t

accel/tcg/tcg-accel-ops-mttcg.c

@@ -24,6 +24,7 @@
  */
 
 #include "qemu/osdep.h"
+#include "qemu/thread.h"
 #include "sysemu/tcg.h"
 #include "sysemu/replay.h"
 #include "sysemu/cpu-timers.h"
@@ -62,11 +63,61 @@ static void mttcg_force_rcu(Notifier *notify, void *data)
  * current CPUState for a given thread.
  */
 
+static void qemu_thread_set_affinity_simple(int core_id) {
+    int nbits =
+#ifdef _WIN32
+        64
+#else
+        sysconf(_SC_NPROCESSORS_ONLN);
+#endif
+    unsigned long *bitmap = bitmap_new(nbits);
+
+    core_id = core_id % nbits;
+    set_bit(core_id, bitmap);
+    
+    QemuThread thread;
+    qemu_thread_get_self(&thread);
+    
+    int ret = qemu_thread_set_affinity(&thread, bitmap, nbits);
+    if (ret) {
+        fprintf(stderr, "Setting CPU affinity failed\n");
+    }
+    g_free(bitmap);
+}
+
+static void qemu_thread_clear_affinity(void) {
+    int nbits =
+#ifdef _WIN32
+        64
+#else
+        sysconf(_SC_NPROCESSORS_ONLN);
+#endif
+    unsigned long *bitmap = bitmap_new(nbits);
+
+    for (int i = 0; i < nbits; i++) {
+        set_bit(i, bitmap);
+    }
+    
+    QemuThread thread;
+    qemu_thread_get_self(&thread);
+    
+    int ret = qemu_thread_set_affinity(&thread, bitmap, nbits);
+    if (ret) {
+        fprintf(stderr, "Setting CPU affinity failed\n");
+    }
+    g_free(bitmap);
+}
+
+#include "ui/xemu-settings.h"
+static bool pinned = false;
+
 static void *mttcg_cpu_thread_fn(void *arg)
 {
     MttcgForceRcuNotifier force_rcu;
     CPUState *cpu = arg;
 
+    qemu_thread_set_affinity_simple(0);
+
     assert(tcg_enabled());
     g_assert(!icount_enabled());
 
@@ -89,6 +140,15 @@ static void *mttcg_cpu_thread_fn(void *arg)
     cpu->exit_request = 1;
 
     do {
+        if (pinned != g_config.perf.pin_cpu_thread) {
+            if (g_config.perf.pin_cpu_thread) {
+                qemu_thread_set_affinity_simple(0);
+            } else {
+                qemu_thread_clear_affinity();
+            }
+            pinned = g_config.perf.pin_cpu_thread;
+        }
+
         if (cpu_can_run(cpu)) {
             int r;
             qemu_mutex_unlock_iothread();

config_spec.yml

@@ -209,3 +209,6 @@ perf:
   cache_shaders:
     type: bool
     default: true
+  pin_cpu_thread:
+    type: bool
+    default: false

ui/xui/main-menu.cc

@@ -58,6 +58,8 @@ void MainMenuGeneralView::Draw()
     Toggle("Hard FPU emulation", &g_config.perf.hard_fpu,
            "Use hardware-accelerated floating point emulation (requires restart)");
 #endif
+    Toggle("Set CPU thread affinity", &g_config.perf.pin_cpu_thread,
+           "Set CPU thread affinity to Logical CPU 0");
 
     Toggle("Cache shaders to disk", &g_config.perf.cache_shaders,
            "Reduce stutter in games by caching previously generated shaders");

util/qemu-thread-win32.c

@@ -15,6 +15,7 @@
 #include "qemu/thread.h"
 #include "qemu/notify.h"
 #include "qemu-thread-common.h"
+#include "qemu/bitmap.h"
 #include <process.h>
 
 static bool name_threads;
@@ -480,7 +481,24 @@ void qemu_thread_create(QemuThread *thread, const char *name,
 int qemu_thread_set_affinity(QemuThread *thread, unsigned long *host_cpus,
                              unsigned long nbits)
 {
-    return -ENOSYS;
+    DWORD_PTR affinity = 0;
+    DWORD_PTR affinity_prev;
+    unsigned long value;
+    assert(nbits <= 64);
+
+    value = find_first_bit(host_cpus, nbits);
+    while (value < nbits) {
+        affinity |= 1ULL << value;
+        value = find_next_bit(host_cpus, nbits, value + 1);
+    }
+
+    affinity_prev =
+        SetThreadAffinityMask(qemu_thread_get_handle(thread), affinity);
+    if (!affinity_prev) {
+        return -1;
+    }
+
+    return 0;
 }
 
 int qemu_thread_get_affinity(QemuThread *thread, unsigned long **host_cpus,