我正在寻找适用于
Android
SystemClock.currentThreadTimeMillis()或Microsoft
GetThreadTimes()或Posix
clock_gettime(CLOCK_THREAD_CPUTIME_ID,)和
pthread_getcpuclockid()功能的iOS模拟,以测量多线程应用程序中函数使用的实际“干净”时间.也就是说,我不想测量功能中花费的实际挂钟时间,而是测量cpu时间.
我发现有关此here on stackoverflow和elsewhere的有趣讨论.不幸的是,它们都不适用于iOS.
在iOS上有这样的功能吗？
解决方法
万一有人在寻找一个好的答案：
不久之前,我在this answer中找到了一些很棒的代码(用于在OSX中查找cpu时间/内存使用情况),并稍微调整了一下.我用它来对ARM上的一些NEON优化进行基准测试.您可能只需要为当前线程获取时间的部分.
#include <sys/types.h>
#include <sys/sysctl.h>
#include <mach/mach_init.h>
#include <mach/mach_host.h>
#include <mach/mach_port.h>
#include <mach/mach_traps.h>
#include <mach/task_info.h>
#include <mach/thread_info.h>
#include <mach/thread_act.h>
#include <mach/vm_region.h>
#include <mach/vm_map.h>
#include <mach/task.h>
typedef struct {
double utime,stime;
} cpuTime;
int get_cpu_time(cpuTime *rpd,bool_t thread_only)
{
task_t task;
kern_return_t error;
mach_msg_type_number_t count;
thread_array_t thread_table;
thread_basic_info_t thi;
thread_basic_info_data_t thi_data;
unsigned table_size;
struct task_basic_info ti;
if (thread_only) {
// just get time of this thread
count = THREAD_BASIC_INFO_COUNT;
thi = &thi_data;
error = thread_info(mach_thread_self(),THREAD_BASIC_INFO,(thread_info_t)thi,&count);
rpd->utime = thi->user_time.seconds + thi->user_time.microseconds * 1e-6;
rpd->stime = thi->system_time.seconds + thi->system_time.microseconds * 1e-6;
return 0;
}
// get total time of the current process
task = mach_task_self();
count = TASK_BASIC_INFO_COUNT;
error = task_info(task,TASK_BASIC_INFO,(task_info_t)&ti,&count);
assert(error == KERN_SUCCESS);
{ /* calculate cpu times,adapted from top/libtop.c */
unsigned i;
// the following times are for threads which have already terminated and gone away
rpd->utime = ti.user_time.seconds + ti.user_time.microseconds * 1e-6;
rpd->stime = ti.system_time.seconds + ti.system_time.microseconds * 1e-6;
error = task_threads(task,&thread_table,&table_size);
assert(error == KERN_SUCCESS);
thi = &thi_data;
// for each active thread,add up thread time
for (i = 0; i != table_size; ++i) {
count = THREAD_BASIC_INFO_COUNT;
error = thread_info(thread_table[i],&count);
assert(error == KERN_SUCCESS);
if ((thi->flags & TH_FLAGS_IDLE) == 0) {
rpd->utime += thi->user_time.seconds + thi->user_time.microseconds * 1e-6;
rpd->stime += thi->system_time.seconds + thi->system_time.microseconds * 1e-6;
}
error = mach_port_deallocate(mach_task_self(),thread_table[i]);
assert(error == KERN_SUCCESS);
}
error = vm_deallocate(mach_task_self(),(vm_offset_t)thread_table,table_size * sizeof(thread_array_t));
assert(error == KERN_SUCCESS);
}
if (task != mach_task_self()) {
mach_port_deallocate(mach_task_self(),task);
assert(error == KERN_SUCCESS);
}
return 0;
}
