8 preemptionPriority);
@@ -59,8 +58,6 @@ namespace skyline {
             std::condition_variable parkedFrontCondition; //!< A conditional variable which is signalled when the front of the parked queue has changed
             std::list<std::shared_ptr<type::KThread>> parkedQueue; //!< A queue of threads which are parked and waiting on core migration
 
-            CoreContext parkedCore{constant::CoreCount, 64}; //!< A psuedo-core which all parked threads are moved onto
-
           public:
             static constexpr std::chrono::milliseconds PreemptiveTimeslice{10}; //!< The duration of time a preemptive thread can run before yielding
             inline static int YieldSignal{SIGRTMIN}; //!< The signal used to cause a yield in running threads
@@ -78,6 +75,7 @@ namespace skyline {
              * @param alwaysInsert If to insert the thread even if it hasn't migrated cores, this is used during thread creation
              * @return A reference to the CoreContext of the core which the calling thread is running on after load balancing
              * @note This inserts the thread into the migrated process's queue after load balancing, there is no need to call it redundantly
+             * @note alwaysInsert makes the assumption that the thread isn't inserted in any core's queue currently
              */
             CoreContext& LoadBalance(const std::shared_ptr<type::KThread> &thread, bool alwaysInsert = false);
 

app/src/main/cpp/skyline/kernel/svc.cpp

@@ -347,7 +347,14 @@ namespace skyline::kernel::svc {
             auto thread{state.process->GetHandle<type::KThread>(handle)};
             state.logger->Debug("svcSetThreadPriority: Setting thread #{}'s priority to {}", thread->id, priority);
             if (thread->priority != priority) {
-                thread->priority = priority;
+                thread->basePriority = priority;
+                u8 newPriority{};
+                do {
+                    // Try to CAS the priority of the thread with it's new base priority
+                    // If the new priority is equivalent to the current priority then we don't need to CAS
+                    newPriority = thread->priority.load();
+                    newPriority = std::min(newPriority, priority);
+                } while (newPriority != priority && thread->priority.compare_exchange_strong(newPriority, priority));
                 state.scheduler->UpdatePriority(thread);
             }
             state.ctx->gpr.w0 = Result{};
@@ -773,6 +780,7 @@ namespace skyline::kernel::svc {
     }
 
     void SendSyncRequest(const DeviceState &state) {
+        SchedulerScopedLock schedulerLock(state);
         state.os->serviceManager.SyncRequestHandler(static_cast<KHandle>(state.ctx->gpr.x0));
         state.ctx->gpr.w0 = Result{};
     }

app/src/main/cpp/skyline/kernel/types/KProcess.cpp

@@ -137,7 +137,7 @@ namespace skyline::kernel::type {
                 u8 priority, ownerPriority;
                 do {
                     // Try to CAS the priority of the owner with the current thread
-                    // If they're equivalent then we don't need to CAS as the priority won't be inherited
+                    // If the new priority is equivalent to the current priority then we don't need to CAS
                     ownerPriority = owner->priority.load();
                     priority = std::min(ownerPriority, state.thread->priority.load());
                 } while (ownerPriority != priority && owner->priority.compare_exchange_strong(ownerPriority, priority));
@@ -198,13 +198,21 @@ namespace skyline::kernel::type {
 
             if (!waiters.empty()) {
                 // If there are threads still waiting on us then try to inherit their priority
-                auto highestPriority{waiters.front()};
-                u8 priority, ownerPriority;
+                auto highestPriorityThread{waiters.front()};
+                u8 newPriority, basePriority;
                 do {
-                    ownerPriority = state.thread->priority.load();
-                    priority = std::min(ownerPriority, highestPriority->priority.load());
-                } while (ownerPriority != priority && nextOwner->priority.compare_exchange_strong(ownerPriority, priority));
+                    basePriority = state.thread->basePriority.load();
+                    newPriority = std::min(basePriority, highestPriorityThread->priority.load());
+                } while (basePriority != newPriority && state.thread->priority.compare_exchange_strong(basePriority, newPriority));
                 state.scheduler->UpdatePriority(state.thread);
+            } else {
+                u8 priority, basePriority;
+                do {
+                    basePriority = state.thread->basePriority.load();
+                    priority = state.thread->priority.load();
+                } while (priority != basePriority && !state.thread->priority.compare_exchange_strong(priority, basePriority));
+                if (priority != basePriority)
+                    state.scheduler->UpdatePriority(state.thread);
             }
 
