KVM Enhancements final...Update on Enhancements: Cyclictest(After) • Cyclic Test in Guest: Latency (in μs ) – Min: 7 – Avg: 9 – Max: 16 RT Linux Guest on KVM Latency ( μs)

KVM Enhancements for OPNFV

Jun Nakajima

Intel Corporation

Contributors: https://wiki.opnfv.org/nfv-kvm

Project: NFV Hypervisors-KVM

1. Minimal Interrupt latency variation for data plane VNFs

2. Inter-VM Communication

3. Fast Live Migration

11/12/2015 KVM Enhancements for NFV

https://wiki.opnfv.org/nfv-kvm

2

Enhancements for NFV Hypervisor

1

1. Exclusive allocation of whole CPU cores to VMs

2

3

3. Inter-VM Communication (direct-memory mapped)

4

2. Direct I/O (e.g. SR-IOV)

4. vSwitch implementation as a high performance VM

General public and enterprise cloud Hypervisor Architecture

NFV Hypervisor Architecture

From ETSI“Network Functions Virtualization (NFV); Infrastructure;Hypervisor Domain”

3

KVM Hypervisor

Hardware

System Configuration

Testing and Perf Tools

NIC

VM

core core

Virtual Switch (vSwitch)

VM

VM

VM

KVM kernel module

2. Inter-VM Communication

1. Minimal Latency Variation

Configuration Information (BIOS, boot,

kernel)Latency Variation

Perf. Tools

Inter-VM Config. Information

Inter-VM Comm. Perf. Tools

Live Migration Perf. Tools

Live Migration Config.

Information3. Fast Live Migration

Scope of the Project

11/12/2015 KVM Enhancements for NFV 4

Minimal Interrupt Latency Variation


Goals of Minimal Interrupt Latency Variation

• Timer latency => AVG 5 us, MAX 15 us

• Interrupt latency => MAX 20 us (Future target: 5 us)

• Maximum guest vCPU pre-emption period => 10 us (Future target: 2 us)

• Cumulative pre-emption within 1 ms window => X < 20 us (Future target: X < 4 us)

https://etherpad.opnfv.org/p/nfv-kvm


User-Level

Linux Kernel

HardwareNIC

core

KVM Modules

User-Level

core

NIC

core core

Real-time Guest

Summary Of Solutions

PREEMPT-RT Kernel

Intr_HandlerExcusive/Static Allocation

Soft “Partitioning”, CPU Binding, Huge Pages

SoftwareReal-Time Linux, Code

inspection, testing/measurements

Hardware TechnologiesCache Allocation

Technology, Advanced VT features


Update on Enhancements: Cyclictest (Initial)

Latency (μs)0

100000

200000

300000

400000

500000

600000

700000

800000

900000

1 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46 49 52 55 58Baseline

w/ RT Extensions

Histogram (Total: 1M Samples)

RT Linux Guest on KVM

Latency(μs)11/12/2015 KVM Enhancements for NFV 8

Update on Enhancements: Cyclictest (After)

• Cyclic Test in Guest: Latency (in μs )

– Min: 7– Avg: 9– Max: 16

RTLinuxGuestonKVM

Latency(μs)

Host:LinuxwithRTpatches

000007 000003000008 11757562000009 67812652000010 159222000011 069100000012 011004000013 000379000014 000207000015 000049000016 000005

Latency

99.69%(Total#:79,810,183)

Occurrences

0

10000000

20000000

30000000

40000000

50000000

60000000

70000000

80000000

0 2 4 6 8 10 12 14 16 18 20 22

Histogram


Update on Enhancements: Cyclictest (Latest)

• Cyclic Test in Guest: Latency (in μs )

– Min: 6 7– Avg: 6 9– Max: 11 (9*) 16

• Host

– 4.1.0 + PREEMPT-RT (upstream)


*: w/ 1Hz tick disabled

Linux Kernel

Hardware

KVM Modules

Intr_Hander

PCIe Device

Interrupt (MSI)

Device Driver

Periodic (1ms)

Update on Enhancements:Latency from Periodic External Interrupts

• Latency from periodic external interrupt:

– Time delta from interrupt occurrence to invocation of interrupt handler in guest (unit: in μs)

Min: 3.98Avg: 4.42Max: 9.10


Inter-VM Communication


Goals of Inter-VM Communication

• Add fast-paths in VMs as optimized inter-VM communication

• Maintain consistent flow table entries in VMs

• Enable protected access to the destination VM or shared memory

– Open the Window when needed– Close it immediately when done


VM1

virtio-net

In-VM Switch

VM2

TX

RX

virtio-net

Simple Flow Table

NIC

In-VM Switch

VM3

TX

RX

virtio-net

In-VM Switch

Inter-VM data transfer

API Libraries

ProcessProcess


Flow Table

Entries

Shared Memory

If (In-VM Switch is present)

vSwitch(e.g.OVS-dpdk,SnabbSwitch)


Update on Enhancements:Upstream Project

• Proposal from Michael S. Tsirkin

– Inter-VM Communication for two VMs– Receiver allows one to access its own memory via existing IOMMU

protection mechanism• Our plan

– Extend Michael’s proposal to support multiple VMs– Work with him for implementation


https://wiki.opnfv.org/vm2vm_mst

15

Update on Enhancements:PoC

• Transfer 64B packets from virtio-net to another VM (fast path)

– Memory Copy– VMFUNC– VMFUNC with

Trampoline Code• 65Mpps with 32-

packet batching*:

11/12/2015 KVM Enhancements for NFV *Intel internal estimation 16

Fast Live Migration


18

Goals of Fast Live Migration

• Migration Time– < 2 sec.

• Down Time– Hypervisor downtime for IO intensive

workload: 10 ms (future 3ms)– Hypervisor downtime for memory

intensive workload: < 500 ms– Network downtime: 25 ms

• Configuration– Typical VM size: 8GB to 16GB– Network throughput: 5Gbps for

64bytes packets

• SR-IOV Migration– Support NIC with kernel Land driver– Support NIC with DPDK driver


19


• Shorten VM Downtime- Clean up operation after completion of

data transmission

- Minimize cpu_synchronize_all_states() calls

• Shorten Total Migration Time- Optimize handling of unused or zero

pages

- Use CPU instructions to optimize zero pages checking

- Use hardware accelerator to compress data before transmitting


Update on Enhancements


Host CPU: Intel(R) Xeon(R) CPU E5-2699 v3 @ 2.30GHz RAM: 64GOS: RHEL 7.1, Kernel: 4.2-rc6 QEMU：2.4.0Ethernet controller: Intel Corporation 82599ES 10-Gigabit SFI/SFP+

Test environment

0

500

1000

1500

2000

Idle guest DPDK FW workload

Totalmigrationtime(ms)

Original

Afteroptimization

0

10

20

30

40

50

Idle guest DPDK FW workload

VMdowntime(ms)

Original

Afteroptimization

Performance data

20

Host

Guest

Host

Guest

10Gbps for LM

10GbE used by pktgen

DPDK L2 FW APP

Eth1 Eth0

pktgen

DPDK L2 FW APP

Eth0 Eth1

Eth1 Eth2Eth0

vitbr0vitbr1

Eth1 Eth2 Eth0

vitbr0 vitbr1

Eth1

Q & AJoin us!


Documents

KVM Enhancements final...Update on Enhancements: Cyclictest(After) • Cyclic Test in Guest: Latency (in μs ) – Min: 7 – Avg: 9 – Max: 16 RT Linux Guest on KVM Latency ( μs)