[GitHub] [tvm] areusch commented on a change in pull request #8220: [DOCS] Add docs for Pass Instrument

[GitBox <gi...@apache.org>]

areusch commented on a change in pull request #8220:
URL: https://github.com/apache/tvm/pull/8220#discussion_r650085612



##########
File path: docs/dev/pass_infra.rst
##########
@@ -389,6 +396,103 @@ To allow other C++ modules to apply this pass, we declare a free function in
 
     TVM_DLL Pass FoldConstant();
 
+.. _pass_instrument_section_tag:
+
+Pass Instrument
+~~~~~~~~~~~~~~~
+
+``PassInstrument`` provides callbacks run when entering/exiting ``PassContext`` and before/after executing passes.
+Multiple ``PassInstrument`` instances can be registed into a single ``PassContext``.
+Instrument instances are called sequentially in the order of ``instruments`` argument passed to ``PassContext``.
+
+.. code:: c++
+
+    namespace instrument {
+
+    class PassInstrumentNode : public Object {
+     public:
+      String name;
+      virtual void EnterPassContext() const = 0;
+      virtual void ExitPassContext() const = 0;
+      virtual bool ShouldRun(const IRModule& mod, const transform::PassInfo& info) const = 0;
+      virtual void RunBeforePass(const IRModule& mod, const transform::PassInfo& info) const = 0;
+      virtual void RunAfterPass(const IRModule& mod, const transform::PassInfo& info) const = 0;
+      /* Other fields are omitted. */
+    };
+
+    class PassInstrument : public ObjectRef {
+     public:
+      TVM_DEFINE_OBJECT_REF_METHODS(PassInstrument, ObjectRef, PassInstrumentNode);
+    };
+
+    }  // namespace instrument
+
+Python interfaces are provided to implement ``PassInstrument`` quickly.
+
+Following four methods are invoked in the life-cycle of ``PassContext``.
+
+.. code:: c++
+
+    TVM_DLL void InstrumentEnterPassContext();
+    TVM_DLL void InstrumentExitPassContext();
+    TVM_DLL bool InstrumentBeforePass(const IRModule& mod, const PassInfo& info) const;
+    TVM_DLL void InstrumentAfterPass(const IRModule& mod, const PassInfo& info) const;
+
+``InstrumentEnterPassContext`` is called immediately when the scope
+of the ``PassContext`` instance is entered.
+
+``InstrumentExitPassContext`` is called when the scope of ``PassContextNode``
+is being leaved, or exceptions occur during the execution of passes.
+This method is also called when instruments is being overriden by ``override_instruments`` in ::py:class:`tvm.transform.PassContext`.
+
+``InstrumentBeforePass`` is called before pass-execution.
+``InstrumentAfterPass`` is called after pass-executioon if the pass should be run. The behavir is like:

Review comment:
       nit: execution, behavior

##########
File path: docs/dev/pass_infra.rst
##########
@@ -389,6 +396,103 @@ To allow other C++ modules to apply this pass, we declare a free function in
 
     TVM_DLL Pass FoldConstant();
 
+.. _pass_instrument_section_tag:
+
+Pass Instrument

Review comment:
       it seems like PassContext may be introduced after this section, no? Perhaps it makes sense to move it downward.

##########
File path: docs/dev/pass_infra.rst
##########
@@ -389,6 +396,103 @@ To allow other C++ modules to apply this pass, we declare a free function in
 
     TVM_DLL Pass FoldConstant();
 
+.. _pass_instrument_section_tag:
+
+Pass Instrument
+~~~~~~~~~~~~~~~
+
+``PassInstrument`` provides callbacks run when entering/exiting ``PassContext`` and before/after executing passes.
+Multiple ``PassInstrument`` instances can be registed into a single ``PassContext``.
+Instrument instances are called sequentially in the order of ``instruments`` argument passed to ``PassContext``.

Review comment:
       Don't abbreviate class names, it will get very confusing: s/Instrument/PassInstrument/