             if (nextWaiter) {

app/src/main/cpp/skyline/kernel/types/KThread.cpp

@@ -10,22 +10,16 @@
 #include "KThread.h"
 
 namespace skyline::kernel::type {
-    KThread::KThread(const DeviceState &state, KHandle handle, KProcess *parent, size_t id, void *entry, u64 argument, void *stackTop, u8 priority, i8 idealCore) : handle(handle), parent(parent), id(id), entry(entry), entryArgument(argument), stackTop(stackTop), priority(priority), idealCore(idealCore), coreId(idealCore), KSyncObject(state, KType::KThread) {
+    KThread::KThread(const DeviceState &state, KHandle handle, KProcess *parent, size_t id, void *entry, u64 argument, void *stackTop, u8 priority, i8 idealCore) : handle(handle), parent(parent), id(id), entry(entry), entryArgument(argument), stackTop(stackTop), priority(priority), basePriority(priority), idealCore(idealCore), coreId(idealCore), KSyncObject(state, KType::KThread) {
         affinityMask.set(coreId);
     }
 
     KThread::~KThread() {
-        std::unique_lock lock(mutex);
-        if (running && pthread != pthread_self()) {
-            pthread_kill(pthread, SIGINT);
-            if (!thread.joinable())
-                pthread_join(pthread, nullptr);
-        }
+        Kill(true);
         if (thread.joinable())
             thread.join();
-
         if (preemptionTimer)
-            timer_delete(*preemptionTimer);
+            timer_delete(preemptionTimer);
     }
 
     void KThread::StartThread() {
@@ -44,7 +38,13 @@ namespace skyline::kernel::type {
         if (setjmp(originalCtx)) { // Returns 1 if it's returning from guest, 0 otherwise
             state.scheduler->RemoveThread();
 
-            running = false;
+            {
+                std::unique_lock lock(statusMutex);
+                running = false;
+                ready = false;
+                statusCondition.notify_all();
+            }
+
             Signal();
 
             if (threadName[0] != 'H' || threadName[1] != 'O' || threadName[2] != 'S' || threadName[3] != '-') {
@@ -55,10 +55,32 @@ namespace skyline::kernel::type {
             return;
         }
 
+        struct sigevent event{
+            .sigev_signo = Scheduler::YieldSignal,
+            .sigev_notify = SIGEV_THREAD_ID,
+            .sigev_notify_thread_id = gettid(),
+        };
+        if (timer_create(CLOCK_THREAD_CPUTIME_ID, &event, &preemptionTimer))
+            throw exception("timer_create has failed with '{}'", strerror(errno));
+
         signal::SetSignalHandler({SIGINT, SIGILL, SIGTRAP, SIGBUS, SIGFPE, SIGSEGV}, nce::NCE::SignalHandler);
+        signal::SetSignalHandler({Scheduler::YieldSignal}, Scheduler::SignalHandler);
+
+        {
+            std::lock_guard lock(statusMutex);
+            ready = true;
+            statusCondition.notify_all();
+        }
 
         try {
-            state.scheduler->WaitSchedule();
+            if (!Scheduler::YieldPending)
+                state.scheduler->WaitSchedule();
+            while (Scheduler::YieldPending) {
+                // If there is a yield pending on us after thread creation
+                state.scheduler->Rotate();
+                Scheduler::YieldPending = false;
+                state.scheduler->WaitSchedule();
+            }
 
