tree e8b1a70d41b2a61c72edae4bbb1114d75171be52
parent fbd59c99e9888c48c7f8298b0325bf4d4e063e28
author Paul E. McKenney <paul.mckenney@linaro.org> 1343325355 -0700
committer Paul E. McKenney <paulmck@linux.vnet.ibm.com> 1343759301 -0700

cpu: No more __stop_machine() in _cpu_down()

The _cpu_down() function invoked as part of the CPU-hotplug offlining
process currently invokes __stop_machine(), which is slow and inflicts
substantial real-time latencies on the entire system.  This patch
substitutes stop_cpus() for __stop_machine() in order to improve
both performance and real-time latency.

This is currently unsafe, because there are a number of uses of
preempt_disable() that are intended to block CPU-hotplug offlining.
These will be fixed, but in the meantime, this commit is one way to help
locate them.

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>