Virtualization Architecture & KVM

1. devconf.cz 2014
Virtualization Architecture & KVM
Pradeep Kumar Surisetty < psuriset@redhat.com>
Principal Software Engineer

2. Why we believe KVM is the best virtualization
platform
Performance
KVM holds the Top 6/11
virtual machine consolidation
scores on SPECvirt (1)
Security
EAL4+ Certification (3)
plus SE Linux enabling
Mandatory Access Control
between virtual machines
Lower Cost
customers report up to
70% savings by using
KVM(2)
Cloud & Virtualization
Management
Red Hat Open Stack for Cloud
Virtualization and Red Hat
Enterprise Virtualization for data-
center Virtualization
(1) Source: SpecVirt_sc2010 results: http://www.spec.org/virt_sc2010/results/specvirt_sc2010_perf.html
(2) Source: Case study on Canary Islands Government migration from VMware to RHEV:
http://www.redhat.com/resourcelibrary/case-studies/canary-islands-government-migrates-telecommunications-platform-from-
vmware-to-red-hat
(3) Source: http://www.redhat.com/solutions/industry/government/certifications.html
(4) Source: http://www.redhat.com/resourcelibrary/articles/enterprise-linux-virtualization-support
Cross Platform
Support and certification for
leading x86_64 operating systems
including RHEL and
Microsoft Windows (4)

3. VMware
ESX 4.1 HP
DL380 G7
(12 Cores,
78 VMs)
RHEL 6
(KVM) IBM
HS22V (12
Cores, 84
VMs)
VMware
ESXi 5.0 HP
DL385 G7
(16 Cores,
102 VMs)
RHEV 3.1
HP DL380p
gen8 (16
Cores,150
VMs)
VMware
ESXi 4.1 HP
BL620c G7
(20 Cores,
120 VMs)
RHEL 6
(KVM) IBM
HX5 w/
MAX5 (20
Cores, 132
VMs)
VMware
ESXi 4.1 HP
DL380 G7
(12 Cores,
168 Vms)
VMware
ESXi 4.1
IBM x3850
X5 (40
Cores, 234
VMs)
RHEL 6
(KVM) HP
DL580 G7
(40 Cores,
288 VMs)
RHEL 6
(KVM) IBM
x3850 X5
(64
Cores,336
VMs)
RHEL 6
(KVM) HP
DL980 G7
(80 Cores,
552 VMs)
0
1,000
2,000
3,000
4,000
5,000
6,000
7,000
8,000
9,000
10,000
1,221 1,367 1,570
2,442
1,878
2,144
2,742
3,824
4,682
5,467
8,956
Best SPECvirt_sc2010 Scores by CPU Cores
(As of May 30, 2013)
System
SPECvirt_sc2010score
Comparison based on best performing Red Hat and VMware solutions by cpu core count published at www.spec.org as of May 17, 2013. SPEC® and the benchmark name SPECvir_sct® are registered
trademarks of the Standard Performance Evaluation Corporation. For more information about SPECvirt_sc2010, see www.spec.org/virt_sc2010/.
2-socket 16
2-socket 12
2-socket 20
4-socket 40
8-socket 64/80

6. Introducing KVM virtualization
KVM hypervisor runs virtual machines on Linux hosts
➢ Mature on x86, recent progress on ARM and ppc
Most popular and best supported hypervisor on OpenStack
➢ https://wiki.openstack.org/wiki/HypervisorSupportMatrix
Built in to Red Hat Enterprise Linux
➢ Qumranet startup created KVM, joined Red Hat in 2008

8. Virtualization goals
 How to Virtualize CPU?
 How to Virutalize Memory?
 How to Virtualize IO?

24. KVM I/O Architecture
KernelKernel
rxtx
QEMUQEMU
Virtual MachineVirtual Machine
Tap
Bridge
KernelKernel
QEMUQEMU
Virtual MachineVirtual Machine
Brid
ge
Ta
p
tx rx
vhost
KernelKernel
tx rx
Virtual MachineVirtual Machine
QEMUQEMU
Physical NIC
Emulated Devices
● Native drivers
● Compatibility
over performance
Virtio Devices
● Paravirtualized
● Performance
over compatibility
Device Assignment
● Native drivers
● Compatibility and
Performance

25. Full virtualization Para-virtualization
Storage transport choices in KVM
devconf.cz 2016

26. Storage transport choices in KVM
●
Full virtualization : IDE, SATA, SCSI
●
Good guest compatibility
●
Lots of trap-and-emulate, bad performance
●
Para virtualization: virtio-blk, virtio-scsi
●
Efficient guest ↔ host communication through virtio ring buffer
(virtqueue)
●
Good performance
●
Provide more virtualization friendly interface, higher
performance.
●
In AIO case, io_submit() is under the global mutex
devconf.cz 2016

27. Storage transport choices in KVM
●
Device assignment (Passthrough)
●
Pass hardware to guest, high-end usage, high performance
●
Limited Number of PCI Devices
●
Hard for Live Migration
devconf.cz 2016

29. Virt-Manager

30. Special Thanks
to
Andrew Theurer
Stefan Hajnoczj

31. Thanks
Irc: #psuriset
Blog: psuriset.com

40. ●
Handles all management and interaction with QEMU
●
(VMs) are defined in Libvirt via XML; referred to a “domain”
●
Translates XML to command line options for calling QEMU
●
Become comfortable with ‘virsh’
●
Libvirt XML reference: http://tinyurl.com/libvirt-xml
Libvirt API

49. KVM I/O Architecture
KernelKernel
rxtx
QEMUQEMU
Virtual MachineVirtual Machine
Tap
Bridge
KernelKernel
QEMUQEMU
Virtual MachineVirtual Machine
Brid
ge
Ta
p
tx rx
vhost
KernelKernel
tx rx
Virtual MachineVirtual Machine
QEMUQEMU
Physical NIC
Emulated Devices
● Native drivers
● Compatibility
over performance
Virtio Devices
● Paravirtualized
● Performance
over compatibility
Device Assignment
● Native drivers
● Compatibility and
Performance