Source code for torch.cuda.memory
# mypy: allow-untyped-defs
r"""This package adds support for device memory management implemented in CUDA."""
import collections
import contextlib
import ctypes
import pickle
import sys
import warnings
from inspect import signature
from typing import Any, Dict, Literal, Optional, Tuple, Union
from typing_extensions import deprecated
import torch
from torch import _C
from torch._utils import _dummy_type
from torch.types import Device
from . import (
_get_amdsmi_device_index,
_get_device_index,
_get_nvml_device_index,
_lazy_init,
is_initialized,
)
from ._memory_viz import memory as _memory, segments as _segments
__all__ = [
"caching_allocator_alloc",
"caching_allocator_delete",
"caching_allocator_enable",
"set_per_process_memory_fraction",
"empty_cache",
"memory_stats",
"memory_stats_as_nested_dict",
"reset_accumulated_memory_stats",
"reset_peak_memory_stats",
"reset_max_memory_allocated",
"reset_max_memory_cached",
"memory_allocated",
"max_memory_allocated",
"memory_reserved",
"max_memory_reserved",
"memory_cached",
"max_memory_cached",
"memory_snapshot",
"memory_summary",
"list_gpu_processes",
"mem_get_info",
"get_allocator_backend",
"CUDAPluggableAllocator",
"change_current_allocator",
"MemPool",
"MemPoolContext",
"use_mem_pool",
]
if not hasattr(torch._C, "_cuda_CUDAAllocator"):
# Define dummy base classes
torch._C.__dict__["_cuda_CUDAAllocator"] = _dummy_type("_cuda_CUDAAllocator")
if not hasattr(torch._C, "_MemPool"):
# Define dummy base classes
torch._C.__dict__["_MemPool"] = _dummy_type("_MemPool")
torch._C.__dict__["_MemPoolContext"] = _dummy_type("_MemPoolContext")
torch._C.__dict__["_cuda_beginAllocateToPool"] = _dummy_type(
"_cuda_beginAllocateToPool"
)
torch._C.__dict__["_cuda_endAllocateCurrentStreamToPool"] = _dummy_type(
"_cuda_endAllocateCurrentStreamToPool"
)
torch._C.__dict__["_cuda_releasePool"] = _dummy_type("_cuda_releasePool")
from torch._C import ( # noqa: F401
_cuda_beginAllocateToPool,
_cuda_CUDAAllocator,
_cuda_endAllocateCurrentStreamToPool,
_cuda_releasePool,
_MemPool,
_MemPoolContext,
)
def _host_allocator():
_lazy_init()
return torch._C._cuda_cudaHostAllocator()
@contextlib.contextmanager
def _free_mutex():
torch._C._cuda_lock_mutex()
try:
yield
finally:
torch._C._cuda_unlock_mutex()
[docs]def caching_allocator_alloc(size, device: Union[Device, int] = None, stream=None):
r"""Perform a memory allocation using the CUDA memory allocator.
Memory is allocated for a given device and a stream, this
function is intended to be used for interoperability with other
frameworks. Allocated memory is released through
:func:`~torch.cuda.caching_allocator_delete`.
Args:
size (int): number of bytes to be allocated.
device (torch.device or int, optional): selected device. If it is
``None`` the default CUDA device is used.
stream (torch.cuda.Stream or int, optional): selected stream. If is ``None`` then
the default stream for the selected device is used.
.. note::
See :ref:`cuda-memory-management` for more details about GPU memory
management.
"""
if device is None:
device = torch.cuda.current_device()
device = _get_device_index(device)
if stream is None:
stream = torch.cuda.current_stream(device)
if isinstance(stream, torch.cuda.streams.Stream):
stream = stream.cuda_stream
if not isinstance(stream, int):
raise TypeError(
"Invalid type for stream argument, must be "
"`torch.cuda.Stream` or `int` representing a pointer "
"to a existing stream"
)
with torch.cuda.device(device):
return torch._C._cuda_cudaCachingAllocator_raw_alloc(size, stream)
[docs]def caching_allocator_delete(mem_ptr):
r"""Delete memory allocated using the CUDA memory allocator.
Memory allocated with :func:`~torch.cuda.caching_allocator_alloc`.
is freed here. The associated device and stream are tracked inside
the allocator.
Args:
mem_ptr (int): memory address to be freed by the allocator.
.. note::
See :ref:`cuda-memory-management` for more details about GPU memory
management.
