Bug 450415 - Investigate adding the Pulse-Per-Second (PPS) patch or equivalent
Summary: Investigate adding the Pulse-Per-Second (PPS) patch or equivalent
Alias: None
Product: Red Hat Enterprise MRG
Classification: Red Hat
Component: realtime-kernel
Version: 1.0
Hardware: All
OS: Linux
Target Milestone: ---
: ---
Assignee: Red Hat Real Time Maintenance
QA Contact:
Depends On:
TreeView+ depends on / blocked
Reported: 2008-06-08 01:17 UTC by Clark Williams
Modified: 2009-09-23 16:22 UTC (History)
3 users (show)

Fixed In Version:
Doc Type: Enhancement
Doc Text:
Clone Of:
Last Closed: 2009-09-23 16:22:06 UTC
Target Upstream Version:

Attachments (Terms of Use)

Description Clark Williams 2008-06-08 01:17:28 UTC
Description of problem:

Many of our customers have expressed a desire to synchronise multiple systems in
a datacenter to sub-millisecond time resolutions. Currently, NTP is unable to
maintain this level of synchronization. We should investigate the utility of
combining a GPS precision time source with either a multi-drop serial interface
or  a dedicated ethernet interface, as a periodic update to NTP.

Comment 1 Clark Williams 2008-06-08 01:19:52 UTC
Ah re-reading my above, I realized that I didn't state that I'm aware that the
current PPS patch is unsuitable for inclusion. We should look at starting from
that and possibly morphing it into a general purpose solution that:

1. Doesn't add it's own system calls
2. Possibly provides a clocksource
3. Doesn't suck

Comment 2 Clark Williams 2008-11-05 21:05:59 UTC
Some links for consideration

LinuxPPS website:

Seventh repost of PPS patch series to LKML:

Comment 3 Matt Castelein 2009-02-18 23:02:44 UTC
Would this just be for RHEL, or would Fedora benefit as well?  I would like to have this functionality without breaking kernel updates.

Comment 4 Clark Williams 2009-02-19 00:07:25 UTC
At present we're just talking about it for the MRT RT (realtime) kernel. I don't know of any plans to add it to RHEL or Fedora, since it's not upstream yet.

Comment 5 Beth Uptagrafft 2009-09-22 21:29:31 UTC
Clark, is this still something we want to pursue?

Comment 6 Clark Williams 2009-09-23 16:22:06 UTC
PPS has been added to the 2.6.31 upstream kernel. closing

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