What is ksm service

As soon as the service is started, also the memory information displayed on the Proxmox VE GUI is identical to the value shown in the windows task manager see screenshot. If you need details about ballooning stats for this VM, go to the KVM monitor and enter 'info balloon'. Modern Linux Kernels does include the Balloon drivers by default.

It works out of the box, and you only need to set the VM to "Automatically allocate memory within this range". Navigation menu Personal tools Log in. In addition, the ksmtuned service is notified by libvirt when a guest virtual machine is created or destroyed.

The ksmtuned service has no options. The ksmtuned service can be tuned with the retune parameter, which instructs ksmtuned to run tuning functions manually. The file output below is the default ksmtuned. KSM Variables and Monitoring. Files in this directory are updated by the kernel and are an accurate record of KSM usage and statistics. These variables can be manually tuned using the virsh node-memory-tune command. For example, the following specifies the number of pages to scan before the shared memory service goes to sleep:.

Changing the log file location is not advised and may require special configuration of SELinux settings. Deactivating KSM. Kernel same-page merging KSM has a performance overhead which may be too large for certain environments or host systems. KSM may also introduce side channels that could be potentially used to leak information across guests. If this is a concern, KSM can be disabled on per-guest basis.

KSM can be deactivated by stopping the ksmtuned and the ksm services. However, this action does not persist after restarting. To deactivate KSM, run the following in a terminal as root:. Stopping the ksmtuned and the ksm deactivates KSM, but this action does not persist after restarting. Persistently deactivate KSM with the systemctl commands:. To delete all of the PageKSM in the system, use the following command:. This page is then marked copy on write. If the contents of the page is modified by a guest, a new page is created for that guest.

This is useful for virtualization with KVM. When a guest is started, it only inherits the memory from the parent qemu-kvm process. Once the guest is running the contents of the guest operating system image can be shared when guests are running the same operating system or applications. KSM only identifies and merges identical pages which does not interfere with the guest or impact the security of the host or the guests.

KSM provides enhanced memory speed and utilization. With KSM, common process data is stored in cache or in main memory. This reduces cache misses for the KVM guests which can improve performance for some applications and operating systems. Secondly, sharing memory reduces the overall memory usage of guests which allows for higher densities and greater utilization of resources. The ksm service starts and stops the KSM kernel thread. The ksmtuned service controls and tunes the ksm , dynamically managing same-page merging.

The ksmtuned service starts ksm and stops the ksm service if memory sharing is not necessary. The ksmtuned service must be told with the retune parameter to run when new guests are created or destroyed.

Both of these services are controlled with the standard service management tools.