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From: Maxime Coquelin <maxime.coquelin@redhat.com>
To: "Ma, WenwuX" <wenwux.ma@intel.com>, "dev@dpdk.org" <dev@dpdk.org>,
	"jasowang@redhat.com" <jasowang@redhat.com>,
	"Xia, Chenbo" <chenbo.xia@intel.com>,
	"david.marchand@redhat.com" <david.marchand@redhat.com>,
	"olivier.matz@6wind.com" <olivier.matz@6wind.com>
Cc: "stable@dpdk.org" <stable@dpdk.org>
Subject: Re: [PATCH 6/6] net/vhost: perform SW checksum in Tx path
Date: Thu, 2 Jun 2022 11:07:08 +0200
Message-ID: <4948f8e2-5fc9-2821-4120-3fdb4111ddd3@redhat.com> (raw)
In-Reply-To: <SA0PR11MB452692DE7F6E73752844C914EBC49@SA0PR11MB4526.namprd11.prod.outlook.com>

Hi Wenwu,

Sorry, I missed your review.

On 5/7/22 05:20, Ma, WenwuX wrote:
> 
>> -----Original Message-----
>> From: Maxime Coquelin <maxime.coquelin@redhat.com>
>> Sent: 2022年5月5日 18:27
>> To: dev@dpdk.org; jasowang@redhat.com; Xia, Chenbo
>> <chenbo.xia@intel.com>; david.marchand@redhat.com;
>> olivier.matz@6wind.com
>> Cc: stable@dpdk.org; Maxime Coquelin <maxime.coquelin@redhat.com>
>> Subject: [PATCH 6/6] net/vhost: perform SW checksum in Tx path
>>
>> Virtio specification supports guest checksum offloading for L4, which is
>> enabled with VIRTIO_NET_F_GUEST_CSUM feature negotiation. However,
>> the Vhost PMD does not advertise Tx checksum offload capabilities.
>>
>> Advertising these offload capabilities at the ethdev level is not enough,
>> because we could still end-up with the application enabling these offloads
>> while the guest not negotiating it.
>>
>> This patch advertizes the Tx checksum offload capabilities, and introduces a
>> compatibility layer to cover the case VIRTIO_NET_F_GUEST_CSUM has not
>> been negotiated but the application does configure the Tx checksum
>> offloads. This function performs the L4 Tx checksum in SW for UDP and TCP.
>> Compared to Rx SW checksum, the Tx SW checksum function needs to
>> compute the pseudo-header checksum, as we cannot knwo whether it was
>> done before.
>>
>> This patch does not advertize SCTP checksum offloading capability for now,
>> but it could be handled later if the need arises.
> 
> In virtio_enqueue_offload(), if RTE_MBUF_F_TX_IP_CKSUM is set, we will
> performs the L3 Tx checksum, why do not we advertise IPV4 checksum offloading capability?
> Will we advertise it later?
> 

Indeed, we have an IPv4 SW checksum fallback in Vhost library.
We could think about adding the capability, but that's not urgent I
think. Do you have a use-case where it is needed?

Regards,
Maxime


  reply	other threads:[~2022-06-02  9:07 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-05-05 10:27 [PATCH 0/6] Vhost checksum offload improvements Maxime Coquelin
2022-05-05 10:27 ` [PATCH 1/6] Revert "app/testpmd: modify mac in csum forwarding" Maxime Coquelin
2022-05-16 13:03   ` Xia, Chenbo
2022-05-17 15:24     ` Zhang, Yuying
2022-05-19 16:27   ` David Marchand
2022-05-05 10:27 ` [PATCH 2/6] vhost: fix missing enqueue pseudo-header calculation Maxime Coquelin
2022-05-16 13:24   ` Xia, Chenbo
2022-05-05 10:27 ` [PATCH 3/6] net/vhost: enable compliant offloading mode Maxime Coquelin
2022-05-16 13:26   ` Xia, Chenbo
2022-05-16 13:28     ` Maxime Coquelin
2022-05-16 13:39       ` Xia, Chenbo
2022-06-07  1:19         ` Ma, WenwuX
2022-06-08  8:19           ` Maxime Coquelin
2022-05-05 10:27 ` [PATCH 4/6] net/vhost: make VLAN stripping flag a boolean Maxime Coquelin
2022-05-16 13:27   ` Xia, Chenbo
2022-05-05 10:27 ` [PATCH 5/6] net/vhost: perform SW checksum in Rx path Maxime Coquelin
2022-05-05 10:27 ` [PATCH 6/6] net/vhost: perform SW checksum in Tx path Maxime Coquelin
2022-05-07  3:20   ` Ma, WenwuX
2022-06-02  9:07     ` Maxime Coquelin [this message]
2022-06-06  9:44       ` Ma, WenwuX
2022-06-08  8:14         ` Maxime Coquelin
2022-06-09  1:03           ` Ma, WenwuX

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