SN0430966-00 Rev. C 4/17 1
Solution Sheet
The Benets of I/O Virtualization in
Windows Server 2012
Virtualize Tier-1 Applications and Increase
VM Density in Hyper-V with Single Root
I/O Virtualization
Ofoading CPU processing for network I/O trafc using
SR-IOV capabilities in Microsoft Windows 2012 Hyper-V
and the QLogic 8300 Series Converged Network Adapter
signicantly reduces system overhead, ensuring that such
critical CPU utilization levels are never reached.
BENEFITS OF SR-IOV OFFLOAD CAPABILITIES
• Reduce system CPU utilization
• Reduce network latency
• Increase network I/O throughput
CHALLENGE
Traditionally, a packet being transferred to a virtual machine (VM) is
received by the physical network port (Physical Function) in the host
server. In these virtual environments, the hypervisor manages network I/O
trafc, which requires high CPU processing to sort packets. The packets are
then routed to the appropriate guest operating systems, as shown in Figure 1.
EXECUTIVE SUMMARY
The advent of server virtualization has had a number of positive
impacts on server resource utilization. Fewer servers with more
memory and CPU cores can now do the work of many servers more
efciently and provide simplied management. When virtualizing
Tier-1 heavy-duty applications like Microsoft
®
SQL Server
®
, there
are times when CPU utilization exceeds critical levels because CPUs
are simply asked to do too much. This situation can be exacerbated
during times of high application trafc or when applications
are moved to other nodes in a cluster due to hardware issues
ormaintenance.
However, ofoading CPU processing for network I/O trafc using
Single Root I/O Virtualization (SR-IOV) capabilities in Microsoft
Windows
®
2012 Hyper-V
®
and the QLogic
®
8300 Series Converged
Network Adapter signicantly reduces system overhead, ensuring
that such critical CPU utilization levels are never reached. Reduced
overall system CPU utilization allows Tier-1 workload performance
to scale. In addition, streaming and nancial applications can benet
with reduced network I/O latency by enabling SR-IOV.
PCIe Bus
Physical
Function
Server
Core
Apps
Guest
OS 1
Apps
Guest
OS 2
Apps
Guest
OS 3
Apps
Guest
OS 4
Apps
Guest
OS 5
Apps
Hypervisor
Without SR-IOV
Figure 1. Packet Routing without SR-IOV
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SN0430966-00 Rev. C 4/17 2
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respective owners.
This document is provided for informational purposes only and may contain errors. Cavium reserves the right, without notice, to make changes to this document or in product design or specications. Cavium disclaims any warranty of any kind, expressed or implied, and does not
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The Benets of I/O Virtualization in Windows Server 2012
Solution Sheet
SOLUTION
SR-IOV enables the VM to use a Virtual Function to send and receive
packets directly to the physical network port, bypassing the traditional
path (through the hypervisor) completely, as shown in Figure 2. This
method boosts the network I/O, reduces network latency, and decreases
the overhead on the host machine’s processor.
PROVEN REDUCTION IN CPU UTILIZATION
In larger virtualized environments (20 or more VMs per host), or when
virtualizing several Tier-1 application workloads, high CPU utilization can
be an issue. Typically, the only way to reduce CPU utilization is to move
VMs off the host server.
However, with the implementation of SR-IOV on the QLogic 8300 Series
Converged Network Adapter, host CPU utilization can be signicantly
reduced. This reduction can be signicant enough that additional VMs can
be added to the host server without negatively affecting host
system performance.
As illustrated in Figure 3, CPU utilization trends upward as VMs are added
to the host server when SR-IOV is not enabled. When SR-IOV is enabled,
CPU utilization tends to level off at a much lower percentage as VMs are
added. Extensive QLogic testing has shown up to 58 percent lower CPU
utilization with SR-IOV enabled.
SUMMARY
Microsoft Windows Server
®
2012 with Hyper-V congured with SR-IOV
and the QLogic Series 8300 Converged Network Adapter together work
to decrease host CPU utilization, reduce network latency, and increase
network I/O throughput. This technology allows virtual systems to do more
and be more efcient at the same time, increasing the overall value of the
virtual environment.
ABOUT CAVIUM
Cavium, Inc. (NASDAQ: CAVM), offers a broad portfolio of infrastructure
solutions for compute, security, storage, switching, connectivity and
baseband processing. Cavium’s highly integrated multi-core SoC products
deliver software compatible solutions across low to high performance
points enabling secure and intelligent functionality in Enterprise, Data
Center and Service Provider Equipment. Cavium processors and solutions
are supported by an extensive ecosystem of operating systems, tools,
application stacks, hardware reference designs and other products.
Cavium is headquartered in San Jose, CA with design centers in California,
Massachusetts, India, Israel, China and Taiwan.
PCIe Bus
Physical
Function
Virtual
Function
Virtual
Function
Virtual
Function
Server
Core
Apps
Guest
OS 1
Apps
Guest
OS 2
Apps
Guest
OS 3
Apps
Guest
OS 4
Apps
Guest
OS 5
Apps
Hypervisor
Virtual
Function
Virtual
Function
With SR-IOV
Figure 2. Packet Routing with SR-IOV
0%
5%
10%
15%
20%
25%
30%
0 1 2 5 10 15 20
CPU Utilization
Number of Virtual Machines
10GbE Network Traffic
Impact on System-level CPU Utilization
No SR-IOV
SR-IOV
Figure 3. CPU Utilization is Lowered by Using SR-IOV