Leader MPM:
This is an experimental variant of the standard worker MPM.
It uses a Leader/Followers design pattern to coordinate work among threads:
http://deuce.doc.wustl.edu/doc/pspdfs/lf.pdf

To use the leader MPM, add "--with-mpm=leader" to the configure
script's arguments when building the httpd.
  
This MPM depends on APR's atomic compare-and-swap operations for
thread synchronization.  If you are compiling for an x86 target
and you don't need to support 386s, or you're compiling for a
SPARC and you don't need to run on pre-UltraSPARC chips, add
"--enable-nonportable-atomics=yes" to the configure script's
arguments.  This will cause APR to implement atomic operations
using efficient opcodes not available in older CPUs.