"""
torch._C._cuda_cudaCachingAllocator_raw_delete(mem_ptr)
[docs]def caching_allocator_enable(value: bool = True) -> None:
r"""Enable or disable the CUDA memory allocator. On by default."""
if is_initialized():
torch._C._cuda_cudaCachingAllocator_enable(value)
[docs]def set_per_process_memory_fraction(
fraction, device: Union[Device, int] = None
) -> None:
r"""Set memory fraction for a process.
The fraction is used to limit an caching allocator to allocated memory on a CUDA device.
The allowed value equals the total visible memory multiplied fraction.
If trying to allocate more than the allowed value in a process, will raise an out of
memory error in allocator.
Args:
fraction(float): Range: 0~1. Allowed memory equals total_memory * fraction.
device (torch.device or int, optional): selected device. If it is
``None`` the default CUDA device is used.
.. note::
In general, the total available free memory is less than the total capacity.
"""
_lazy_init()
if device is None:
device = torch.cuda.current_device()
device = _get_device_index(device)
if not isinstance(fraction, float):
raise TypeError("Invalid type for fraction argument, must be `float`")
if fraction < 0 or fraction > 1:
raise ValueError(f"Invalid fraction value: {fraction}. Allowed range: 0~1")
torch._C._cuda_setMemoryFraction(fraction, device)
[docs]def empty_cache() -> None:
r"""Release all unoccupied cached memory currently held by the caching
allocator so that those can be used in other GPU application and visible in
`nvidia-smi`.
.. note::
:func:`~torch.cuda.empty_cache` doesn't increase the amount of GPU
memory available for PyTorch. However, it may help reduce fragmentation
of GPU memory in certain cases. See :ref:`cuda-memory-management` for
more details about GPU memory management.
"""
if is_initialized():
torch._C._cuda_emptyCache()
[docs]def memory_stats(device: Union[Device, int] = None) -> Dict[str, Any]:
r"""Return a dictionary of CUDA memory allocator statistics for a given device.
The return value of this function is a dictionary of statistics, each of
which is a non-negative integer.
Core statistics:
- ``"allocated.{all,large_pool,small_pool}.{current,peak,allocated,freed}"``:
number of allocation requests received by the memory allocator.
- ``"allocated_bytes.{all,large_pool,small_pool}.{current,peak,allocated,freed}"``:
amount of allocated memory.
- ``"segment.{all,large_pool,small_pool}.{current,peak,allocated,freed}"``:
number of reserved segments from ``cudaMalloc()``.
- ``"reserved_bytes.{all,large_pool,small_pool}.{current,peak,allocated,freed}"``:
amount of reserved memory.
- ``"active.{all,large_pool,small_pool}.{current,peak,allocated,freed}"``:
number of active memory blocks.
- ``"active_bytes.{all,large_pool,small_pool}.{current,peak,allocated,freed}"``:
amount of active memory.
- ``"inactive_split.{all,large_pool,small_pool}.{current,peak,allocated,freed}"``:
number of inactive, non-releasable memory blocks.
- ``"inactive_split_bytes.{all,large_pool,small_pool}.{current,peak,allocated,freed}"``:
amount of inactive, non-releasable memory.
For these core statistics, values are broken down as follows.
Pool type:
- ``all``: combined statistics across all memory pools.
- ``large_pool``: statistics for the large allocation pool
(as of October 2019, for size >= 1MB allocations).
- ``small_pool``: statistics for the small allocation pool
(as of October 2019, for size < 1MB allocations).
Metric type:
- ``current``: current value of this metric.
- ``peak``: maximum value of this metric.
- ``allocated``: historical total increase in this metric.
- ``freed``: historical total decrease in this metric.
In addition to the core statistics, we also provide some simple event
counters:
- ``"num_alloc_retries"``: number of failed ``cudaMalloc`` calls that
result in a cache flush and retry.
- ``"num_ooms"``: number of out-of-memory errors thrown.
- ``"num_sync_all_streams"``: number of ``synchronize_and_free_events`` calls.
- ``"num_device_alloc"``: number of CUDA allocation calls. This includes both
cuMemMap and cudaMalloc.
- ``"num_device_free"``: number of CUDA free calls. This includes both cuMemUnmap
and cudaFree.
The caching allocator can be configured via ENV to not split blocks larger than a
defined size (see Memory Management section of the Cuda Semantics documentation).
This helps avoid memory fragmentation but may have a performance
penalty. Additional outputs to assist with tuning and evaluating impact:
- ``"max_split_size"``: blocks above this size will not be split.
- ``"oversize_allocations.{current,peak,allocated,freed}"``:
number of over-size allocation requests received by the memory allocator.
