In this chapter
This chapter describes the time synchronization statistics that can be obtained for all time synchronization modes for SmartNICs with Napatech LinkCapture™ Software.
Available statistics
 NT400D11
 NT50B01
 NT40A11
 The Intel® Programmable Acceleration Card with Intel® Arria® 10 GX FPGA running Napatech LinkCapture™ Software
This table shows the time synchronization statistics. The statistics are calculated on the differences between the time of the SmartNIC timestamping clock and the time provided by a time synchronization event.
Statistics  Description 

Standard deviation  Standard deviation in ns of offset from reference
measured since last reset. Note: The standard deviation computed in the time
synchronization statistics may deviate up to 1 ns from the standard deviation that
can be obtained from a sequence of sampled NTTS values. The statistics are
computed from 100 of the 50,000 time synchronization pulses received per second,
while the NTTS samples are taken once per second. Therefore the two results may
be based upon different signals.

Peaktopeak jitter  Difference in ns between high and low offset measured since last reset . 
Current skew  Last measured offset from reference in ns. 
Lowest skew  Lowest offset from reference in ns measured since last reset. 
Highest skew  Highest offset from reference in ns measured since last reset. 
Mean skew  Calculated mean offset from reference in ns. 
Time since reset  Number of seconds since last reset of information/statistics. 
Loss of input reference signal  Number of times the reference signal has been lost since last reset. 
Loss of synchronization  Number of times the synchronization has been lost since last reset. 
Hard synchronization events  Number of hard synchronization events since last reset. 
The time synchronization statistics can be obtained by using the NT_InfoRead function in the information stream (see DN0449) with the NT_INFO_CMD_READ_TIMESYNC_STAT command. The NtTsStatSupport_e enumeration shows to which degree the SmartNIC in question supports time synchronization statistics. The NtInfoTimeSyncStatistics_s structure contains the statistics.
The statistics can also be displayed using the monitoring tool (see DN0449).
Resetting statistics
The statistics are reset one minute after a master signal has been detected for the first time. Thereafter the statistics are continuously updated as long as a skew against a reference master can be calculated. No reset is made in case of failover or fallback. The calculation of the skew will just be made against the new reference.
The time synchronization statistics can be reset from an application using the NT_ConfigWrite function (see DN0449).