Rename runtime-config to executor-config and add documentation for Model Library Format

docs/dev/index.rst

@@ -410,3 +410,4 @@ microTVM
    :maxdepth: 1
 
    microtvm_design
+   model_library_format

docs/dev/model_library_format.rst

@@ -0,0 +1,167 @@
+..  Licensed to the Apache Software Foundation (ASF) under one
+    or more contributor license agreements.  See the NOTICE file
+    distributed with this work for additional information
+    regarding copyright ownership.  The ASF licenses this file
+    to you under the Apache License, Version 2.0 (the
+    "License"); you may not use this file except in compliance
+    with the License.  You may obtain a copy of the License at
+
+..    http://www.apache.org/licenses/LICENSE-2.0
+
+..  Unless required by applicable law or agreed to in writing,
+    software distributed under the License is distributed on an
+    "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+    KIND, either express or implied.  See the License for the
+    specific language governing permissions and limitations
+    under the License.
+
+Model Library Format
+====================
+
+About Model Library Format
+--------------------------
+
+TVM traditionally exports generated libraries as Dynamic Shared Objects
+(e.g. DLLs (Windows) or .so (linux)). Inference can be performed on those libraries by loading them
+into an executable using ``libtvm_runtime.so``. This process is very dependent on services provided
+by traditional OS.
+
+For deployment to unconventional platforms (e.g. those lacking traditional OS), the microTVM project
+can be used to export a generated library in pieces. In this case, microTVM provides another output
+format, Model Library Format. Model Library Format is a tarball containing a file for each part of
+the TVM compiler output.
+
+What can be Exported
+--------------------
+
+At the time of writing, export is limited to full models built with ``tvm.relay.build``.
+
+Directory Layout
+----------------
+
+Model Library Format is traditionally contained within a tarball. All paths are relative to the root
+of the tarball:
+
+- ``/`` - Root of the tarball
+
+  - ``codegen`` - Root directory for all generated device code
+
+    - (see `codegen`_ section)
+
+  - ``executor-config/`` - Configuration for the executor which drives model inference
+
+    - ``graph/`` - Root directory containing configuration for the GraphExecutor
+
+      - ``graph.json`` - GraphExecutor JSON configuration
+
+  -  ``metadata.json`` - Machine-parseable metadata for this model
+
+  - ``parameters/`` - Root directory where simplified parameters are placed
+
+    - ``<model_name>.params`` - Parameters for the model tvm.relay._save_params format
+
+  - ``src/`` - Root directory for all source code consumed by TVM
+
+    - ``relay.txt`` - Relay source code for the generated model
+
+Description of Sub-directories
+------------------------------
+
+.. _subdir_codegen:
+
+``codegen``
+^^^^^^^^^^^
+
+All TVM-generated code is placed in this directory. At the time of writing, there is 1 file per
+Module in the generated Module tree, though this restriction may change in the future. Files in
+this directory should have filenames of the form ``<target>/(lib|src)/<unique_name>.<format>``.
+
+These components are described below:
+
+ * ``<target>`` - Identifies the TVM target on which the code should run. Currently, only ``host``
+   is supported.
+ * ``<unique_name>`` - A unique slug identifying this file. Currently ``lib<n>``, with ``<n>>` an
+   autoincrementing integer.
+ * ``<format>`` - Suffix identifying the filename format. Currently ``c`` or ``o``.
+
+An example directory tree for a CPU-only model is shown below:
+
+- ``codegen/`` - Codegen directory
+
+  - ``host/`` - Generated code for ``target_host``
+
+    -  ``lib/`` - Generated binary object files
+
+      - ``lib0.o`` - LLVM module (if ``llvm`` target is used)
+      - ``lib1.o`` - LLVM CRT Metadata Module (if ``llvm`` target is used)
+    - ``src/`` - Generated C source
+
+      - ``lib0.c`` - C module (if ``c`` target is used)
+      - ``lib1.c`` - C CRT Metadata module (if ``c`` target is used)
+
+``executor-config``
+^^^^^^^^^^^^^^^^^^^
+
+Contains machine-parseable configuration for executors which can drive model inference. Currently,
+only the GraphExecutor produces configuration for this directory, in ``graph/graph.json``. This
+file should be read in and the resulting string supplied to the ``GraphExecutor()`` constructor for
+parsing.
+
+``parameters``
+^^^^^^^^^^^^^^
+
+Contains machine-parseable parameters. A variety of formats may be provided, but at present, only
+the format produced by ``tvm.relay._save_params`` is supplied. When building with
+``tvm.relay.build``,  the ``name`` parameter is considered to be the model name. A single file is
+created in this directory ``<model_name>.json``.
+
+``src``
+^^^^^^^
+
+Contains source code parsed by TVM. Currently, just the Relay source code is created in
+``src/relay.txt``.
+
+Metadata
+--------
+
+Machine-parseable metadata is placed in a file ``metadata.json`` at the root of the tarball.
+Metadata is a dictionary with these keys:
+
+- ``export_datetime``: Timestamp when this Model Library Format was generated, in
+  `strftime <https://docs.python.org/3/library/datetime.html#strftime-strptime-behavior>`_
+  format ``"%Y-%M-%d %H:%M:%SZ",``.
+- ``memory``: A summary of the memory usage of each generated function. Documented in
+  `Memory Usage Summary`_.
+- ``model_name``: The name of this model (e.g. the ``name`` parameter supplied to
+  ``tvm.relay.build``).
+- ``runtimes``: A list of runtimes supported by this model. Currently, this list is always
+  ``["graph"]``.
+- ``target``: A dictionary mapping ``device_type`` (the underlying integer, as a string) to the
+  sub-target which describes that relay backend used for that ``device_type``.
+- ``version``: A numeric version number that identifies the format used in this Model Library
+  Format. This number is incremented when the metadata structure or on-disk structure changes.
+  This document reflects version ``3``.
+
+Memory Usage Summary
+^^^^^^^^^^^^^^^^^^^^
+
+A dictionary with these sub-keys:
+
+ - ``"main"``: ``list[MainFunctionWorkspaceUsage]``. A list summarizing memory usage for each
+   workspace used by the main function and all sub-functions invoked.
+ - ``"operator_functions"``: ``map[string, list[FunctionWorkspaceUsage]]``. Maps operator function
+   name to a list summarizing memory usage for each workpace used by the function.
+
+A ``MainFunctionWorkspaceUsage`` is a dict with these keys:
+
+- ``"device"``: ``int``. The ``device_type`` associated with this workspace.
+- ``"workspace_size_bytes"``: ``int``. Number of bytes needed in this workspace by this function
+  and all sub-functions invoked.
+- ``"constants_size_bytes"``: ``int``. Size of the constants used by the main function.
+- ``"io_size_bytes"``: ``int``. Sum of the sizes of the buffers used from this workspace by this
+  function and sub-functions.
+
+A ``FunctionWorkspaceUsage`` is a dict with these keys:
+
+- ``"device"``: ``int``. The ``device_type`` associated with this workspace.
+- ``"workspace_size_bytes"``: ``int``. Number of bytes needed in this workspace by this function.

