Clock_gettime() off by seconds from dwContext_getCurrentTime()

Autonomous Vehicles DRIVE AGX Orin DRIVE AGX Orin General
1

Please provide the following info (tick the boxes after creating this topic):
Software Version
DRIVE OS 6.0.10.0
DRIVE OS 6.0.8.1
DRIVE OS 6.0.6
DRIVE OS 6.0.5
DRIVE OS 6.0.4 (rev. 1)
DRIVE OS 6.0.4 SDK
other

Target Operating System
Linux
QNX
other

Hardware Platform
DRIVE AGX Orin Developer Kit (940-63710-0010-300)
DRIVE AGX Orin Developer Kit (940-63710-0010-200)
DRIVE AGX Orin Developer Kit (940-63710-0010-100)
DRIVE AGX Orin Developer Kit (940-63710-0010-D00)
DRIVE AGX Orin Developer Kit (940-63710-0010-C00)
DRIVE AGX Orin Developer Kit (not sure its number)
other

SDK Manager Version
2.1.0
other

Host Machine Version
native Ubuntu Linux 20.04 Host installed with SDK Manager
native Ubuntu Linux 20.04 Host installed with DRIVE OS Docker Containers
native Ubuntu Linux 18.04 Host installed with DRIVE OS Docker Containers
other

Issue Description

  1. when running the code below, i see a difference between the OS time and the nvidia time.
    this difference changes across reboots, i’ve seen a difference of 10seconds, 20seconds…
    how do i keep these clocks in synced? where can i read documentation about it?
  2. i’d like to be able to sync the OS time using ntp/ptp, but when i try i see that this only affects the OS time, not the nvidia time. what’s the best practice to using ntp/ptp?
#include <dw/core/context/Context.h>
#include <dw/core/base/Version.h>
#include <time.h>
#include <cstdio>

int main()
{

	dwContextHandle_t context1;
	dwInitialize(&context1, DW_VERSION, nullptr);

	struct timespec realtime;
	if (clock_gettime(CLOCK_REALTIME, &realtime) != 0) {
		perror("CLOCK_REALTIME");
	}	

	dwTime_t time1;
	dwContext_getCurrentTime(&time1, context1);

	std::printf("clock_gettime: %ld %ld\n", realtime.tv_sec, realtime.tv_nsec);
	std::printf("DriveWorks1:   %ld %ld\n", time1 / 1000000, time1 % 1000000);

}
2

Hi @TS_AB ,
DriveWorks SDK Reference: Core Context is based on CLOCK_MONOTONIC.
May I know why you want to sync OS time with dwContext_getCurrentTime()? DW APIs get the sensor timestamps in PTP and CLOCK_REAL time can be synced to PTP using phc2sys