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Virtualization Performance
H. Reza TaheriSenior Staff Eng.VMware
2Copyright © 2006 VMware, Inc. All rights reserved.
Three Key Properties of Virtualization
Partitioning• Run multiple operating
systems on one physical machine
• Fully utilize server resources• Support high availability by
clustering virtual machines
Encapsulation• Encapsulate the entire state
of the virtual machine in hardware-independent files
• Save the virtual machine state as a snapshot in time
• Re-use or transfer whole virtual machines with a simple file copy
Isolation• Isolate faults and security at
the virtual-machine level• Dynamically control CPU,
memory, disk and network resources per virtual machine
• Guarantee service levels
3Copyright © 2006 VMware, Inc. All rights reserved.
Hosted vs. Native Virtualization
Native/Hypervisor Hosted
• Device support is inherited from host operating system for maximum hardware compatibility
• Virtualization installs like an application rather than like an operating system
• Can run alongside conventional applications
• Maximum performance with lowest overhead using certified hardware
• Highly efficient direct I/O pass-through architecture for network and disk
• Highly secure micro-kernel virtualization layer—only 100Ks of lines of code versus 10–25 million lines of host operating system code
• Advanced features like VMotion available
(ESX Server)(Workstation, VMware Player, VMware Server, ACE, VMware Server)
4Copyright © 2006 VMware, Inc. All rights reserved.
ESX Server Architecture
Hardware
VM
Device Drivers
Storage Stack Network Stack
VM
VMM VMM
VMkernel
POSIX API
VMX VMX
Peripheral Device Drivers
ManagementAgents and Interfaces
Service Console
VMX VMX VM VM
VMM VMM
ResourceManagement
5Copyright © 2006 VMware, Inc. All rights reserved.
Virtual Machines in ESX Server
(Up to 2 CD-ROMs)
1-4 ports 1-4 ports
1-4 adapters1-4 adapters;
1-15 devices each
Up to 16GB RAM
1-2 drives
VM Chipset 1 CPU (4 CPUs with
VMware SMP)
6Copyright © 2006 VMware, Inc. All rights reserved.
Hot Migration: VMotion® Technology
VMotion Technology moves running virtual machines from one host to another while maintaining continuous service availability
• - Enables Continuous Workload Consolidation• - Enables Zero-Downtime Maintenance
7Copyright © 2006 VMware, Inc. All rights reserved.
Resource Pools
Aggregate collections of disparate hardware resources into unified logical resource pools
• Customer Impact• Failed server mean less resources
not a failed application
• Dedicated (virtual) infrastructure for each business unit; central IT retains control over hardware
• Delegation of resource and virtual machine management down to the business unit
• Management of an entire SOA application stack as a single entity
Servers, Storage, Networking
Business Unit
Department A Department B
Aggregate Resources
Resource Pool 2CPU 36GHz, Mem 58GB
Priority HIGH
Resource Pool 3CPU 12GHz, Mem 22GB
Priority LOW
CPU 48 GHz, Mem 80GB
8Copyright © 2006 VMware, Inc. All rights reserved.
VMware HA: Restart VMs if ESX Server fails
Virtual Machine
Virtual Machine
Virtual Machine
Virtual Machine
Virtual Machine
Virtual Machine
Virtual Machine Virtual Machine
X
VC
9Copyright © 2006 VMware, Inc. All rights reserved.
CPU Utilization Distribution
1
10
100
1000
10000
100000
0 20 40 60 80 100
% CPU Utilization
Nu
mb
er o
f S
yste
ms
Workload Characteristics
Consolidation targets are often <30% Utilized• Windows average utilization: 5-8%
•Linux/Unix average: 10-35%
10Copyright © 2006 VMware, Inc. All rights reserved.
Exchange performance in a virtualized environment
• Many workloads on VM run at/near native H/W speed
• Let’s focus on something that does not!
• Study with:• Exchange 2003
• WS 2K3 EE
• Loadsim 2003
• 4-way Dell servers
• Native supports 1.4X as many users
• Alternative observation: VM has 1.6X the CPU usage for the same # of users
• Where does the time go?
11Copyright © 2006 VMware, Inc. All rights reserved.
• 2-socket, Woodcrest system• Exchange 2003
• WS 2K3 EE
• Loadsim 2003
• Perfmon and Vtune on native
• VMware s/w and h/w monitoring tools on VM
12Copyright © 2006 VMware, Inc. All rights reserved.
Change in h/w profile
• Native CPU usage is ~60%
• VM CPU usage is ~90% at ~4% less throughput• 73% in the guest+monitor
• ~20 in hypervisor
• VM has 1.5X the CPU usage at 0.96% the throughput
• 1.38X more instructions; 1.09X the CPI• The product matches the 1.5X
• 2-3X increase in TLB misses
• 40-80% more L1 misses
• L2:• 34% more data misses
• 90% more imisses, but much fewer than dmisses