Red Hat Bugzilla – Bug 315181
whole system pauses for approx. 1 second when running chrony
Last modified: 2007-11-30 17:12:17 EST
The whole system pauses for approximately 1 second every few minutes.
The kernel thread events/0 consumes 100% of the CPU preventing any other
task from being scheduled for approximately 1 second. This started after
updating from kernel 2.6.20-1.2962.fc6.i686 to 18.104.22.168-42.fc6.i686. This
only occurs when running chrony (http://chrony.sunsite.dk/) to synchronise
time. (Chrony monitors and adjusts the hardware RTC as well as the kernel
software clock). Each pause is triggered every few minutes when chrony
accesses the RTC clock.
Version-Release number of selected component (if applicable):
(Confirmed with kernel 22.214.171.124-42.fc6.i686, 126.96.36.199-45.fc6 and
Steps to Reproduce:
1. Boot kernel 2.6.22.x-*.fc6
2. Run chrony
Whole OS pauses for approximately 1 second every few minutes.
No OS pauses.
This was caused by switching the kernel configuration from the old PC
compatible RTC driver to the new portable RTC class drivers.
diff -y /boot/config-2.6.20-1.2962.fc6 /boot/config-188.8.131.52-22.fc6
CONFIG_RTC=y | # CONFIG_RTC is not set
My investigation is detailed in this email to the fedora-list.
This is also a known bug in the Debian bug tracking system.
The RTC driver configuration change is reversed in Fedora 7 kernel
184.108.40.206-91.fc7. Fragment from the update notification:
Revert to the old RTC driver (#265721, #284191)
These other Red Hat bugzilla bugs are reported as to be fixed by reverting
the configuration change to use the old PC compatible RTC driver again and
is due for release in kernel 220.127.116.11-61.fc6.
I expect that this bug will be resolved by the same fix.
Should be fixed in -61. Test kernels are at
If you know how to install them manually you can test.
The test kernel fixes my bug. No more pauses.