The patches below are from Laurent Vivier who didn't make them public.  They
add a new feature to ptrace on the host which cuts down on the number of
context switches needed for a UML system call, plus makes UML use it.

There's some interest in this, so I'm putting it out as-is.  I haven't played
with it.

Laurent did some performance testing and found ~40% speedup on a getpid
loop, and a 3.5% speedup on a kernel build.

				Jeff