Bug 1206504 – RFE: option to correct clock for leap second by slewing

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Bug 1206504 - RFE: option to correct clock for leap second by slewing

Summary:	RFE: option to correct clock for leap second by slewing

Status:	CLOSED ERRATA

Aliases:	None

Product:	Red Hat Enterprise Linux 7
Classification:	Red Hat
Component:	chrony (Show other bugs)
Sub Component:
Version:	7.1
Hardware:	Unspecified Unspecified

Priority	unspecified Severity unspecified
Target Milestone:	rc
Target Release:	---
Assigned To:	Miroslav Lichvar
QA Contact:	Jakub Prokes
Docs Contact:

URL:
Whiteboard:
Keywords:	FutureFeature

Depends On:
Blocks:
	Show dependency tree / graph

Reported:	2015-03-27 06:05 EDT by Miroslav Lichvar
Modified:	2016-10-24 03:32 EDT (History)
CC List:	7 users (show)

See Also:
Fixed In Version:	chrony-2.0-1.el7
Doc Type:	Enhancement
Doc Text:	The chronyd service now supports four modes of handling leap seconds, configured using the "leapsecmode" option. The clock can be either stepped by the kernel (the default "system" mode), stepped by chronyd ("step" mode), slowly adjusted by slewing ("slew" mode), or the leap second can be ignored and corrected later in normal operation ("ignore" mode). If you select slewing, the correction will always start at 0:00:00 UTC and will be applied at a rate specified in the "maxslewrate" option.
Story Points:	---
Clone Of:
Environment:
Last Closed:	2015-11-19 03:29:44 EST
Type:	Bug
Regression:	---
Mount Type:	---
Documentation:	---
CRM:
Verified Versions:
Category:	---
oVirt Team:	---
RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---

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External Trackers
Tracker	ID	Priority	Status	Summary	Last Updated
Red Hat Product Errata	RHSA-2015:2241	normal	SHIPPED_LIVE	Moderate: chrony security, bug fix, and enhancement update	2015-11-19 03:59:36 EST

Groups: None (edit)

Description Miroslav Lichvar 2015-03-27 06:05:01 EDT

Description of problem:
When leap second is inserted to UTC, the system clock is corrected by the kernel by stepping the clock backwards at 0:00:00 UTC. This can be a problem for applications which need the system time to be monotonic or without any jumps.

The development version of chrony now has a new option "leapsecmode" which can be used to select between different leap second handling modes. The clock can be either stepped by the kernel (the default), stepped by chronyd, slowly adjusted by slewing, or the leap second can be ignored and corrected later in normal operation.

When the slewing mode is used, the correction starts at 0:00:00 UTC and is applied at the slewing rate set by the maxslewrate directive. The fixed starting time means that clocks on all NTP clients using the same setting stay together during that correction.

http://git.tuxfamily.org/chrony/chrony.git/commit/?id=f8db83249133127f32281f80a2fc1ce1faaba203

Version-Release number of selected component (if applicable):
chrony-1.29.1

Comment 4 errata-xmlrpc 2015-11-19 03:29:44 EST

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://rhn.redhat.com/errata/RHSA-2015-2241.html

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