增加 Android 系统下进程和线程的 CPU 亲和性设置参考程序.

Signed-off-by: rick.chan <chenyang@autoai.com>

Android/Native/CpuAffinity/Android.mk

@@ -0,0 +1,13 @@
+LOCAL_PATH := $(call my-dir)
+
+include $(CLEAR_VARS)
+
+LOCAL_MODULE                := CpuAffinityDemo
+LOCAL_MODULE_TAGS           := optional
+LOCAL_VENDOR_MODULE         := true
+LOCAL_LDLIBS                := -lc
+
+LOCAL_SRC_FILES := \
+    main.cpp
+
+include $(BUILD_EXECUTABLE)

Android/Native/CpuAffinity/main.cpp

@@ -0,0 +1,79 @@
+/**
+ * @file	main.cpp
+ * @author	Rick Chan
+ * @brief	Android 系统下进程和线程的 CPU 亲和性设置参考程序.
+ * @version	0.1
+ * @date	2021-06-07
+ * 
+ * @copyright	Copyright (c) 2020
+ * 
+ */
+#include <stdio.h>
+#include <unistd.h>
+#include <errno.h>
+#include <pthread.h>
+#include <sys/syscall.h>
+
+int SetProcessAffinity(void) {
+    cpu_set_t set;
+    pid_t pid = getpid();
+
+    // 进程只在核 3 和核 7 上执行.
+    CPU_ZERO(&set);
+    CPU_SET(3, &set);
+    CPU_SET(7, &set);
+
+    int res, err;
+    (void)res;
+    (void)err;
+    res = sched_setaffinity(pid, sizeof(set), &set);
+    err = errno;
+
+    return res;
+}
+
+void SetThreadAffinity(int mask) {
+    int err, syscallres;
+    pid_t pid = gettid();
+	// Linux 下可以直接使用 pthread_setaffinity_np() 函数将当前线程绑定在具体的 CPU 上, 而 Android 屏蔽了该 API, 需要通过 syscall(__NR_sched_setaffinity) 来实现.
+    syscallres = syscall(__NR_sched_setaffinity, pid, sizeof(mask), &mask);
+    if (syscallres) {
+        err = errno;
+    }
+}
+
+void* DemoRoutine0(void* arg)
+{
+    (void)arg;
+    // DemoRoutine0 只运行在核 3 上.
+    SetThreadAffinity(1<<3);
+    while(1);
+    return nullptr;
+}
+
+void* DemoRoutine1(void* arg)
+{
+    (void)arg;
+    // DemoRoutine0 只运行在核 7 上.
+    SetThreadAffinity(1<<7);
+    while(1);
+    return nullptr;
+}
+
+int main(void)
+{
+    pthread_t demoThrd0, demoThrd1;
+    cpu_set_t set;
+
+    sched_getaffinity(getpid(), sizeof(set), &set);
+    printf("Init CPU Setbits=%lu.\r\n", set.__bits[0]);
+    SetProcessAffinity();
+    sched_getaffinity(getpid(), sizeof(set), &set);
+    printf("Init CPU Setbits=%lu.\r\n", set.__bits[0]);
+
+    pthread_create(&demoThrd0, nullptr, DemoRoutine0, nullptr);
+    pthread_create(&demoThrd1, nullptr, DemoRoutine1, nullptr);
+    pthread_join(demoThrd0, nullptr);
+    pthread_join(demoThrd1, nullptr);
+    return 0;
+}