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(beta) Building a Simple CPU Performance Profiler with FX#

Author: James Reed

In this tutorial, we are going to use FX to do the following:

  1. Capture PyTorch Python code in a way that we can inspect and gather statistics about the structure and execution of the code

  2. Build out a small class that will serve as a simple performance “profiler”, collecting runtime statistics about each part of the model from actual runs.

For this tutorial, we are going to use the torchvision ResNet18 model for demonstration purposes.

import torch
import torch.fx
import torchvision.models as models

rn18 = models.resnet18()
rn18.eval()
ResNet(
  (conv1): Conv2d(3, 64, kernel_size=(7, 7), stride=(2, 2), padding=(3, 3), bias=False)
  (bn1): BatchNorm2d(64, eps=1e-05, momentum=0.1, affine=True, track_running_stats=True)
  (relu): ReLU(inplace=True)
  (maxpool): MaxPool2d(kernel_size=3, stride=2, padding=1, dilation=1, ceil_mode=False)
  (layer1): Sequential(
    (0): BasicBlock(
      (conv1): Conv2d(64, 64, kernel_size=(3, 3), stride=(1, 1), padding=(1, 1), bias=False)
      (bn1): BatchNorm2d(64, eps=1e-05, momentum=0.1, affine=True, track_running_stats=True)
      (relu): ReLU(inplace=True)
      (conv2): Conv2d(64, 64, kernel_size=(3, 3), stride=(1, 1), padding=(1, 1), bias=False)
      (bn2): BatchNorm2d(64, eps=1e-05, momentum=0.1, affine=True, track_running_stats=True)
    )
    (1): BasicBlock(
      (conv1): Conv2d(64, 64, kernel_size=(3, 3), stride=(1, 1), padding=(1, 1), bias=False)
      (bn1): BatchNorm2d(64, eps=1e-05, momentum=0.1, affine=True, track_running_stats=True)
      (relu): ReLU(inplace=True)
      (conv2): Conv2d(64, 64, kernel_size=(3, 3), stride=(1, 1), padding=(1, 1), bias=False)
      (bn2): BatchNorm2d(64, eps=1e-05, momentum=0.1, affine=True, track_running_stats=True)
    )
  )
  (layer2): Sequential(
    (0): BasicBlock(
      (conv1): Conv2d(64, 128, kernel_size=(3, 3), stride=(2, 2), padding=(1, 1), bias=False)
      (bn1): BatchNorm2d(128, eps=1e-05, momentum=0.1, affine=True, track_running_stats=True)
      (relu): ReLU(inplace=True)
      (conv2): Conv2d(128, 128, kernel_size=(3, 3), stride=(1, 1), padding=(1, 1), bias=False)
      (bn2): BatchNorm2d(128, eps=1e-05, momentum=0.1, affine=True, track_running_stats=True)
      (downsample): Sequential(
        (0): Conv2d(64, 128, kernel_size=(1, 1), stride=(2, 2), bias=False)
        (1): BatchNorm2d(128, eps=1e-05, momentum=0.1, affine=True, track_running_stats=True)
      )
    )
    (1): BasicBlock(
      (conv1): Conv2d(128, 128, kernel_size=(3, 3), stride=(1, 1), padding=(1, 1), bias=False)
      (bn1): BatchNorm2d(128, eps=1e-05, momentum=0.1, affine=True, track_running_stats=True)
      (relu): ReLU(inplace=True)
      (conv2): Conv2d(128, 128, kernel_size=(3, 3), stride=(1, 1), padding=(1, 1), bias=False)
      (bn2): BatchNorm2d(128, eps=1e-05, momentum=0.1, affine=True, track_running_stats=True)
    )
  )
  (layer3): Sequential(
    (0): BasicBlock(
      (conv1): Conv2d(128, 256, kernel_size=(3, 3), stride=(2, 2), padding=(1, 1), bias=False)
      (bn1): BatchNorm2d(256, eps=1e-05, momentum=0.1, affine=True, track_running_stats=True)
      (relu): ReLU(inplace=True)
      (conv2): Conv2d(256, 256, kernel_size=(3, 3), stride=(1, 1), padding=(1, 1), bias=False)
      (bn2): BatchNorm2d(256, eps=1e-05, momentum=0.1, affine=True, track_running_stats=True)
      (downsample): Sequential(
        (0): Conv2d(128, 256, kernel_size=(1, 1), stride=(2, 2), bias=False)
        (1): BatchNorm2d(256, eps=1e-05, momentum=0.1, affine=True, track_running_stats=True)
      )
    )
    (1): BasicBlock(
      (conv1): Conv2d(256, 256, kernel_size=(3, 3), stride=(1, 1), padding=(1, 1), bias=False)
      (bn1): BatchNorm2d(256, eps=1e-05, momentum=0.1, affine=True, track_running_stats=True)
      (relu): ReLU(inplace=True)
      (conv2): Conv2d(256, 256, kernel_size=(3, 3), stride=(1, 1), padding=(1, 1), bias=False)
      (bn2): BatchNorm2d(256, eps=1e-05, momentum=0.1, affine=True, track_running_stats=True)
    )
  )
  (layer4): Sequential(
    (0): BasicBlock(
      (conv1): Conv2d(256, 512, kernel_size=(3, 3), stride=(2, 2), padding=(1, 1), bias=False)
      (bn1): BatchNorm2d(512, eps=1e-05, momentum=0.1, affine=True, track_running_stats=True)
      (relu): ReLU(inplace=True)
      (conv2): Conv2d(512, 512, kernel_size=(3, 3), stride=(1, 1), padding=(1, 1), bias=False)
      (bn2): BatchNorm2d(512, eps=1e-05, momentum=0.1, affine=True, track_running_stats=True)
      (downsample): Sequential(
        (0): Conv2d(256, 512, kernel_size=(1, 1), stride=(2, 2), bias=False)
        (1): BatchNorm2d(512, eps=1e-05, momentum=0.1, affine=True, track_running_stats=True)
      )
    )
    (1): BasicBlock(
      (conv1): Conv2d(512, 512, kernel_size=(3, 3), stride=(1, 1), padding=(1, 1), bias=False)
      (bn1): BatchNorm2d(512, eps=1e-05, momentum=0.1, affine=True, track_running_stats=True)
      (relu): ReLU(inplace=True)
      (conv2): Conv2d(512, 512, kernel_size=(3, 3), stride=(1, 1), padding=(1, 1), bias=False)
      (bn2): BatchNorm2d(512, eps=1e-05, momentum=0.1, affine=True, track_running_stats=True)
    )
  )
  (avgpool): AdaptiveAvgPool2d(output_size=(1, 1))
  (fc): Linear(in_features=512, out_features=1000, bias=True)
)

