From: Reshma Pattan <reshma.pattan@intel.com>
To: dev@dpdk.org, longtb5@viettel.com.vn, john.mcnamara@intel.com
Cc: Reshma Pattan <reshma.pattan@intel.com>
Subject: [dpdk-dev] [PATCH] doc: update timestamp validity for latency measurement
Date: Thu, 4 Oct 2018 13:23:59 +0100 [thread overview]
Message-ID: <1538655839-32339-1-git-send-email-reshma.pattan@intel.com> (raw)
Updated the doc on how packets are marked to identify
their timestamp as valid and considered for latency
measurement.
Suggested-by: Bao-Long Tran <longtb5@viettel.com.vn>
Signed-off-by: Reshma Pattan <reshma.pattan@intel.com>
---
This change is relevant to the below patch and must be applied
after that.
http://patches.dpdk.org/patch/45328/
---
doc/guides/prog_guide/metrics_lib.rst | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/doc/guides/prog_guide/metrics_lib.rst b/doc/guides/prog_guide/metrics_lib.rst
index 5cbe17c90..e68e4e743 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.
--
2.17.1
next reply other threads:[~2018-10-04 12:24 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-04 12:23 Reshma Pattan [this message]
2018-11-14 10:14 ` Kovacevic, Marko
2018-11-19 0:37 ` Thomas Monjalon
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