// Copyright 2018 yuzu emulator team
// Licensed under GPLv2 or any later version
// Refer to the license.txt file included.
#pragma once
#include <atomic>
#include <memory>
#include <vector>
#include "common/common_types.h"
#include "common/multi_level_queue.h"
#include "core/hardware_properties.h"
#include "core/hle/kernel/thread.h"
namespace Core {
class ARM_Interface;
class System;
} // namespace Core
namespace Kernel {
class KernelCore;
class Process;
class GlobalScheduler final {
public:
explicit GlobalScheduler(KernelCore& kernel);
~GlobalScheduler();
/// Adds a new thread to the scheduler
void AddThread(std::shared_ptr<Thread> thread);
/// Removes a thread from the scheduler
void RemoveThread(std::shared_ptr<Thread> thread);
/// Returns a list of all threads managed by the scheduler
const std::vector<std::shared_ptr<Thread>>& GetThreadList() const {
return thread_list;
}
/**
* Add a thread to the suggested queue of a cpu core. Suggested threads may be
* picked if no thread is scheduled to run on the core.
*/
void Suggest(u32 priority, std::size_t core, Thread* thread);
/**
* Remove a thread to the suggested queue of a cpu core. Suggested threads may be
* picked if no thread is scheduled to run on the core.
*/
void Unsuggest(u32 priority, std::size_t core, Thread* thread);
/**
* Add a thread to the scheduling queue of a cpu core. The thread is added at the
* back the queue in its priority level.
*/
void Schedule(u32 priority, std::size_t core, Thread* thread);
/**
* Add a thread to the scheduling queue of a cpu core. The thread is added at the
* front the queue in its priority level.
*/
void SchedulePrepend(u32 priority, std::size_t core, Thread* thread);
/// Reschedule an already scheduled thread based on a new priority
void Reschedule(u32 priority, std::size_t core, Thread* thread);
/// Unschedules a thread.
void Unschedule(u32 priority, std::size_t core, Thread* thread);
/// Selects a core and forces it to unload its current thread's context
void UnloadThread(std::size_t core);
/**
* Takes care of selecting the new scheduled thread in three steps:
*
* 1. 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.
*
* 2. 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.
*
* 3. 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(std::size_t core);
bool HaveReadyThreads(std::size_t core_id) const {
return !scheduled_queue[core_id].empty();
}
/**
* Takes a thread and moves it to the back of the it's priority list.
*
* @note This operation can be redundant and no scheduling is changed if marked as so.
*/
bool YieldThread(Thread* thread);
/**
* 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.
*
* @note This operation can be redundant and no scheduling is changed if marked as so.
*/
bool YieldThreadAndBalanceLoad(Thread* thread);
/**
* Takes a thread and moves it out of the scheduling queue.
* and into the suggested queue. If no thread can be scheduled afterwards in that core,
* a suggested thread is obtained instead.
*
* @note This operation can be redundant and no scheduling is changed if marked as so.
*/
bool YieldThreadAndWaitForLoadBalancing(Thread* thread);
/**
* Rotates the scheduling queues of threads at a preemption priority and then does
* some core rebalancing. Preemption priorities can be found in the array
* 'preemption_priorities'.
*
* @note This operation happens every 10ms.
*/
void PreemptThreads();
u32 CpuCoresCount() const {
return Core::Hardware::NUM_CPU_CORES;
}
void SetReselectionPending() {
is_reselection_pending.store(true, std::memory_order_release);
}
bool IsReselectionPending() const {
return is_reselection_pending.load(std::memory_order_acquire);
}
void Shutdown();
private:
/**
* Transfers a thread into an specific core. If the destination_core is -1
* it will be unscheduled from its source code and added into its suggested
* queue.
*/
void TransferToCore(u32 priority, s32 destination_core, Thread* thread);
bool AskForReselectionOrMarkRedundant(Thread* current_thread, const Thread* winner);
static constexpr u32 min_regular_priority = 2;
std::array<Common::MultiLevelQueue<Thread*, THREADPRIO_COUNT>, Core::Hardware::NUM_CPU_CORES>
scheduled_queue;
std::array<Common::MultiLevelQueue<Thread*, THREADPRIO_COUNT>, Core::Hardware::NUM_CPU_CORES>
suggested_queue;
std::atomic<bool> is_reselection_pending{false};
// The priority levels at which the global scheduler preempts threads every 10 ms. They are
// ordered from Core 0 to Core 3.
std::array<u32, Core::Hardware::NUM_CPU_CORES> preemption_priorities = {59, 59, 59, 62};
/// Lists all thread ids that aren't deleted/etc.
std::vector<std::shared_ptr<Thread>> thread_list;
KernelCore& kernel;
};
class Scheduler final {
public:
explicit Scheduler(Core::System& system, Core::ARM_Interface& cpu_core, std::size_t core_id);
~Scheduler();
/// Returns whether there are any threads that are ready to run.
bool HaveReadyThreads() const;
/// Reschedules to the next available thread (call after current thread is suspended)
void TryDoContextSwitch();
/// Unloads currently running thread
void UnloadThread();
/// Select the threads in top of the scheduling multilist.
void SelectThreads();
/// Gets the current running thread
Thread* GetCurrentThread() const;
/// Gets the currently selected thread from the top of the multilevel queue
Thread* GetSelectedThread() const;
/// Gets the timestamp for the last context switch in ticks.
u64 GetLastContextSwitchTicks() const;
bool ContextSwitchPending() const {
return is_context_switch_pending;
}
/// Shutdowns the scheduler.
void Shutdown();
private:
friend class GlobalScheduler;
/// Switches the CPU's active thread context to that of the specified thread
void SwitchContext();
/**
* Called on every context switch to update the internal timestamp
* This also updates the running time ticks for the given thread and
* process using the following difference:
*
* ticks += most_recent_ticks - last_context_switch_ticks
*
* The internal tick timestamp for the scheduler is simply the
* most recent tick count retrieved. No special arithmetic is
* applied to it.
*/
void UpdateLastContextSwitchTime(Thread* thread, Process* process);
std::shared_ptr<Thread> current_thread = nullptr;
std::shared_ptr<Thread> selected_thread = nullptr;
Core::System& system;
Core::ARM_Interface& cpu_core;
u64 last_context_switch_time = 0;
u64 idle_selection_count = 0;
const std::size_t core_id;
bool is_context_switch_pending = false;
};
} // namespace Kernel