##########
File path: tutorials/dev/use_pass_instrument.py
##########
@@ -0,0 +1,229 @@
+# 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.
+# pylint: disable=line-too-long
+"""
+.. _tutorial-use-pass-instrument:
+
+How to Use TVM Pass Instrument
+==============================
+**Author**: `Chi-Wei Wang <https://github.com/chiwwang>`_
+
+As more and more passes are implemented, it becomes useful to instrument
+passes execution, analyze per-pass effects and observe various events.
+Pass infrastructure provides instrument mechanism. One can pass a list of
+instrument instances to :py:class:`tvm.transform.PassContext`.
+Also a decorator :py:func:`tvm.instrument.pass_instrument` is provided
+to easily implement instrument classes.
+
+This tutorial demostrates how developers can use ``PassContext`` to instrument
+passes. Please also refer to the :ref:`pass-infra`.
+"""
+import tvm
+import tvm.relay as relay
+from tvm.relay.testing import resnet
+from tvm.contrib.download import download_testdata
+from tvm.relay.build_module import bind_params_by_name
+from tvm.ir.instrument import (
+    PassTimingInstrument,
+    pass_instrument,
+)
+
+
+###############################################################################
+# Create An Example Relay Program
+# -------------------------------
+# We use pre-defined resnet-18 network in Relay.
+batch_size = 1
+num_of_image_class = 1000
+image_shape = (3, 224, 224)
+output_shape = (batch_size, num_of_image_class)
+relay_mod, relay_params = resnet.get_workload(num_layers=18, batch_size=1, image_shape=image_shape)
+print(relay_mod.astext(show_meta_data=False))
+
+
+###############################################################################
+# Create PassContext With Instruments
+# -----------------------------------
+# It is as simple as passing ``instruments`` argument to ``PassContext`` constructor.
+# A built-in ``PassTimingInstrument`` is used to profile the execution time of
+# each passes.
+timing_inst = PassTimingInstrument()
+with tvm.transform.PassContext(instruments=[timing_inst]):
+    relay_mod = relay.transform.InferType()(relay_mod)
+    relay_mod = relay.transform.FoldScaleAxis()(relay_mod)
+    # before exiting the context, get profile results.
+    profiles = timing_inst.render()
+print(profiles)
+
+
+###############################################################################
+# One can also use the current ``PassContext`` and register
+# ``PassInstrument`` instances by ``override_instruments`` method.
+# Note that ``override_instruments`` executes ``exit_pass_ctx`` callbacks
+# if any instrument already exists. Then it switches to new instruments
+# and calls ``enter_pass_ctx`` callbacks of new instruments.
+# Refer to following sections and :py:func:`tvm.instrument.pass_instrument` for these callbacks.
+cur_pass_ctx = tvm.transform.PassContext.current()
+cur_pass_ctx.override_instruments([timing_inst])
+relay_mod = relay.transform.InferType()(relay_mod)
+relay_mod = relay.transform.FoldScaleAxis()(relay_mod)
+profiles = timing_inst.render()
+print(profiles)
+
+
+###############################################################################
+# Register empty list to clear instruments.
+#
+# Note that ``exit_pass_ctx`` of ``PassTimingInstrument`` is called.
+# Profiles are cleared so nothing is printed.
+cur_pass_ctx.override_instruments([])
+# Uncomment the call to .render() to see a warning like:
+# Warning: no passes have been profiled, did you enable pass profiling?
+# profiles = timing_inst.render()
+
+
+###############################################################################
+# Create Customized Instrument Class
+# ----------------------------------
+# A customized instrument class can be easily created by
+# :py:func:`tvm.instrument.pass_instrument` decorator.
+#
+# Let's create an instrument class which calculate the difference of ``CallNode``
+# counting per ``op.name`` before and after passes.
+
+# decorate the class
+@pass_instrument
+class RelayCallNodeDiffer:
+    def __init__(self):
+        self._op_diff = []
+        # Passes can be nested.
+        # Use stack to make sure we get correct before/after pairs.
+        self._op_cnt_before_stack = []
+
+    def enter_pass_ctx(self):
+        self._op_diff = []
+        self._op_cnt_before_stack = []
+
+    def exit_pass_ctx(self):
+        assert len(self._op_cnt_before_stack) == 0, "The stack is not empty. Something wrong."
+
+    def run_before_pass(self, mod, info):
+        self._op_cnt_before_stack.append((info.name, self._count_nodes(mod)))
+
+    def run_after_pass(self, mod, info):
+        # Pop out the latest recorded pass.
+        name_before, op_to_cnt_before = self._op_cnt_before_stack.pop()
+        assert name_before == info.name, "name_before: {}, info.name: {} doesn't match".format(
+            name_before, info.name
+        )
+        cur_depth = len(self._op_cnt_before_stack)
+        op_to_cnt_after = self._count_nodes(mod)
+        op_diff = self._diff(op_to_cnt_after, op_to_cnt_before)
+        # only record passes causing differences.
+        if op_diff:
+            self._op_diff.append((cur_depth, info.name, op_diff))
+
+    def get_pass_to_op_diff(self):
+        """
+        return [
+          (depth, pass_name, {op_name: diff_num, ...}), ...
+        ]
+        """
+        return self._op_diff
+
+    @staticmethod
+    def _count_nodes(mod):
+        ret = {}
+
+        def visit(node):
+            if isinstance(node, relay.expr.Call):
+                try:
+                    op_name = node.op.name
+                except AttributeError:
+                    # Some CallNode may not have 'name' such as relay.Function
+                    return
+                try:
+                    ret[op_name] += 1
+                except KeyError:
+                    ret[op_name] = 1
+
+        relay.analysis.post_order_visit(mod["main"], visit)
+        return ret
+
+    @staticmethod
+    def _diff(d_after, d_before):
+        # d_after - d_before
+        ret = {}
+        key_after, key_before = set(d_after), set(d_before)
+        for k in key_before & key_after:
+            tmp = d_after[k] - d_before[k]
+            if tmp:
+                ret[k] = d_after[k] - d_before[k]
+        for k in key_after - key_before:
+            ret[k] = d_after[k]
+        for k in key_before - key_after:
+            ret[k] = -d_before[k]
+        return ret
+
+
+###############################################################################
+# Apply Passes and Multiple Instrument Classes
+# --------------------------------------------
+# Apply any pass you wish. Here :py:class:`tvm.relay.transform.ConvertLayout`
+# and :py:class:`tvm.relay.transform.FoldConstant` are used.
+#
+# ``ConvertLayout`` might add ``layout_transform`` Op while ``FoldConstant`` can
+# reduce the number of ``CallNode``.
+#
+# We can also use multiple instrument classes in a ``PassContext``.
+# However, it should be noted that instrument methods are executed sequentially,
+# obeying the order of ``instruments`` argument.
+# So for instrument classes like ``PassTimingInstrument``, it is inevitable to
+# count-up the execution time of other instrument classes to the final
+# profile result.
+call_node_inst = RelayCallNodeDiffer()
+desired_layouts = {
+    "nn.conv2d": ["NHWC", "HWIO"],
+}
+# Because layout_transform may be added as a successor of Constant,
+# we run FoldConstant twice.
+# Though it is obvious only the FoldConstant after the ConvertLayout matter,
+# we want to show how many layout_transform is added as a successor of
+# Constant.
+pass_seq = tvm.transform.Sequential(
+    [
+        relay.transform.FoldConstant(),
+        relay.transform.ConvertLayout(desired_layouts),
+        relay.transform.FoldConstant(),
+    ]
+)
+# bind parameters to make VarNode as ConstantNode.
+relay_mod["main"] = bind_params_by_name(relay_mod["main"], relay_params)
+# timing_inst is put after call_node_inst.
+# So the execution time of ``call_node.inst.run_after_pass()`` is also counted.
+with tvm.transform.PassContext(opt_level=3, instruments=[call_node_inst, timing_inst]):

