Hello Olivier, > -----Original Message----- > From: Olivier MATZ [mailto:olivier.matz at 6wind.com] > Sent: Friday, October 31, 2014 4:50 PM > To: Walukiewicz, Miroslaw; dev at dpdk.org > Subject: Re: [dpdk-dev] [PATCH v2] pmd: Add generic support for TCP TSO > (Transmit Segmentation Offload) > > Hello Miroslaw, > > On 10/21/2014 01:29 PM, miroslaw.walukiewicz at intel.com wrote: > > From: Miroslaw Walukiewicz <miroslaw.walukiewicz at intel.com> > > > > The NICs supported by DPDK have a possibility to accelerate TCP > > traffic by sergnention offload. The application preprares a packet > > with valid TCP header with size up to 64K and NIC makes packet > > segmenation generating valid checksums and TCP segments. > > > > The patch defines a generic support for TSO offload. > > - Add new PKT_TX_TCP_SEG flag. > > Only packets with this flag set in ol_flags will be handled as > > TSO packets. > > > > - Add new fields in indicating TCP TSO segment size and TCP header len. > > The TSO requires from application setting following fields in mbuf. > > 1. L2 header len including MAC/VLANs/SNAP if present > > 2. L3 header len including IP options > > 3. L4 header len (new field) including TCP options > > 4. tso_segsz (new field) the size of TCP segment > > > > The apllication has obligation to compute the pseudo header checksum > > instead of full TCP checksum and put it in the TCP header csum field. > > > > Handling complexity of creation combined l2_l3_len field > > a new macro RTE_MBUF_TO_L2_L3_LEN() is defined to retrieve this > > part of rte_mbuf. > > > > The patch you submitted does not include any changes in a driver > (let's say ixgbe as it is the reference) taking advantage it. > So it's difficult to validate that your modifications are sufficient > to implement TSO.
I wanted to agree on the generic TSO API first and next to make driver modifications in next patches. > > In addition of a driver, I think that testpmd should be modified > to validate your changes and give an example to people wanting to use > this feature. > > Based on your patch, I'll try to submit a series in the coming days > (maybe today if the winds are favourable) that includes the remaining > patches from the original TSO series [1] that were not applied by > Bruce's mbuf rework. > Thank you Olivier, I will follow your patches with my i40e TSO changes when generic API will be accepted by community. > Regards, > Olivier > > [1] http://dpdk.org/ml/archives/dev/2014-May/002537.html
