CONSOLIDATING DPDK VHOST into TF v ROUTER Zhihong

CONSOLIDATING DPDK VHOST into TF v. ROUTER Zhihong Wang – Intel

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Virt. IO is the de-facto para-virtual I/O standard for VMs and host applications communication. • Communication peer is Virt. IO front-end and backend (aka vhost) VMs and host applications communicate via sharing VM’s memory. • Dequeue: packets sent from VM to host • Enqueue: packets sent from host to VM Network Platforms Group 3

Virt. IO in DPDK v. DPA 2017 2018 packed ring vhost delay copy Network Platforms Group 4

Vhost in TF v. Router provides an userspace vhost implementation. Features TF vhost Checksum offloading Y TCP Segment Offloading Y Mergeable RX buffer Y Multiqueue Y Network Platforms Group 5

Vhost in DPDK provides a highly optimized vhost implementation, called vhost-user. Features TF vhost DPDK vhost Checksum offloading Y Y TCP Segment Offloading Y Y Mergeable RX buffer Y Y Multiqueue Y Y Live migration N Y UDP Fragmentation Offloading N Y Network Platforms Group 6

What’s More in DPDK Vhost? Enabling HW-accelerated vhost Virt. IO 1. 1 Dequeue zero copy scheme (aka delay copy) Network Platforms Group 7

v. DPA – Enabling HW-Accelerated Vhost Device pass-through is the commonest mechanism for VMs to use HW-based vhost. • Complicate HW design for supporting Virt. IO 0. 95 and 1. 0. • Require modifying VM drivers to support live migration. v. DPA (vhost Data Plane Acceleration), the DPDK vhost extension, use SW to manage control path and enables HW to accelerate data path. • SW control plane keeps flexibility. • Live migration friendly and simply HW design. Network Platforms Group 8

Virt. IO 1. 1 introduces more efficient ring structure and operations (i. e. packed ring and in order completion). • Reduce cache misses for SW backend and the number of PCI transactions per descriptor for HW backend. • Simplify driver operations. DPDK is leading the evolution of Virt. IO spec, and vhost-user is the only implementation of Virt. IO 1. 1. • DPDK code has upstream. • Linux kernel and QEMU code are ongoing. Network Platforms Group 9

Dequeue Zero-Copy Scheme Virt. IO Front-end packets copy packets Vhost-User Dequeue zero copy Copy packets from VM’s memory to host memory Network Platforms Group 10

Dequeue Zero-Copy Scheme Virt. IO Front-end packets copy packets No copy packets Vhost-User Dequeue zero copy • Vhost-user occupies descriptors and directly gives the packet buffers to the host application; • Return the descriptors and buffers until the application finishing processing. Totally eliminates memory copy operations in dequeue. Network Platforms Group 11

Performance Comparison Compare DPDK vhost and TF original vhost performance. Configuration Packet Size 64 bytes CPU Core Number 1 per application CPU Frequency 2. 2 GHZ Network Platforms Group 12

Throughput Comparison (MPPS) CPU Cycles Comparison 20% 49% . . eq u. ue e+ D eq 37% Vhost-User En TF Original Backend qu eu D En qu eu ue e 54% TF Original Backend Network Platforms Group Vhost-User 13

Our Proposal Consolidate DPDK vhost into TF v. Router Major Contributors • High Virt. IO performance • Hardware-accelerated vhost • Virt. IO spec evolution • DPDK is a big family Network Platforms Group 14

Total Contributors • Landing zone of new techniques 5 2 • Fast community feedbacks for users and developers . 0 • Four releases per year 18 1 18 8 . 1 17 5 . 0 17 2 17 . 0 1 Total Contributors 17 7 . 1 . 0 16 2 4 16 . 0 16 2. 1 2. 0 2. 1. 8 180 160 140 120 100 80 60 40 20 0 7 1800 1600 1400 1200 1000 800 600 400 200 0 1. Total Commits DPDK Release Statistics Total Commits Network Platforms Group 15

Summary DPDK vhost supports rich functions and high performance. DPDK vhost is leading the technique evolution. DPDK community is big. Let’s bring DPDK vhost-user into TF v. Router! Network Platforms Group 16