             asm volatile(
             "MRS X0, TPIDR_EL0\n\t"
@@ -161,10 +183,13 @@ namespace skyline::kernel::type {
     }
 
     void KThread::Start(bool self) {
-        std::unique_lock lock(mutex);
+        std::unique_lock lock(statusMutex);
         if (!running) {
-            running = true;
             state.scheduler->LoadBalance(shared_from_this(), true); // This will automatically insert the thread into the core queue after load balancing
+
+            running = true;
+            killed = false;
+            statusCondition.notify_all();
             if (self) {
                 pthread = pthread_self();
                 lock.unlock();
@@ -177,22 +202,23 @@ namespace skyline::kernel::type {
     }
 
     void KThread::Kill(bool join) {
-        std::lock_guard lock(mutex);
-        if (running) {
-            pthread_kill(pthread, SIGINT);
-            if (join) {
-                if (thread.joinable())
-                    thread.join();
-                else
-                    pthread_join(pthread, nullptr);
+        std::unique_lock lock(statusMutex);
+        if (!killed && running) {
+            statusCondition.wait(lock, [this]() { return ready || killed; });
+            if (!killed) {
+                pthread_kill(pthread, SIGINT);
+                killed = true;
+                statusCondition.notify_all();
             }
-            running = false;
         }
+        if (join)
+            statusCondition.wait(lock, [this]() { return !running; });
     }
 
     void KThread::SendSignal(int signal) {
-        std::lock_guard lock(mutex);
-        if (running)
+        std::unique_lock lock(statusMutex);
+        statusCondition.wait(lock, [this]() { return ready || killed; });
+        if (!killed && running)
             pthread_kill(pthread, signal);
     }
 }

app/src/main/cpp/skyline/kernel/types/KThread.h

@@ -24,9 +24,11 @@ namespace skyline {
             void StartThread();
 
           public:
-            std::mutex mutex; //!< Synchronizes all thread state changes
+            std::mutex statusMutex; //!< Synchronizes all thread state changes, running/ready
+            std::condition_variable statusCondition; //!< A conditional variable signalled on the status of the thread changing
             bool running{false}; //!< If the host thread that corresponds to this thread is running, this doesn't reflect guest scheduling changes
             bool killed{false}; //!< If this thread was previously running and has been killed
+            bool ready{false}; //!< If this thread is ready to recieve signals or not
 
             KHandle handle;
             size_t id; //!< Index of thread in parent process's KThread vector
@@ -38,6 +40,7 @@ namespace skyline {
             u64 entryArgument;
             void *stackTop;
 
+            std::condition_variable_any wakeCondition; //!< A conditional variable which is signalled to wake the current thread while it's sleeping
             std::atomic<u8> basePriority; //!< The priority of the thread for the scheduler without any priority-inheritance
             std::atomic<u8> priority; //!< The priority of the thread for the scheduler
             i8 idealCore; //!< The ideal CPU core for this thread to run on
@@ -46,7 +49,7 @@ namespace skyline {
             std::mutex coreMigrationMutex; //!< Synchronizes operations which depend on which core the thread is running on
             u64 timesliceStart{}; //!< Start of the scheduler timeslice
             u64 averageTimeslice{}; //!< A weighted average of the timeslice duration for this thread
-            std::optional<timer_t> preemptionTimer{}; //!< A kernel timer used for preemption interrupts
+            timer_t preemptionTimer{}; //!< A kernel timer used for preemption interrupts
             bool isPreempted{}; //!< If the preemption timer has been armed and will fire
             std::mutex waiterMutex; //!< Synchronizes operations on mutation of the waiter members
             u32* waitKey; //!< The key of the mutex which this thread is waiting on

app/src/main/cpp/skyline/nce.cpp

@@ -25,10 +25,10 @@ namespace skyline::nce {
                 throw exception("Unimplemented SVC 0x{:X}", svc);
             }
 
