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scheduler: Add explanations for YieldWith and WithoutLoadBalancing

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This commit is contained in:
Zach Hilman
2018-11-22 00:33:53 -05:00
parent 409dcf0e0a
commit 820d81b9a5
6 changed files with 141 additions and 79 deletions
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4
src/common/thread_queue_list.h
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@@ -6,7 +6,6 @@
#include <array>
#include <deque>
#include <functional>
#include <boost/range/algorithm_ext/erase.hpp>
namespace Common {
@@ -50,7 +49,8 @@ struct ThreadQueueList {
return T();
}
T get_first_filter(std::function<bool(T)> filter) const {
template <typename UnaryPredicate>
T get_first_filter(UnaryPredicate filter) const {
const Queue* cur = first;
while (cur != nullptr) {
if (!cur->data.empty()) {

61
src/core/hle/kernel/scheduler.cpp
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@@ -9,6 +9,7 @@
#include "common/logging/log.h"
#include "core/arm/arm_interface.h"
#include "core/core.h"
#include "core/core_cpu.h"
#include "core/core_timing.h"
#include "core/hle/kernel/kernel.h"
#include "core/hle/kernel/process.h"
@@ -169,7 +170,7 @@ void Scheduler::UnscheduleThread(Thread* thread, u32 priority) {
ready_queue.remove(priority, thread);
}
void Scheduler::RescheduleThread(Thread* thread, u32 priority) {
void Scheduler::MoveThreadToBackOfPriorityQueue(Thread* thread, u32 priority) {
std::lock_guard<std::mutex> lock(scheduler_mutex);
// Thread is not in queue
@@ -189,12 +190,64 @@ void Scheduler::SetThreadPriority(Thread* thread, u32 priority) {
ready_queue.prepare(priority);
}
Thread* Scheduler::GetNextSuggestedThread(u32 core) {
Thread* Scheduler::GetNextSuggestedThread(u32 core) const {
std::lock_guard<std::mutex> lock(scheduler_mutex);
const auto mask = 1 << core;
const u32 mask = 1U << core;
return ready_queue.get_first_filter(
[&mask](Thread* thread) { return (thread->GetAffinityMask() & mask) != 0; });
[mask](Thread const* thread) { return (thread->GetAffinityMask() & mask) != 0; });
}
void Scheduler::YieldWithoutLoadBalancing(Thread* thread) {
ASSERT(thread != nullptr);
// Avoid yielding if the thread isn't even running.
ASSERT(thread->GetStatus() == ThreadStatus::Running);
// Sanity check that the priority is valid
ASSERT(thread->GetPriority() < THREADPRIO_COUNT);
// Yield this thread
MoveThreadToBackOfPriorityQueue(thread, thread->GetPriority());
Reschedule();
}
void Scheduler::YieldWithLoadBalancing(Thread* thread) {
ASSERT(thread != nullptr);
const auto priority = thread->GetPriority();
const auto core = static_cast<u32>(thread->GetProcessorID());
// Avoid yielding if the thread isn't even running.
ASSERT(thread->GetStatus() == ThreadStatus::Running);
// Sanity check that the priority is valid
ASSERT(priority < THREADPRIO_COUNT);
// Reschedule thread to end of queue.
MoveThreadToBackOfPriorityQueue(thread, priority);
Thread* suggested_thread = nullptr;
// Search through all of the cpu cores (except this one) for a suggested thread.
// Take the first non-nullptr one
for (unsigned cur_core = 0; cur_core < Core::NUM_CPU_CORES; ++cur_core) {
if (cur_core == core)
continue;
const auto res =
Core::System::GetInstance().CpuCore(cur_core).Scheduler().GetNextSuggestedThread(core);
if (res != nullptr) {
suggested_thread = res;
break;
}
}
// If a suggested thread was found, queue that for this core
if (suggested_thread != nullptr)
suggested_thread->ChangeCore(core, suggested_thread->GetAffinityMask());
}
void Scheduler::YieldAndWaitForLoadBalancing(Thread* thread) {
UNIMPLEMENTED_MSG("Wait for load balancing thread yield type is not implemented!");
}
} // namespace Kernel

