Updating README with ML collectives information

This commit was SVN r27101.

README

@@ -431,6 +431,45 @@ Collectives
   MPI process onto Mellanox QDR InfiniBand switch CPUs and HCAs.
 
 
+- The "ML" coll component is an implementation of MPI collective 
+  operations that takes advantage of communication hierarchies 
+  in modern systems. A ML collective operation is implemented by 
+  combining multiple independently progressing collective primitives 
+  implemented over different communication hierarchies, hence a ML 
+  collective operation is also reffered to as a hierarchical collective 
+  operation. The number of collective primitives that are included in a 
+  ML collective operation is a function of subgroups(hierarchies). 
+  Typically, MPI processes in a single communication hierarchy such as 
+  CPU socket, node, or subnet are grouped together into a single subgroup
+  (hierarchy). The number of subgroups are configurable at runtime, 
+  and each different collective operation could be configured to have 
+  a different of number of subgroups.
+
+  The component frameworks and components used by\required for a 
+  "ML" collective operation.
+
+  Frameworks: 
+  * "sbgp" - Provides functionality for grouping processes into subgroups
+  * "bcol" - Provides collective primitives optimized for a particular 
+           communication hierarchy
+
+  Components:
+  * sbgp components     - Provides grouping functionality over a CPU socket(
+                          "basesocket"), shared memory ("basesmuma"), 
+                          Mellanox's ConnectX HCA ("ibnet"), and other 
+                          interconnects supported by PML ("p2p")
+
+  * BCOL components     - Provides optimized collective primitives for 
+                          shared memory ("basesmuma"), Mellanox's ConnectX 
+                          HCA ("iboffload"), and other interconnects supported 
+                          by PML ("ptpcoll")
+
+  * "ofacm"             - Provides connection manager functionality for InfiniBand communications
+  * "verbs"             - Provides commonly used verbs utilities
+  * "netpatterns"       - Provides an implementation of algorithm patterns 
+  * "commpatterns"      - Provides collectives for bootstrap
+   
+
 Network Support
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