The Linux kernel supports the following overcommit handling modes.




Heuristic overcommit handling. Obvious overcommits of address space are refused. Used for a typical system. It ensures a seriously wild allocation fails while allowing overcommit to reduce swap usage. root is allowed to allocate slighly more memory in this mode. This is the default.


Always overcommit. Appropriate for some scientific applications.


Don't overcommit. The total address space commit for the system is not permitted to exceed swap + a configurable percentage (default is 50) of physical RAM. Depending on the percentage you use, in most situations this means a process will not be killed while accessing pages but will receive errors on memory allocation as appropriate.

The overcommit policy is set via the sysctl `vm.overcommit_memory'.

The overcommit percentage is set via `vm.overcommit_ratio'.

The current overcommit limit and amount committed are viewable in /proc/meminfo as CommitLimit and Committed_AS respectively.


How It Works

The overcommit is based on the following rules:


To Do

LinuxMM: OverCommitAccounting (last edited 2017-12-30 01:05:10 by localhost)