- ``"oversize_segments.{current,peak,allocated,freed}"``:
number of over-size reserved segments from ``cudaMalloc()``.
The caching allocator can be configured via ENV to round memory allocations in order
to reduce fragmentation. Sometimes the overhead from rounding can be higher than
the fragmentation it helps reduce. The following stat can be used to check if
rounding adds too much overhead:
- ``"requested_bytes.{all,large_pool,small_pool}.{current,peak,allocated,freed}"``:
memory requested by client code, compare this with allocated_bytes to check if
allocation rounding adds too much overhead.
Args:
device (torch.device or int, optional): selected device. Returns
statistics for the current device, given by :func:`~torch.cuda.current_device`,
if :attr:`device` is ``None`` (default).
.. note::
See :ref:`cuda-memory-management` for more details about GPU memory
management.
.. note::
With :ref:`backend:cudaMallocAsync<cuda-memory-envvars>`, some stats are not
meaningful, and are always reported as zero.
"""
result = []
def _recurse_add_to_result(prefix, obj):
if isinstance(obj, dict):
if len(prefix) > 0:
prefix += "."
for k, v in obj.items():
_recurse_add_to_result(prefix + k, v)
else:
result.append((prefix, obj))
stats = memory_stats_as_nested_dict(device=device)
_recurse_add_to_result("", stats)
result.sort()
return collections.OrderedDict(result)
def memory_stats_as_nested_dict(device: Union[Device, int] = None) -> Dict[str, Any]:
r"""Return the result of :func:`~torch.cuda.memory_stats` as a nested dictionary."""
if not is_initialized():
return {}
device = _get_device_index(device, optional=True)
return torch._C._cuda_memoryStats(device)
def reset_accumulated_memory_stats(device: Union[Device, int] = None) -> None:
r"""Reset the "accumulated" (historical) stats tracked by the CUDA memory allocator.
See :func:`~torch.cuda.memory_stats` for details. Accumulated stats correspond to
the `"allocated"` and `"freed"` keys in each individual stat dict, as well as
`"num_alloc_retries"` and `"num_ooms"`.
Args:
device (torch.device or int, optional): selected device. Returns
statistic for the current device, given by :func:`~torch.cuda.current_device`,
if :attr:`device` is ``None`` (default).
.. note::
See :ref:`cuda-memory-management` for more details about GPU memory
management.
"""
device = _get_device_index(device, optional=True)
return torch._C._cuda_resetAccumulatedMemoryStats(device)
[docs]def reset_peak_memory_stats(device: Union[Device, int] = None) -> None:
r"""Reset the "peak" stats tracked by the CUDA memory allocator.
See :func:`~torch.cuda.memory_stats` for details. Peak stats correspond to the
`"peak"` key in each individual stat dict.
Args:
device (torch.device or int, optional): selected device. Returns
statistic for the current device, given by :func:`~torch.cuda.current_device`,
if :attr:`device` is ``None`` (default).
.. note::
See :ref:`cuda-memory-management` for more details about GPU memory
management.
"""
device = _get_device_index(device, optional=True)
return torch._C._cuda_resetPeakMemoryStats(device)
[docs]def reset_max_memory_allocated(device: Union[Device, int] = None) -> None:
r"""Reset the starting point in tracking maximum GPU memory occupied by tensors for a given device.
See :func:`~torch.cuda.max_memory_allocated` for details.
Args:
device (torch.device or int, optional): selected device. Returns
statistic for the current device, given by :func:`~torch.cuda.current_device`,
if :attr:`device` is ``None`` (default).
.. warning::
This function now calls :func:`~torch.cuda.reset_peak_memory_stats`, which resets
/all/ peak memory stats.
.. note::
See :ref:`cuda-memory-management` for more details about GPU memory
management.
"""
warnings.warn(
"torch.cuda.reset_max_memory_allocated now calls torch.cuda.reset_peak_memory_stats, "
"which resets /all/ peak memory stats.",
FutureWarning,
)
return reset_peak_memory_stats(device=device)
[docs]def reset_max_memory_cached(device: Union[Device, int] = None) -> None:
r"""Reset the starting point in tracking maximum GPU memory managed by the caching allocator for a given device.
See :func:`~torch.cuda.max_memory_cached` for details.
Args:
device (torch.device or int, optional): selected device. Returns
statistic for the current device, given by :func:`~torch.cuda.current_device`,
if :attr:`device` is ``None`` (default).
.. warning::
This function now calls :func:`~torch.cuda.reset_peak_memory_stats`, which resets
/all/ peak memory stats.
.. note::
See :ref:`cuda-memory-management` for more details about GPU memory
management.