Now that we have our model, we want to inspect deeper into its performance. That is, for the following invocation, which parts of the model are taking the longest?

input = torch.randn(5, 3, 224, 224)
output = rn18(input)

A common way of answering that question is to go through the program source, add code that collects timestamps at various points in the program, and compare the difference between those timestamps to see how long the regions between the timestamps take.

That technique is certainly applicable to PyTorch code, however it would be nicer if we didn’t have to copy over model code and edit it, especially code we haven’t written (like this torchvision model). Instead, we are going to use FX to automate this “instrumentation” process without needing to modify any source.

First, let’s get some imports out of the way (we will be using all of these later in the code).

import statistics, tabulate, time
from typing import Any, Dict, List
from torch.fx import Interpreter

참고

tabulate is an external library that is not a dependency of PyTorch. We will be using it to more easily visualize performance data. Please make sure you’ve installed it from your favorite Python package source.

Capturing the Model with Symbolic Tracing#

Next, we are going to use FX’s symbolic tracing mechanism to capture the definition of our model in a data structure we can manipulate and examine.

traced_rn18 = torch.fx.symbolic_trace(rn18)
print(traced_rn18.graph)
graph():
    %x : torch.Tensor [num_users=1] = placeholder[target=x]
    %conv1 : [num_users=1] = call_module[target=conv1](args = (%x,), kwargs = {})
    %bn1 : [num_users=1] = call_module[target=bn1](args = (%conv1,), kwargs = {})
    %relu : [num_users=1] = call_module[target=relu](args = (%bn1,), kwargs = {})
    %maxpool : [num_users=2] = call_module[target=maxpool](args = (%relu,), kwargs = {})
    %layer1_0_conv1 : [num_users=1] = call_module[target=layer1.0.conv1](args = (%maxpool,), kwargs = {})
    %layer1_0_bn1 : [num_users=1] = call_module[target=layer1.0.bn1](args = (%layer1_0_conv1,), kwargs = {})
    %layer1_0_relu : [num_users=1] = call_module[target=layer1.0.relu](args = (%layer1_0_bn1,), kwargs = {})
    %layer1_0_conv2 : [num_users=1] = call_module[target=layer1.0.conv2](args = (%layer1_0_relu,), kwargs = {})
    %layer1_0_bn2 : [num_users=1] = call_module[target=layer1.0.bn2](args = (%layer1_0_conv2,), kwargs = {})
    %add : [num_users=1] = call_function[target=operator.add](args = (%layer1_0_bn2, %maxpool), kwargs = {})
    %layer1_0_relu_1 : [num_users=2] = call_module[target=layer1.0.relu](args = (%add,), kwargs = {})
    %layer1_1_conv1 : [num_users=1] = call_module[target=layer1.1.conv1](args = (%layer1_0_relu_1,), kwargs = {})
    %layer1_1_bn1 : [num_users=1] = call_module[target=layer1.1.bn1](args = (%layer1_1_conv1,), kwargs = {})
    %layer1_1_relu : [num_users=1] = call_module[target=layer1.1.relu](args = (%layer1_1_bn1,), kwargs = {})
    %layer1_1_conv2 : [num_users=1] = call_module[target=layer1.1.conv2](args = (%layer1_1_relu,), kwargs = {})