python/tvm/micro/model_library_format.py

@@ -227,7 +227,7 @@ def export_model_library_format(mod: executor_factory.ExecutorFactoryModule, fil
     runtime = ["aot"] if is_aot else ["graph"]
 
     metadata = {
-        "version": 2,
+        "version": 3,
         "model_name": mod.libmod_name,
         "export_datetime": datetime.datetime.now().strftime("%Y-%m-%d %H:%M:%SZ"),
         "memory": _build_memory_map(mod),
@@ -252,7 +252,7 @@ def export_model_library_format(mod: executor_factory.ExecutorFactoryModule, fil
         f.write(str(mod.ir_mod))
 
     if not is_aot:
-        graph_config_dir_path = tempdir.relpath(os.path.join("runtime-config", "graph"))
+        graph_config_dir_path = tempdir.relpath(os.path.join("executor-config", "graph"))
         os.makedirs(graph_config_dir_path)
         with open(os.path.join(graph_config_dir_path, "graph.json"), "w") as f:
             f.write(mod.get_executor_config())

tests/python/unittest/test_micro_model_library_format.py

@@ -33,7 +33,7 @@
 
 
 def validate_graph_json(extract_dir, factory):
-    with open(os.path.join(extract_dir, "runtime-config", "graph", "graph.json")) as graph_f:
+    with open(os.path.join(extract_dir, "executor-config", "graph", "graph.json")) as graph_f:
         graph_json = graph_f.read()
         assert graph_json == factory.graph_json