How can i disable overcommit_memory?

Hi @agalysson,

Memory overcommit can be disabled by vm.overcommit_memory=2

0 is the default mode, where kernel heuristically determines the allocation by calculating the free memory compared to the allocation request being made. And setting it to 1 enables the wizardry mode, where kernel always advertises that it has enough free memory for any allocation. Setting to 2, means that processes can only allocate up to a configurable amount (overcommit_ratio) of RAM and will start getting allocation failure or OOM messages when it goes beyond that amount

Is it safe to do so, no. I haven’t seen any proper use case where disabling memory overcommit actually helped, unless you are 100% certain of the workload and hardware capacity. In case you are interested, install kernel-docs package and go to /Documentation/sysctl/vm.txt to read more, or read it online.

If you set vm.overcommit_memory=2 then it will overcommit up to the percentage of physical RAM configured in vm.overcommit_ratio (default is 50%).

echo 0/1/2 > /proc/sys/vm/overcommit_memory 

This will not survive a reboot. For persistence, put this in /etc/sysctl.conf file:

vm.overcommit_memory=X

and run sysctl -p. No need to reboot.

Regards, Kalin