EDM01-36v10 DAG_9.2X2_Card_User_Guide - Synchronizing clock time
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©2010 - 2012 Endace Technology Ltd. Confidential - Version 10 - May 2012
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.