"""
warnings.warn(
"torch.cuda.reset_max_memory_cached now calls torch.cuda.reset_peak_memory_stats, "
"which resets /all/ peak memory stats.",
FutureWarning,
)
return reset_peak_memory_stats(device=device)
[docs]def memory_allocated(device: Union[Device, int] = None) -> int:
r"""Return the current GPU memory occupied by tensors in bytes for a given device.
Args:
device (torch.device or int, optional): selected device. Returns
statistic for the current device, given by :func:`~torch.cuda.current_device`,
if :attr:`device` is ``None`` (default).
.. note::
This is likely less than the amount shown in `nvidia-smi` since some
unused memory can be held by the caching allocator and some context
needs to be created on GPU. See :ref:`cuda-memory-management` for more
details about GPU memory management.
"""
return memory_stats(device=device).get("allocated_bytes.all.current", 0)
[docs]def max_memory_allocated(device: Union[Device, int] = None) -> int:
r"""Return the maximum GPU memory occupied by tensors in bytes for a given device.
By default, this returns the peak allocated memory since the beginning of
this program. :func:`~torch.cuda.reset_peak_memory_stats` can be used to
reset the starting point in tracking this metric. For example, these two
functions can measure the peak allocated memory usage of each iteration in a
training loop.
Args:
device (torch.device or int, optional): selected device. Returns
statistic for the current device, given by :func:`~torch.cuda.current_device`,
if :attr:`device` is ``None`` (default).
.. note::
See :ref:`cuda-memory-management` for more details about GPU memory
management.
"""
return memory_stats(device=device).get("allocated_bytes.all.peak", 0)
[docs]def memory_reserved(device: Union[Device, int] = None) -> int:
r"""Return the current GPU memory managed by the caching allocator in bytes for a given device.
Args:
device (torch.device or int, optional): selected device. Returns
statistic for the current device, given by :func:`~torch.cuda.current_device`,
if :attr:`device` is ``None`` (default).
.. note::
See :ref:`cuda-memory-management` for more details about GPU memory
management.
"""
return memory_stats(device=device).get("reserved_bytes.all.current", 0)
[docs]def max_memory_reserved(device: Union[Device, int] = None) -> int:
r"""Return the maximum GPU memory managed by the caching allocator in bytes for a given device.
By default, this returns the peak cached memory since the beginning of this
program. :func:`~torch.cuda.reset_peak_memory_stats` can be used to reset
the starting point in tracking this metric. For example, these two functions
can measure the peak cached memory amount of each iteration in a training
loop.
Args:
device (torch.device or int, optional): selected device. Returns
statistic for the current device, given by :func:`~torch.cuda.current_device`,
if :attr:`device` is ``None`` (default).
.. note::
See :ref:`cuda-memory-management` for more details about GPU memory
management.
"""
return memory_stats(device=device).get("reserved_bytes.all.peak", 0)
[docs]@deprecated(
"`torch.cuda.memory_cached` has been renamed to `torch.cuda.memory_reserved`",
category=FutureWarning,
)
def memory_cached(device: Union[Device, int] = None) -> int:
r"""Deprecated; see :func:`~torch.cuda.memory_reserved`."""
return memory_reserved(device=device)
[docs]@deprecated(
"`torch.cuda.max_memory_cached` has been renamed to `torch.cuda.max_memory_reserved`",
category=FutureWarning,
)
def max_memory_cached(device: Union[Device, int] = None) -> int:
r"""Deprecated; see :func:`~torch.cuda.max_memory_reserved`."""
return max_memory_reserved(device=device)
[docs]def memory_snapshot():
r"""Return a snapshot of the CUDA memory allocator state across all devices.
Interpreting the output of this function requires familiarity with the
memory allocator internals.
.. note::
See :ref:`cuda-memory-management` for more details about GPU memory
management.
"""
return torch._C._cuda_memorySnapshot()["segments"]
[docs]def memory_summary(device: Union[Device, int] = None, abbreviated: bool = False) -> str:
r"""Return a human-readable printout of the current memory allocator statistics for a given device.
This can be useful to display periodically during training, or when
handling out-of-memory exceptions.
Args:
device (torch.device or int, optional): selected device. Returns
printout for the current device, given by :func:`~torch.cuda.current_device`,
if :attr:`device` is ``None`` (default).
abbreviated (bool, optional): whether to return an abbreviated summary
(default: False).
.. note::
See :ref:`cuda-memory-management` for more details about GPU memory
management.
