Red Hat Bugzilla – Bug 432093
Kernel defaults to nonworking clocksource, yum stalls, time jumped
Last modified: 2009-07-14 14:23:45 EDT
Host: i386, 4gb, Fedora 8, 22.214.171.124-115.fc8, running vmware server
guest: rawhide from recent alpha 1 dvd, 2.6.24-2.fc9, 784 mb
I tried to run "yum update".
It downloaded >300 packages, started transaction, then stalled at 1/721
packages, after having installed hwdata.
On a second ssh I noticed the date jumped back to 2001-07-18.
I was unable to run "top" (it stalled)
I was unable to kill yum.
I was unable to poweroff (it did not shut down).
# cat /sys/devices/system/clocksource/clocksource0/current_clocksource
# cat /sys/devices/system/clocksource/clocksource0/available_clocksource
tsc acpi_pm jiffies
I have power cycled the vm, now having booted with boot option
It looks good this time (so far).
clocksource output same as above.
yum running and updating, clock still good.
Warren asked me to run another test with clocksource=acpi_pm (instead of nohz=off).
I will test that after the current yum update is done.
Yeah, if this is an SMP machine acpi_pm is the only viable clock source.
As said before, I had booted with nohz=off and I was able to complete the yum
Now I have booted with 2.6.24-23.fc9, using no kernel options.
I'm building mozilla inside this vm, works so far, will report progress.
Now the vm crashed. (note the host is running absolutely stable)
ssh sessions stalled.
vm still responds to ping, but can not login with ssh
interactive managing using vmware console does not work either
I can move the mouse (console cursor), but not enter anything.
Note that clock did NOT jump before the crash.
Rebooting, now trying clocksource=acpi_pm
using clocksource=acpi_pm I was able to complete a full build a full mozilla
In that case, closing this bug.
(In reply to comment #5)
> In that case, closing this bug.
How would an average user know that the explicit boot option is required?
Shouldn't the kernel set this clocksource on its own?
Hmm....good question. There is
thhat documents it, though.
Jon, in comment 1 you said, for SMP machines, the only clocksource that makes
sense is acpi_pm.
If that is true, then why doesn't the kernel use that clocksource automatically?
I propose to reopen this bug until we agree on the right solution. Changed summary.
(I think it should not be necessary that end users search and discover this boot
Could you shed a little more light on this? I just said what I said in comment
#1 since you had said that to me in another bug I think. However, I just
checked, and my c2d system is using tsc. I completed a full compile of
seamonkey in mock without issue there. Is this one of those 'tsc works unless
it doesn't' type things? :)
Or is there something that I've missed here?
The kernel tries to determine whether the tsc is reliable. Sometimes it gets
that wrong. That's why we have the overrides. So it can be made to work but it
isn't transparent to the user when that happens.
Changing version to '9' as part of upcoming Fedora 9 GA.
More information and reason for this action is here:
Kai, this is a vmware only problem or can you see that on real hardware as well ?
I saw it with vmware, only.
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