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From: "Morten Brørup" <mb@smartsharesystems.com>
To: "David Marchand" <david.marchand@redhat.com>, <dev@dpdk.org>
Cc: <thomas@monjalon.net>, <ferruh.yigit@amd.com>, <stable@dpdk.org>,
	"Olivier Matz" <olivier.matz@6wind.com>,
	"Jijiang Liu" <jijiang.liu@intel.com>,
	"Andrew Rybchenko" <andrew.rybchenko@oktetlabs.ru>,
	<konstantin.ananyev@huawei.com>,
	"Ferruh Yigit" <ferruh.yigit@amd.com>,
	"Kaiwen Deng" <kaiwenx.deng@intel.com>, <qiming.yang@intel.com>,
	<yidingx.zhou@intel.com>,
	"Aman Singh" <aman.deep.singh@intel.com>,
	"Yuying Zhang" <yuying.zhang@intel.com>,
	"Thomas Monjalon" <thomas@monjalon.net>,
	"Jerin Jacob" <jerinj@marvell.com>
Subject: RE: [PATCH v2 3/8] mbuf: fix Tx checksum offload examples
Date: Fri, 5 Apr 2024 18:20:08 +0200	[thread overview]
Message-ID: <98CBD80474FA8B44BF855DF32C47DC35E9F36C@smartserver.smartshare.dk> (raw)
In-Reply-To: <20240405144604.906695-4-david.marchand@redhat.com>

> From: David Marchand [mailto:david.marchand@redhat.com]
> Sent: Friday, 5 April 2024 16.46
> 
> Mandate use of rte_eth_tx_prepare() in the mbuf Tx checksum offload
> examples.

I strongly disagree with this change!

It will cause a huge performance degradation for shaping applications:

A packet will be processed and finalized at an output or forwarding pipeline stage, where some other fields might also be written, so zeroing e.g. the out_ip checksum at this stage has low cost (no new cache misses).

Then, the packet might be queued for QoS or similar.

If rte_eth_tx_prepare() must be called at the egress pipeline stage, it has to write to the packet and cause a cache miss per packet, instead of simply passing on the packet to the NIC hardware.

It must be possible to finalize the packet at the output/forwarding pipeline stage!


Also, how is rte_eth_tx_prepare() supposed to work for cloned packets egressing on different NIC hardware?


In theory, it might get even worse if we make this opaque instead of transparent and standardized:
One PMD might reset out_ip checksum to 0x0000, and another PMD might reset it to 0xFFFF.


I can only see one solution:
We need to standardize on common minimum requirements for how to prepare packets for each TX offload.


  reply	other threads:[~2024-04-05 16:20 UTC|newest]

Thread overview: 52+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-04-05 12:49 [PATCH 0/8] Fix outer UDP checksum for Intel nics David Marchand
2024-04-05 12:49 ` [PATCH 1/8] net/ice: fix check for outer UDP checksum offload David Marchand
2024-04-05 14:19   ` David Marchand
2024-04-05 12:49 ` [PATCH 2/8] net/ice: enhance debug when HW fails to transmit David Marchand
2024-04-05 12:49 ` [PATCH 3/8] mbuf: fix Tx checksum offload examples David Marchand
2024-04-05 12:49 ` [PATCH 4/8] app/testpmd: fix outer IP checksum offload David Marchand
2024-04-05 12:49 ` [PATCH 5/8] net: fix outer UDP checksum in Intel prepare helper David Marchand
2024-04-05 12:49 ` [PATCH 6/8] net/i40e: fix outer UDP checksum offload for X710 David Marchand
2024-04-05 12:49 ` [PATCH 7/8] net/iavf: remove outer UDP checksum offload for X710 VF David Marchand
2024-04-05 12:49 ` [PATCH 8/8] net: clear outer UDP checksum in Intel prepare helper David Marchand
2024-04-05 14:45 ` [PATCH v2 0/8] Fix outer UDP checksum for Intel nics David Marchand
2024-04-05 14:45   ` [PATCH v2 1/8] net/ice: fix check for outer UDP checksum offload David Marchand
2024-04-08 15:05     ` Bruce Richardson
2024-04-05 14:45   ` [PATCH v2 2/8] net/ice: enhance debug when HW fails to transmit David Marchand
2024-04-08 15:23     ` Bruce Richardson
2024-04-11  8:30       ` David Marchand
2024-04-11  8:42         ` Bruce Richardson
2024-04-15  8:32           ` David Marchand
2024-04-05 14:45   ` [PATCH v2 3/8] mbuf: fix Tx checksum offload examples David Marchand
2024-04-05 16:20     ` Morten Brørup [this message]
2024-04-08 10:12       ` David Marchand
2024-04-09 13:38       ` Konstantin Ananyev
2024-04-09 14:44         ` Morten Brørup
2024-04-10 10:35           ` Konstantin Ananyev
2024-04-10 12:20             ` Morten Brørup
2024-04-12 12:46               ` Konstantin Ananyev
2024-04-12 14:44                 ` Morten Brørup
2024-04-12 15:17                   ` Konstantin Ananyev
2024-04-12 15:54                     ` Morten Brørup
2024-04-16  9:16                       ` Konstantin Ananyev
2024-04-16 11:36                         ` Konstantin Ananyev
2024-04-15 15:07                   ` Ferruh Yigit
2024-04-16  7:14                     ` Morten Brørup
2024-04-16  9:26                       ` Konstantin Ananyev
2024-04-05 14:45   ` [PATCH v2 4/8] app/testpmd: fix outer IP checksum offload David Marchand
2024-04-05 14:45   ` [PATCH v2 5/8] net: fix outer UDP checksum in Intel prepare helper David Marchand
2024-04-05 14:46   ` [PATCH v2 6/8] net/i40e: fix outer UDP checksum offload for X710 David Marchand
2024-04-05 14:46   ` [PATCH v2 7/8] net/iavf: remove outer UDP checksum offload for X710 VF David Marchand
2024-04-05 14:46   ` [PATCH v2 8/8] net: clear outer UDP checksum in Intel prepare helper David Marchand
2024-04-18  8:20 ` [PATCH v3 0/7] Fix outer UDP checksum for Intel nics David Marchand
2024-04-18  8:20   ` [PATCH v3 1/7] net/ice: fix check for outer UDP checksum offload David Marchand
2024-04-19 11:46     ` Morten Brørup
2024-04-18  8:20   ` [PATCH v3 2/7] net/ice: enhance debug when HW fails to transmit David Marchand
2024-04-18  8:20   ` [PATCH v3 3/7] app/testpmd: fix outer IP checksum offload David Marchand
2024-06-11 18:25     ` Ferruh Yigit
2024-04-18  8:20   ` [PATCH v3 4/7] net: fix outer UDP checksum in Intel prepare helper David Marchand
2024-04-18  8:20   ` [PATCH v3 5/7] net/i40e: fix outer UDP checksum offload for X710 David Marchand
2024-04-18  8:20   ` [PATCH v3 6/7] net/iavf: remove outer UDP checksum offload for X710 VF David Marchand
2024-04-18  8:20   ` [PATCH v3 7/7] net: clear outer UDP checksum in Intel prepare helper David Marchand
2024-05-03 13:10   ` [PATCH v3 0/7] Fix outer UDP checksum for Intel nics David Marchand
2024-05-27 18:06   ` Ali Alnubani
2024-06-11 21:10     ` Ferruh Yigit

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