limit distributed user option to one flag (#2512)

* limit user option to one flag

* add space for if

* check if intel cpu only backend

* cosmetic

* make it clear

* Align to look pretty

* docs update

CMakeLists.txt

@@ -144,23 +144,37 @@ option(NGRAPH_DEX_ONLY "Build CPU DEX without codegen" FALSE)
 option(NGRAPH_CODE_COVERAGE_ENABLE "Enable code coverage data collection" FALSE)
 option(NGRAPH_LIB_VERSIONING_ENABLE "Enable shared library versioning" FALSE)
 option(NGRAPH_PYTHON_BUILD_ENABLE "Enable build nGraph python package wheel" FALSE)
-option(NGRAPH_DISTRIBUTED_MLSL_ENABLE "Add distributed MLSL mode for CPU only backend" FALSE)
-option(NGRAPH_DISTRIBUTED_OMPI_ENABLE "Add distributed Open-MPI mode for all backend" FALSE)
 option(NGRAPH_PLAIDML_ENABLE "Enable the PlaidML backend" ${PLAIDML_FOUND})
+option(NGRAPH_DISTRIBUTED_ENABLE "Enable distributed training using MLSL/OpenMPI" OFF)
 
-if (NGRAPH_GPUH_ENABLE)
-    set(NGRAPH_GPU_ENABLE TRUE)
+if (NGRAPH_CPU_ENABLE
+        AND
+    ((NOT NGRAPH_GPU_ENABLE) AND (NOT NGRAPH_GPUH_ENABLE) 
+        AND (NOT NGRAPH_GENERIC_CPU_ENABLE) AND (NOT NGRAPH_INTELGPU_ENABLE))
+   )
+    set(NGRAPH_INTEL_CPU_ONLY_ENABLE ON)
 endif()
 
-if (NGRAPH_DISTRIBUTED_MLSL_ENABLE AND NGRAPH_DISTRIBUTED_OMPI_ENABLE)
+if (NGRAPH_DISTRIBUTED_ENABLE)
+    if ("${NGRAPH_DISTRIBUTED_ENABLE}" STREQUAL "MLSL")
+        if (NGRAPH_INTEL_CPU_ONLY_ENABLE)
+            set(NGRAPH_DISTRIBUTED_MLSL_ENABLE TRUE)
+        else()
             message(FATAL_ERROR
-                "Does not support the use of two distributed libraries simultaneously.\n"
-                "If CPU only backend recommend Intel MLSL by setting NGRAPH_DISTRIBUTED_MLSL_ENABLE flag to true.\n"
-                "For all other backends use OpenMPI by setting NGRAPH_DISTRIBUTED_OMPI_ENABLE flag to true.\n")
-elseif(NGRAPH_DISTRIBUTED_MLSL_ENABLE  OR NGRAPH_DISTRIBUTED_OMPI_ENABLE)
-    set(NGRAPH_DISTRIBUTED_ENABLE TRUE)
-else()
-    set(NGRAPH_DISTRIBUTED_ENABLE FALSE)
+                    "-DNGRAPH_DISTRIBUTED_ENABLE=MLSL to be used, if Intel CPU is the only backend enabled.\n"
+                    "Use -DNGRAPH_DISTRIBUTED_ENABLE=OMPI for all other situations.\n")
+        endif()
+    elseif("${NGRAPH_DISTRIBUTED_ENABLE}" STREQUAL  "OMPI")
+        set(NGRAPH_DISTRIBUTED_OMPI_ENABLE TRUE)
+    else()
+        message(FATAL_ERROR
+                    "Invalid arguments passed to NGRAPH_DISTRIBUTED_ENABLE, must select  one of  MLSL, OMPI or OFF.\n"
+                    "If using Intel CPU only backend, recommend Intel MLSL by setting -DNGRAPH_DISTRIBUTED_ENABLE=MLSL .\n")
+    endif()
+endif()
+
+if (NGRAPH_GPUH_ENABLE)
+    set(NGRAPH_GPU_ENABLE TRUE)
 endif()
 
