From mboxrd@z Thu Jan 1 00:00:00 1970 From: Reshma Pattan Subject: [PATCH] doc: update timestamp validity for latency measurement Date: Thu, 4 Oct 2018 13:23:59 +0100 Message-ID: <1538655839-32339-1-git-send-email-reshma.pattan@intel.com> Cc: Reshma Pattan To: dev@dpdk.org, longtb5@viettel.com.vn, john.mcnamara@intel.com Return-path: Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) by dpdk.org (Postfix) with ESMTP id 9A8D61B120 for ; Thu, 4 Oct 2018 14:24:05 +0200 (CEST) List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" Updated the doc on how packets are marked to identify their timestamp as valid and considered for latency measurement. Suggested-by: Bao-Long Tran Signed-off-by: Reshma Pattan --- 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