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Source code for torch.autograd.profiler

import subprocess
import re
import os
import sys
import itertools
from collections import defaultdict, namedtuple

import torch
from torch._six import FileNotFoundError


class range(object):
    def __init__(self, name):
        self.name = name

    def __enter__(self):
        torch.autograd._push_range(self.name)

    def __exit__(self, *args):
        torch.autograd._pop_range()
        return False


class EventList(list):
    """A list of Events (for pretty printing)"""
    def __init__(self, *args, **kwargs):
        super(EventList, self).__init__(*args, **kwargs)

    def __str__(self):
        return self.table()

    def table(self, sort_by=None):
        """Prints an EventList as a nicely formatted table.

        Arguments:
            sort_by (str, optional): Attribute used to sort entries. By default
                they are printed in the same order as they were registered.
                Valid keys include: ``cpu_time``, ``cuda_time``, ``cpu_time_total``,
                ``cuda_time_total``, ``count``.

        Returns:
            A string containing the table.
        """
        return build_table(self, sort_by)

    def export_chrome_trace(self, path):
        """Exports an EventList as a Chrome tracing tools file.

        The checkpoint can be later loaded and inspected under ``chrome://tracing`` URL.

        Arguments:
            path (str): Path where the trace will be written.
        """
        import json
        with open(path, 'w') as f:
            chrome_events = []
            next_id = 0
            for evt in self:
                chrome_events.append(dict(
                    name=evt.name,
                    ph='X',
                    ts=evt.cpu_interval.start,
                    dur=evt.cpu_interval.elapsed_us(),
                    tid=evt.thread,
                    pid='CPU functions',
                    args={},
                ))
                for k in evt.kernels:
                    # 's' and 'f' draw Flow arrows from
                    # the CPU launch to the GPU kernel
                    chrome_events.append(dict(
                        name=evt.name,
                        ph='s',
                        ts=evt.cpu_interval.start,
                        tid=evt.thread,
                        pid='CPU functions',
                        id=next_id,
                        cat='cpu_to_cuda',
                        args={},
                    ))
                    chrome_events.append(dict(
                        name=k.name,
                        ph='f',
                        ts=k.interval.start,
                        tid=k.device,
                        pid='CUDA functions',
                        id=next_id,
                        cat='cpu_to_cuda',
                        args={},
                    ))
                    chrome_events.append(dict(
                        name=k.name,
                        ph='X',
                        ts=k.interval.start,
                        dur=k.interval.elapsed_us(),
                        tid=k.device,
                        pid='CUDA functions',
                        args={},
                    ))
                    next_id += 1

            json.dump(chrome_events, f)

    def key_averages(self):
        """Averages all function events over their keys.

        Returns:
            An EventList containing FunctionEventAvg objects.
        """
        stats = defaultdict(FunctionEventAvg)
        for evt in self:
            stats[evt.key] += evt
        return EventList(stats.values())

    def total_average(self):
        """Averages all events.

        Returns:
            A FunctionEventAvg object.
        """
        total_stat = FunctionEventAvg()
        for evt in self:
            total_stat += evt
            total_stat.key = None
        total_stat.key = 'Total'
        return total_stat


