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Bug 315471 - [RHEL 5.2]: Tick divider bugs on x86_64
Summary: [RHEL 5.2]: Tick divider bugs on x86_64
Alias: None
Product: Red Hat Enterprise Linux 5
Classification: Red Hat
Component: kernel
Version: 5.1
Hardware: All
OS: Linux
Target Milestone: rc
: ---
Assignee: Chris Lalancette
QA Contact: Martin Jenner
Depends On: 305011
Blocks: 420521 422431 422441
TreeView+ depends on / blocked
Reported: 2007-10-02 15:05 UTC by Chris Lalancette
Modified: 2009-07-20 09:59 UTC (History)
12 users (show)

Fixed In Version: RHBA-2008-0314
Doc Type: Bug Fix
Doc Text:
Clone Of:
Last Closed: 2008-05-21 14:56:57 UTC
Target Upstream Version:

Attachments (Terms of Use)

System ID Priority Status Summary Last Updated
Red Hat Product Errata RHBA-2008:0314 normal SHIPPED_LIVE Updated kernel packages for Red Hat Enterprise Linux 5.2 2008-05-20 18:43:34 UTC

Description Chris Lalancette 2007-10-02 15:05:49 UTC
+++ This bug was initially created as a clone of Bug #305011 +++

Description of problem:
On x86_64, the tick divider patch seems to have multiple bugs, which cause
problems on VMware ESX server.  In particular, because not all of the clocks are
being properly divided, it needs many more interrupts than a kernel re-compiled
to 100HZ would, and can cause time drift.  The problems identified so far are:

1)  It does not set the local APIC to the "divided" value; it leaves it at the
undivided value.
2)  It does not properly account for lost ticks when using PM-timer (it thinks
there are more lost ticks than there actually are).
3)  It does not properly account for lost ticks when using TSC.

A preliminary patch (based on input from VMware) is attached.

-- Additional comment from on 2007-09-25 09:16 EST --
Created an attachment (id=205451)
Patch to fix some of the tick divider problems

-- Additional comment from on 2007-09-28 13:15 EST --
requesting this for async errata after 5.1 GA release. The current broken 5.1
implementation will cause problems for fv and VMware clients.

requested for the first 5.1.z kernel errata

-- Additional comment from on 2007-10-02 08:37 EST --
Looks sane on a first glance

Comment 1 RHEL Product and Program Management 2007-10-18 21:36:02 UTC
This request was evaluated by Red Hat Product Management for inclusion in a Red
Hat Enterprise Linux maintenance release.  Product Management has requested
further review of this request by Red Hat Engineering, for potential
inclusion in a Red Hat Enterprise Linux Update release for currently deployed
products.  This request is not yet committed for inclusion in an Update

Comment 4 Don Zickus 2007-11-29 17:07:15 UTC
in 2.6.18-58.el5
You can download this test kernel from

Comment 5 Johnny Hughes 2008-01-03 12:13:57 UTC
I would like to report that "divider=10 clocksource=pit" causes a hang on bootup.

This happens with the 2.6.18-53.1.4.el5 kernel and the latest one from the link
in #4 (kernel-2.6.18-62.el5).

Comment 7 Mike Gahagan 2008-05-02 20:21:12 UTC
confirmed fix is in the -92 kernel.

Comment 8 Akemi Yagi 2008-05-03 00:58:29 UTC
(In reply to comment #7)
> confirmed fix is in the -92 kernel.

I tried the -92 kernel from  However
addition of divider=10 AND clocksource=pit did cause a hang.  If I do not add
clocksource=pit, the system boots normally.  It looks like the issue still
exists in this test kernel.


Comment 9 Chris Lalancette 2008-05-03 13:53:03 UTC
Right.  That bug is being tracked separately, here:

Chris Lalancette

Comment 11 errata-xmlrpc 2008-05-21 14:56:57 UTC
An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on the solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.

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