    %layer1_1_bn2 : [num_users=1] = call_module[target=layer1.1.bn2](args = (%layer1_1_conv2,), kwargs = {})
    %add_1 : [num_users=1] = call_function[target=operator.add](args = (%layer1_1_bn2, %layer1_0_relu_1), kwargs = {})
    %layer1_1_relu_1 : [num_users=2] = call_module[target=layer1.1.relu](args = (%add_1,), kwargs = {})
    %layer2_0_conv1 : [num_users=1] = call_module[target=layer2.0.conv1](args = (%layer1_1_relu_1,), kwargs = {})
    %layer2_0_bn1 : [num_users=1] = call_module[target=layer2.0.bn1](args = (%layer2_0_conv1,), kwargs = {})
    %layer2_0_relu : [num_users=1] = call_module[target=layer2.0.relu](args = (%layer2_0_bn1,), kwargs = {})
    %layer2_0_conv2 : [num_users=1] = call_module[target=layer2.0.conv2](args = (%layer2_0_relu,), kwargs = {})
    %layer2_0_bn2 : [num_users=1] = call_module[target=layer2.0.bn2](args = (%layer2_0_conv2,), kwargs = {})
    %layer2_0_downsample_0 : [num_users=1] = call_module[target=layer2.0.downsample.0](args = (%layer1_1_relu_1,), kwargs = {})
    %layer2_0_downsample_1 : [num_users=1] = call_module[target=layer2.0.downsample.1](args = (%layer2_0_downsample_0,), kwargs = {})
    %add_2 : [num_users=1] = call_function[target=operator.add](args = (%layer2_0_bn2, %layer2_0_downsample_1), kwargs = {})
    %layer2_0_relu_1 : [num_users=2] = call_module[target=layer2.0.relu](args = (%add_2,), kwargs = {})
    %layer2_1_conv1 : [num_users=1] = call_module[target=layer2.1.conv1](args = (%layer2_0_relu_1,), kwargs = {})
    %layer2_1_bn1 : [num_users=1] = call_module[target=layer2.1.bn1](args = (%layer2_1_conv1,), kwargs = {})
    %layer2_1_relu : [num_users=1] = call_module[target=layer2.1.relu](args = (%layer2_1_bn1,), kwargs = {})
    %layer2_1_conv2 : [num_users=1] = call_module[target=layer2.1.conv2](args = (%layer2_1_relu,), kwargs = {})
    %layer2_1_bn2 : [num_users=1] = call_module[target=layer2.1.bn2](args = (%layer2_1_conv2,), kwargs = {})
    %add_3 : [num_users=1] = call_function[target=operator.add](args = (%layer2_1_bn2, %layer2_0_relu_1), kwargs = {})
    %layer2_1_relu_1 : [num_users=2] = call_module[target=layer2.1.relu](args = (%add_3,), kwargs = {})
    %layer3_0_conv1 : [num_users=1] = call_module[target=layer3.0.conv1](args = (%layer2_1_relu_1,), kwargs = {})
    %layer3_0_bn1 : [num_users=1] = call_module[target=layer3.0.bn1](args = (%layer3_0_conv1,), kwargs = {})
    %layer3_0_relu : [num_users=1] = call_module[target=layer3.0.relu](args = (%layer3_0_bn1,), kwargs = {})
    %layer3_0_conv2 : [num_users=1] = call_module[target=layer3.0.conv2](args = (%layer3_0_relu,), kwargs = {})
    %layer3_0_bn2 : [num_users=1] = call_module[target=layer3.0.bn2](args = (%layer3_0_conv2,), kwargs = {})
    %layer3_0_downsample_0 : [num_users=1] = call_module[target=layer3.0.downsample.0](args = (%layer2_1_relu_1,), kwargs = {})
    %layer3_0_downsample_1 : [num_users=1] = call_module[target=layer3.0.downsample.1](args = (%layer3_0_downsample_0,), kwargs = {})
    %add_4 : [num_users=1] = call_function[target=operator.add](args = (%layer3_0_bn2, %layer3_0_downsample_1), kwargs = {})
