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From: PATRICK KEROULAS <patrick.keroulas@radio-canada.ca>
To: Slava Ovsiienko <viacheslavo@mellanox.com>
Cc: "dev@dpdk.org" <dev@dpdk.org>,
	Vivien Didelot <vivien.didelot@gmail.com>,
	 Shahaf Shuler <shahafs@mellanox.com>,
	Raslan Darawsheh <rasland@mellanox.com>,
	Matan Azrad <matan@mellanox.com>
Subject: Re: [dpdk-dev] mlx5 & pdump: convert HW timestamps to nanoseconds
Date: Fri, 29 May 2020 16:56:00 -0400
Message-ID: <CALEF-=D-qtmO-urE4WB3xJCPO1d086a4T=0isk3xhd=90RpJcQ@mail.gmail.com> (raw)
In-Reply-To: <AM4PR05MB3265F9A5814408F1E961ECDED2B00@AM4PR05MB3265.eurprd05.prod.outlook.com>

On Tue, May 26, 2020 at 12:00 PM Slava Ovsiienko <viacheslavo@mellanox.com>
>> Hi, Patrick
> ConnectX HW timestamp is the captured value of internal 64-bit counter
running at the frequency,
> reported in the device_frequency_khz field of struct
> This structure is queried in mlx5_devx_cmd_query_hca_attr() routine.
> So, with known frequency it is possible to recalculate timestamp ticks to
desired units.

Hello Slava,

Assuming that the NIC clock is already synced thanks to a PTP client,
does the bit counter give an absolute time value (0 => 1 January 1970
00:00:00)? Or do I need to calculate a time duration from the process
start time?

I just want to validate the path from mlx5 eth dev(Rx) to eth pcap (Tx) :
- query the oscillator frequency at the mlx5_eth_dev init step
- store the freq with other hca_attr, carried by dev config which should
  be shared with the secondary process
- in eth_pcap_tx_dumper(), retrieve the freq from the dev given by
- convert all the incoming mbuf->timestamp using this freq whose
  variation should be negligible over the capture duration

Last question: what is your opinion about this other method?

Thanks a lot!

  reply	other threads:[~2020-05-29 20:56 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-19 18:20 PATRICK KEROULAS
2020-05-21 15:33 ` Thomas Monjalon
2020-05-21 19:57   ` PATRICK KEROULAS
2020-05-21 20:09     ` Thomas Monjalon
2020-05-22 18:43       ` PATRICK KEROULAS
2020-05-26  7:44         ` Tom Barbette
2020-05-29 20:46           ` N. Benes
2020-05-26 16:00         ` Slava Ovsiienko
2020-05-29 20:56           ` PATRICK KEROULAS [this message]
2020-05-31 19:47             ` Slava Ovsiienko
2020-06-02 19:18           ` PATRICK KEROULAS
2020-06-03  7:48             ` Slava Ovsiienko
2020-06-05  0:09               ` PATRICK KEROULAS
2020-06-05 16:30                 ` Slava Ovsiienko

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