如何衡量iOS线程的实际CPU时间? [英] How do you measure actual on-CPU time for an iOS thread?
问题描述
我正在为Android的寻找iOS模拟SystemClock.currentThreadTimeMillis()或Microsoft的 GetThreadTimes()或Posix clock_gettime(CLOCK_THREAD_CPUTIME_ID,)和 pthread_getcpuclockid()用于测量多线程应用程序中函数使用的实际清理时间。也就是说,我不想测量函数中花费的实际挂钟时间,而是测量CPU上的时间。
I am looking for an iOS analog for Android's SystemClock.currentThreadTimeMillis() or Microsoft's GetThreadTimes() or Posix clock_gettime(CLOCK_THREAD_CPUTIME_ID, ) and pthread_getcpuclockid() functions to measure the actual "clean" time used by a function in a multithreaded application. That is, I don't want to measure the actual wall clock time spent in a function, but the on-CPU time.
我发现有趣的讨论这里有stackoverflow 和其他地方。不幸的是,它们都不适用于iOS。
I found interesting discussions about this here on stackoverflow and elsewhere. Unfortunately, neither applies to iOS.
在iOS上是否有相似的功能?
Is there a comparable function for this on iOS?
推荐答案
如果有人在寻找一个好的答案:
In case anyone is looking for a good answer:
前一段时间我在这个答案(用于查找OSX中的CPU时间/内存使用情况),并稍微调整一下。我用它来对ARM上的一些NEON优化进行基准测试。您可能只需要获取当前线程时间的部分。
A while ago I found some great code in this answer (for finding CPU time/memory usage in OSX), and adapted it slightly. I used this for benchmarking some NEON optimizations on the ARM. You would probably only need the section which gets time for the current thread.
#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], THREAD_BASIC_INFO, (thread_info_t)thi, &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;
}
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