Hope summary below could answer your questions. From: lukego at gmail.com [mailto:luk...@gmail.com] On Behalf Of Luke Gorrie Sent: Monday, November 24, 2014 7:58 PM To: Thomas Monjalon Cc: Zhou, Danny; dev at dpdk.org; Fastabend, John R Subject: Re: [dpdk-dev] bifurcated driver
On 5 November 2014 at 14:00, Thomas Monjalon <thomas.monjalon at 6wind.com<mailto:thomas.monjalon at 6wind.com>> wrote: It seems to be close to the bifurcated driver needs. Not sure if it can solve the security issues if there is no dedicated MMU in the NIC. I feel we should sum up pros and cons of - igb_uio - uio_pci_generic - VFIO - ibverbs - bifurcated driver I am also curious about the pros and cons of the bifurcated driver compared with SR-IOV. DZ: I have a slide to compare all of them except for ibverbs, but system does not allows me to paste a captured picture. I can send it to you in a separated email. What are the practical differences between running a bifurcated driver vs. running SR-IOV mode where the kernel owns the PF and userspace applications own the VFs? DZ: SRIOV can be treated as a rx/tx queue partition approach following PCIe spec, but it diffs from bifurcated driver from as illustrated below: a) On ixgbe, each VF can only have at maximum two rx/tx qpairs, while bifurcated driver supports allocating multiple rx/tx qpairs per user space request. b) Each PF/VF has a dedicated MAC address and/or VLAN ID, and L2 switch inside a NIC distributes packets to PF/VF based on MAC address or VLAN ID. While bifurcated driver builds on top of in_NIC flow director which allows up-to 8K L3/L4 filters (e.g. 5-tuple to rx queue), rather than fixed L2 filter, to distribute traffics to either kernel or user space. c) VF does not have dedicated flow director. Specifically, could I run the ixgbe driver in the kernel (max_vfs=N), control it via ethtool, and then access the queues via userspace VF drivers? If so, how would this differ from the bifurcated driver? DZ: Yes you can do this. But L3/L4 filters you setup to PF (VF does not support it) via ethtool to flow director takes no effect if the packet?s DMAC matches a VF? MAC, as the packet will be distributed by L2 switch to the VF that rx queue belongs to. Ixgbe does not support per-VF flow director that allows you setup filters distributing packet to two rx queue inside a VF. Cheers, -Luke
