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From: PATRICK KEROULAS <patrick.keroulas@radio-canada.ca>
To: Olivier Matz <olivier.matz@6wind.com>
Cc: Vivien Didelot <vivien.didelot@gmail.com>,
	dev@dpdk.org,  Ferruh Yigit <ferruh.yigit@intel.com>
Subject: Re: [dpdk-dev] [RFC PATCH 1/3] net/mlx5: add timestamp-to-ns converter from libibverbs
Date: Tue, 7 Jul 2020 11:23:55 -0400
Message-ID: <CALEF-=BMZrhrCgwVp6nVbV5g6497Nuc-PV32_HyLQU4KFQrH7Q@mail.gmail.com> (raw)
In-Reply-To: <20200626064151.GV12564@platinum>

On Fri, Jun 26, 2020 at 2:41 AM Olivier Matz <olivier.matz@6wind.com> wrote:
> Should mlx5dv_get_clock_info() be called for each convesion? In the man
> page [1], we can read this:
>
>        If the clock_info becomes too old then time conversion will return
>        wrong conversion results.  The user must ensure that
>        mlx5dv_get_clock_info(3) is called at least once every
>        max_clock_info_update_nsec as returned by the mlx5dv_query_device(3)
>        function.
>
> I understand this as mlx5dv_get_clock_info() being slower than
> mlx5dv_ts_to_ns(), and should not be called for each packet.

Right. I plan to use rte_timer (like in drivers/net/ena/) to query clock info
periodically.

>
> I suppose that when rdma-core library does a conversion to nanosec, it
> takes in account the fact that system and device are not synchronized
> (are they?).

PTP daemon like linuxptp is in charge of syncing both device and system
clocks with external master.

Thanks.
PK

  reply	other threads:[~2020-07-07 15:24 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-25 19:01 [dpdk-dev] [RFC PATCH 0/3] mlx5 to PCAP capture with hardware timestamps Vivien Didelot
2020-06-25 19:01 ` [dpdk-dev] [RFC PATCH 1/3] net/mlx5: add timestamp-to-ns converter from libibverbs Vivien Didelot
2020-06-26  6:41   ` Olivier Matz
2020-07-07 15:23     ` PATRICK KEROULAS [this message]
2020-06-25 19:01 ` [dpdk-dev] [RFC PATCH 2/3] ethdev: add API to convert raw timestamps to nsec Vivien Didelot
2020-06-25 19:01 ` [dpdk-dev] [RFC PATCH 3/3] net/pcap: support hardware Tx timestamps Vivien Didelot
2020-06-26  6:48   ` Olivier Matz
2020-07-06 18:36     ` PATRICK KEROULAS
2020-07-07 14:47       ` Olivier Matz
2020-07-10 19:23         ` PATRICK KEROULAS
2020-06-30 14:59   ` Stephen Hemminger
2020-07-08 14:34 ` [dpdk-dev] [RFC PATCH 0/3] mlx5 to PCAP capture with hardwaretimestamps Morten Brørup

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