Endace DAG 9.2X2 - Readable DUCK; Reading the Current DAG Time; Performance

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EDM01-36v10 DAG_9.2X2_Card_User_Guide - Synchronizing clock time

Readable DUCK

The DAG 9.2X2 firmware images allow the user to read the current time directly from the DUCK clock.

This can be useful for verifying clock synchronization.

To check if a firmware image supports reading the DAG clock time, check if the output from the following

command includes the information about the

DUCK Reader version.

Note:

The factory firmware may not support the DUCK Reader. Please ensure you load the current release

firmware onto the DAG card first, see Configuring the DAG card (page 15).

Command:

daginf -d0 -v

Reading the current DAG time

You can read the current DAG time using dagconfig, using the following command:

Command:

dagconfig -G duck_timestamp

Output:

duck_timestamp = 2009-07-07 1:33:31.657349680 UTC

The current time is also available programmatically via the DAG Configuration and Status API.

The time-stamp format that the DUCK provides represents time as a single 64-bit fixed point number,

representing seconds since midnight on January 1, 1970. The returned value can also be converted into

a struct timeval representation. For more information refer to

EDM04-34 Configuration & Status API

Overview

Performance

Reading the current DAG time requires reading hardware registers on the DAG card over the PCIe Gen

2.0 bus. This operation can take several microseconds to complete.

The DAG clock should not be read at high rates, for example after receiving or sending each packet. The

additional PCIe Gen 2.0 bus accesses from reading the current time may affect packet

capture/transmission performance if performed more than 1000 times per second.