Red Hat Bugzilla – Bug 315471
[RHEL 5.2]: Tick divider bugs on x86_64
Last modified: 2009-07-20 05:59:33 EDT
+++ 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
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 email@example.com on 2007-09-25 09:16 EST --
Created an attachment (id=205451)
Patch to fix some of the tick divider problems
-- Additional comment from firstname.lastname@example.org 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 email@example.com on 2007-10-02 08:37 EST --
Looks sane on a first glance
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
You can download this test kernel from http://people.redhat.com/dzickus/el5
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).
confirmed fix is in the -92 kernel.
(In reply to comment #7)
> confirmed fix is in the -92 kernel.
I tried the -92 kernel from http://people.redhat.com/dzickus/el5. 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.
Right. That bug is being tracked separately, here:
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.