[core/hle] use boost::container::small_vector<> instead of std::set<> of dummy threads (#3025)

2048 bytes of static storage (128 threads) is more than enough for most applications

Highly hit or miss (most likely miss) - check with TOTK beforehand, should bring perf stuff to Android; in theory

Signed-off-by: lizzie lizzie@eden-emu.dev
Reviewed-on: https://git.eden-emu.dev/eden-emu/eden/pulls/3025
Reviewed-by: DraVee <dravee@eden-emu.dev>
Reviewed-by: Maufeat <sahyno1996@gmail.com>
Co-authored-by: lizzie <lizzie@eden-emu.dev>
Co-committed-by: lizzie <lizzie@eden-emu.dev>

src/core/hle/kernel/global_scheduler_context.cpp

@@ -1,7 +1,11 @@
+// SPDX-FileCopyrightText: Copyright 2025 Eden Emulator Project
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 // SPDX-FileCopyrightText: Copyright 2020 yuzu Emulator Project
 // SPDX-License-Identifier: GPL-2.0-or-later
 
 #include <mutex>
+#include <ranges>
 
 #include "common/assert.h"
 #include "core/core.h"
@@ -17,57 +21,61 @@ GlobalSchedulerContext::GlobalSchedulerContext(KernelCore& kernel)
 
 GlobalSchedulerContext::~GlobalSchedulerContext() = default;
 
-void GlobalSchedulerContext::AddThread(KThread* thread) {
+/// @brief Adds a new thread to the scheduler
+void GlobalSchedulerContext::AddThread(KThread* thread) noexcept {
     std::scoped_lock lock{m_global_list_guard};
     m_thread_list.push_back(thread);
 }
 
-void GlobalSchedulerContext::RemoveThread(KThread* thread) {
+/// @brief Removes a thread from the scheduler
+void GlobalSchedulerContext::RemoveThread(KThread* thread) noexcept {
     std::scoped_lock lock{m_global_list_guard};
-    std::erase(m_thread_list, thread);
+    m_thread_list.erase(std::ranges::find(m_thread_list, thread));
 }
 
-void GlobalSchedulerContext::PreemptThreads() {
+/// @brief 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 GlobalSchedulerContext::PreemptThreads() noexcept {
     // The priority levels at which the global scheduler preempts threads every 10 ms. They are
     // ordered from Core 0 to Core 3.
-    static constexpr std::array<u32, Core::Hardware::NUM_CPU_CORES> preemption_priorities{
+    static constexpr std::array<u32, Core::Hardware::NUM_CPU_CORES> per_core{
         59,
         59,
         59,
         63,
     };
-
     ASSERT(KScheduler::IsSchedulerLockedByCurrentThread(m_kernel));
-    for (u32 core_id = 0; core_id < Core::Hardware::NUM_CPU_CORES; core_id++) {
-        const u32 priority = preemption_priorities[core_id];
-        KScheduler::RotateScheduledQueue(m_kernel, core_id, priority);
-    }
+    for (u32 core_id = 0; core_id < per_core.size(); core_id++)
+        KScheduler::RotateScheduledQueue(m_kernel, core_id, per_core[core_id]);
 }
 
-bool GlobalSchedulerContext::IsLocked() const {
+/// @brief Returns true if the global scheduler lock is acquired
+bool GlobalSchedulerContext::IsLocked() const noexcept {
     return m_scheduler_lock.IsLockedByCurrentThread();
 }
 
-void GlobalSchedulerContext::RegisterDummyThreadForWakeup(KThread* thread) {
+void GlobalSchedulerContext::RegisterDummyThreadForWakeup(KThread* thread) noexcept {
     ASSERT(this->IsLocked());
-
-    m_woken_dummy_threads.insert(thread);
+    m_woken_dummy_threads.push_back(thread);
 }
 
-void GlobalSchedulerContext::UnregisterDummyThreadForWakeup(KThread* thread) {
+void GlobalSchedulerContext::UnregisterDummyThreadForWakeup(KThread* thread) noexcept {
     ASSERT(this->IsLocked());
-
-    m_woken_dummy_threads.erase(thread);
+    if(auto it = std::ranges::find(m_woken_dummy_threads, thread); it != m_woken_dummy_threads.end()) {
+        *it = m_woken_dummy_threads.back();
+        m_woken_dummy_threads.pop_back();
+    }
 }
 
-void GlobalSchedulerContext::WakeupWaitingDummyThreads() {
+void GlobalSchedulerContext::WakeupWaitingDummyThreads() noexcept {
     ASSERT(this->IsLocked());
-
-    for (auto* thread : m_woken_dummy_threads) {
-        thread->DummyThreadEndWait();
+    if (m_woken_dummy_threads.size() > 0) {
+        for (auto* thread : m_woken_dummy_threads)
+            thread->DummyThreadEndWait();
+        m_woken_dummy_threads.clear();
     }
-
-    m_woken_dummy_threads.clear();
 }
 
 } // namespace Kernel

src/core/hle/kernel/global_scheduler_context.h

@@ -1,11 +1,13 @@
+// SPDX-FileCopyrightText: Copyright 2025 Eden Emulator Project
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 // SPDX-FileCopyrightText: Copyright 2020 yuzu Emulator Project
 // SPDX-License-Identifier: GPL-2.0-or-later
 
 #pragma once
 
 #include <atomic>
-#include <set>
-#include <vector>
+#include <boost/container/small_vector.hpp>
 