[docs]class profile(object): """Context manager that manages autograd profiler state and holds a summary of results. Arguments: enabled (bool, optional): Setting this to False makes this context manager a no-op. Default: ``True``. use_cuda (bool, optional): Enables timing of CUDA events as well using the cudaEvent API. Adds approximately 4us of overhead to each tensor operation. Default: ``False`` .. warning: This context managers should not be called recursively, i.e. at most one instance should be enabled at any given time. Example: >>> x = torch.randn((1, 1), requires_grad=True) >>> with torch.autograd.profiler.profile() as prof: ... y = x ** 2 ... y.backward() >>> # NOTE: some columns were removed for brevity ... print(prof) ------------------------------------- --------------- --------------- Name CPU time CUDA time ------------------------------------- --------------- --------------- PowConstant 142.036us 0.000us N5torch8autograd9GraphRootE 63.524us 0.000us PowConstantBackward 184.228us 0.000us MulConstant 50.288us 0.000us PowConstant 28.439us 0.000us Mul 20.154us 0.000us N5torch8autograd14AccumulateGradE 13.790us 0.000us N5torch8autograd5CloneE 4.088us 0.000us """ def __init__(self, enabled=True, use_cuda=False): self.enabled = enabled self.use_cuda = use_cuda self.function_events = None if not self.enabled: return self.entered = False def __enter__(self): if not self.enabled: return if self.entered: raise RuntimeError("autograd profiler traces are not reentrant") self.entered = True profiler_kind = torch.autograd.ProfilerState.CUDA if self.use_cuda \ else torch.autograd.ProfilerState.CPU torch.autograd._enable_profiler(profiler_kind) return self def __exit__(self, exc_type, exc_val, exc_tb): if not self.enabled: return records = torch.autograd._disable_profiler() self.function_events = EventList(parse_cpu_trace(records)) return False def __repr__(self): if self.function_events is None: return '<unfinished torch.autograd.profile>' return repr(self.function_events) def __str__(self): if self.function_events is None: return '<unfinished torch.autograd.profile>' return str(self.function_events) def _check_finish(self): if self.function_events is None: raise RuntimeError("can't export a trace that didn't finish running")
[docs] def table(self, sort_by=None): self._check_finish() return self.function_events.table(sort_by)
table.__doc__ = EventList.table.__doc__
[docs] def export_chrome_trace(self, path): self._check_finish() return self.function_events.export_chrome_trace(path)
export_chrome_trace.__doc__ = EventList.export_chrome_trace.__doc__
[docs] def key_averages(self): self._check_finish() return self.function_events.key_averages()
key_averages.__doc__ = EventList.key_averages.__doc__
[docs] def total_average(self): self._check_finish() return self.function_events.total_average()
total_average.__doc__ = EventList.total_average.__doc__
[docs]class emit_nvtx(object): """Context manager that makes every autograd operation emit an NVTX range. It is useful when running the program under nvprof:: nvprof --profile-from-start off -o trace_name.prof -- <regular command here> Unfortunately, there's no way to force nvprof to flush the data it collected to disk, so for CUDA profiling one has to use this context manager to annotate nvprof traces and wait for the process to exit before inspecting them. Then, either NVIDIA Visual Profiler (nvvp) can be used to visualize the timeline, or :func:`torch.autograd.profiler.load_nvprof` can load the results for inspection e.g. in Python REPL. .. warning: This context manager should not be called recursively, i.e. at most one instance should be enabled at any given time. Arguments: enabled (bool, optional): Setting this to False makes this context manager a no-op. Default: ``True``. Example: >>> with torch.cuda.profiler.profile(): ... model(x) # Warmup CUDA memory allocator and profiler ... with torch.autograd.profiler.emit_nvtx(): ... model(x) **Forward-backward correlation** When viewing a profile created using :class:`emit_nvtx` in the Nvidia Visual Profiler, correlating each backward-pass op with the corresponding forward-pass op can be difficult. To ease this task, :class:`emit_nvtx` appends sequence number information to the ranges it generates. During the forward pass, each function range is decorated with ``seq=<N>``. ``seq`` is a running counter, incremented each time a new backward Function object is created and stashed for backward. Thus, the `seq=<N>` annotation associated with each forward function range tells you that if a backward Function object is created by this forward function, the backward object will receive sequence number N. During the backward pass, the top-level range wrapping each C++ backward Function's ``apply()`` call is decorated with ``stashed seq=<M>``. ``M`` is the sequence number that the backward object was created with. By comparing ``stashed seq`` numbers in backward with ``seq`` numbers in forward, you can track down which forward op created each backward Function. Any functions executed during the backward pass are also decorated with ``seq=<N>``. During default backward (with ``create_graph=False``) this information is irrelevant, and in