70
src/core/hle/kernel/scheduler.h
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@@ -49,13 +49,79 @@ public:
void UnscheduleThread(Thread* thread, u32 priority);
/// Moves a thread to the back of the current priority queue
void RescheduleThread(Thread* thread, u32 priority);
void MoveThreadToBackOfPriorityQueue(Thread* thread, u32 priority);
/// Sets the priority of a thread in the scheduler
void SetThreadPriority(Thread* thread, u32 priority);
/// Gets the next suggested thread for load balancing
Thread* GetNextSuggestedThread(u32 core);
Thread* GetNextSuggestedThread(u32 core) const;
/**
* YieldWithoutLoadBalancing -- analogous to normal yield on a system
* Moves the thread to the end of the ready queue for its priority, and then reschedules the
* system to the new head of the queue.
*
* Example (Single Core -- but can be extrapolated to multi):
* ready_queue[prio=0]: ThreadA, ThreadB, ThreadC (->exec order->)
* Currently Running: ThreadR
*
* ThreadR calls YieldWithoutLoadBalancing
*
* ThreadR is moved to the end of ready_queue[prio=0]:
* ready_queue[prio=0]: ThreadA, ThreadB, ThreadC, ThreadR (->exec order->)
* Currently Running: Nothing
*
* System is rescheduled (ThreadA is popped off of queue):
* ready_queue[prio=0]: ThreadB, ThreadC, ThreadR (->exec order->)
* Currently Running: ThreadA
*
* If the queue is empty at time of call, no yielding occurs. This does not cross between cores
* or priorities at all.
*/
void YieldWithoutLoadBalancing(Thread* thread);
/**
* YieldWithLoadBalancing -- yield but with better selection of the new running thread
* Moves the current thread to the end of the ready queue for its priority, then selects a
* 'suggested thread' (a thread on a different core that could run on this core) from the
* scheduler, changes its core, and reschedules the current core to that thread.
*
* Example (Dual Core -- can be extrapolated to Quad Core, this is just normal yield if it were
* single core):
* ready_queue[core=0][prio=0]: ThreadA, ThreadB (affinities not pictured as irrelevant
* ready_queue[core=1][prio=0]: ThreadC[affinity=both], ThreadD[affinity=core1only]
* Currently Running: ThreadQ on Core 0 || ThreadP on Core 1
*
* ThreadQ calls YieldWithLoadBalancing
*
* ThreadQ is moved to the end of ready_queue[core=0][prio=0]:
* ready_queue[core=0][prio=0]: ThreadA, ThreadB
* ready_queue[core=1][prio=0]: ThreadC[affinity=both], ThreadD[affinity=core1only]
* Currently Running: ThreadQ on Core 0 || ThreadP on Core 1
*
* A list of suggested threads for each core is compiled
* Suggested Threads: {ThreadC on Core 1}
* If this were quad core (as the switch is), there could be between 0 and 3 threads in this
* list. If there are more than one, the thread is selected by highest prio.
*
* ThreadC is core changed to Core 0:
* ready_queue[core=0][prio=0]: ThreadC, ThreadA, ThreadB, ThreadQ
* ready_queue[core=1][prio=0]: ThreadD
* Currently Running: None on Core 0 || ThreadP on Core 1
*
* System is rescheduled (ThreadC is popped off of queue):
* ready_queue[core=0][prio=0]: ThreadA, ThreadB, ThreadQ
* ready_queue[core=1][prio=0]: ThreadD
* Currently Running: ThreadC on Core 0 || ThreadP on Core 1
*
* If no suggested threads can be found this will behave just as normal yield. If there are
* multiple candidates for the suggested thread on a core, the highest prio is taken.
*/
void YieldWithLoadBalancing(Thread* thread);
/// Currently unknown -- asserts as unimplemented on call
void YieldAndWaitForLoadBalancing(Thread* thread);
/// Returns a list of all threads managed by the scheduler
const std::vector<SharedPtr<Thread>>& GetThreadList() const {

