下面写个小程序测试一下,就是连续两次调用 clock_gettime() 函数,然后打印时间间隔,看我的电脑记一次时,最快能达到多少纳秒。程序如下: #include <iostream> #include <iomanip> #include <sys/time.h> using namespace std; void print_timer(struct timespec start, struc
CPU time used (per clock(): 1580.00 ms CPU time used (per clock_gettime()): 1582.76 ms Wall time passed: 792.13 ms 引用 C11 standard (ISO/IEC 9899:2011): 7.27.2.1 The clock function (p: 389) C99 standard (ISO/IEC 9899:1999): 7.23.2.1 The clock function (p: 339) C89/...
int clock_gettime(clockid_t clk_id, struct timespec *tp); 获取时间戳,精度达到纳秒,时间存储结构体如下: struct timespec { time_t tv_sec; /* seconds */ long tv_nsec; /* nanoseconds */ }; 参数clk_id有很多种取值,常见的有:CLOCK_REALTIME(系统时间,受系统时间调整影响,所以不保证是递增),CL...
(clock_gettime HAVE_CLOCK_GETTIME) if(NOT HAVE_CLOCK_GETTIME) set(DEFINE_CLOCK_GETTIME "-DNO_CLOCK_GETTIME_IN_MAC") endif() endif() set(CMAKE_CPP_FLAGS "${DEFINE_CLOCK_GETTIME} -DGFLAGS_NS=${GFLAGS_NS}") set(CMAKE_CXX_FLAGS "${CMAKE_CPP_FLAGS} -DNDEBUG -O2 -D__const__...
// if(timeus 90- timeusOld > 250){ // qDebug // } ecrt_master_application_time(master, TIMESPEC2NS(wakeupTime)); #ifdef MEASURE_TIMING clock_gettime(CLOCK_MONOTONIC, &startTime); latency_ns = DIFF_NS(wakeupTime, startTime); ...
clock_gettime() 。默认是nanosecond 级精度,是系统调用(_sys_clock_gettime()),会有开销。调用频繁的话,可能造成损失性能。但是Linux 2.6.32后可以指定参数CLOCK_REALTIME_COARSE和CLOCK_MONOTONIC_COARSE,粗粒度地获取时间,而不需要发生上下文切换(和gettimeofday()一样也是vdso技术,https://access.redhat.com/docu...
clock_gettime() 。默认是nanosecond 级精度,是系统调用(*sys*clock_gettime()),会有开销。调用频繁的话,可能造成损失性能。但是Linux 2.6.32后可以指定参数CLOCK_REALTIME_COARSE和CLOCK_MONOTONIC_COARSE,粗粒度地获取时间,而不需要发生上下文切换(和gettimeofday()一样也是vdso技术,[https://access.redhat.com/...
clock_gettime() 。默认是nanosecond 级精度,是系统调用(_sys_clock_gettime()),会有开销。调用频繁的话,可能造成损失性能。但是Linux 2.6.32后可以指定参数CLOCK_REALTIME_COARSE和CLOCK_MONOTONIC_COARSE,粗粒度地获取时间,而不需要发生上下文切换(和gettimeofday()一样也是vdso技术,https://access.redhat.com/docu...
int timeout_ms; struct timespec expiration; clock_gettime(CLOCK_MONOTONIC, &expiration); expiration.tv_sec += INITIAL_DELAY;// Wait up to INITIAL_DELAY seconds for an initial keypress, it no key was initially down while (pressedKey == 0 && (timeout_ms = getRemainingTime(expiration)) >...
clock_gettime(CLOCK_MONOTONIC, ¤t_time); // 检查是否超过 3 秒未收到目标包 double elapsed_time = (current_time.tv_sec - last_valid_packet_time.tv_sec) + (current_time.tv_nsec - last_valid_packet_time.tv_nsec) / 1e9; if...