From 7b9f428b23e1761e7b6c177d2e8eb9219ac6b7f6 Mon Sep 17 00:00:00 2001
From: bunnei <bunneidev@gmail.com>
Date: Mon, 23 Mar 2015 23:55:21 -0400
Subject: [PATCH] Thread: Implement priority boost for starved threads.
SVC: Return correct error code on invalid CreateThread processor ID.
SVC: Assert when creating a thread with an invalid userland priority.
---
src/common/thread_queue_list.h | 18 ++++++++++++
src/core/hle/function_wrappers.h | 7 +++++
src/core/hle/kernel/thread.cpp | 48 ++++++++++++++++++++++++--------
src/core/hle/kernel/thread.h | 25 ++++++++++-------
src/core/hle/svc.cpp | 22 +++++++++++----
5 files changed, 92 insertions(+), 28 deletions(-)
diff --git a/src/common/thread_queue_list.h b/src/common/thread_queue_list.h
index 444abf1151..4f27fc8992 100644
--- a/src/common/thread_queue_list.h
+++ b/src/common/thread_queue_list.h
@@ -40,6 +40,18 @@ struct ThreadQueueList {
return -1;
}
+ T get_first() {
+ Queue *cur = first;
+ while (cur != nullptr) {
+ if (!cur->data.empty()) {
+ return cur->data.front();
+ }
+ cur = cur->next_nonempty;
+ }
+
+ return T();
+ }
+
T pop_first() {
Queue *cur = first;
while (cur != nullptr) {
@@ -79,6 +91,12 @@ struct ThreadQueueList {
cur->data.push_back(thread_id);
}
+ void move(const T& thread_id, Priority old_priority, Priority new_priority) {
+ remove(old_priority, thread_id);
+ prepare(new_priority);
+ push_back(new_priority, thread_id);
+ }
+
void remove(Priority priority, const T& thread_id) {
Queue *cur = &queues[priority];
boost::remove_erase(cur->data, thread_id);
diff --git a/src/core/hle/function_wrappers.h b/src/core/hle/function_wrappers.h
index 0b6b6f5180..be2626eef6 100644
--- a/src/core/hle/function_wrappers.h
+++ b/src/core/hle/function_wrappers.h
@@ -46,6 +46,13 @@ template<ResultCode func(u32*, u32, u32, u32, u32, u32)> void Wrap(){
FuncReturn(retval);
}
+template<ResultCode func(u32*, s32, u32, u32, u32, s32)> void Wrap() {
+ u32 param_1 = 0;
+ u32 retval = func(¶m_1, PARAM(0), PARAM(1), PARAM(2), PARAM(3), PARAM(4)).raw;
+ Core::g_app_core->SetReg(1, param_1);
+ FuncReturn(retval);
+}
+
template<ResultCode func(s32*, u32*, s32, bool, s64)> void Wrap() {
s32 param_1 = 0;
s32 retval = func(¶m_1, (Handle*)Memory::GetPointer(PARAM(1)), (s32)PARAM(2),
diff --git a/src/core/hle/kernel/thread.cpp b/src/core/hle/kernel/thread.cpp
index be1aed615a..3a1e15ac67 100644
--- a/src/core/hle/kernel/thread.cpp
+++ b/src/core/hle/kernel/thread.cpp
@@ -140,6 +140,29 @@ void ArbitrateAllThreads(u32 address) {
}
}
+/// Boost low priority threads (temporarily) that have been starved
+static void PriorityBoostStarvedThreads() {
+ u64 current_ticks = CoreTiming::GetTicks();
+
+ for (auto& thread : thread_list) {
+ // TODO(bunnei): Threads that have been waiting to be scheduled for `boost_ticks` (or
+ // longer) will have their priority temporarily adjusted to 1 higher than the highest
+ // priority thread to prevent thread starvation. This general behavior has been verified
+ // on hardware. However, this is almost certainly not perfect, and the real CTR OS scheduler
+ // should probably be reversed to verify this.
