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

[Yong Wang]

> -----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 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?
> 
>