问使用Linuxptp读取时间戳

EN

In Time Sensitive Networks there will be 1 Grandmaster(GM) Node and several Slaves nodes

So, How this time synchronization works is that On every boot up all the devices in the network will share their capability information such as their time source, priority values, mac address info etc.,
based on those information shared by all the devices they'll select the most accurate time providing device as Grandmaster(GM)(usually device with GPS as its time source)

Once this is done GM would start sending Sync and Follow Up message which is used by all the Slaves nodes to calculate the time difference between slave node clock and Grandmaster clock
Similarly, Slave nodes would send PDelay Request messages to calculate Link Delay and adjust the Slave Clock to Grandmaster Clock

So, coming to reading the synchronized time from the Slave Node would be through 
man page of clock_gettime:
https://linux.die.net/man/3/clock_gettime

// Calculate time taken by a request

struct timespec requestStart, requestEnd;
clock_gettime(CLOCK_REALTIME, &requestStart);
function_call();
clock_gettime(CLOCK_REALTIME, &requestEnd);