From 1852910ef0fd7393da62b88aee66ee092208748e Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sat, 27 Apr 2024 12:41:58 +0200 Subject: Adding upstream version 5.3.1. Signed-off-by: Daniel Baumann --- modules/detect_time_jump/README.rst | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) create mode 100644 modules/detect_time_jump/README.rst (limited to 'modules/detect_time_jump/README.rst') diff --git a/modules/detect_time_jump/README.rst b/modules/detect_time_jump/README.rst new file mode 100644 index 0000000..066f5a3 --- /dev/null +++ b/modules/detect_time_jump/README.rst @@ -0,0 +1,22 @@ +.. SPDX-License-Identifier: GPL-3.0-or-later + +.. _mod-detect_time_jump: + +Detect discontinuous jumps in the system time +============================================= + +This module detect discontinuous jumps in the system time when resolver +is running. It clears cache when a significant backward time jumps occurs. + +Time jumps are usually created by NTP time change or by admin intervention. +These change can affect cache records as they store timestamp and TTL in real +time. + +If you want to preserve cache during time travel you should disable +this module by ``modules.unload('detect_time_jump')``. + +Due to the way monotonic system time works on typical systems, +suspend-resume cycles will be perceived as forward time jumps, +but this direction of shift does not have the risk of using records +beyond their intended TTL, so forward jumps do not cause erasing the cache. + -- cgit v1.2.3