![]() ![]() ![]() The graph below shows a good spread across the CPUs.ĭid you know: Fastvue Reporter produces clean, simple, web usage reports using data from your firewall that you can confidently send to department managers and HR team. In Fastvue Reporter's case you will not see this bad behavior since it multi-threads rather nicely. This allows us to see if there is a process running on the VM that might not be threading efficiently and spiking a single CPU core to 100% while the remainder stays low. Each virtual processor here maps to a logical processor as seen above. When you select this counter you will notice that it lists the virtual machines VPU’s. I have added all the instances of the CPU’s so you can see that there are 32 cores all using different percentages and an overall much lower _TotalĪ very useful counter is Hyper-V Hypervisor Virtual Processor. The counter you want to look for is Hyper-V Hypervisor Logical Processor. This is why there is often very low usage here but high total CPU usage. As mentioned earlier, this is deceptive as one would think it is for the host’s hardware, but it is in actual fact the usage for the host’s operating system. NOTE: When you start Perfmon, the default counter is %Processor Time. But to dive a little deeper and see which cores are being used and by what process, we will have to break out Perfmon. They Hyper-V management console is great for getting a high level overview. Seeing 10% usage here would equate to 10% across 32 CPUs, or if we work it back to the amount of resources allocated to the VM it would be 20 % across the 16 VCPUs The CPU usage column is representative of the host’s total CPU resources. The simplest way to monitor CPU usage to look at Hyper-V management console. ![]() Now that we have allocated the virtual CPU we need to see how they behave and how they impact the host. This is a deceiving number since it is not a percentage and the values have to be between 0 and 10 000. A VM with a higher weight would get more CPU time than a similar spec VM with a lower weight. ![]() Relative weight This value is used by the processor scheduler to determine which virtual machine gets preference for CPU calls. Total System CPU / Allocated CPU * Limit. Percentage of total system resources This is a calculated value based on the amount of allocated CPUs and the maximum limit set. This limit or cap is across all the allocated CPUs. Virtual machine Limit (percentage) This indicates what percentage of every core the VM can consume. Total system CPU / Allocated CPU * Reserve. Percentage of total system resources This is a calculated value and it takes the number of allocated CPUs. This is a percentage of the amount of allocated system CPU so 10% here would be 10% of all 16 cores. Virtual machine reserve (percentage) This is a reserve that the host will keep for this virtual machine. The maximum number that can be specified is the maximum number of cores on the hardware Number of virtual processors This is the amount of cores that the virtual machine can see and use. Before we start allocating CPU's, let consider the available resource controls and how they may effect not just this VM, but also the host and other VMs. To understand how this all maps together, let’s have a look at the Hyper-V VM processor configuration. Configuring Your Virtual Machine's Processors Each virtual CPU maps down to a physical core. As a result you will be able to allocate a maximum of 32 virtual CPUs to a virtual server. So as an example, if you have a 4 socket server where each processor has 8 cores, this will present 32 logical processors. The amount of virtual processors available are determined by the number of cores available on the hardware. Virtual CPU’s can be allocated to a virtual machine. Truly understanding Hyper-V virtual and physical CPU usage first requires us to dive into a little bit of theory. Here most people are surprised to see that their CPU usage is minimal, this despite the indication that the VM’s CPU’s are 100% utilized. The typical first approach is to log into the Hyper-V host and open up task manager. When running virtual servers in Hyper-V, there is often some confusion when determining how much CPU is actually being used.
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