"""
device = _get_device_index(device, optional=True)
stats = memory_stats(device=device)
def _format_size(sz, pref_sz):
prefixes = ["B ", "KiB", "MiB", "GiB", "TiB", "PiB"]
prefix = prefixes[0]
for new_prefix in prefixes[1:]:
if pref_sz < 768 * 1024:
break
prefix = new_prefix
sz //= 1024
pref_sz /= 1024
return f"{sz:6d} {prefix}"
def _format_count(cnt, pref_cnt):
prefixes = [" ", "K", "M"]
prefix = prefixes[0]
for new_prefix in prefixes[1:]:
if pref_cnt < 750 * 1000:
break
prefix = new_prefix
cnt //= 1000
pref_cnt /= 1000
return f"{cnt:7d} {prefix} "
metrics_to_display = [
("allocated_bytes", "Allocated memory", _format_size),
("active_bytes", "Active memory", _format_size),
("requested_bytes", "Requested memory", _format_size),
("reserved_bytes", "GPU reserved memory", _format_size),
("inactive_split_bytes", "Non-releasable memory", _format_size),
("allocation", "Allocations", _format_count),
("active", "Active allocs", _format_count),
("segment", "GPU reserved segments", _format_count),
("inactive_split", "Non-releasable allocs", _format_count),
]
lines = []
lines.append("=" * 75)
lines.append(" {_:16} PyTorch CUDA memory summary, device ID {device:<17d} ")
lines.append("-" * 75)
lines.append(
" {_:9} CUDA OOMs: {num_ooms:<12d} | {_:6} cudaMalloc retries: {num_alloc_retries:<8d} "
)
lines.append("=" * 75)
lines.append(
" Metric | Cur Usage | Peak Usage | Tot Alloc | Tot Freed "
)
for metric_key, metric_name, formatter in metrics_to_display:
lines.append("-" * 75)
submetrics = [("all", metric_name)]
if not abbreviated:
submetrics.append(("large_pool", " from large pool"))
submetrics.append(("small_pool", " from small pool"))
current_prefval, peak_prefval, allocated_prefval, freed_prefval = (
None,
None,
None,
None,
)
for submetric_key, submetric_name in submetrics:
prefix = metric_key + "." + submetric_key + "."
current = stats[prefix + "current"]
peak = stats[prefix + "peak"]
allocated = stats[prefix + "allocated"]
freed = stats[prefix + "freed"]
if current_prefval is None:
current_prefval = current
peak_prefval = peak
allocated_prefval = allocated
freed_prefval = freed
lines.append(
f" {submetric_name:<21} | {formatter(current, current_prefval)} | {formatter(peak, peak_prefval)} | "
f"{formatter(allocated, allocated_prefval)} | {formatter(freed, freed_prefval)} ",
)
metrics_to_display = [
("oversize_allocations", "Oversize allocations", _format_count),
("oversize_segments", "Oversize GPU segments", _format_count),
]
for metric_key, metric_name, formatter in metrics_to_display:
lines.append("-" * 75)
prefix = metric_key + "."
current = stats[prefix + "current"]
peak = stats[prefix + "peak"]
allocated = stats[prefix + "allocated"]
freed = stats[prefix + "freed"]
lines.append(
f" {metric_name:<21} | {formatter(current, current)} | {formatter(peak, peak)} | "
f"{formatter(allocated, allocated)} | {formatter(freed, freed)} ",
)
lines.append("=" * 75)
fmt_dict = {"_": "", "device": device}
for k, v in stats.items():
fmt_dict[k.replace(".", "-")] = v
return "|" + "|\n|".join(lines).format(**fmt_dict) + "|\n"
[docs]def list_gpu_processes(device: Union[Device, int] = None) -> str:
r"""Return a human-readable printout of the running processes and their GPU memory use for a given device.
This can be useful to display periodically during training, or when
handling out-of-memory exceptions.
Args:
device (torch.device or int, optional): selected device. Returns
printout for the current device, given by :func:`~torch.cuda.current_device`,
if :attr:`device` is ``None`` (default).
