Bug 211902 - Time runnig at double speed on 2.6.18-1.2200.fc5/2.6.18-1.2798.fc6 (i586)
Time runnig at double speed on 2.6.18-1.2200.fc5/2.6.18-1.2798.fc6 (i586)
Product: Fedora
Classification: Fedora
Component: kernel (Show other bugs)
i386 Linux
medium Severity medium
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Assigned To: Kernel Maintainer List
Brian Brock
Depends On:
  Show dependency treegraph
Reported: 2006-10-23 15:22 EDT by David Bentley
Modified: 2007-12-31 02:05 EST (History)
5 users (show)

See Also:
Fixed In Version: F8
Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of:
Last Closed: 2007-12-31 02:05:31 EST
Type: ---
Regression: ---
Mount Type: ---
Documentation: ---
Verified Versions:
Category: ---
oVirt Team: ---
RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: ---

Attachments (Terms of Use)
dmesg output (15.65 KB, text/plain)
2006-10-23 15:27 EDT, David Bentley
no flags Details
dmesg output (15.66 KB, text/plain)
2006-10-23 15:28 EDT, David Bentley
no flags Details
dmesg output (16.96 KB, text/plain)
2006-10-28 15:26 EDT, David Bentley
no flags Details
Info as requested sorry for the delay hope it helps (8.32 KB, text/plain)
2007-02-08 14:49 EST, David Bentley
no flags Details

  None (edit)
Description David Bentley 2006-10-23 15:22:00 EDT
From Bugzilla Helper:
User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv: Gecko/20060913 Fedora/ Firefox/ pango-text

Description of problem:
Time is advancing at double speed on my K6 III/450 ASUS P5A based machine when running the latest kernel. 

All is OK with the previous kernel.

In the dmesg output both kernels show similar values for processor speed
2187 451.098 mhz 903.21 bogo mips and lpj 1806438
2200 451.068 mhz 902.78 bogo mips and lpj 1805564

So a timing loop error exists somwhere in the 2200 i586 kernel to cause the clck to run at double speed.

i initially spotted this thinking my ADSL had gone slow as a speed test which usually takes 27 seconds and returns a speed of 960k was returning a speed of 480k and showing as taking 54 seconds but speed tests on another machine gave the expected valus so I timed the test and found it to be reporting taking twice as long as it actually was ant therefore showing half the speed. I then booted into the previous kernel and found all was well again.

I will attach complete dmesg output from both kernels.

Version-Release number of selected component (if applicable):
kernel 2.6.18-1.2200.fc5 i586

How reproducible:

Steps to Reproduce:
boot into 2200

Actual Results:
see description

Expected Results:
Not to be in a time warp

Additional info:
Comment 1 David Bentley 2006-10-23 15:27:00 EDT
Created attachment 139158 [details]
dmesg output
Comment 2 David Bentley 2006-10-23 15:28:01 EDT
Created attachment 139159 [details]
dmesg output
Comment 3 David Bentley 2006-10-28 15:26:51 EDT
Created attachment 139649 [details]
dmesg output

I originally filed this bug against the latest kernel for FC5 but just having
installed FC6 the default kernel has the same problem on my ASUS P5A so I will
be reverting it back to FC5 after this bug update.
Comment 4 David Bentley 2006-10-28 15:34:20 EDT
Modifying bug to FC6 but it may be more appropriate to leave it as FC5 or even
show it as DEVEL as this is where the frantic kernel updates will get done once
FC7 development starts in ernist.

IF it would help I could run this system in rawhide mode or just boot into any
test kernel for FC5 to help diagnose the problem.
Comment 5 David Bentley 2006-10-28 15:39:22 EDT
Updated to show FC6 Kernel in summary
Comment 6 Dave Jones 2006-11-20 15:25:03 EST
does it go normal again if you boot with clocksource=tsc ?
Comment 7 john stultz 2006-11-20 17:08:30 EST
Looks to be due to the removal of verify_pmtmr_rate(). If I recall, it was
pulled as it slowed down boot times and there was some question as if it was
actually necessary (x86_64 didn't need it).

The question now regarding a fix is:

1) Do we just blacklist the affected chipset, using the current acpi_pm
blacklist infrastructure? Or... 
2) Re-add the verify_pmtmr_rate dynamic detection code.

Comment 8 David Bentley 2006-11-27 11:27:10 EST
I can confirm that if you boot with clocksource=tsc all is now well using the
latest FC5 kernel (2.6.18-1.2239.fc5) on my ASUS P5A box.

I presume the same fix should work for FC6 but I will wait for confirmation
before going through a backup of all data and installing FC6.

Presumably I could add this parameter during instalation so I may be able to
test if the fix works for FC6 without having to re-install if there is some way
of checking the time (from a console perhaps) before you commit yourself to do
the install. 
Comment 9 john stultz 2006-12-04 14:48:31 EST
David, could you please attach dmidecode output?
Comment 10 john stultz 2006-12-06 16:42:50 EST
A fix for this (re-adding the verify_pmtmr_rate code) has been sent to Andrew.
Comment 11 Ron Piggott 2007-01-15 20:15:53 EST
I have tried the above recommendations and this didn't correct the time on my
computer.  Please advise how I should proceed.
Comment 12 Ron Piggott 2007-01-28 20:01:44 EST
I have added clocksource=tsc to the /etc/grub.conf file and the clock is now
running at normal speed.  I have 2.6.19-1.2895.fc6 for my kernel
Comment 13 Samuel Sieb 2007-01-28 22:50:48 EST
clocksource=tsc worked for me too.  I was really wondering what was going on
when my server started running at double time...
Comment 14 David Bentley 2007-02-08 14:40:54 EST
Re comment #9

Sorry I missed the request for further info my ISP's spam filter has
occasionally been eating e-mails that should get forwarded to my test-list folder.

Anyway I am attaching it now.
Comment 15 David Bentley 2007-02-08 14:49:47 EST
Created attachment 147696 [details]
Info as requested sorry for the delay hope it helps

System is now running FC6 and since instalation has had the suggested fix (i.e
clocksource=tsc) added to the grub file.

System is currentl upto date running the latest kernel and I havent tried it
without the fix.
Comment 16 Jon Stanley 2007-12-30 21:40:49 EST
Per comment #15, I'm not sure whether you think that this bug can be closed or not.


I'm reviewing this bug as part of the kernel bug triage project, an attempt to
isolate current bugs in the Fedora kernel.


I am CC'ing myself to this bug, however this version of Fedora is no longer

Please attempt to reproduce this bug with a current version of Fedora (presently
Fedora 8). If the bug no longer exists, please close the bug or I'll do so in a
few days if there is no further information lodged.

Thanks for using Fedora!
Comment 17 Samuel Sieb 2007-12-31 01:59:50 EST
I'm running F8 now and I don't need that kernel parameter.  It's working fine now.
Comment 18 Jon Stanley 2007-12-31 02:05:31 EST
In that case, I'll close this one CURRENTRELEASE.  Thanks!

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