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From: Stephen Hemminger <stephen@networkplumber.org>
To: Mikael R Carlsson <Mikael.R.Carlsson@tietoevry.com>
Cc: "users@dpdk.org" <users@dpdk.org>
Subject: Re: Configure timestamp source for dpdk-pdump on E810 and DPDK 19.11
Date: Fri, 6 May 2022 08:02:06 -0700
Message-ID: <20220506080206.1c9cc5d7@hermes.local> (raw)
In-Reply-To: <DU0PR04MB92261EA274F5EC329FE4E6CBA6C59@DU0PR04MB9226.eurprd04.prod.outlook.com>

On Fri, 6 May 2022 07:46:39 +0000
Mikael R Carlsson <Mikael.R.Carlsson@tietoevry.com> wrote:

> Hi!
> I am using a Intel E810-XXVDA4 and DPDK version 19.11. During troubleshooting we have captures outgoing traffic with dpdk-pdump:
> dpdk-pdump -- --pdump 'port=1,queue=*,tx-dev=/tmp/tx.pcap
> I have opened the pcap-file in wireshark and I can see that some packets are delayed. However, system behavior indicates that the delays I see in the pcap file are not correct, they are too big. My questions is, how is the timestamp on packets in the pcap from dpdk-pdump created, like NIC HW generated, CPU time at disk write etc. or something else? Are there any run-time or build-time options to change the source of the timestamps?
>   / Mikael

Follow up.  The older dump-pdump in 19.11 does timestamps when packet is read
from the ring which is bad.

You might have better luck with DPDK 20.11 and the dpdk-dumpcap which puts
timestamp in when packet is put into ring.

Let me give picture:

        Application (primary)
           | 1                       2
           +--+-------------------------> wire
              |             dumpcap (secondary)
              +---========--------------> capture file

The ==== is ringbuffer between processes

1. Where 20.11 with dpdk-dumpcap gets timestamp
2. Where you want the timestamp but is not possible
3. Where 19.11 and dpdk-pdump gets timestamp

      parent reply	other threads:[~2022-05-06 15:02 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-05-06  7:46 Mikael R Carlsson
2022-05-06 14:55 ` Stephen Hemminger
2022-05-06 15:02 ` Stephen Hemminger [this message]

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