+
+ const u64 boost_timeout = 2000000; // Boost threads that have been ready for > this long
+
+ u64 delta = current_ticks - thread->last_running_ticks;
+
+ if (thread->status == THREADSTATUS_READY && delta > boost_timeout && !thread->idle) {
+ const s32 boost_priority = std::max(ready_queue.get_first()->current_priority - 1, 0);
+ ready_queue.move(thread, thread->current_priority, boost_priority);
+ thread->current_priority = boost_priority;
+ }
+ }
+}
+
/**
* Switches the CPU's active thread context to that of the specified thread
* @param new_thread The thread to switch to
@@ -151,6 +174,7 @@ static void SwitchContext(Thread* new_thread) {
// Save context for previous thread
if (previous_thread) {
+ previous_thread->last_running_ticks = CoreTiming::GetTicks();
Core::g_app_core->SaveContext(previous_thread->context);
if (previous_thread->status == THREADSTATUS_RUNNING) {
@@ -168,6 +192,9 @@ static void SwitchContext(Thread* new_thread) {
ready_queue.remove(new_thread->current_priority, new_thread);
new_thread->status = THREADSTATUS_RUNNING;
+ // Restores thread to its nominal priority if it has been temporarily changed
+ new_thread->current_priority = new_thread->nominal_priority;
+
Core::g_app_core->LoadContext(new_thread->context);
} else {
current_thread = nullptr;
@@ -364,7 +391,8 @@ ResultVal<SharedPtr<Thread>> Thread::Create(std::string name, VAddr entry_point,
thread->status = THREADSTATUS_DORMANT;
thread->entry_point = entry_point;
thread->stack_top = stack_top;
- thread->initial_priority = thread->current_priority = priority;
+ thread->nominal_priority = thread->current_priority = priority;
+ thread->last_running_ticks = CoreTiming::GetTicks();
thread->processor_id = processor_id;
thread->wait_set_output = false;
thread->wait_all = false;
@@ -400,18 +428,11 @@ static void ClampPriority(const Thread* thread, s32* priority) {
void Thread::SetPriority(s32 priority) {
ClampPriority(this, &priority);
- if (current_priority == priority) {
- return;
- }
+ // If thread was ready, adjust queues
+ if (status == THREADSTATUS_READY)
+ ready_queue.move(this, current_priority, priority);
- 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;
+ nominal_priority = current_priority = priority;
}
SharedPtr<Thread> SetupIdleThread() {
@@ -440,6 +461,9 @@ SharedPtr<Thread> SetupMainThread(u32 stack_size, u32 entry_point, s32 priority)
void Reschedule() {
Thread* prev = GetCurrentThread();
+
+ PriorityBoostStarvedThreads();
+
Thread* next = PopNextReadyThread();
HLE::g_reschedule = false;
diff --git a/src/core/hle/kernel/thread.h b/src/core/hle/kernel/thread.h
index bde4eecf2c..92f2c423b0 100644
--- a/src/core/hle/kernel/thread.h
+++ b/src/core/hle/kernel/thread.h
@@ -17,16 +17,19 @@
#include "core/hle/kernel/kernel.h"
#include "core/hle/result.h"
-enum ThreadPriority {
- THREADPRIO_HIGHEST = 0x0, ///< Highest thread priority
- THREADPRIO_DEFAULT = 0x30, ///< Default thread priority for userland apps
- THREADPRIO_LOWEST = 0x3F, ///< Lowest thread priority
+enum ThreadPriority : s32{
+ THREADPRIO_HIGHEST = 0, ///< Highest thread priority
+ THREADPRIO_USERLAND_MAX = 24, ///< Highest thread priority for userland apps
