CONFIG_HZ=1000 and CONFIG_HZ_1000=y should be changed to
CONFIG_HZ_100=y and CONFIG_HZ=100 in the s390/s390x kernel.

Rationale:
HZ for s390 kernels was always 100 since s390 is a virtualized architecture
that allows huge CPU overcommitment. With a higher HZ value the cost of the
timer interrupts is rising which reduces the performance of Linux guests
that run on shared CPUs. Since the high HZ value is not needed on s390 (no
multimedia stuff :) the HZ value should be changed to 100.