From 7b9f428b23e1761e7b6c177d2e8eb9219ac6b7f6 Mon Sep 17 00:00:00 2001 From: bunnei Date: Mon, 23 Mar 2015 23:55:21 -0400 Subject: 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/core/hle/kernel/thread.cpp | 48 +++++++++++++++++++++++++++++++----------- src/core/hle/kernel/thread.h | 25 +++++++++++++--------- 2 files changed, 51 insertions(+), 22 deletions(-) (limited to 'src/core/hle/kernel') diff --git a/src/core/hle/kernel/thread.cpp b/src/core/hle/kernel/thread.cpp index be1aed61..3a1e15ac 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> 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 SetupIdleThread() { @@ -440,6 +461,9 @@ SharedPtr 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 bde4eecf..92f2c423 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; -- cgit v1.2.3