iOS 和 Mac 线程的 CPU 使用率

Question

有谁知道是否可以获得应用程序中特定线程、进程或某些代码的 CPU 使用情况？如果你看一下 AUGraph，它有一个返回平均 CPU 使用率的函数。他们是怎么做到的？

Answer 1

我不确定这是否也适用于 iOS，但对于 OS X，您可以通过访问 Mach/BSD 子系统来获取所需的信息。基本上，您可以获得给定进程的线程列表，然后对所有线程的使用情况求和以获得进程的 CPU 使用情况。如果只需要一个线程cpu使用情况，则不需要求和。

它并不像人们希望的那样简单明了，但它就是这样(此代码基于 Amit Singh“Mac OS X 内部结构”):

            pid_t pid = ...;   //-- this is the process id you need info for
            task_t port;
            task_for_pid(mach_task_self(), pid, &port);

            task_info_data_t tinfo;
            mach_msg_type_number_t task_info_count;

            task_info_count = TASK_INFO_MAX;
            kr = task_info(port, TASK_BASIC_INFO, (task_info_t)tinfo, &task_info_count);
            if (kr != KERN_SUCCESS) {
                    continue; //-- skip this task
            }

            task_basic_info_t        basic_info;
            thread_array_t         thread_list;
            mach_msg_type_number_t thread_count;

            thread_info_data_t     thinfo;
            mach_msg_type_number_t thread_info_count;

            thread_basic_info_t basic_info_th;
            uint32_t stat_thread = 0; // Mach threads

            basic_info = (task_basic_info_t)tinfo;

            // get threads in the task
            kr = task_threads(port, &thread_list, &thread_count);
            if (kr != KERN_SUCCESS) {
                    <HANDLE ERROR>
                    continue;
            }
            if (thread_count > 0)
                    stat_thread += thread_count;

            long tot_sec = 0;
            long tot_usec = 0;
            long tot_cpu = 0;
            int j;

            for (j = 0; j < thread_count; j++) {
                    thread_info_count = THREAD_INFO_MAX;
                    kr = thread_info(thread_list[j], THREAD_BASIC_INFO,
                                     (thread_info_t)thinfo, &thread_info_count);
                    if (kr != KERN_SUCCESS) {
                            <HANDLE ERROR>
                            continue;
                    }
                    basic_info_th = (thread_basic_info_t)thinfo;


                    if (!(basic_info_th->flags & TH_FLAGS_IDLE)) {
                            tot_sec = tot_sec + basic_info_th->user_time.seconds + basic_info_th->system_time.seconds;
                            tot_usec = tot_usec + basic_info_th->system_time.microseconds + basic_info_th->system_time.microseconds;
                            tot_cpu = tot_cpu + basic_info_th->cpu_usage;
                    }

            } // for each thread

我不知道是否有更好的方法来做到这一点，可能是这样，但这个方法对我有用。