fact, ``N`` may simply be 0 for all such functions. Only the top-level ranges associated with backward Function objects' ``apply()`` methods are useful, as a way to correlate these Function objects with the earlier forward pass. **Double-backward** If, on the other hand, a backward pass with ``create_graph=True`` is underway (in other words, if you are setting up for a double-backward), each function's execution during backward is given a nonzero, useful ``seq=<N>``. Those functions may themselves create Function objects to be executed later during double-backward, just as the original functions in the forward pass did. The relationship between backward and double-backward is conceptually the same as the relationship between forward and backward: The functions still emit current-sequence-number-tagged ranges, the Function objects they create still stash those sequence numbers, and during the eventual double-backward, the Function objects' ``apply()`` ranges are still tagged with ``stashed seq`` numbers, which can be compared to `seq` numbers from the backward pass. .. warning: The sequence number is thread-local, and some forward functions don't create an associated backward Function object (instead delegating that to sub-functions further down the call chain). For these reasons, the correspondence of stashed sequence numbers in backward Function ``apply()`` ranges with `seq` numbers in forward-pass ranges is not guaranteed to be 1 to 1. The sequence numbers alone may not be enough to fully disambiguate which forward function created which backward Function object. You may need to make a judgment based on analytic knowledge of what the expected correspondence should be. """ def __init__(self, enabled=True): self.enabled = enabled self.entered = False def __enter__(self): if not self.enabled: return if self.entered: raise RuntimeError("NVTX annotation context manager is not reentrant") self.entered = True torch.cuda.synchronize() torch.autograd._enable_profiler(torch.autograd.ProfilerState.NVTX) return self def __exit__(self, exc_type, exc_val, exc_tb): if not self.enabled: return torch.cuda.synchronize() torch.autograd._disable_profiler() return False
[docs]def load_nvprof(path): """Opens an nvprof trace file and parses autograd annotations. Arguments: path (str): path to nvprof trace """ return EventList(parse_nvprof_trace(path))
################################################################################ # FunctionEvent def format_time(time_us): """Defines how to format time in FunctionEvent""" return '{:.3f}us'.format(time_us) def attr_formatter(name): return property(lambda self: format_time(getattr(self, name))) class FormattedTimesMixin(object): """Helpers for FunctionEvent and FunctionEventAvg. The subclass should define `*_time_total` and `count` attributes. """ cpu_time_str = attr_formatter('cpu_time') cuda_time_str = attr_formatter('cuda_time') cpu_time_total_str = attr_formatter('cpu_time_total') cuda_time_total_str = attr_formatter('cuda_time_total') @property def cpu_time(self): return 0.0 if self.count == 0 else 1.0 * self.cpu_time_total / self.count @property def cuda_time(self): return 0.0 if self.count == 0 else 1.0 * self.cuda_time_total / self.count class Interval(object): def __init__(self, start, end): self.start = start self.end = end def elapsed_us(self): return self.end - self.start Kernel = namedtuple('Kernel', ['name', 'device', 'interval']) # TODO: record TID too class FunctionEvent(FormattedTimesMixin): """Profiling information about a single function.""" def __init__(self, id, name, thread, cpu_start, cpu_end): self.id = id self.name = name self.cpu_interval = Interval(cpu_start, cpu_end) self.thread = thread self.kernels = [] self.count = 1 def append_kernel(self, name, device, start, end): self.kernels.append(Kernel(name, device, Interval(start, end))) @property def cuda_time_total(self): return sum(kinfo.interval.elapsed_us() for kinfo in self.kernels) @property def cpu_time_total(self): return self.cpu_interval.elapsed_us() @property def key(self): return self.name def __repr__(self): return '<FunctionEvent id={} cpu_time={} cuda_time={} name={} thread={}>'.format( self.id, self.cpu_time_str, self.cuda_time_str, self.name, self.thread) class FunctionEventAvg(FormattedTimesMixin): """Used to average stats over multiple FunctionEvent objects.""" def __init__(self): self.key = None self.count = self.cpu_time_total = self.cuda_time_total = 0 def __iadd__(self, other): if self.key is None: self.key = other.key assert isinstance(other, FunctionEvent) assert other.key == self.key self.cpu_time_total += other.cpu_time self.cuda_time_total += other.cuda_time self.count += 1 return self def __repr__(self): return '<FunctionEventAvg cpu_time={} cuda_time={} key={}>'.format( self.cpu_time_str, self.cuda_time_str, self.key) ################################################################################ # Utilities class StringTable(defaultdict): def __missing__(self, key): self[key] = torch._C._demangle(key) return self[key] ################################################################################ # CPU checkpoints def parse_cpu_trace(thread_records): next_id = 0 start_record = None cuda_records = {} functions = [] record_stack = [] string_table = StringTable() # cuda start events and the overall profiler start event don't happen # at exactly the same time because we need to record an event on each device # and each record takes ~4us. So we adjust here by the difference # adding the difference in CPU time between the profiler start event # and the CPU time of the cuda start event for the device def adjusted_time(cuda_record): assert cuda_record.device() != -1 cuda_time_0 = cuda_records[cuda_record.device()] return cuda_time_0.cuda_elapsed_us(cuda_record) + start_record.cpu_elapsed_us(cuda_time_0) # '__start_profile' is not guarenteed to be first, so we must find it here for record in itertools.chain(*thread_records): if record.name() == '__start_profile': start_record = record elif record.name() == '__cuda_start_event': assert record.device() != -1 cuda_records[record.device()] = record assert start_record is not None for record in itertools.chain(*thread_records): if record.kind() == 'mark': continue elif record.kind() == 'push': record_stack.append((next_id, record)) next_id += 1 elif record.kind() == 'pop': function_id, start = record_stack.pop() fe = FunctionEvent( id=function_id, name=string_table[start.name()], thread=start.thread_id(), cpu_start=start_record.cpu_elapsed_us(start), cpu_end=start_record.cpu_elapsed_us(record)) if start.has_cuda(): cuda_start = adjusted_time(start) cuda_end = adjusted_time(record) fe.append_kernel(start.name(), start.device(), cuda_start, cuda_end) functions.append(fe) functions.sort(key=lambda evt: evt.cpu_interval.start) return functions ################################################################################ # CUDA checkpoints class EnforceUnique(object): """Raises an error if a key is seen more than once.""" def __init__(self): self.seen = set() def see(self, *key): if key in self.seen: raise RuntimeError('duplicate key: ' + str(key)) self.seen.add(key) def parse_nvprof_trace(path): import sqlite3 conn = sqlite3.connect(path) conn.row_factory = sqlite3.Row # Parse strings table strings = {} for r in conn.execute("SELECT _id_ as id, value FROM StringTable"): strings[r["id"]] = torch._C._demangle(r["value"]) # First, find all functions and create FunctionEvents for them marker_query = """ SELECT start.id AS marker_id, start.name, start.timestamp AS start_time, end.timestamp AS end_time FROM CUPTI_ACTIVITY_KIND_MARKER AS start INNER JOIN CUPTI_ACTIVITY_KIND_MARKER AS end ON start.id = end.id WHERE start.name != 0 AND end.name = 0 """ functions = [] functions_map = {} unique = EnforceUnique() for row in conn.execute(marker_query): unique.see(row['marker_id']) evt = FunctionEvent(id=row['marker_id'], name=strings[row['name']], cpu_start=row['start_time'], cpu_end=row['end_time'], thread=0) # TODO: find in sqlite database functions.append(evt) functions_map[evt.id] = evt # Now, correlate all kernels with FunctionEvents kernel_query = """ SELECT start.id AS marker_id, start.name, start.timestamp, end.timestamp, runtime._id_ AS runtime_id, runtime.cbid, runtime.start AS runtime_start, runtime.end AS runtime_end, kernel.start AS kernel_start, kernel.end AS kernel_end, kernel.name AS kernel_name FROM CUPTI_ACTIVITY_KIND_MARKER AS start INNER JOIN CUPTI_ACTIVITY_KIND_MARKER AS end ON start.id = end.id INNER JOIN CUPTI_ACTIVITY_KIND_RUNTIME as runtime ON (start.timestamp < runtime.start AND runtime.end < end.timestamp) INNER JOIN CUPTI_ACTIVITY_KIND_CONCURRENT_KERNEL AS kernel ON kernel.correlationId = runtime.correlationId """ unique = EnforceUnique() for row in conn.execute(kernel_query): unique.see(row['marker_id'], row['runtime_id']) assert row['cbid'] == 13 # 13 == Launch evt = functions_map[row['marker_id']] evt.append_kernel(row['kernel_name'], 0, row['kernel_start'], row['kernel_end']) functions.sort(key=lambda evt: evt.cpu_interval.start) return functions ################################################################################ # Pretty printer def build_table(events, sort_by=None, header=None): """Prints a summary of events (which can be a list of FunctionEvent or FunctionEventAvg).""" if sort_by is not None: events = sorted(events, key=lambda evt: getattr(evt, sort_by)) name_lengths = [len(evt.key) for evt in events] if len(name_lengths) == 0: return "" max_name_length = max(name_lengths) max_name_length += 4 # Add some nice padding col_width = 15 col_format = ' {: >' + str(col_width) + '}' row_format = '{: <' + str(max_name_length) + '}' + col_format * 5 header_sep = '-' * max_name_length + (' ' + '-' * col_width) * 5 # Have to use a list because nonlocal is Py3 only... result = [] def append(s): result.append(s) result.append('\n') # Yes, newline after the end as well # Actual printing if header is not None: line_length = max_name_length + (col_width + 2) * 5 append('=' * line_length) append(header) append(header_sep) append(row_format.format('Name', 'CPU time', 'CUDA time', 'Calls', 'CPU total', 'CUDA total')) append(header_sep) for evt in events: append(row_format.format(evt.key, evt.cpu_time_str, evt.cuda_time_str, evt.count, evt.cpu_time_total_str, evt.cuda_time_total_str)) return ''.join(result)

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