[dpdk-dev] [PATCH v12 0/6] add Tx preparation

[Ferruh Yigit]

On 12/6/2016 6:25 PM, Yong Wang wrote:
>> -----Original Message-----
>> From: Ananyev, Konstantin [mailto:konstantin.ananyev at intel.com]
>> Sent: Sunday, December 4, 2016 4:11 AM
>> To: Yong Wang <yongwang at vmware.com>; Thomas Monjalon
>> <thomas.monjalon at 6wind.com>
>> Cc: Harish Patil <harish.patil at qlogic.com>; dev at dpdk.org; Rahul Lakkireddy
>> <rahul.lakkireddy at chelsio.com>; Stephen Hurd
>> <stephen.hurd at broadcom.com>; Jan Medala <jan at semihalf.com>; Jakub
>> Palider <jpa at semihalf.com>; John Daley <johndale at cisco.com>; Adrien
>> Mazarguil <adrien.mazarguil at 6wind.com>; Alejandro Lucero
>> <alejandro.lucero at netronome.com>; Rasesh Mody
>> <rasesh.mody at qlogic.com>; Jacob, Jerin <Jerin.Jacob at cavium.com>;
>> Yuanhan Liu <yuanhan.liu at linux.intel.com>; Kulasek, TomaszX
>> <tomaszx.kulasek at intel.com>; olivier.matz at 6wind.com
>> Subject: RE: [dpdk-dev] [PATCH v12 0/6] add Tx preparation
>>
>> Hi
>>
>>
>>
>>>>
>>
>>>> 2016-11-30 17:42, Ananyev, Konstantin:
>>
>>>>>>> Please, we need a comment for each driver saying
>>
>>>>>>> "it is OK, we do not need any checksum preparation for TSO"
>>
>>>>>>> or
>>
>>>>>>> "yes we have to implement tx_prepare or TSO will not work in this
>>
>>>> mode"
>>
>>>>>>>
>>
>>>>>>
>>
>>>>>> qede PMD doesn’t currently support TSO yet, it only supports Tx
>>
>>>> TCP/UDP/IP
>>
>>>>>> csum offloads.
>>
>>>>>> So Tx preparation isn’t applicable. So as of now -
>>
>>>>>> "it is OK, we do not need any checksum preparation for TSO"
>>
>>>>>
>>
>>>>> Thanks for the answer.
>>
>>>>> Though please note that it not only for TSO.
>>
>>>>
>>
>>>> Oh yes, sorry, my wording was incorrect.
>>
>>>> We need to know if any checksum preparation is needed prior
>>
>>>> offloading its final computation to the hardware or driver.
>>
>>>> So the question applies to TSO and simple checksum offload.
>>
>>>>
>>
>>>> We are still waiting answers for
>>
>>>> 	bnxt, cxgbe, ena, nfp, thunderx, virtio and vmxnet3.
>>
>>>
>>
>>> The case for a virtual device is a little bit more complicated as packets
>> offloaded from a virtual device can eventually be delivered to
>>
>>> another virtual NIC or different physical NICs that have different offload
>> requirements.  In ESX, the hypervisor will enforce that the packets
>>
>>> offloaded will be something that the hardware expects.  The contract for
>> vmxnet3 is that the guest needs to fill in pseudo header checksum
>>
>>> for both l4 checksum only and TSO + l4 checksum offload cases.
>>
>>
>>
>> Ok, so at first glance that looks to me very similar to Intel HW requirements.
>>
>> Could you confirm would rte_net_intel_cksum_prepare()
>>
>> also work for vmxnet3 or some extra modifications are required?
>>
>> You can look at it here: https://urldefense.proofpoint.com/v2/url?u=http-
>> 3A__dpdk.org_dev_patchwork_patch_17184_&d=DgIGaQ&c=uilaK90D4TOV
>> oH58JNXRgQ&r=v4BBYIqiDq552fkYnKKFBFyqvMXOR3UXSdFO2plFD1s&m=NS
>> 4zOl2je_tyGhnOJMSnu37HmJxOZf-1KLYcVsu8iYY&s=dL-NOC-
>> 18HclXUURQzuyW5Udw4NY13pKMndYvfgCfbA&e= .
>>
>> Note that for Intel HW the rules for pseudo-header csum calculation
>>
>> differ for TSO and non-TSO case.
>>
>> For TSO length inside pseudo-header are set to 0, while for non-tso case
>>
>> It should be set to L3 payload length.
>>
>> Is it the same for vmxnet3 or no?
>>
>> Thanks
>>
>> Konstantin
>>
> 
> Yes and this is the same for vmxnet3.
> 

This means vmxnet3 PMD also should be updated, right? Should that update
be part of tx_prep patchset? Or separate patch?

>>>
>>
>>>>> This is for any TX offload for which the upper layer SW would have
>>
>>>>> to modify the contents of the packet.
>>
>>>>> Though as I can see for qede neither PKT_TX_IP_CKSUM or
>>
>>>> PKT_TX_TCP_CKSUM
>>
>>>>> exhibits any extra requirements for the user.
>>
>>>>> Is that correct?
>>
>>
>