r8 - 2015-03-15 - 22:19:17 - HarlanStennYou are here: NTP >  Support Web > OtherDocumentation > LockingNtpdInMemory
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ntp-4.2.8p15 was released on 23 June 2020. It addresses 1 medium-severity security issue in ntpd, and provides 13 non-security bugfixes over 4.2.8p13.

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REFACTOR See LockingNtpdInMemoryDev for discussion of this topic.

6.9. Locking ntpd in memory

Currently, ntpd will lock itself in memory if the appropriate system calls are available.

This is generally good because it means ntpd can quickly respond to time updates.

For some OSes, the amount of locked memory is currently hardcoded in ntpd.c.

This is Suboptimal.

  • AIX: reserve 32k of extra stack space (less 8 4k pages).
  • WINNT callls SetProcessWorkingSetSize() and VirtualLock(), at about 4MB(?).
  • Systems that use setrlimit() and mlockall() seem to reserve an extra 50 4k pages.
    • this seems to be too much for some *BSD systems, and not enough for some linux systems.

If the ntp.conf file contains rlimit memlock 0 then no memory will be locked. But this needs to be re-examined and better documented, as there is code in ntpd.c for rlimit and then later, when ntp_config() is called, we get a value for do_memlock.

Related Topics: NtpdProcessResidencyIssues, bug_small.png Bug #387

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