Red Hat Bugzilla – Bug 305011
[RHEL 5.1.z]: Tick divider bugs on x86_64
Last modified: 2009-07-20 05:59:27 EDT
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.
Created attachment 205451 [details]
Patch to fix some of the tick divider problems
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
A patch for this issue has been included in build 2.6.18-53.1.2
confirmed fix is in the -53.1.2 kernel, looks to have already been verified by
setting back to on_qa as this will go out to customers in a later erratum.
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.