DPDK patches and discussions
 help / color / mirror / Atom feed
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>
wrote:
>> 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
mlx5_ifc_cmd_hca_cap_bits{}.
> 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
  (mlx5_devx_cmd_query_hca_attr())
- 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
  mbuf->port
- 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?
https://github.com/linux-rdma/rdma-core/blob/7af01c79e00555207dee6132d72e7bfc1bb5485e/providers/mlx5/mlx5dv.h#L1201

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

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to='CALEF-=D-qtmO-urE4WB3xJCPO1d086a4T=0isk3xhd=90RpJcQ@mail.gmail.com' \
    --to=patrick.keroulas@radio-canada.ca \
    --cc=dev@dpdk.org \
    --cc=matan@mellanox.com \
    --cc=rasland@mellanox.com \
    --cc=shahafs@mellanox.com \
    --cc=viacheslavo@mellanox.com \
    --cc=vivien.didelot@gmail.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

DPDK patches and discussions

This inbox may be cloned and mirrored by anyone:

	git clone --mirror https://inbox.dpdk.org/dev/0 dev/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 dev dev/ https://inbox.dpdk.org/dev \
		dev@dpdk.org
	public-inbox-index dev

Example config snippet for mirrors.
Newsgroup available over NNTP:
	nntp://inbox.dpdk.org/inbox.dpdk.dev


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git