summaryrefslogtreecommitdiff
diff options
context:
space:
mode:
-rw-r--r--doc/guides/prog_guide/metrics_lib.rst9
1 files changed, 9 insertions, 0 deletions
diff --git a/doc/guides/prog_guide/metrics_lib.rst b/doc/guides/prog_guide/metrics_lib.rst
index 5cbe17c..e68e4e7 100644
--- a/doc/guides/prog_guide/metrics_lib.rst
+++ b/doc/guides/prog_guide/metrics_lib.rst
@@ -271,3 +271,12 @@ de-initialise the latency library.
.. code-block:: c
rte_latencystats_uninit();
+
+Timestamp and latency calculation
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The Latency stats library marks the time in the timestamp field of the
+mbuf for the ingress packets and sets the ``PKT_RX_TIMESTAMP`` flag of
+``ol_flags`` for the mbuf to indicate the marked time as a valid one.
+At the egress, the mbufs with the flag set are considered having valid
+timestamp and are used for the latency calculation.