Add a base README for list_plugins tool

Author: rmccorm4

.gitignore

@@ -7,3 +7,8 @@ resnet50/
 # TensorRT Engines
 *.plan
 *.engine
+
+# Plugins
+*.d
+*.o
+*.so

plugins/README.md

@@ -0,0 +1,91 @@
+# Plugins
+
+This directory contains some tools and samples related to
+TensorRT Plugins.
+
+## Listing Registered Plugins
+
+```
+$ python list_plugins.py -h
+usage: list_plugins.py [-h] [-p [PLUGINS [PLUGINS ...]]]
+
+Script to list registered TensorRT plugins. Can optionally load custom plugin
+libraries.
+
+optional arguments:
+  -h, --help            show this help message and exit
+  -p [PLUGINS [PLUGINS ...]], --plugins [PLUGINS [PLUGINS ...]]
+                        Path to a plugin (.so) library file. Accepts multiple
+                        arguments.
+```
+
+Default `TRT_RELEASE` plugins:
+```
+$ python list_plugins.py   
+2020-03-13 22:12:35 - __main__ - INFO - Registering plugins...
+2020-03-13 22:12:35 - __main__ - INFO - Registered Plugin Names:
+['RnRes2Br2bBr2c_TRT',
+ 'RnRes2Br1Br2c_TRT',
+ 'CgPersistentLSTMPlugin_TRT',
+ 'SingleStepLSTMPlugin',
+ ...
+ 'SpecialSlice_TRT',
+ 'InstanceNormalization_TRT']
+```
+
+## Registering OSS Plugins 
+
+When building the OSS components, the default plugin library may be overwritten
+or given precendence to the OSS plugin library. As long as you have both .so
+library files, you can load both:
+
+Build OSS Components:
+```
+$ wget https://raw.githubusercontent.com/rmccorm4/tensorrt-utils/master/OSS/build_OSS.sh
+$ source build_OSS.sh
+```
+
+Load and list multiple plugin libraries:
+```
+$ python list_plugins.py --plugins TensorRT/build/out/libnvinfer_plugin.so
+2020-03-13 22:18:51 - __main__ - INFO - Loading plugin library: /mnt/TensorRT/build/out/libnvinfer_plugin.so
+2020-03-13 22:18:51 - __main__ - INFO - Registering plugins...
+2020-03-13 22:18:51 - __main__ - INFO - Registered Plugin Names:
+['RnRes2Br2bBr2c_TRT',
+ 'RnRes2Br1Br2c_TRT',
+ 'CgPersistentLSTMPlugin_TRT',
+ 'SingleStepLSTMPlugin',
+ 'CustomEmbLayerNormPluginDynamic',    <------ OSS Plugins added
+ 'CustomFCPluginDynamic',              <------ OSS Plugins added
+ 'CustomGeluPluginDynamic',            <------ OSS Plugins added
+ 'CustomQKVToContextPluginDynamic',    <------ OSS Plugins added
+ 'CustomSkipLayerNormPluginDynamic',   <------ OSS Plugins added
+ ...
+ 'SpecialSlice_TRT',
+ 'InstanceNormalization_TRT']
+```
+
+## Registering Custom Plugins
+
+Same concept as above for OSS plugins, just giving an example to be extra clear:
+```
+$ pushd CustomIPluginV2/
+$ make
+g++ -g -std=c++11 -DNDEBUG -fPIC -MD -MP -I. -I/usr/local/cuda/include -I/usr/src/tensorrt/include -o CustomPlugin.o -c CustomPlugin.cpp
+g++ -g -std=c++11 -DNDEBUG -shared -o CustomPlugin.so CustomPlugin.o -L/usr/local/cuda/lib64 -L/usr/src/tensorrt/lib  -lnvinfer -lcudart
+
+$ popd
+$ python list_plugins.py --plugins CustomIPluginV2/CustomPlugin.so
+2020-03-13 22:16:06 - __main__ - INFO - Loading plugin library: CustomIPluginV2/CustomPlugin.so
+Plugin attribute number: 5
+2020-03-13 22:16:06 - __main__ - INFO - Registering plugins...
+2020-03-13 22:16:06 - __main__ - INFO - Registered Plugin Names:
+['RnRes2Br2bBr2c_TRT',
+ 'RnRes2Br1Br2c_TRT',
+ 'CgPersistentLSTMPlugin_TRT',
+ 'SingleStepLSTMPlugin',
+ 'CustomPlugin',           <------------- Custom plugin registered
+ ...
+ 'SpecialSlice_TRT',
+ 'InstanceNormalization_TRT']
+```

plugins/list_plugins.py

@@ -63,7 +63,6 @@ def get_all_plugin_names(plugin_registry):
     parser.add_argument("-p", "--plugins", nargs="*", default=[], help="Path to a plugin (.so) library file. Accepts multiple arguments.")
     args = parser.parse_args()
 
-    print(args.plugins)
     for plugin_library in args.plugins:
         # Example default plugin library: "/usr/lib/x86_64-linux-gnu/libnvinfer_plugin.so"
         logger.info("Loading plugin library: {}".format(plugin_library))