pin CPU thread to a fast core

Author: landfillbaby

Source/Core/Common/ArmCPUDetect.cpp

@@ -2,6 +2,7 @@
 // SPDX-License-Identifier: GPL-2.0-or-later
 
 #include "Common/CPUDetect.h"
+#include "Common/CPUDetectFastestCore.h"
 
 #include <cstring>
 #include <fstream>
@@ -224,6 +225,8 @@ void CPUInfo::Detect()
 
   num_cores = std::max(static_cast<int>(std::thread::hardware_concurrency()), 1);
 
+  fastest_core = CPUDetectFastestCore(num_cores);
+
 #ifdef __APPLE__
   SysctlByName(&model_name, "machdep.cpu.brand_string");
 

Source/Core/Common/CMakeLists.txt

@@ -37,6 +37,7 @@ add_library(common
   Config/Layer.h
   Contains.h
   CPUDetect.h
+  CPUDetectFastestCore.h
   Crypto/AES.cpp
   Crypto/AES.h
   Crypto/bn.cpp

Source/Core/Common/CPUDetect.h

@@ -23,6 +23,7 @@ struct CPUInfo
 
   bool HTT = false;
   int num_cores = 0;
+  int fastest_core = 0;
 
   bool bSSE3 = false;
   bool bSSSE3 = false;

Source/Core/Common/CPUDetectFastestCore.h

@@ -0,0 +1,39 @@
+// Copyright 2013 Dolphin Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include <fstream>
+#include <sstream>
+#include <string>
+
+#include "Common/CommonTypes.h"
+#include "Common/FileUtil.h"
+
+static int CPUDetectFastestCore(int num_cores)
+{
+  int fastest_core = 0;
+  u32 fastest_freq = 0;
+#ifdef __linux__
+  std::ostringstream ss;
+  for (int i = 0; i < num_cores; i++)
+  {
+    ss.str("/sys/devices/system/cpu/cpu");
+    ss << i << "/cpufreq/cpuinfo_max_freq";
+
+    std::ifstream file;
+    File::OpenFStream(file, ss.str(), std::ios_base::in);
+    if (!file)
+      continue;
+
+    u32 freq;
+    file >> freq;
+    if (freq > fastest_freq)
+    {
+      fastest_freq = freq;
+      fastest_core = i;
+    }
+  }
+#else
+  // TODO
+#endif
+  return fastest_core;
+}

Source/Core/Common/Thread.cpp

@@ -122,8 +122,7 @@ void SetThreadAffinity(std::thread::native_handle_type thread, u32 mask)
 {
 #ifdef __APPLE__
   thread_policy_set(pthread_mach_thread_np(thread), THREAD_AFFINITY_POLICY, (integer_t*)&mask, 1);
-#elif (defined __linux__ || defined BSD4_4 || defined __FreeBSD__ || defined __NetBSD__) &&        \
-    !(defined ANDROID)
+#elif (defined __linux__ || defined BSD4_4 || defined __FreeBSD__ || defined __NetBSD__)
 #ifndef __NetBSD__
 #ifdef __FreeBSD__
   cpuset_t cpu_set;
@@ -136,7 +135,11 @@ void SetThreadAffinity(std::thread::native_handle_type thread, u32 mask)
     if ((mask >> i) & 1)
       CPU_SET(i, &cpu_set);
 
+#ifdef ANDROID
+  sched_setaffinity(pthread_gettid_np(thread), sizeof(cpu_set), &cpu_set);
+#else
   pthread_setaffinity_np(thread, sizeof(cpu_set), &cpu_set);
+#endif
 #else
   cpuset_t* cpu_set = cpuset_create();
 

Source/Core/Common/x64CPUDetect.cpp

@@ -2,6 +2,7 @@
 // SPDX-License-Identifier: GPL-2.0-or-later
 
 #include "Common/CPUDetect.h"
+#include "Common/CPUDetectFastestCore.h"
 
 #ifdef _WIN32
 #include <windows.h>
@@ -117,6 +118,8 @@ void CPUInfo::Detect()
   // CPUID data ourselves.
   num_cores = std::max(static_cast<int>(std::thread::hardware_concurrency()), 1);
 
+  fastest_core = CPUDetectFastestCore(num_cores); // TODO: cpuid?
+
   // Assume CPU supports the CPUID instruction. Those that don't can barely
   // boot modern OS anyway.
 

Source/Core/Core/HW/CPU.cpp

@@ -9,6 +9,7 @@
 
 #include "AudioCommon/AudioCommon.h"
 #include "Common/CommonTypes.h"
+#include "Common/CPUDetect.h"
 #include "Common/Event.h"
 #include "Common/Thread.h"
 #include "Common/Timer.h"
@@ -120,6 +121,13 @@ void CPUManager::Run()
     timing = std::thread(&CPUManager::StartTimePlayedTimer, this);
   }
 
+  // Pin the thread to the fastest core
+  // if (Config::Get(Config::MAIN_THREAD_PINNING)) // TODO
+  {
+    u32 mask = static_cast<u32>(1) << cpu_info.fastest_core;
+    Thread::SetCurrentThreadAffinity(mask);
+  }
+
   std::unique_lock state_lock(m_state_change_lock);
   while (m_state != State::PowerDown)
   {

Source/Core/DolphinLib.props

@@ -40,6 +40,7 @@
     <ClInclude Include="Common\Config\Layer.h" />
     <ClInclude Include="Common\Contains.h" />
     <ClInclude Include="Common\CPUDetect.h" />
+    <ClInclude Include="Common\CPUDetectFastestCore.h" />
     <ClInclude Include="Common\Crypto\AES.h" />
     <ClInclude Include="Common\Crypto\bn.h" />
     <ClInclude Include="Common\Crypto\ec.h" />