Preemption Statistics Tool

This patch instructs the preemptible kernel to
generate and provide statistics on non-preemptible
regions in the linux kernel.  These regions correspond
to held locks.  The goal would be to find the worst-case
locking times and do something about them.

Requires preempt-kernel patch.

Note if you are using this with the lock-break patch,
one of the two will fail to patch on config.in -- it is
a trivial hand edit.

Use:
Patch source.  Enable CONFIG_PREEMPT_TIMES.  Compile.

Read /proc/latencytimes once to enable.

Read /proc/latencytimes again for top 20 worst-case results.
Each read clears the buffer.