Review comment:
       it would be super awesome to add another section demonstrating an exception case here!

##########
File path: docs/dev/pass_infra.rst
##########
@@ -389,6 +396,103 @@ To allow other C++ modules to apply this pass, we declare a free function in
 
     TVM_DLL Pass FoldConstant();
 
+.. _pass_instrument_section_tag:
+
+Pass Instrument
+~~~~~~~~~~~~~~~
+
+``PassInstrument`` provides callbacks run when entering/exiting ``PassContext`` and before/after executing passes.
+Multiple ``PassInstrument`` instances can be registed into a single ``PassContext``.
+Instrument instances are called sequentially in the order of ``instruments`` argument passed to ``PassContext``.
+
+.. code:: c++
+
+    namespace instrument {
+
+    class PassInstrumentNode : public Object {
+     public:
+      String name;
+      virtual void EnterPassContext() const = 0;
+      virtual void ExitPassContext() const = 0;
+      virtual bool ShouldRun(const IRModule& mod, const transform::PassInfo& info) const = 0;
+      virtual void RunBeforePass(const IRModule& mod, const transform::PassInfo& info) const = 0;
+      virtual void RunAfterPass(const IRModule& mod, const transform::PassInfo& info) const = 0;
+      /* Other fields are omitted. */
+    };
+
+    class PassInstrument : public ObjectRef {
+     public:
+      TVM_DEFINE_OBJECT_REF_METHODS(PassInstrument, ObjectRef, PassInstrumentNode);
+    };
+
+    }  // namespace instrument
+
+Python interfaces are provided to implement ``PassInstrument`` quickly.

Review comment:
       Perhaps it would be good to include a pointer to these, since a pointer to the C++ ones are above.