 if (NGRAPH_ONNX_IMPORT_ENABLE)
@@ -185,8 +199,6 @@ NORMALIZE_BOOL(NGRAPH_INTERPRETER_ENABLE)
 NORMALIZE_BOOL(NGRAPH_NOP_ENABLE)
 NORMALIZE_BOOL(NGRAPH_GPUH_ENABLE)
 NORMALIZE_BOOL(NGRAPH_GENERIC_CPU_ENABLE)
-NORMALIZE_BOOL(NGRAPH_DISTRIBUTED_MLSL_ENABLE)
-NORMALIZE_BOOL(NGRAPH_DISTRIBUTED_OMPI_ENABLE)
 NORMALIZE_BOOL(NGRAPH_DEBUG_ENABLE)
 NORMALIZE_BOOL(NGRAPH_ONNX_IMPORT_ENABLE)
 NORMALIZE_BOOL(NGRAPH_DEX_ONLY)
@@ -205,8 +217,6 @@ message(STATUS "NGRAPH_INTERPRETER_ENABLE:      ${NGRAPH_INTERPRETER_ENABLE}")
 message(STATUS "NGRAPH_NOP_ENABLE:              ${NGRAPH_NOP_ENABLE}")
 message(STATUS "NGRAPH_GPUH_ENABLE:             ${NGRAPH_GPUH_ENABLE}")
 message(STATUS "NGRAPH_GENERIC_CPU_ENABLE:      ${NGRAPH_GENERIC_CPU_ENABLE}")
-message(STATUS "NGRAPH_DISTRIBUTED_MLSL_ENABLE: ${NGRAPH_DISTRIBUTED_MLSL_ENABLE}")
-message(STATUS "NGRAPH_DISTRIBUTED_OMPI_ENABLE: ${NGRAPH_DISTRIBUTED_OMPI_ENABLE}")
 message(STATUS "NGRAPH_DEBUG_ENABLE:            ${NGRAPH_DEBUG_ENABLE}")
 message(STATUS "NGRAPH_ONNX_IMPORT_ENABLE:      ${NGRAPH_ONNX_IMPORT_ENABLE}")
 message(STATUS "NGRAPH_DEX_ONLY:                ${NGRAPH_DEX_ONLY}")
@@ -215,6 +225,7 @@ message(STATUS "NGRAPH_LIB_VERSIONING_ENABLE:   ${NGRAPH_LIB_VERSIONING_ENABLE}"
 message(STATUS "NGRAPH_PYTHON_BUILD_ENABLE:     ${NGRAPH_PYTHON_BUILD_ENABLE}")
 message(STATUS "NGRAPH_USE_PREBUILT_LLVM:       ${NGRAPH_USE_PREBUILT_LLVM}")
 message(STATUS "NGRAPH_PLAIDML_ENABLE:          ${NGRAPH_PLAIDML_ENABLE}")
+message(STATUS "NGRAPH_DISTRIBUTED_ENABLE:      ${NGRAPH_DISTRIBUTED_ENABLE}")
 
 #-----------------------------------------------------------------------------------------------
 # Installation logic...

doc/sphinx/source/buildlb.rst

@@ -54,8 +54,6 @@ as needed:
    -- NGRAPH_NOP_ENABLE:               ON
    -- NGRAPH_GPUH_ENABLE:              OFF
    -- NGRAPH_GENERIC_CPU_ENABLE:       OFF
-   -- NGRAPH_DISTRIBUTED_MLSL_ENABLE:  OFF
-   -- NGRAPH_DISTRIBUTED_OMPI_ENABLE:  OFF
    -- NGRAPH_DEBUG_ENABLE:             OFF
    -- NGRAPH_ONNX_IMPORT_ENABLE:       OFF
    -- NGRAPH_DEX_ONLY:                 OFF
@@ -64,7 +62,7 @@ as needed:
    -- NGRAPH_PYTHON_BUILD_ENABLE:      OFF
    -- NGRAPH_USE_PREBUILT_LLVM:        OFF
    -- NGRAPH_PLAIDML_ENABLE:           OFF
-
+   -- NGRAPH_DISTRIBUTED_ENABLE:       OFF
 
 .. important:: The default :program:`cmake` procedure (no build flags) will  
    install ``ngraph_dist`` to an OS-level location like ``/usr/bin/ngraph_dist``

doc/sphinx/source/core/constructing-graphs/distribute-train.rst

@@ -16,12 +16,12 @@ more than one device.
 Frameworks can implement distributed training with nGraph versions prior to 
 `0.13`:
 
-* Use ``-DNGRAPH_DISTRIBUTED_OMPI_ENABLE=TRUE`` to enable distributed training 
+* Use ``-DNGRAPH_DISTRIBUTED_ENABLE=OMPI`` to enable distributed training 
   with OpenMPI. Use of this flag requires that OpenMPI be a pre-existing library 
   in the system. If it's not present on the system, install `OpenMPI`_ version 
   ``2.1.1`` or later before running the compile. 
 
-* Use ``-DNGRAPH_DISTRIBUTED_MLSL_ENABLE=TRUE`` to enable the option for 
+* Use ``-DNGRAPH_DISTRIBUTED_ENABLE=MLSL`` to enable the option for 
   :abbr:`Intel® Machine Learning Scaling Library (MLSL)` for Linux* OS:
 
   .. note:: The Intel® MLSL option applies to Intel® Architecture CPUs