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From: Stephen Hemminger <stephen@networkplumber.org>
To: fwefew 4t4tg <7532yahoo@gmail.com>
Cc: users@dpdk.org
Subject: Re: Callback or hook into completion queues?
Date: Tue, 7 Mar 2023 14:14:03 -0800	[thread overview]
Message-ID: <20230307141403.5657b8e9@hermes.local> (raw)
In-Reply-To: <CA+Tq66XG1wfLSWX-ibyTXTNFMGmADGHAf8zgrooVeiDto_-y8A@mail.gmail.com>

On Tue, 7 Mar 2023 17:07:41 -0500
fwefew 4t4tg <7532yahoo@gmail.com> wrote:

> Once I call rte_eth_tx_burst() (Mellanox Connect5-LX) is there a way to
> inspect or get a callback when transmitted packets go into the NIC's
> completion queue?

Not in DPDK.

> This is related to the earlier question on timestamping with rdtsc().
> Ideally I'd take the timestamp as soon (close) to the time the packet is on
> the wire.

> I've looked at tx callbacks however this is invoked as the packet is about
> to go into the "hardware queue for transmission" meaning there's lot's of
> work + serialization of packet's data to electrical signals at NIC
> bandwidth to come before the packet is on the wire.
> The ideal time to get run rdtsc() is when the NIC delivers a completion
> event to a CQ for packets sent.
> Presumably there's something in the mlx5 driver or perhaps DMA library to
> do this?

Not that I have ever seen.

      reply	other threads:[~2023-03-07 22:14 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-03-07 22:07 fwefew 4t4tg
2023-03-07 22:14 ` Stephen Hemminger [this message]

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