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authorLuca Boccassi <luca.boccassi@gmail.com>2018-11-19 12:59:01 +0000
committerLuca Boccassi <luca.boccassi@gmail.com>2018-11-19 12:59:24 +0000
commit29058550643267a554e0368806dece63b047c5cb (patch)
treea6f573fe3fbc14585529b83cfcc65da2dceefbf5 /doc/guides/prog_guide/metrics_lib.rst
parent8a853e3f0275efc8b05cb195085d45946942744a (diff)
New upstream version 18.11-rc4upstream/18.11-rc4
Change-Id: I861e1a2f7df210f57f44f1ad56b9ef789a4675e3 Signed-off-by: Luca Boccassi <luca.boccassi@gmail.com>
Diffstat (limited to 'doc/guides/prog_guide/metrics_lib.rst')
-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 5cbe17c9..e68e4e74 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.