Hyper-V 3 limits the CPU usage of virtual machines

Hyper-V 3 limits the CPU utilization of virtual machines. Windows Server 2012 is coming soon. The latest Hyper-V 3 brings us more surprises, in the next three blog posts, we will learn about the virtual machine CPU competition mechanism. Part 1: CPU resources allocated to virtual machines; Part 2: limits the CPU usage of virtual machines; Part 3: competition for CPU resource priority part 2 limits the CPU usage of the Virtual Machine (all resources are 100%). You can specify the CPU resources used by the Virtual Machine (expressed in percentage ), that is to say, you can limit the CPU resources used by virtual machines. The "Virtual Machine restrictions" option is provided in Virtual Machine attribute settings, which ensures the maximum CPU processing capability that can be used by virtual machines. If the CPU resources used by the Virtual Machine exceed the limit value, the maximum CPU usage value is the set value (percentage ). After a new virtual machine is created by default, the maximum CPU processing capacity is set to 100 by default. The default setting has a fatal defect. When multiple virtual machines run simultaneously and the CPU usage of the virtual machine reaches 100%, the system will stop responding so that the system will go down. This is a fatal defect for applications. Therefore, it is a good way to limit the maximum processing capability of virtual machines. Www.2cto.com
Figure Virtual Machine CPU resource usage test: for example, in the same host machine: l Virtual Machine (Windows Server 2008 R2) sets the Virtual Machine limit (percentage) to 50%, the virtual machine can use up to 50% of the CPU processor's data processing capability. N

L if the Virtual Machine (Windows Server 2003 R2) sets a virtual machine limit (percentage) of 30% (2-16), the virtual machine can use up to 30% of the CPU processor's data processing capability. N

After a virtual machine named "Windows Server 2003 R2" is started, because the application system requires high CPU processing resources, go to the "performance" tab in "Task Manager, we can see that the CPU usage is above 99%.

The figure shows that the "virtual machine limit" is set to 30%, that is to say, the maximum hardware CPU resources that can be used by the virtual machine is 30%. Although the Virtual Machine prompts that the CPU usage is close to 100%, what is the physical CPU usage? Open "Hyper-V manager" and you can see the CPU usage of the virtual machine. The CPU usage is 29%, close to 30%, which reaches the maximum usage of CPU resources allocated to the virtual machine ,. In this way, when other virtual machines are running, they will not be unable to respond to client requests because a virtual machine occupies a large amount of CPU resources. Www.2cto.com

The figure shows the physical CPU utilization by using the "performance" tab in the "Task Manager" of Windows 8 Server, which is about 30%, instead of 100% for the VM.

Figure CPU limit mechanism when a host has a certain number of virtual machines, it is recommended that the maximum CPU usage of each virtual machine application be calculated through the benchmark test, then, use the "virtual machine restrictions" option to assign a limit value to each virtual machine. In this way, even if multiple virtual machines reach the application peak, the processing capability of other virtual machines will not be affected to ensure the stable operation of the system. Author: wangshujiang