android指定cpu,android将线程绑定在指定CPU

linux下可以直接调用pthread_setaffinity_np，将当前线程绑定在具体的cpu上，而android该API被屏蔽了，需要调用sched这个系统API，详情见下面代码：

package nativelibs;

public class Affinity {

static {

System.loadLibrary("Affinity");

}

public static native void bindToCpu(int cpu);

}

void set_cur_thread_affinity(int mask) {

int err, syscallres;

pid_t pid = gettid();

syscallres = syscall(__NR_sched_setaffinity, pid, sizeof(mask), &mask);

if (syscallres) {

err = errno;

LOGE("Error in the syscall setaffinity: mask = %d, err=%d",mask,errno);

}

LOGD("tid = %d has setted affinity success",pid);

}

ok，具体的JNI代码如下：

#include

#define TAG "Affinity"

#define DEBUG 1

#ifndef CPU_ZERO

#define CPU_SETSIZE 1024

#define __NCPUBITS (8 * sizeof (unsigned long))

typedef struct

{

unsigned long __bits[CPU_SETSIZE / __NCPUBITS];

} cpu_set_t;

#define CPU_SET(cpu, cpusetp) \

((cpusetp)->__bits[(cpu)/__NCPUBITS] |= (1UL << ((cpu) % __NCPUBITS)))

#define CPU_ZERO(cpusetp) \

memset((cpusetp), 0, sizeof(cpu_set_t))

#else

#define CPU_SET(cpu,cpustep) ((void)0)

#define CPU_ZERO(cpu,cpustep) ((void)0)

#endif

#ifdef DEBUG

#define LOGD(...) __android_log_print(ANDROID_LOG_DEBUG,TAG,__VA_ARGS__)

#define LOGE(...) __android_log_print(ANDROID_LOG_ERROR,TAG,__VA_ARGS__)

#else

#define LOGD(...) ((void)0)

#define LOGE(...) ((void)0)

#endif

void set_cur_thread_affinity(int mask) {

int err, syscallres;

pid_t pid = gettid();

syscallres = syscall(__NR_sched_setaffinity, pid, sizeof(mask), &mask);

if (syscallres) {

err = errno;

LOGE("Error in the syscall setaffinity: mask = %d, err=%d",mask,errno);

}

LOGD("tid = %d has setted affinity success",pid);

}

static int getCores() {

return sysconf(_SC_NPROCESSORS_CONF);

}

JNIEXPORT int JNICALL Java_nativelibs_Affinity_getCores(JNIEnv *env, jclass type) {

return getCores();

}

JNIEXPORT void JNICALL Java_nativelibs_Affinity_bindToCpu(JNIEnv *env, jclass type, jint cpu) {

int cores = getCores();

LOGD("get cpu number = %d\n",cores);

if (cpu >= cores) {

LOGE("your set cpu is beyond the cores,exit...");

return;

}

cpu_set_t mask;

CPU_ZERO(&mask);

CPU_SET(cpu,&mask);

set_cur_thread_affinity((int)(&mask));

LOGD("set affinity to %d success",cpu);

}