Document the updates to leader/followers MPM

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@96608 13f79535-47bb-0310-9956-ffa450edef68

diff --git a/CHANGES b/CHANGES
index bbba4e82b477d4692ded35944e32f6129fd3e985..ec3428aeb9a10b9516eb194e5ef499883c9d36ef 100644 (file)
--- a/CHANGES
+++ b/CHANGES
@@ -1,5 +1,9 @@
 Changes with Apache 2.0.41
 
+  *) Restored the experimental leader/followers MPM to working
+     condition and converted its thread synchronization from
+     mutexes to atomic CAS.  [Brian Pane]
+
   *) Fix Logic on non-html file removal in mod_deflate
      [Kris Verbeeck <Kris.Verbeeck@ubizen.com>]
 

diff --git a/server/mpm/experimental/leader/README b/server/mpm/experimental/leader/README
index a0dbde3efb0dc6c5c7782eefe8049e25a7e17c15..1981a5beedb5f986cd519ccd4df1624830c2eba5 100644 (file)
--- a/server/mpm/experimental/leader/README
+++ b/server/mpm/experimental/leader/README
@@ -3,6 +3,13 @@ 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
 
-As of Apache 2.0.39, the key learnings from the development of the
-leader MPMs have been applied to the worker MPM.  Worker now is
-running faster than leader in benchmark testing.
+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.