"""
if not torch.version.hip:
try:
import pynvml # type: ignore[import]
except ModuleNotFoundError:
return "pynvml module not found, please install pynvml"
from pynvml import NVMLError_DriverNotLoaded
try:
pynvml.nvmlInit()
except NVMLError_DriverNotLoaded:
return "cuda driver can't be loaded, is cuda enabled?"
device = _get_nvml_device_index(device)
handle = pynvml.nvmlDeviceGetHandleByIndex(device)
procs = pynvml.nvmlDeviceGetComputeRunningProcesses(handle)
else:
try:
import amdsmi # type: ignore[import]
except ModuleNotFoundError:
return "amdsmi module not found, please install amdsmi"
try:
amdsmi.amdsmi_init() # type: ignore[attr-defined]
except amdsmi.AmdSmiException: # type: ignore[attr-defined]
return "amdsmi driver can't be loaded, is ROCm installed?"
device = _get_amdsmi_device_index(device)
try:
handle = amdsmi.amdsmi_get_processor_handles()[device] # type: ignore[attr-defined]
procs = amdsmi.amdsmi_get_gpu_process_list(handle) # type: ignore[attr-defined]
except amdsmi.AmdSmiException: # type: ignore[attr-defined]
return "amdsmi cannot list processes from other users"
lines = []
lines.append(f"GPU:{device}")
if len(procs) == 0:
lines.append("no processes are running")
for p in procs:
if not torch.version.hip:
mem = p.usedGpuMemory / (1024 * 1024)
pid = p.pid
else:
try:
proc_info = amdsmi.amdsmi_get_gpu_process_info(handle, p) # type: ignore[possibly-undefined]
except AttributeError:
# https://github.com/ROCm/amdsmi/commit/c551c3caedbd903ba828e7fdffa5b56d475a15e7
# is a BC-breaking change that removes amdsmi_get_gpu_process_info API from amdsmi
proc_info = p
mem = proc_info["memory_usage"]["vram_mem"] / (1024 * 1024)
pid = proc_info["pid"]
lines.append(f"process {pid:>10d} uses {mem:>12.3f} MB GPU memory")
return "\n".join(lines)
[docs]def mem_get_info(device: Union[Device, int] = None) -> Tuple[int, int]:
r"""Return the global free and total GPU memory for a given device using cudaMemGetInfo.
Args:
device (torch.device or int or str, optional): selected device. Returns
statistic for the current device, given by :func:`~torch.cuda.current_device`,
if :attr:`device` is ``None`` (default) or if the device index is not specified.
.. note::
See :ref:`cuda-memory-management` for more
details about GPU memory management.
"""
if device is None:
device = torch.cuda.current_device()
# optional=True allows `device = torch.device('cuda')` for which device.index is None
device = _get_device_index(device, optional=True)
return torch.cuda.cudart().cudaMemGetInfo(device)
def _record_memory_history_legacy(
enabled: bool,
record_context=True,
trace_alloc_max_entries=1,
trace_alloc_record_context=False,
device: Union[Device, int] = None,
record_context_cpp=False,
):
_C._cuda_record_memory_history_legacy(
enabled,
record_context,
trace_alloc_max_entries,
trace_alloc_record_context,
record_context_cpp,
)
[docs]def _record_memory_history(
enabled: Literal[None, "state", "all"] = "all", *args, **kwargs
) -> None:
"""Enable recording of stack traces associated with memory
allocations, so you can tell what allocated any piece of memory in
:func:`torch.cuda.memory._snapshot()`.
In addition too keeping stack traces with each current allocation and free,
this will also enable recording of a history of all alloc/free events.
Use :func:`torch.cuda.memory._snapshot()` to retrieve this information,
and the tools in `_memory_viz.py` to visualize snapshots.
The Python trace collection is fast (2us per trace), so you may consider
enabling this on production jobs if you anticipate ever having to debug
memory issues.
C++ trace collection is also fast (~50ns/frame), which for many typical programs
works out to ~2us per trace, but can vary depending on stack depth.
Args:
enabled (Literal[None, "state", "all"], optional):
`None`, disable recording memory history.
`"state"`, keep information for currenly allocated memory.
`"all"`, additionally keep a history of all alloc/free calls.
Defaults to "all".
context (Literal[None, "state", "alloc", "all"], optional):
`None`, Do not record any tracebacks.
`"state"`, Record tracebacks for currently allocated memory.
`"alloc"`, additionally keep tracebacks for alloc calls.
`"all"`, additionally keep tracebacks for free calls.
Defaults to "all".
stacks (Literal["python", "all"], optional):
`"python"`, include Python, TorchScript, and inductor frames in tracebacks
`"all"`, additionally include C++ frames
Defaults to "all".
max_entries (int, optional): Keep a maximum of `max_entries`
alloc/free events in the recorded history recorded.