21
src/core/hle/kernel/svc.cpp
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@@ -965,16 +965,23 @@ static void SleepThread(s64 nanoseconds) {
if (!Core::System::GetInstance().CurrentScheduler().HaveReadyThreads())
return;
enum class SleepType : s64 {
YieldWithoutLoadBalancing = 0,
YieldWithLoadBalancing = 1,
YieldAndWaitForLoadBalancing = 2,
};
if (nanoseconds <= 0) {
switch (nanoseconds) {
case 0:
GetCurrentThread()->YieldNormal();
auto& scheduler{Core::System::GetInstance().CurrentScheduler()};
switch (static_cast<SleepType>(nanoseconds)) {
case SleepType::YieldWithoutLoadBalancing:
scheduler.YieldWithoutLoadBalancing(GetCurrentThread());
break;
case -1:
GetCurrentThread()->YieldWithLoadBalancing();
case SleepType::YieldWithLoadBalancing:
scheduler.YieldWithLoadBalancing(GetCurrentThread());
break;
case -2:
GetCurrentThread()->YieldAndWaitForLoadBalancing();
case SleepType::YieldAndWaitForLoadBalancing:
scheduler.YieldAndWaitForLoadBalancing(GetCurrentThread());
break;
default:
UNREACHABLE_MSG(

60
src/core/hle/kernel/thread.cpp
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@@ -388,66 +388,6 @@ bool Thread::InvokeWakeupCallback(ThreadWakeupReason reason, SharedPtr<Thread> t
return wakeup_callback(reason, std::move(thread), std::move(object), index);
}
void Thread::YieldNormal() {
// Avoid yielding if the thread isn't even running.
if (status != ThreadStatus::Running) {
return;
}
if (nominal_priority < THREADPRIO_COUNT) {
scheduler->RescheduleThread(this, nominal_priority);
scheduler->Reschedule();
}
}
void Thread::YieldWithLoadBalancing() {
auto priority = nominal_priority;
auto core = processor_id;
// Avoid yielding if the thread isn't even running.
if (status != ThreadStatus::Running) {
Core::System::GetInstance().CpuCore(processor_id).PrepareReschedule();
return;
}
SharedPtr<Thread> next;
const auto& threads = scheduler->GetThreadList();
if (priority < THREADPRIO_COUNT) {
// Reschedule thread to end of queue.
scheduler->RescheduleThread(this, priority);
const auto iter = std::find_if(threads.begin(), threads.end(),
[&priority](const SharedPtr<Thread>& thread) {
return thread->GetNominalPriority() == priority;
});
if (iter != threads.end())
next = iter->get();
}
Thread* suggested_thread = nullptr;
for (int i = 0; i < 4; ++i) {
if (i == core)
continue;
const auto res =
Core::System::GetInstance().CpuCore(i).Scheduler().GetNextSuggestedThread(core);
if (res != nullptr) {
suggested_thread = res;
break;
}
}
if (suggested_thread != nullptr)
suggested_thread->ChangeCore(core, suggested_thread->GetAffinityMask());
}
void Thread::YieldAndWaitForLoadBalancing() {
UNIMPLEMENTED_MSG("Wait for load balancing thread yield type is not implemented!");
}
////////////////////////////////////////////////////////////////////////////////////////////////////
/**

4
src/core/hle/kernel/thread.h
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@@ -371,10 +371,6 @@ public:
return affinity_mask;
}
void YieldNormal();
void YieldWithLoadBalancing();
void YieldAndWaitForLoadBalancing();
private:
explicit Thread(KernelCore& kernel);
~Thread() override;