+ THREADPRIO_DEFAULT = 48, ///< Default thread priority for userland apps
+ THREADPRIO_LOWEST = 63, ///< Lowest thread priority
};
-enum ThreadProcessorId {
- THREADPROCESSORID_0 = 0xFFFFFFFE, ///< Enables core appcode
- THREADPROCESSORID_1 = 0xFFFFFFFD, ///< Enables core syscore
- THREADPROCESSORID_ALL = 0xFFFFFFFC, ///< Enables both cores
+enum ThreadProcessorId : s32 {
+ THREADPROCESSORID_DEFAULT = -2, ///< Run thread on default core specified by exheader
+ THREADPROCESSORID_ALL = -1, ///< Run thread on either core
+ THREADPROCESSORID_0 = 0, ///< Run thread on core 0 (AppCore)
+ THREADPROCESSORID_1 = 1, ///< Run thread on core 1 (SysCore)
+ THREADPROCESSORID_MAX = 2, ///< Processor ID must be less than this
};
enum ThreadStatus {
@@ -134,8 +137,10 @@ public:
u32 entry_point;
u32 stack_top;
- s32 initial_priority;
- s32 current_priority;
+ s32 nominal_priority; ///< Nominal thread priority, as set by the emulated application
+ s32 current_priority; ///< Current thread priority, can be temporarily changed
+
+ u64 last_running_ticks; ///< CPU tick when thread was last running
s32 processor_id;
diff --git a/src/core/hle/svc.cpp b/src/core/hle/svc.cpp
index e89e972387..82e187466b 100644
--- a/src/core/hle/svc.cpp
+++ b/src/core/hle/svc.cpp
@@ -312,7 +312,7 @@ static ResultCode GetResourceLimitCurrentValues(s64* values, Handle resource_lim
}
/// Creates a new thread
-static ResultCode CreateThread(u32* out_handle, u32 priority, u32 entry_point, u32 arg, u32 stack_top, u32 processor_id) {
+static ResultCode CreateThread(Handle* out_handle, s32 priority, u32 entry_point, u32 arg, u32 stack_top, s32 processor_id) {
using Kernel::Thread;
std::string name;
@@ -323,6 +323,21 @@ static ResultCode CreateThread(u32* out_handle, u32 priority, u32 entry_point, u
name = Common::StringFromFormat("unknown-%08x", entry_point);
}
+ // TODO(bunnei): Implement resource limits to return an error code instead of the below assert.
+ // The error code should be: Description::NotAuthorized, Module::OS, Summary::WrongArgument,
+ // Level::Permanent
+ ASSERT_MSG(priority >= THREADPRIO_USERLAND_MAX, "Unexpected thread priority!");
+
+ if (priority > THREADPRIO_LOWEST) {
+ return ResultCode(ErrorDescription::OutOfRange, ErrorModule::OS,
+ ErrorSummary::InvalidArgument, ErrorLevel::Usage);
+ }
+
+ if (processor_id > THREADPROCESSORID_MAX) {
+ return ResultCode(ErrorDescription::OutOfRange, ErrorModule::Kernel,
+ ErrorSummary::InvalidArgument, ErrorLevel::Permanent);
+ }
+
CASCADE_RESULT(SharedPtr<Thread> thread, Kernel::Thread::Create(
name, entry_point, priority, arg, processor_id, stack_top));
CASCADE_RESULT(*out_handle, Kernel::g_handle_table.Create(std::move(thread)));
@@ -331,11 +346,6 @@ static ResultCode CreateThread(u32* out_handle, u32 priority, u32 entry_point, u
"threadpriority=0x%08X, processorid=0x%08X : created handle=0x%08X", entry_point,
name.c_str(), arg, stack_top, priority, processor_id, *out_handle);
- if (THREADPROCESSORID_1 == processor_id) {
- LOG_WARNING(Kernel_SVC,
- "thread designated for system CPU core (UNIMPLEMENTED) will be run with app core scheduling");
- }
-
HLE::Reschedule(__func__);
return RESULT_SUCCESS;
--
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