Chapter 5. Increasing the amount of memory that users are allowed to pin in the system
Remote direct memory access (RDMA) operations require the pinning of physical memory. As a consequence, the kernel is not allowed to write memory into the swap space. If a user pins too much memory, the system can run out of memory, and the kernel terminates processes to free up more memory. Therefore, memory pinning is a privileged operation.
If non-root users need to run large RDMA applications, it is necessary to increase the amount of memory to maintain pages in primary memory pinned all the time.
Procedure
As the
rootuser, create the file/etc/security/limits.confwith the following contents:@rdma soft memlock unlimited @rdma hard memlock unlimited
Verification
Log in as a member of the
rdmagroup after editing the/etc/security/limits.conffile.Note that Red Hat Enterprise Linux applies updated
ulimitsettings when the user logs in.Use the
ulimit -lcommand to display the limit:$ ulimit -l unlimitedIf the command returns
unlimited, the user can pin an unlimited amount of memory.
Additional resources
-
limits.conf(5)man page