    %layer3_0_relu_1 : [num_users=2] = call_module[target=layer3.0.relu](args = (%add_4,), kwargs = {})
    %layer3_1_conv1 : [num_users=1] = call_module[target=layer3.1.conv1](args = (%layer3_0_relu_1,), kwargs = {})
    %layer3_1_bn1 : [num_users=1] = call_module[target=layer3.1.bn1](args = (%layer3_1_conv1,), kwargs = {})
    %layer3_1_relu : [num_users=1] = call_module[target=layer3.1.relu](args = (%layer3_1_bn1,), kwargs = {})
    %layer3_1_conv2 : [num_users=1] = call_module[target=layer3.1.conv2](args = (%layer3_1_relu,), kwargs = {})
    %layer3_1_bn2 : [num_users=1] = call_module[target=layer3.1.bn2](args = (%layer3_1_conv2,), kwargs = {})
    %add_5 : [num_users=1] = call_function[target=operator.add](args = (%layer3_1_bn2, %layer3_0_relu_1), kwargs = {})
    %layer3_1_relu_1 : [num_users=2] = call_module[target=layer3.1.relu](args = (%add_5,), kwargs = {})
    %layer4_0_conv1 : [num_users=1] = call_module[target=layer4.0.conv1](args = (%layer3_1_relu_1,), kwargs = {})
    %layer4_0_bn1 : [num_users=1] = call_module[target=layer4.0.bn1](args = (%layer4_0_conv1,), kwargs = {})
    %layer4_0_relu : [num_users=1] = call_module[target=layer4.0.relu](args = (%layer4_0_bn1,), kwargs = {})
    %layer4_0_conv2 : [num_users=1] = call_module[target=layer4.0.conv2](args = (%layer4_0_relu,), kwargs = {})
    %layer4_0_bn2 : [num_users=1] = call_module[target=layer4.0.bn2](args = (%layer4_0_conv2,), kwargs = {})
    %layer4_0_downsample_0 : [num_users=1] = call_module[target=layer4.0.downsample.0](args = (%layer3_1_relu_1,), kwargs = {})
    %layer4_0_downsample_1 : [num_users=1] = call_module[target=layer4.0.downsample.1](args = (%layer4_0_downsample_0,), kwargs = {})
    %add_6 : [num_users=1] = call_function[target=operator.add](args = (%layer4_0_bn2, %layer4_0_downsample_1), kwargs = {})
    %layer4_0_relu_1 : [num_users=2] = call_module[target=layer4.0.relu](args = (%add_6,), kwargs = {})
    %layer4_1_conv1 : [num_users=1] = call_module[target=layer4.1.conv1](args = (%layer4_0_relu_1,), kwargs = {})
    %layer4_1_bn1 : [num_users=1] = call_module[target=layer4.1.bn1](args = (%layer4_1_conv1,), kwargs = {})
    %layer4_1_relu : [num_users=1] = call_module[target=layer4.1.relu](args = (%layer4_1_bn1,), kwargs = {})
    %layer4_1_conv2 : [num_users=1] = call_module[target=layer4.1.conv2](args = (%layer4_1_relu,), kwargs = {})
    %layer4_1_bn2 : [num_users=1] = call_module[target=layer4.1.bn2](args = (%layer4_1_conv2,), kwargs = {})
    %add_7 : [num_users=1] = call_function[target=operator.add](args = (%layer4_1_bn2, %layer4_0_relu_1), kwargs = {})
    %layer4_1_relu_1 : [num_users=1] = call_module[target=layer4.1.relu](args = (%add_7,), kwargs = {})
    %avgpool : [num_users=1] = call_module[target=avgpool](args = (%layer4_1_relu_1,), kwargs = {})
    %flatten : [num_users=1] = call_function[target=torch.flatten](args = (%avgpool, 1), kwargs = {})
    %fc : [num_users=1] = call_module[target=fc](args = (%flatten,), kwargs = {})
    return fc

