[TEST] Rework Android CPU affinity/ threading 2

src/common/thread.cpp

@@ -1,5 +1,6 @@
 // SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
 // SPDX-License-Identifier: GPL-3.0-or-later
+
 // SPDX-FileCopyrightText: 2013 Dolphin Emulator Project
 // SPDX-FileCopyrightText: 2014 Citra Emulator Project
 // SPDX-License-Identifier: GPL-2.0-or-later
@@ -111,6 +112,35 @@ const cpu_set_t& PerformanceCoreMask() {
     static const cpu_set_t mask = ComputePerformanceCoreMask();
     return mask;
 }
+
+cpu_set_t ComputeEfficiencyCoreMask() {
+    cpu_set_t mask;
+    CPU_ZERO(&mask);
+
+    const cpu_set_t& performance = PerformanceCoreMask();
+    if (CPU_COUNT(&performance) == 0) {
+        return mask;
+    }
+
+    cpu_set_t allowed;
+    CPU_ZERO(&allowed);
+    if (sched_getaffinity(gettid(), sizeof(allowed), &allowed) != 0) {
+        return mask;
+    }
+
+    const int total = static_cast<int>(std::thread::hardware_concurrency());
+    for (int cpu = 0; cpu < total; ++cpu) {
+        if (CPU_ISSET(cpu, &allowed) && !CPU_ISSET(cpu, &performance)) {
+            CPU_SET(cpu, &mask);
+        }
+    }
+    return mask;
+}
+
+const cpu_set_t& EfficiencyCoreMask() {
+    static const cpu_set_t mask = ComputeEfficiencyCoreMask();
+    return mask;
+}
 } // Anonymous namespace
 #endif
 
@@ -234,6 +264,18 @@ void SetCurrentThreadToPerformanceCores() {
 #endif
 }
 
+void SetCurrentThreadToEfficiencyCores() {
+#if defined(__ANDROID__)
+    const cpu_set_t& mask = EfficiencyCoreMask();
+    if (CPU_COUNT(&mask) == 0) {
+        return;
+    }
+    if (sched_setaffinity(gettid(), sizeof(mask), &mask) != 0) {
+        LOG_DEBUG(Common, "Could not restrict thread to efficiency cores: {}", GetLastErrorMsg());
+    }
+#endif
+}
+
 #ifdef ARCHITECTURE_x86_64
 // On Linux and UNIX systems, a futex would nominally be used to cover the costs
 // the idea is that it's intuitivelly cheaper to use a direct instruction as opposed to a full futex call

src/common/thread.h

@@ -99,8 +99,14 @@ enum class ThreadPriority : u32 {
     Critical = 4,
 };
 
+enum class ThreadPlacement : u32 {
+    Default = 0,
+    Background = 1,
+};
+
 void SetCurrentThreadPriority(ThreadPriority new_priority);
 void SetCurrentThreadName(const char* name);
 void SetCurrentThreadToPerformanceCores();
+void SetCurrentThreadToEfficiencyCores();
 
 } // namespace Common

src/common/thread_worker.h

@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: Copyright 2025 Eden Emulator Project
+// SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
 // SPDX-License-Identifier: GPL-3.0-or-later
 
 // SPDX-FileCopyrightText: Copyright 2020 yuzu Emulator Project
@@ -37,10 +37,15 @@ class StatefulThreadWorker {
     using StateMaker = std::conditional_t<with_state, std::function<StateType()>, DummyCallable>;
 
 public:
-    explicit StatefulThreadWorker(size_t num_workers, std::string name, StateMaker func = {})
+    explicit StatefulThreadWorker(size_t num_workers, std::string name, StateMaker func = {},
+                                  ThreadPlacement placement = ThreadPlacement::Default)
         : workers_queued{num_workers}, thread_name{std::move(name)} {
-        const auto lambda = [this, func](std::stop_token stop_token) {
+        const auto lambda = [this, func, placement](std::stop_token stop_token) {
             Common::SetCurrentThreadName(thread_name.c_str());
+            if (placement == ThreadPlacement::Background) {
+                Common::SetCurrentThreadPriority(ThreadPriority::Low);
+                Common::SetCurrentThreadToEfficiencyCores();
+            }
             {
                 [[maybe_unused]] std::conditional_t<with_state, StateType, int> state{func()};
                 while (!stop_token.stop_requested()) {