 #include "common/common_types.h"
 #include "core/hardware_properties.h"
@@ -31,59 +33,42 @@ class GlobalSchedulerContext final {
     friend class KScheduler;
 
 public:
+    static constexpr size_t MAX_THREADS = 256;
     using LockType = KAbstractSchedulerLock<KScheduler>;
+    using ThreadList = boost::container::small_vector<KThread*, MAX_THREADS>;
 
     explicit GlobalSchedulerContext(KernelCore& kernel);
     ~GlobalSchedulerContext();
 
-    /// Adds a new thread to the scheduler
-    void AddThread(KThread* thread);
-
-    /// Removes a thread from the scheduler
-    void RemoveThread(KThread* thread);
-
-    /// Returns a list of all threads managed by the scheduler
+    /// @brief Returns a list of all threads managed by the scheduler
     /// This is only safe to iterate while holding the scheduler lock
-    const std::vector<KThread*>& GetThreadList() const {
+    ThreadList const& GetThreadList() const noexcept {
         return m_thread_list;
     }
-
-    /**
-     * 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();
-
-    /// Returns true if the global scheduler lock is acquired
-    bool IsLocked() const;
-
-    void UnregisterDummyThreadForWakeup(KThread* thread);
-    void RegisterDummyThreadForWakeup(KThread* thread);
-    void WakeupWaitingDummyThreads();
-
-    LockType& SchedulerLock() {
+    LockType& SchedulerLock() noexcept {
         return m_scheduler_lock;
     }
+    void AddThread(KThread* thread) noexcept;
+    void RemoveThread(KThread* thread) noexcept;
+    void PreemptThreads() noexcept;
+    bool IsLocked() const noexcept;
+    void UnregisterDummyThreadForWakeup(KThread* thread) noexcept;
+    void RegisterDummyThreadForWakeup(KThread* thread) noexcept;
+    void WakeupWaitingDummyThreads() noexcept;
 
 private:
     friend class KScopedSchedulerLock;
     friend class KScopedSchedulerLockAndSleep;
 
     KernelCore& m_kernel;
-
     std::atomic_bool m_scheduler_update_needed{};
     KSchedulerPriorityQueue m_priority_queue;
     LockType m_scheduler_lock;
-
+    std::mutex m_global_list_guard;
     /// Lists dummy threads pending wakeup on lock release
-    std::set<KThread*> m_woken_dummy_threads;
-
+    ThreadList m_woken_dummy_threads;
     /// Lists all thread ids that aren't deleted/etc.
-    std::vector<KThread*> m_thread_list;
-    std::mutex m_global_list_guard;
+    ThreadList m_thread_list;
 };
 
 } // namespace Kernel

src/core/hle/kernel/k_scheduler.cpp

@@ -527,35 +527,27 @@ void KScheduler::ClearPreviousThread(KernelCore& kernel, KThread* thread) {
 
 void KScheduler::OnThreadStateChanged(KernelCore& kernel, KThread* thread, ThreadState old_state) {
     ASSERT(IsSchedulerLockedByCurrentThread(kernel));
-
     // Check if the state has changed, because if it hasn't there's nothing to do.
-    const ThreadState cur_state = thread->GetRawState();
-    if (cur_state == old_state) {
-        return;
-    }
-
-    // Update the priority queues.
-    if (old_state == ThreadState::Runnable) {
-        // If we were previously runnable, then we're not runnable now, and we should remove.
-        GetPriorityQueue(kernel).Remove(thread);
-        IncrementScheduledCount(thread);
-        SetSchedulerUpdateNeeded(kernel);
-
-        if (thread->IsDummyThread()) {
+    if (const ThreadState cur_state = thread->GetRawState(); cur_state != old_state) {
+        // Update the priority queues.
+        if (old_state == ThreadState::Runnable) {
+            // If we were previously runnable, then we're not runnable now, and we should remove.
+            GetPriorityQueue(kernel).Remove(thread);
+            IncrementScheduledCount(thread);
+            SetSchedulerUpdateNeeded(kernel);
             // HACK: if this is a dummy thread, it should no longer wake up when the
             // scheduler lock is released.
-            kernel.GlobalSchedulerContext().UnregisterDummyThreadForWakeup(thread);
-        }
-    } else if (cur_state == ThreadState::Runnable) {
-        // If we're now runnable, then we weren't previously, and we should add.
-        GetPriorityQueue(kernel).PushBack(thread);
-        IncrementScheduledCount(thread);
-        SetSchedulerUpdateNeeded(kernel);
-
-        if (thread->IsDummyThread()) {
+            if (thread->IsDummyThread())
+                kernel.GlobalSchedulerContext().UnregisterDummyThreadForWakeup(thread);
+        } else if (cur_state == ThreadState::Runnable) {
+            // If we're now runnable, then we weren't previously, and we should add.
+            GetPriorityQueue(kernel).PushBack(thread);
+            IncrementScheduledCount(thread);
+            SetSchedulerUpdateNeeded(kernel);
             // HACK: if this is a dummy thread, it should wake up when the scheduler
             // lock is released.
-            kernel.GlobalSchedulerContext().RegisterDummyThreadForWakeup(thread);
+            if (thread->IsDummyThread())
+                kernel.GlobalSchedulerContext().RegisterDummyThreadForWakeup(thread);
         }
     }
 }