This gives us a Graph representation of the ResNet18 model. A Graph consists of a series of Nodes connected to each other. Each Node represents a call-site in the Python code (whether to a function, a module, or a method) and the edges (represented as args and kwargs on each node) represent the values passed between these call-sites. More information about the Graph representation and the rest of FX’s APIs ca be found at the FX documentation https://pytorch.org/docs/master/fx.html.

Creating a Profiling Interpreter#

Next, we are going to create a class that inherits from torch.fx.Interpreter. Though the GraphModule that symbolic_trace produces compiles Python code that is run when you call a GraphModule, an alternative way to run a GraphModule is by executing each Node in the Graph one by one. That is the functionality that Interpreter provides: It interprets the graph node- by-node.

By inheriting from Interpreter, we can override various functionality and install the profiling behavior we want. The goal is to have an object to which we can pass a model, invoke the model 1 or more times, then get statistics about how long the model and each part of the model took during those runs.

Let’s define our ProfilingInterpreter class:

class ProfilingInterpreter(Interpreter):
    def __init__(self, mod : torch.nn.Module):
        # Rather than have the user symbolically trace their model,
        # we're going to do it in the constructor. As a result, the
        # user can pass in any ``Module`` without having to worry about
        # symbolic tracing APIs
        gm = torch.fx.symbolic_trace(mod)
        super().__init__(gm)

        # We are going to store away two things here:
        #
        # 1. A list of total runtimes for ``mod``. In other words, we are
        #    storing away the time ``mod(...)`` took each time this
        #    interpreter is called.
        self.total_runtime_sec : List[float] = []
        # 2. A map from ``Node`` to a list of times (in seconds) that
        #    node took to run. This can be seen as similar to (1) but
        #    for specific sub-parts of the model.
        self.runtimes_sec : Dict[torch.fx.Node, List[float]] = {}

    ######################################################################
    # Next, let's override our first method: ``run()``. ``Interpreter``'s ``run``
    # method is the top-level entry point for execution of the model. We will
    # want to intercept this so that we can record the total runtime of the
    # model.

    def run(self, *args) -> Any:
        # Record the time we started running the model
        t_start = time.time()
        # Run the model by delegating back into Interpreter.run()
        return_val = super().run(*args)
        # Record the time we finished running the model
        t_end = time.time()
        # Store the total elapsed time this model execution took in the
        # ``ProfilingInterpreter``
        self.total_runtime_sec.append(t_end - t_start)
        return return_val