-            if (kernel::Scheduler::YieldPending) {
+            while (kernel::Scheduler::YieldPending) {
                 state.scheduler->Rotate(false);
-                state.scheduler->WaitSchedule();
                 kernel::Scheduler::YieldPending = false;
+                state.scheduler->WaitSchedule();
             }
         } catch (const signal::SignalException &e) {
             if (e.signal != SIGINT) {

app/src/main/cpp/skyline/services/timesrv/ITimeZoneService.cpp

@@ -7,12 +7,12 @@ namespace skyline::service::timesrv {
     ITimeZoneService::ITimeZoneService(const DeviceState &state, ServiceManager &manager) : BaseService(state, manager) {}
 
     Result ITimeZoneService::ToCalendarTimeWithMyRule(type::KSession &session, ipc::IpcRequest &request, ipc::IpcResponse &response) {
-        auto curTime{std::time(nullptr)};
-        auto calender{*std::gmtime(&curTime)};
+        auto& time{request.Pop<u64>()};
+        auto calender{*std::gmtime(reinterpret_cast<const time_t *>(&time))};
 
         CalendarTime calendarTime{
             .year = static_cast<u16>(calender.tm_year),
-            .month = static_cast<u8>(calender.tm_mon),
+            .month = static_cast<u8>(calender.tm_mon + 1),
             .day = static_cast<u8>(calender.tm_hour),
             .minute = static_cast<u8>(calender.tm_min),
             .second = static_cast<u8>(calender.tm_sec),
@@ -22,7 +22,7 @@ namespace skyline::service::timesrv {
         CalendarAdditionalInfo calendarInfo{
             .dayWeek = static_cast<u32>(calender.tm_wday),
             .dayMonth = static_cast<u32>(calender.tm_mday),
-            .name = *reinterpret_cast<const u64 *>(calender.tm_zone),
+            .tzName = *reinterpret_cast<const u64 *>(calender.tm_zone),
             .dst = static_cast<i32>(calender.tm_isdst),
             .utcRel = static_cast<u32>(calender.tm_gmtoff),
         };

app/src/main/cpp/skyline/services/timesrv/ITimeZoneService.h

@@ -13,28 +13,28 @@ namespace skyline::service::timesrv {
     class ITimeZoneService : public BaseService {
       private:
         /**
-         * @brief A particular time point in calendar format
+         * @brief A particular time point in Nintendo's calendar format
          */
         struct CalendarTime {
-            u16 year; //!< The Year component of the date
-            u8 month; //!< The Month component of the date
-            u8 day; //!< The Day component of the date
-            u8 hour; //!< The Hour component of the date
-            u8 minute; //!< The Minute component of the date
-            u8 second; //!< The Second component of the date
+            u16 year; //!< Amount of years that have passed since 1900
+            u8 month; //!< Month of the year (1-12) [POSIX time uses 0-11]
+            u8 day; //!< Day of the month (1-31)
+            u8 hour; //!< Hour of the day (0-23)
+            u8 minute; //!< Minute of the hour (0-59)
+            u8 second; //!< Second of the minute (0-60)
             u8 _pad_;
         };
         static_assert(sizeof(CalendarTime) == 0x8);
 
         /**
-         * @brief Information that is packaged along with CalendarTime
+         * @brief Additional metadata about the time alongside CalendarTime
          */
         struct CalendarAdditionalInfo {
-            u32 dayWeek; //!< The amount of days since Sunday
-            u32 dayMonth; //!< The amount of days since the start of the month
-            u64 name; //!< The name of the time zone
+            u32 dayWeek; //!< Amount of days since Sunday
+            u32 dayMonth; //!< Amount of days since the start of the month
+            u64 tzName; //!< The name of the time zone
             i32 dst; //!< If DST is in effect or not
-            u32 utcRel; //!< The offset of the time from GMT in seconds
+            u32 utcRel; //!< Offset of the time from GMT in seconds
         };
         static_assert(sizeof(CalendarAdditionalInfo) == 0x18);