"""
if isinstance(enabled, bool):
return _record_memory_history_legacy(enabled, *args, **kwargs)
else:
return _record_memory_history_impl(enabled, *args, **kwargs)
def _record_memory_history_impl(
enabled: Optional[str] = "all",
context: Optional[str] = "all",
stacks: str = "all",
max_entries: int = sys.maxsize,
device: Union[Device, int] = None,
):
_C._cuda_record_memory_history(enabled, context, stacks, max_entries)
_record_memory_history.__signature__ = signature(_record_memory_history_impl) # type: ignore[attr-defined]
[docs]def _snapshot(device: Union[Device, int] = None):
"""Save a snapshot of CUDA memory state at the time it was called.
The state is represented as a dictionary with the following structure.
.. code-block:: python
class Snapshot(TypedDict):
segments : List[Segment]
device_traces: List[List[TraceEntry]]
class Segment(TypedDict):
# Segments are memory returned from a cudaMalloc call.
# The size of reserved memory is the sum of all Segments.
# Segments are cached and reused for future allocations.
# If the reuse is smaller than the segment, the segment
# is split into more then one Block.
# empty_cache() frees Segments that are entirely inactive.
address: int
total_size: int # cudaMalloc'd size of segment
stream: int
segment_type: Literal['small', 'large'] # 'large' (>1MB)
allocated_size: int # size of memory in use
active_size: int # size of memory in use or in active_awaiting_free state
blocks : List[Block]
class Block(TypedDict):
# A piece of memory returned from the allocator, or
# current cached but inactive.
size: int
requested_size: int # size requested during malloc, may be smaller than
# size due to rounding
address: int
state: Literal['active_allocated', # used by a tensor
'active_awaiting_free', # waiting for another stream to finish using
# this, then it will become free
'inactive',] # free for reuse
frames: List[Frame] # stack trace from where the allocation occurred
class Frame(TypedDict):
filename: str
line: int
name: str
class TraceEntry(TypedDict):
# When `torch.cuda.memory._record_memory_history()` is enabled,
# the snapshot will contain TraceEntry objects that record each
# action the allocator took.
action: Literal[
'alloc' # memory allocated
'free_requested', # the allocated received a call to free memory
'free_completed', # the memory that was requested to be freed is now
# able to be used in future allocation calls
'segment_alloc', # the caching allocator ask cudaMalloc for more memory
# and added it as a segment in its cache
'segment_free', # the caching allocator called cudaFree to return memory
# to cuda possibly trying free up memory to
# allocate more segments or because empty_caches was called
'oom', # the allocator threw an OOM exception. 'size' is
# the requested number of bytes that did not succeed
'snapshot' # the allocator generated a memory snapshot
# useful to coorelate a previously taken
# snapshot with this trace
]
addr: int # not present for OOM
frames: List[Frame]
size: int
stream: int
device_free: int # only present for OOM, the amount of
# memory cuda still reports to be free
Returns:
The Snapshot dictionary object
"""
return _C._cuda_memorySnapshot()
[docs]def _dump_snapshot(filename="dump_snapshot.pickle"):
"""
Save a pickled version of the `torch.memory._snapshot()` dictionary to a file.
This file can be opened by the interactive snapshot viewer at pytorch.org/memory_viz
Args:
filename (str, optional): Name of the file to create. Defaults to "dump_snapshot.pickle".
"""
s = _snapshot()
with open(filename, "wb") as f:
pickle.dump(s, f)
def _save_segment_usage(filename="output.svg", snapshot=None):
if snapshot is None:
snapshot = _snapshot()
with open(filename, "w") as f:
f.write(_segments(snapshot))
def _save_memory_usage(filename="output.svg", snapshot=None):
if snapshot is None:
snapshot = _snapshot()
with open(filename, "w") as f:
f.write(_memory(snapshot))
def _set_allocator_settings(env: str):
return torch._C._cuda_cudaCachingAllocator_set_allocator_settings(env)
[docs]def get_allocator_backend() -> str:
r"""Return a string describing the active allocator backend as set by
``PYTORCH_CUDA_ALLOC_CONF``. Currently available backends are
``native`` (PyTorch's native caching allocator) and `cudaMallocAsync``
(CUDA's built-in asynchronous allocator).
.. note::
See :ref:`cuda-memory-management` for details on choosing the allocator backend.
"""
return torch._C._cuda_getAllocatorBackend()
class _CUDAAllocator:
r"""Wrapper over internal CUDA memory allocators."""
def __init__(self, allocator: torch._C._cuda_CUDAAllocator):
self._allocator = allocator
def allocator(self):
return self._allocator
[docs]class CUDAPluggableAllocator(_CUDAAllocator):
r"""CUDA memory allocator loaded from a so file."""
def __init__(self, path_to_so_file: str, alloc_fn_name: str, free_fn_name: str):
r"""Memory allocators are compiled in .so files and loaded dynamically using ctypes.
