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virt-querying-metrics.adoc

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Virtualization metrics

The following metric descriptions include example Prometheus Query Language (PromQL) queries. These metrics are not an API and might change between versions. For a complete list of virtualization metrics, see KubeVirt components metrics.

Note

The following examples use topk queries that specify a time period. If virtual machines are deleted during that time period, they can still appear in the query output.

vCPU metrics

The following query can identify virtual machines that are waiting for Input/Output (I/O):

kubevirt_vmi_vcpu_wait_seconds_total

Returns the wait time (in seconds) on I/O for vCPUs of a virtual machine. Type: Counter.

A value above '0' means that the vCPU wants to run, but the host scheduler cannot run it yet. This inability to run indicates that there is an issue with I/O.

Note

To query the vCPU metric, the schedstats=enable kernel argument must first be applied to the MachineConfig object. This kernel argument enables scheduler statistics used for debugging and performance tuning and adds a minor additional load to the scheduler.
Example vCPU wait time query
topk(3, sum by (name, namespace) (rate(kubevirt_vmi_vcpu_wait_seconds_total[6m]))) > 0 (1)

  1. This query returns the top 3 VMs waiting for I/O at every given moment over a six-minute time period.

Network metrics

The following queries can identify virtual machines that are saturating the network:

kubevirt_vmi_network_receive_bytes_total

Returns the total amount of traffic received (in bytes) on the virtual machine’s network. Type: Counter.

kubevirt_vmi_network_transmit_bytes_total

Returns the total amount of traffic transmitted (in bytes) on the virtual machine’s network. Type: Counter.

Example network traffic query
topk(3, sum by (name, namespace) (rate(kubevirt_vmi_network_receive_bytes_total[6m])) + sum by (name, namespace) (rate(kubevirt_vmi_network_transmit_bytes_total[6m]))) > 0 (1)

  1. This query returns the top 3 VMs transmitting the most network traffic at every given moment over a six-minute time period.

Storage metrics

Storage-related traffic

The following queries can identify VMs that are writing large amounts of data:

kubevirt_vmi_storage_read_traffic_bytes_total

Returns the total amount (in bytes) of the virtual machine’s storage-related traffic. Type: Counter.

kubevirt_vmi_storage_write_traffic_bytes_total

Returns the total amount of storage writes (in bytes) of the virtual machine’s storage-related traffic. Type: Counter.

Example storage-related traffic query
topk(3, sum by (name, namespace) (rate(kubevirt_vmi_storage_read_traffic_bytes_total[6m])) + sum by (name, namespace) (rate(kubevirt_vmi_storage_write_traffic_bytes_total[6m]))) > 0 (1)

  1. This query returns the top 3 VMs performing the most storage traffic at every given moment over a six-minute time period.

Storage snapshot data

kubevirt_vmsnapshot_disks_restored_from_source

Returns the total number of virtual machine disks restored from the source virtual machine. Type: Gauge.

kubevirt_vmsnapshot_disks_restored_from_source_bytes

Returns the amount of space in bytes restored from the source virtual machine. Type: Gauge.

Examples of storage snapshot data queries
kubevirt_vmsnapshot_disks_restored_from_source{vm_name="simple-vm", vm_namespace="default"} (1)

  1. This query returns the total number of virtual machine disks restored from the source virtual machine.

kubevirt_vmsnapshot_disks_restored_from_source_bytes{vm_name="simple-vm", vm_namespace="default"} (1)

  1. This query returns the amount of space in bytes restored from the source virtual machine.

I/O performance

The following queries can determine the I/O performance of storage devices:

kubevirt_vmi_storage_iops_read_total

Returns the amount of write I/O operations the virtual machine is performing per second. Type: Counter.

kubevirt_vmi_storage_iops_write_total

Returns the amount of read I/O operations the virtual machine is performing per second. Type: Counter.

Example I/O performance query
topk(3, sum by (name, namespace) (rate(kubevirt_vmi_storage_iops_read_total[6m])) + sum by (name, namespace) (rate(kubevirt_vmi_storage_iops_write_total[6m]))) > 0 (1)

  1. This query returns the top 3 VMs performing the most I/O operations per second at every given moment over a six-minute time period.

Guest memory swapping metrics

The following queries can identify which swap-enabled guests are performing the most memory swapping:

kubevirt_vmi_memory_swap_in_traffic_bytes

Returns the total amount (in bytes) of memory the virtual guest is swapping in. Type: Gauge.

kubevirt_vmi_memory_swap_out_traffic_bytes

Returns the total amount (in bytes) of memory the virtual guest is swapping out. Type: Gauge.

Example memory swapping query
topk(3, sum by (name, namespace) (rate(kubevirt_vmi_memory_swap_in_traffic_bytes[6m])) + sum by (name, namespace) (rate(kubevirt_vmi_memory_swap_out_traffic_bytes[6m]))) > 0 (1)

  1. This query returns the top 3 VMs where the guest is performing the most memory swapping at every given moment over a six-minute time period.

Note

Memory swapping indicates that the virtual machine is under memory pressure. Increasing the memory allocation of the virtual machine can mitigate this issue.