    ######################################################################
    # Now, let's override ``run_node``. ``Interpreter`` calls ``run_node`` each
    # time it executes a single node. We will intercept this so that we
    # can measure and record the time taken for each individual call in
    # the model.

    def run_node(self, n : torch.fx.Node) -> Any:
        # Record the time we started running the op
        t_start = time.time()
        # Run the op by delegating back into Interpreter.run_node()
        return_val = super().run_node(n)
        # Record the time we finished running the op
        t_end = time.time()
        # If we don't have an entry for this node in our runtimes_sec
        # data structure, add one with an empty list value.
        self.runtimes_sec.setdefault(n, [])
        # Record the total elapsed time for this single invocation
        # in the runtimes_sec data structure
        self.runtimes_sec[n].append(t_end - t_start)
        return return_val

    ######################################################################
    # Finally, we are going to define a method (one which doesn't override
    # any ``Interpreter`` method) that provides us a nice, organized view of
    # the data we have collected.

    def summary(self, should_sort : bool = False) -> str:
        # Build up a list of summary information for each node
        node_summaries : List[List[Any]] = []
        # Calculate the mean runtime for the whole network. Because the
        # network may have been called multiple times during profiling,
        # we need to summarize the runtimes. We choose to use the
        # arithmetic mean for this.
        mean_total_runtime = statistics.mean(self.total_runtime_sec)

        # For each node, record summary statistics
        for node, runtimes in self.runtimes_sec.items():
            # Similarly, compute the mean runtime for ``node``
            mean_runtime = statistics.mean(runtimes)
            # For easier understanding, we also compute the percentage
            # time each node took with respect to the whole network.
            pct_total = mean_runtime / mean_total_runtime * 100
            # Record the node's type, name of the node, mean runtime, and
            # percent runtime.
            node_summaries.append(
                [node.op, str(node), mean_runtime, pct_total])

        # One of the most important questions to answer when doing performance
        # profiling is "Which op(s) took the longest?". We can make this easy
        # to see by providing sorting functionality in our summary view
        if should_sort:
            node_summaries.sort(key=lambda s: s[2], reverse=True)

        # Use the ``tabulate`` library to create a well-formatted table
        # presenting our summary information
        headers : List[str] = [
            'Op type', 'Op', 'Average runtime (s)', 'Pct total runtime'
        ]
        return tabulate.tabulate(node_summaries, headers=headers)

참고

We use Python’s time.time function to pull wall clock timestamps and compare them. This is not the most accurate way to measure performance, and will only give us a first- order approximation. We use this simple technique only for the purpose of demonstration in this tutorial.

Investigating the Performance of ResNet18#

We can now use ProfilingInterpreter to inspect the performance characteristics of our ResNet18 model;

