diff --git a/src/core/hle/kernel/scheduler.cpp b/src/core/hle/kernel/scheduler.cpp index 878aeed6d..537640152 100644 --- a/src/core/hle/kernel/scheduler.cpp +++ b/src/core/hle/kernel/scheduler.cpp @@ -19,6 +19,11 @@ namespace Kernel { +/* + * SelectThreads, Yield functions originally by TuxSH. + * licensed under GPLv2 or later under exception provided by the author. + */ + void GlobalScheduler::AddThread(SharedPtr thread) { thread_list.push_back(std::move(thread)); } @@ -29,15 +34,23 @@ void GlobalScheduler::RemoveThread(Thread* thread) { } /* - * SelectThreads, Yield functions originally by TuxSH. - * licensed under GPLv2 or later under exception provided by the author. + * UnloadThread selects a core and forces it to unload its current thread's context */ - void GlobalScheduler::UnloadThread(s32 core) { Scheduler& sched = Core::System::GetInstance().Scheduler(core); sched.UnloadThread(); } +/* + * SelectThread takes care of selecting the new scheduled thread. + * It does it in 3 steps: + * - First a thread is selected from the top of the priority queue. If no thread + * is obtained then we move to step two, else we are done. + * - Second we try to get a suggested thread that's not assigned to any core or + * that is not the top thread in that core. + * - Third is no suggested thread is found, we do a second pass and pick a running + * thread in another core and swap it with its current thread. + */ void GlobalScheduler::SelectThread(u32 core) { auto update_thread = [](Thread* thread, Scheduler& sched) { if (thread != sched.selected_thread) { @@ -51,105 +64,58 @@ void GlobalScheduler::SelectThread(u32 core) { }; Scheduler& sched = Core::System::GetInstance().Scheduler(core); Thread* current_thread = nullptr; + // Step 1: Get top thread in schedule queue. current_thread = scheduled_queue[core].empty() ? nullptr : scheduled_queue[core].front(); - if (!current_thread) { - Thread* winner = nullptr; - std::set sug_cores; - for (auto thread : suggested_queue[core]) { - s32 this_core = thread->GetProcessorID(); - Thread* thread_on_core = nullptr; - if (this_core >= 0) { - thread_on_core = scheduled_queue[this_core].front(); - } - if (this_core < 0 || thread != thread_on_core) { - winner = thread; - break; - } - sug_cores.insert(this_core); + if (current_thread) { + update_thread(current_thread, sched); + return; + } + // Step 2: Try selecting a suggested thread. + Thread* winner = nullptr; + std::set sug_cores; + for (auto thread : suggested_queue[core]) { + s32 this_core = thread->GetProcessorID(); + Thread* thread_on_core = nullptr; + if (this_core >= 0) { + thread_on_core = scheduled_queue[this_core].front(); } - if (winner && winner->GetPriority() > 2) { - if (winner->IsRunning()) { - UnloadThread(winner->GetProcessorID()); - } - TransferToCore(winner->GetPriority(), core, winner); - current_thread = winner; - } else { - for (auto& src_core : sug_cores) { - auto it = scheduled_queue[src_core].begin(); - it++; - if (it != scheduled_queue[src_core].end()) { - Thread* thread_on_core = scheduled_queue[src_core].front(); - Thread* to_change = *it; - if (thread_on_core->IsRunning() || to_change->IsRunning()) { - UnloadThread(src_core); - } - TransferToCore(thread_on_core->GetPriority(), core, thread_on_core); - current_thread = thread_on_core; - } + if (this_core < 0 || thread != thread_on_core) { + winner = thread; + break; + } + sug_cores.insert(this_core); + } + // if we got a suggested thread, select it, else do a second pass. + if (winner && winner->GetPriority() > 2) { + if (winner->IsRunning()) { + UnloadThread(winner->GetProcessorID()); + } + TransferToCore(winner->GetPriority(), core, winner); + update_thread(winner, sched); + return; + } + // Step 3: Select a suggested thread from another core + for (auto& src_core : sug_cores) { + auto it = scheduled_queue[src_core].begin(); + it++; + if (it != scheduled_queue[src_core].end()) { + Thread* thread_on_core = scheduled_queue[src_core].front(); + Thread* to_change = *it; + if (thread_on_core->IsRunning() || to_change->IsRunning()) { + UnloadThread(src_core); } + TransferToCore(thread_on_core->GetPriority(), core, thread_on_core); + current_thread = thread_on_core; + break; } } update_thread(current_thread, sched); } -void GlobalScheduler::SelectThreads() { - auto update_thread = [](Thread* thread, Scheduler& sched) { - if (thread != sched.selected_thread) { - if (thread == nullptr) { - ++sched.idle_selection_count; - } - sched.selected_thread = thread; - } - sched.context_switch_pending = sched.selected_thread != sched.current_thread; - std::atomic_thread_fence(std::memory_order_seq_cst); - }; - - auto& system = Core::System::GetInstance(); - - std::unordered_set picked_threads; - // This maintain the "current thread is on front of queue" invariant - std::array current_threads; - for (u32 i = 0; i < NUM_CPU_CORES; i++) { - Scheduler& sched = system.Scheduler(i); - current_threads[i] = scheduled_queue[i].empty() ? nullptr : scheduled_queue[i].front(); - if (current_threads[i]) - picked_threads.insert(current_threads[i]); - update_thread(current_threads[i], sched); - } - - // Do some load-balancing. Allow second pass. - std::array current_threads_2 = current_threads; - for (u32 i = 0; i < NUM_CPU_CORES; i++) { - if (!scheduled_queue[i].empty()) { - continue; - } - Thread* winner = nullptr; - for (auto thread : suggested_queue[i]) { - if (thread->GetProcessorID() < 0 || thread != current_threads[i]) { - if (picked_threads.count(thread) == 0 && !thread->IsRunning()) { - winner = thread; - break; - } - } - } - if (winner) { - TransferToCore(winner->GetPriority(), i, winner); - current_threads_2[i] = winner; - picked_threads.insert(winner); - } - } - - // See which to-be-current threads have changed & update accordingly - for (u32 i = 0; i < NUM_CPU_CORES; i++) { - Scheduler& sched = system.Scheduler(i); - if (current_threads_2[i] != current_threads[i]) { - update_thread(current_threads_2[i], sched); - } - } - - reselection_pending.store(false, std::memory_order_release); -} - +/* + * YieldThread takes a thread and moves it to the back of the it's priority list + * This operation can be redundant and no scheduling is changed if marked as so. + */ void GlobalScheduler::YieldThread(Thread* yielding_thread) { // Note: caller should use critical section, etc. u32 core_id = static_cast(yielding_thread->GetProcessorID()); @@ -164,6 +130,12 @@ void GlobalScheduler::YieldThread(Thread* yielding_thread) { AskForReselectionOrMarkRedundant(yielding_thread, winner); } +/* + * YieldThreadAndBalanceLoad takes a thread and moves it to the back of the it's priority list. + * Afterwards, tries to pick a suggested thread from the suggested queue that has worse time or + * a better priority than the next thread in the core. + * This operation can be redundant and no scheduling is changed if marked as so. + */ void GlobalScheduler::YieldThreadAndBalanceLoad(Thread* yielding_thread) { // Note: caller should check if !thread.IsSchedulerOperationRedundant and use critical section, // etc. @@ -213,6 +185,12 @@ void GlobalScheduler::YieldThreadAndBalanceLoad(Thread* yielding_thread) { AskForReselectionOrMarkRedundant(yielding_thread, winner); } +/* + * YieldThreadAndWaitForLoadBalancing takes a thread and moves it out of the scheduling queue + * and into the suggested queue. If no thread can be squeduled afterwards in that core, + * a suggested thread is obtained instead. + * This operation can be redundant and no scheduling is changed if marked as so. + */ void GlobalScheduler::YieldThreadAndWaitForLoadBalancing(Thread* yielding_thread) { // Note: caller should check if !thread.IsSchedulerOperationRedundant and use critical section, // etc. @@ -256,8 +234,8 @@ void GlobalScheduler::YieldThreadAndWaitForLoadBalancing(Thread* yielding_thread void GlobalScheduler::AskForReselectionOrMarkRedundant(Thread* current_thread, Thread* winner) { if (current_thread == winner) { - // Nintendo (not us) has a nullderef bug on current_thread->owner, but which is never - // triggered. + // TODO(blinkhawk): manage redundant operations, this is not implemented. + // as its mostly an optimization. // current_thread->SetRedundantSchedulerOperation(); } else { reselection_pending.store(true, std::memory_order_release); diff --git a/src/core/hle/kernel/scheduler.h b/src/core/hle/kernel/scheduler.h index 50fa7376b..82ed64b55 100644 --- a/src/core/hle/kernel/scheduler.h +++ b/src/core/hle/kernel/scheduler.h @@ -48,14 +48,12 @@ public: } void Schedule(u32 priority, u32 core, Thread* thread) { - ASSERT_MSG(thread->GetProcessorID() == core, - "Thread must be assigned to this core."); + ASSERT_MSG(thread->GetProcessorID() == core, "Thread must be assigned to this core."); scheduled_queue[core].add(thread, priority); } void SchedulePrepend(u32 priority, u32 core, Thread* thread) { - ASSERT_MSG(thread->GetProcessorID() == core, - "Thread must be assigned to this core."); + ASSERT_MSG(thread->GetProcessorID() == core, "Thread must be assigned to this core."); scheduled_queue[core].add(thread, priority, false); } @@ -84,17 +82,47 @@ public: Suggest(priority, source_core, thread); } + /* + * UnloadThread selects a core and forces it to unload its current thread's context + */ void UnloadThread(s32 core); - void SelectThreads(); + /* + * SelectThread takes care of selecting the new scheduled thread. + * It does it in 3 steps: + * - First a thread is selected from the top of the priority queue. If no thread + * is obtained then we move to step two, else we are done. + * - Second we try to get a suggested thread that's not assigned to any core or + * that is not the top thread in that core. + * - Third is no suggested thread is found, we do a second pass and pick a running + * thread in another core and swap it with its current thread. + */ void SelectThread(u32 core); bool HaveReadyThreads(u32 core_id) { return !scheduled_queue[core_id].empty(); } + /* + * YieldThread takes a thread and moves it to the back of the it's priority list + * This operation can be redundant and no scheduling is changed if marked as so. + */ void YieldThread(Thread* thread); + + /* + * YieldThreadAndBalanceLoad takes a thread and moves it to the back of the it's priority list. + * Afterwards, tries to pick a suggested thread from the suggested queue that has worse time or + * a better priority than the next thread in the core. + * This operation can be redundant and no scheduling is changed if marked as so. + */ void YieldThreadAndBalanceLoad(Thread* thread); + + /* + * YieldThreadAndWaitForLoadBalancing takes a thread and moves it out of the scheduling queue + * and into the suggested queue. If no thread can be squeduled afterwards in that core, + * a suggested thread is obtained instead. + * This operation can be redundant and no scheduling is changed if marked as so. + */ void YieldThreadAndWaitForLoadBalancing(Thread* thread); u32 CpuCoresCount() const {