##########
File path: docs/dev/pass_infra.rst
##########
@@ -389,6 +396,103 @@ To allow other C++ modules to apply this pass, we declare a free function in
 
     TVM_DLL Pass FoldConstant();
 
+.. _pass_instrument_section_tag:
+
+Pass Instrument
+~~~~~~~~~~~~~~~
+
+``PassInstrument`` provides callbacks run when entering/exiting ``PassContext`` and before/after executing passes.
+Multiple ``PassInstrument`` instances can be registed into a single ``PassContext``.
+Instrument instances are called sequentially in the order of ``instruments`` argument passed to ``PassContext``.
+
+.. code:: c++
+
+    namespace instrument {
+
+    class PassInstrumentNode : public Object {
+     public:
+      String name;
+      virtual void EnterPassContext() const = 0;
+      virtual void ExitPassContext() const = 0;
+      virtual bool ShouldRun(const IRModule& mod, const transform::PassInfo& info) const = 0;
+      virtual void RunBeforePass(const IRModule& mod, const transform::PassInfo& info) const = 0;
+      virtual void RunAfterPass(const IRModule& mod, const transform::PassInfo& info) const = 0;
+      /* Other fields are omitted. */
+    };
+
+    class PassInstrument : public ObjectRef {
+     public:
+      TVM_DEFINE_OBJECT_REF_METHODS(PassInstrument, ObjectRef, PassInstrumentNode);
+    };
+
+    }  // namespace instrument
+
+Python interfaces are provided to implement ``PassInstrument`` quickly.
+
+Following four methods are invoked in the life-cycle of ``PassContext``.
+
+.. code:: c++
+
+    TVM_DLL void InstrumentEnterPassContext();
+    TVM_DLL void InstrumentExitPassContext();
+    TVM_DLL bool InstrumentBeforePass(const IRModule& mod, const PassInfo& info) const;
+    TVM_DLL void InstrumentAfterPass(const IRModule& mod, const PassInfo& info) const;
+
+``InstrumentEnterPassContext`` is called immediately when the scope
+of the ``PassContext`` instance is entered.
+
+``InstrumentExitPassContext`` is called when the scope of ``PassContextNode``
+is being leaved, or exceptions occur during the execution of passes.
+This method is also called when instruments is being overriden by ``override_instruments`` in ::py:class:`tvm.transform.PassContext`.
+
+``InstrumentBeforePass`` is called before pass-execution.
+``InstrumentAfterPass`` is called after pass-executioon if the pass should be run. The behavir is like:
+
+.. code:: c++
+
+      if (pass_ctx.InstrumentBeforePass(ir_module, pass_info)) {
+        new_ir_module = run_pass(ir_module, pass_ctx);
+        pass_ctx.InstrumentAfterPass(new_ir_module, pass_info);
+        return new_ir_module;
+      }
+
+Here is a brief introduction of each methods. See (`src/ir/transform.cc`_) for more details.
+
+- ``InstrumentEnterPassContext``
+
+  * ``EnterPassContext()`` is executed in the order of ``instruments`` passed to the ``PassContext``.
+  * When an exception raises, ``PassContext`` disable the pass instrumentation
+    by clearing all registered ``PassInstrument`` instances.
+  * Then ``PassContext`` execute ``ExitPassContext()`` method of each ``PassInstrument``
+    instances which successfully finished ``EnterPassContext()``
+  * For example, if ``PassInstrument`` A, B, and C are registered to a ``PassContext``
+    and A finished ``EnterPassContext()`` while B throws an exception, then C
+    is never executed; ``ExitPassContext()`` of A is executed.
+
+- ``InstrumentExitPassContext``
+
+  * ``ExitPassContext()`` of each ``PassInstrument`` instances are executed in
+    the order of ``instruments`` passed to the ``PassContext``.
+  * While an exception occurs, ``instruments`` is cleared.
+  * That means, instances registered after the one throwing exceptions do not execute ``ExitPassContext``.
+
+- ``InstrumentBeforePass``
+
+  * ``ShouldRun`` callbakc is executed if the pass is not listed as a required pass.

Review comment:
       i think you could just delete the word callback here. ShouldRun is an interface method.

##########
File path: docs/dev/pass_infra.rst
##########
@@ -389,6 +396,103 @@ To allow other C++ modules to apply this pass, we declare a free function in
 
     TVM_DLL Pass FoldConstant();
 
+.. _pass_instrument_section_tag:
+
+Pass Instrument
+~~~~~~~~~~~~~~~
+
+``PassInstrument`` provides callbacks run when entering/exiting ``PassContext`` and before/after executing passes.

Review comment:
       Since PassInstrument is an interface, it might be more helpful to speak about the interface as a whole rather than mention callbacks, which are just one way of implementing the interface. e.g.
   
   The PassInstrument interface allows you to run code when entering/exiting PassContext and before ...




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