1. Accelerating the Path to the Guest
Maryam Tahhan and Kevin Traynor
Intel

2. Legal Disclaimers
Intel processor numbers are not a measure of performance. Processor numbers differentiate features within each processor family, not across different processor families: Go to: Learn About Intel® Processor Numbers
Intel, the Intel logo and Xeon are trademarks of Intel Corporation in the U.S. and/or other countries.
*Other names and brands may be claimed as the property of others.
Copyright © 2014 Intel Corporation. All rights reserved
Intel Confidential

3. Agenda
NFV
Guest access methods
Summary
Q&A

4. Network Function Virtualization (NFV)
By 2017 mobile traffic will have grown 13x in the space of 5 years.*
In 2017 there will be 3x more connected devices than people on earth.*
Service Providers are moving to virtualize the functionality of network components in an effort to move away from custom ASICs, and operate on standard servers.
The network functions running on a guest require near native performance. *

5. Legacy virtio-net
Guest
virtio-net is a para-virtualized network driver based on virtio.
A guest with a virtio_net driver, shares a number of virtqueues with QEMU.
The mechanism by which traffic is passed is comprised of two parts:
The datapath.
The notification path.
Operating System
Virtio Driver
QEMU TX RX 1 2
Kernel Space
OVS Datapath
Tap
KVM 1
Eth X 2

6. Intel® Data Plane Development Kit and ivshmem
Intel® DPDK
ivshmem
Physically contiguous memory
1GB pages
/dev/hugepages/rte_map0
Hugepages
Lockless
Efficient for IPC
Rx/Tx pairs
Rings
aka Nahanni*
QEMU* 1.4.0
Host Initiated
ivshmem
Command line
hugepage location
ivshmem device
QEMU
Patch

7. QEMU Operating System OVS client ivshmem Shared Memory Memory 1GB
DPDK Ring API
ivshmem
PCI dev (04:00.0)
BAR2
1GB
Shared Memory
Memory RX TX
mempool
OVS Datapath
DPDK Ring API
DPDK PMD
Kernel Space

8. Intel® DPDK rings and ivshmem Characteristics
Current
Future
Zero copy
Fast performance
Performance
Guests can access host memory
Unsuitable for untrusted guests
Security
Host initiated sharing
Shared at guest start up
Live Migration
DPDK Guest application
Compatibility
Upstream Patch
Maintenance
QEMU
Regions of memory
Security groups
Security
Modifications needed
Difficult
Live migration

9. VhostNet us-vhost QEMU QEMU Operating System Operating System
Virtio Driver
Virtio Driver RX TX 1
OVS Datapath
DPDK vhost RX TX
IOCTL 1 2
DPDK x
Kernel Space
ioeventfd
KVM
vhost-net
Kernel Space
CUSE
KVM
irqfd 2
OVS Datapath
Tap
eventfd
link
ioeventfd
Eth X
irqfd

10. us-vhost Characteristics
Current
Future
Less copies and context switches.
Performance
Virtqueues mapped to vswitchd address space.
Security
Solution exists.
Live Migration
DPDK guest application
Virtio-net
Compatibility
zero copy
Merge-able buffers
Performance
virtio-net backend enhancements
Features
Library provided by DPDK
us-vhost Library
vhost-user
QEMU

11. Accelerated performance
Use Case Comparison
Use Case 1
Highest performance
Trusted Guests
DPDK VNF
No live migration
Use Case 2
Accelerated performance
Untrusted Guests
DPDK & Virtio-net VNFs
Live migration
dpdkr & ivshmem
us-vhost

12. Summary
NFV requires high bandwidth, low latency interfaces into the Network Function Virtualisation Infrastructure
2 accelerated paths to the guest recently enabled in netdev-dpdk
Trade off between performance, security, live migration and compatibility
DPDK has an active community supporting it

13. Q & A