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From: "Morten Brørup" <mb@smartsharesystems.com>
To: "Bruce Richardson" <bruce.richardson@intel.com>
Cc: <dev@dpdk.org>
Subject: Intel i40e rx burst API non-conformance?
Date: Wed, 9 Jul 2025 16:59:51 +0200	[thread overview]
Message-ID: <98CBD80474FA8B44BF855DF32C47DC35E9FDAB@smartserver.smartshare.dk> (raw)

Looking at the i40e driver source code, I think it doesn't conform to the API when requesting small bursts.

Let's say the hardware has received 31 packets.
rte_eth_rx_burst(...,16) will return 16 packets and leave 15 in the driver's staging buffer (which has capacity for 32 packets).

Time passes, and more packets are received.

Now, rte_eth_rx_burst(...,16) will only return the 15 packets from the staging buffer, and not proceed to check for more [1].
It thereby (according to my interpretation of the API description) informs the application that no more packets are ready to be received, which is incorrect.

[1]: https://elixir.bootlin.com/dpdk/v25.07-rc2/source/drivers/net/intel/i40e/i40e_rxtx.c#L640

PS: I stumbled across this while reviewing how the very old 32 packet limit bugs (where it truncated large rx/tx requests to 32 packets) had been fixed.


             reply	other threads:[~2025-07-09 14:59 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-07-09 14:59 Morten Brørup [this message]
2025-07-09 15:28 ` Bruce Richardson
2025-07-09 16:09   ` Morten Brørup

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