hwclock --systohc can hang on busy or virtual machine

Issue

• If the hwclock command with the --systohc option is not able to run continuously (without being interrupted for more than 100 ms) for at least 500 ms, it will never finish. This can occur on a machine that is busy or on a virtual machine where the physical CPUs are shared across a larger number of virtual CPUs.

The command

# sudo /sbin/hwclock --systohc -D

prints messages of following pattern:

Time elapsed since reference time has been 5.364920 seconds.
Delaying further to reach the new time.

and never terminates.

This causes a reboot or shutdown of a machine to effectively hang.

Additional info:

The design flaw in 2.17.2's hwclock that causes this problem was masked (not fixed!) by a bug introduced by a change made circa 2011-07-25. This ensures that it always terminates, but not correctly nor in the manner intended (nor was the intent of that change to fix the bug described above).

• We want to change the hwclock to the one as viewed on the date command.