針對平臺優化的APP,需要根據具體的CPU型號來將一些任務重,佔CPU資源多的線程綁定到CPU上處理能力更強的大核上,可參考如下代碼:
1、將整個進程中的各個線程綁定到指定CPU核
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <sched.h>
#include <ctype.h>
#include <pthread.h>
#include <unistd.h>
#include <errno.h>
#include <sys/types.h>
#include <dirent.h>
#include <grp.h>
#include <inttypes.h>
#include <pwd.h>
#include <string.h>
#include <jni.h>
#include <time.h>
#include <poll.h>
#include <errno.h>
#include <fcntl.h>
#include <cutils/log.h>
#include <sys/stat.h>
#include <cutils/properties.h>
JNIEXPORT int JNICALL Java_com_google_vrtoolkit_cardboard_GLSurfaceView2_BindThreadsToCpu45(JNIEnv* env, jobject obj){
DIR *task_dir;
struct dirent *tid_dir;
int pid,tid;
int ret;
char filename[64];
ALOGD("BindThreadsToCpu45 : Current platform = rk3399");
cpu_set_t mask;
struct sched_param param;
CPU_ZERO(&mask);
CPU_SET(4, &mask);
CPU_SET(5, &mask);
extern int errno;
// bind whole processId to cpu 4 & 5
pid = getpid();
ret = sched_setaffinity(pid, sizeof(mask), &mask);
if(ret < 0){
ALOGE("BindThreadsToCpu45 -> bind process sched_setaffinity return %d, errno = %d\n",ret,errno);
return -1;
}else{
ALOGD("BindThreadsToCpu45 -> bind process sched_setaffinity success!");
}
// bind all threads before
sprintf(filename, "/proc/%d/task", pid);
task_dir = opendir(filename);
if (!task_dir) ALOGE("opendir failed!");
while ((tid_dir = readdir(task_dir))) {
if (!isdigit(tid_dir->d_name[0]))
continue;
tid = atoi(tid_dir->d_name);
ret = sched_setaffinity(tid, sizeof(mask), &mask);
if(ret < 0){
ALOGE("BindThreadsToCpu45 -> bind thread %d sched_setaffinity return %d, errno = %d\n",tid,ret,errno);
return -1;
}else{
ALOGD("BindThreadsToCpu45 -> bind thread %d sched_setaffinity success!",tid);
}
}
return 0;
}
android將線程綁定在指定CPU
原文地址:https://blog.csdn.net/lyx2007825/article/details/53885205
linux下可以直接調用pthread_setaffinity_np,將當前線程綁定在具體的cpu上,而android該API被屏蔽了,需要調用sched這個系統API,詳情見下面代碼:
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,具體的JNI代碼如下:
#include <jni.h>
#include <android/log.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <pthread.h>
#include <sys/syscall.h>
#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);
}