interp = ProfilingInterpreter(rn18)
interp.run(input)
print(interp.summary(True))
Op type        Op                       Average runtime (s)    Pct total runtime
-------------  ---------------------  ---------------------  -------------------
call_module    layer1_0_conv2                   0.00284696            10.4592
call_module    layer1_0_conv1                   0.00282502            10.3787
call_module    layer1_1_conv2                   0.00265503             9.75413
call_module    layer1_1_conv1                   0.001688               6.20144
call_module    conv1                            0.00162578             5.97283
call_module    layer2_1_conv2                   0.00150108             5.51473
call_module    layer2_0_downsample_0            0.000996351            3.66043
call_module    bn1                              0.000786543            2.88963
call_module    layer4_0_conv2                   0.000708818            2.60408
call_module    layer4_1_conv2                   0.000691652            2.54101
call_module    layer2_1_conv1                   0.000686884            2.5235
call_module    layer4_0_conv1                   0.000617743            2.26948
call_module    layer3_1_conv1                   0.000557661            2.04875
call_module    layer4_1_conv1                   0.0005126              1.88321
call_module    layer3_1_conv2                   0.000489712            1.79912
call_module    layer3_0_downsample_0            0.00046134             1.69489
call_module    layer3_0_conv2                   0.000443697            1.63007
call_module    maxpool                          0.000440121            1.61693
call_function  add                              0.000430822            1.58277
call_module    layer2_0_conv2                   0.000421762            1.54948
call_module    layer3_0_conv1                   0.000375509            1.37956
call_function  add_1                            0.00037384             1.37343
call_module    layer4_0_downsample_0            0.000359297            1.32
call_module    layer2_0_conv1                   0.000353336            1.2981
call_function  add_2                            0.000306845            1.1273
call_function  add_3                            0.000246048            0.903939
call_module    avgpool                          0.000120878            0.444086
call_module    layer2_1_bn2                     0.000117302            0.430948
call_module    relu                             0.000111103            0.408174
call_module    layer1_0_bn1                     0.000104666            0.384524
call_module    layer1_1_bn2                     8.72612e-05            0.320583
call_module    layer1_0_bn2                     8.70228e-05            0.319707
call_module    fc                               8.63075e-05            0.317079
call_module    layer1_0_relu                    8.44002e-05            0.310072
call_module    layer4_1_bn2                     8.13007e-05            0.298685
call_function  add_5                            7.93934e-05            0.291678
call_module    layer1_1_bn1                     7.89165e-05            0.289926
call_function  add_7                            7.89165e-05            0.289926
call_function  add_6                            7.77245e-05            0.285547
call_module    layer3_1_bn2                     7.36713e-05            0.270656
call_module    layer2_0_bn1                     7.22408e-05            0.265401
call_module    layer2_1_relu                    7.10487e-05            0.261021
call_module    layer2_0_relu                    7.03335e-05            0.258393
call_module    layer2_1_bn1                     7.00951e-05            0.257517
call_module    layer4_0_bn2                     6.98566e-05            0.256642
call_module    layer3_0_bn2                     6.91414e-05            0.254014
call_module    layer2_0_bn2                     6.86646e-05            0.252262
call_module    layer3_0_bn1                     6.77109e-05            0.248758
call_module    layer1_1_relu                    6.65188e-05            0.244379
call_module    layer2_0_downsample_1            6.62804e-05            0.243503
call_module    layer4_0_relu                    6.60419e-05            0.242627
call_module    layer4_1_bn1                     6.50883e-05            0.239123
call_module    layer3_0_relu                    6.48499e-05            0.238247
call_function  add_4                            6.48499e-05            0.238247
call_module    layer4_0_bn1                     6.46114e-05            0.237372
call_module    layer3_0_downsample_1            6.24657e-05            0.229488
call_module    layer4_0_downsample_1            6.22272e-05            0.228612
call_module    layer3_1_bn1                     6.03199e-05            0.221605
call_module    layer4_1_relu                    5.96046e-05            0.218977
call_module    layer3_1_relu                    5.79357e-05            0.212846
call_module    layer1_1_relu_1                  5.62668e-05            0.206715
call_module    layer4_0_relu_1                  5.48363e-05            0.201459
call_module    layer1_0_relu_1                  5.38826e-05            0.197956
call_module    layer3_0_relu_1                  5.126e-05              0.188321
call_module    layer4_1_relu_1                  5.00679e-05            0.183941
call_module    layer2_1_relu_1                  4.91142e-05            0.180437
call_module    layer3_1_relu_1                  4.57764e-05            0.168175
call_module    layer2_0_relu_1                  4.50611e-05            0.165547
output         output                           2.81334e-05            0.103357
placeholder    x                                2.76566e-05            0.101606
call_function  flatten                          1.4782e-05             0.0543064

There are two things we should call out here:

Conclusion#

As we can see, using FX we can easily capture PyTorch programs (even ones we don’t have the source code for!) in a machine-interpretable format and use that for analysis, such as the performance analysis we’ve done here. FX opens up an exciting world of possibilities for working with PyTorch programs.

Finally, since FX is still in beta, we would be happy to hear any feedback you have about using it. Please feel free to use the PyTorch Forums (https://discuss.pytorch.org/) and the issue tracker (pytorch/pytorch#issues) to provide any feedback you might have.

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