To change the active allocator use the :func:`torch.memory.cuda.change_current_allocator` function.
Args:
path_to_so_file(str): Path in the filesystem to the `.so` file containing
the allocator functions
alloc_fn_name(str): Name of the function to perform the memory allocation
in the so file. The signature must be:
void* alloc_fn_name(ssize_t size, int device, cudaStream_t stream);
free_fn_name(str): Name of the function to perform the memory release
in the so file. The signature must be:
void free_fn_name(void* ptr, size_t size, cudaStream_t stream);
.. warning::
This is currently supported only in unix OSs
.. note::
See :ref:`cuda-memory-management` for details on creating and using a custom allocator
"""
allocator = ctypes.CDLL(path_to_so_file)
alloc_fn = ctypes.cast(getattr(allocator, alloc_fn_name), ctypes.c_void_p).value
free_fn = ctypes.cast(getattr(allocator, free_fn_name), ctypes.c_void_p).value
assert alloc_fn is not None
assert free_fn is not None
self._allocator = torch._C._cuda_customAllocator(alloc_fn, free_fn)
[docs]def change_current_allocator(allocator: _CUDAAllocator) -> None:
r"""Change the currently used memory allocator to be the one provided.
If the current allocator has already been used/initialized, this function will error.
Args:
allocator (torch.cuda.memory._CUDAAllocator): allocator to be set as the active one.
.. note::
See :ref:`cuda-memory-management` for details on creating and using a custom allocator
"""
torch._C._cuda_changeCurrentAllocator(allocator.allocator())
def _get_current_allocator() -> _CUDAAllocator:
r"""Return the allocator being currently used.
.. note::
See :ref:`cuda-memory-management` for details on creating and using a custom allocator
"""
return _CUDAAllocator(torch._C._cuda_getAllocator())
[docs]class MemPoolContext(_MemPoolContext):
r"""MemPoolContext holds the currently active pool and stashes the previous
pool. On deletion it makes the previous pool active.
Args:
pool(torch.cuda.MemPool): a MemPool object to be made active so that
allocations route to this pool.
"""
def __init__(self, pool: _MemPool):
super().__init__(pool)
[docs] @staticmethod
def active_pool() -> Optional[_MemPool]:
r"""Returns the active MemPool"""
return _MemPoolContext.active_pool()
[docs]class MemPool(_MemPool):
r"""MemPool represents a pool of memory in a caching allocator. Currently,
it's just the ID of the pool object maintained in the CUDACachingAllocator.
Args:
allocator(torch._C._cuda_CUDAAllocator, optional): a
torch._C._cuda_CUDAAllocator object that can be used to
define how memory gets allocated in the pool. If :attr:`allocator`
is ``None`` (default), memory allocation follows the default/
current configuration of the CUDACachingAllocator.
"""
def __init__(self, allocator: Optional[_cuda_CUDAAllocator] = None):
super().__init__(allocator, True)
@property
def id(self) -> Tuple[int, int]:
r"""Returns the ID of this pool as a tuple of two ints."""
return super().id
@property
def allocator(self) -> Optional[_cuda_CUDAAllocator]:
r"""Returns the allocator this MemPool routes allocations to."""
return super().allocator
[docs] def use_count(self) -> int:
r"""Returns the reference count of this pool."""
return super().use_count()
[docs] def snapshot(self):
r"""Return a snapshot of the CUDA memory allocator pool state across all
devices.
Interpreting the output of this function requires familiarity with the
memory allocator internals.
.. note::
See :ref:`cuda-memory-management` for more details about GPU memory
management.
"""
try:
ctx = MemPoolContext(self)
snapshot = torch.cuda.memory_snapshot()
finally:
del ctx
return snapshot
[docs]@contextlib.contextmanager
def use_mem_pool(pool: MemPool, device: Union[Device, int] = None):
r"""A context manager that routes allocations to a given pool.
Args:
pool(torch.cuda.MemPool): a MemPool object to be made active so that
allocations route to this pool.
device (torch.device or int, optional): selected device. Uses MemPool on
the current device, given by :func:`~torch.cuda.current_device`,
if :attr:`device` is ``None`` (default).
"""
ctx = MemPoolContext(pool)
device_index = (
torch.cuda.current_device() if device is None else _get_device_index(device)
)
_cuda_beginAllocateToPool(device_index, pool.id)
try:
yield
finally:
_cuda_endAllocateCurrentStreamToPool(device_index, pool.id)
_cuda_releasePool(device_index, pool.id)
del ctx
