KSM behaviour on reboot

[M@ario]

Hello,

I have one Proxmox node that uses KSM heavily (118GB assigned on 96GB physical RAM). Recently I had to reboot that node and after the reboot the VMs started up and began to eat up the RAM quickly.
cat /sys/kernel/mm/ksm/run showed KSM running, but pages_shared and pages_sharing ware both 0. After about 5 minutes the server was swapping like hell and was totally unresponsive. Only after I killed some VMs, the server was usable again and then suddendly also KSM kicked in.

So the questions is: Is this expected behaviour?
It seems logical that KSM needs some time to scan the memory for the first time. But how log should that take and how can one speed up this?

 

[tom]

its the expected behavior. I suggest you do not start all VMs immediately on reboot, so you do not run into swapping. see http://pve.proxmox.com/wiki/Virtual_Machine_Startup_and_Shutdown_Behavior

 

[spirit]

Hello,

I have one Proxmox node that uses KSM heavily (118GB assigned on 96GB physical RAM). Recently I had to reboot that node and after the reboot the VMs started up and began to eat up the RAM quickly.
cat /sys/kernel/mm/ksm/run showed KSM running, but pages_shared and pages_sharing ware both 0. After about 5 minutes the server was swapping like hell and was totally unresponsive. Only after I killed some VMs, the server was usable again and then suddendly also KSM kicked in.

So the questions is: Is this expected behaviour?
It seems logical that KSM needs some time to scan the memory for the first time. But how log should that take and how can one speed up this?

you can tune it in /etc/ksmtuned.conf