This article describes the issue of the xntpd[xxxx]: mlockall(): Resource temporarily unavailable error message being generated, when a configuration is committed.

When committing a configuration, the following log messages are generated:

Feb 9 23:50:36  xntpd: ntpd exiting on signal 1
Feb 9 23:50:36  xntpd[1304]: ntpd 4.2.0-a Sat Aug 25 06:07:26 UTC 2012 (1)
Feb 9 23:50:36  xntpd[1304]: mlockall(): Resource temporarily unavailable


This is a cosmetic issue and it can ignored in low-end platforms. Mlockall() system call locks down a certain portion of the physical memory address space, until a process exits or executes another program.

On low-end systems, the physical memory is a scarce resource; so each process has been allocated a fixed limit on how much they can lock down. When a process starts to use more and more memory during its run, at one point of time in their run, it will not be able to lock down any more, as it has reached the maximum on the limit.

When NTPD starts, it tries to lock the physical memory pages. During its run, in the future, it will try to lock down again and again on the pages that are mapped to its process. This might fail during future mappings, as the resource limits have been exceeded.

These messages are generated, when NTPD tries to lock down once again and mlockall() fails to do so; which essentially translates to try again in the future. This will not cause NTPD to fail in processing events. This message can be safely ignored on lower-end platforms.