|clock_nanosleep()| fires too early
Posted by Anonymous on Thu 17th Oct 2024 13:45
raw | new post

VOID RTLX_AlarmThread ( VOID* pAlarmFunc )
{
  ULONGLONG            ullCurTime   = 0;
  ULONG                ulTimeOffset  = ulCycleTime ? ulCycleTime : 2000000;
  INT                  iRet         = 0;
  static RTLX_TIMESPEC rSleepTime;
  //, remainTime;
  clock_gettime(CLOCK_MONOTONIC, &rSleepTime);

#if 0
  // Set sleep time (= check interval)
  rSleepTime.tv_nsec = RTOS_TIME_SHIFT_NIC_TIMED / 4;
  rSleepTime.tv_sec  = 0;
#endif
//  remainTime.tv_sec = 0;
  RTLX_VERBOSE(1, "Successfully started NIC-timed alarm thread\n");

  RTOS_SetThreadPriority(RTOS_THREAD_PRIORITY_TIMER);  // was -2 !!!


  while(TRUE)
  {
    // Active wait for next cycle based on NIC timer:
    // poll NIC clock every rSleepTime until time reached
    // Not ideal in terms of CPU utilization and jitter
    // behavior, but simple and effective
    iRet = RTLX_ReadTimeNic(
                             &(arIgbDev[0]),
                             &ullCurTime
                           );
    if (iRet != RTOS_RET_OK)
    {
      RTLX_VERBOSE(0, "Error reading time from NIC\n");
    }
    // sleep till next time stamp
    ulTimeOffset = ullCycleOffset - ullCurTime;
    rSleepTime.tv_nsec += ulTimeOffset;
    rSleepTime.tv_sec  += rSleepTime.tv_nsec / NANOSEC_PER_SEC;
    rSleepTime.tv_nsec %= NANOSEC_PER_SEC;
    pNicAlarmFunc();
    do {
        iRet = clock_nanosleep(CLOCK_MONOTONIC, TIMER_ABSTIME, &rSleepTime, NULL);
        SystemTraceDebugMarker("sleep finish -RTLX_AlarmThread NIC ulTimeOffset= %lu", ulTimeOffset );
    } while (iRet == EINTR);
    // Time reached, so start cycle
    RTLX_SET_NIC_TIMED_OFFSET(ullCycleOffset, ulCycleTime);
  }
}