To facilitate the integration of the new backend, we plan to publish a new development note that details all the key components,hoping to speed up the development of other accelerators.
This PR is the beginning of this note, and involve the part of registration of operators and we will gradually improve it and keep in sync with OpenReg's code.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/158644
Approved by: https://github.com/albanD
Previously, DTensor kept its own copy of the generator state after the
first time a random operator was called on a DTensor. This copy would
evolve independently from the generator outside of DTensor.
After adding support for users to pass a specific generator into
random operators (e.g. `uniform_(..., generator=)`), it was determined
(in discussion on #159991) to change the semantics so that any random
operations performed on DTensor would evolve the state of the publicly
visible generators (either the default one or user-passed one).
The upsides are (1) it is now possible to call torch.manual_seed() at
any point in the program and have a consistent effect on DTensor, (2)
DTensor ops have an observable effect on the generator. The downside is
that users are now responsible for seeding their generator before using
DTensor, ensuring all ranks use the same seed.
Fixes#159991
confirmed docs rendered OK
<img width="897" height="414" alt="image" src="https://github.com/user-attachments/assets/c082f0f0-5447-47aa-834f-65342eb237cd" />
Pull Request resolved: https://github.com/pytorch/pytorch/pull/160482
Approved by: https://github.com/wanchaol
A single-device version of Muon. Algorithm refers Keller Jordan's [Muon blogpost](https://kellerjordan.github.io/posts/muon/), and optionally incorporates [Moonshot's](https://github.com/MoonshotAI/Moonlight/blob/master/Moonlight.pdf) learning rate adjustment strategy.
This implementation maintains a minimalist API and is consistent with other optimizer conventions. PyTorch team prefers to handle parameter filtering at a higher level, with the Muon optimizer performing only the msign computation for orthogonalization on all parameters it receives. Users are responsible for grouping parameters for different optimizers as needed. An example usage is shown below, and a more detailed example will be added to the [PyTorch examples](https://github.com/pytorch/examples) directory.
**Usage**
```python
model = MyModelForCausalLM
# filter out your params manually
muon_params = [...]
adamw_params = [...]
muon = Muon(
params = muon_params
lr=lr,
wd=wd,
)
adamw = AdamW(
params = adamw_params
lr=lr,
wd=wd,
)
# in training loop
loss = model(input)
loss.backward()
muon.step()
adamw.step()
muon.zero_grad()
adamw.zero_grad()
```
~~**Additional usage**~~
~~Users are also able to pass in self-defined `msign` function for orthogonalization, and learning rate adjustment function. Interface defined below:~~
```python
~~AdjustLrFn: TypeAlias = Callable[[float, torch.Size], float]~~
~~MsignFn: TypeAlias = Callable[[Tensor, BaseMsignFnConfig], Tensor]~~
```
As discussed with team and in comment, we prefer to make the interface simpler and cleaner, thus we removed the callback interface, and canonicalize the original NS algorithm for Muon. The only configs available to users are `ns_steps`, `coefficients`, and `eps`, configurable through kwargs.
By default, we use 5-step Newton-Schulz, with coefficients proposed by [Keller](https://kellerjordan.github.io/posts/muon/). We use LR adjustment proposed by [Moonshot](https://github.com/MoonshotAI/Moonlight/blob/master/Moonlight.pdf), which grafts learning rate from AdamW.
**Testing**
~~1. Unit tests: the newly introduced Muon is covered in `test/test_optim.py`. We updated the test cases to pass named parameters to the optimizer under test. Additionally, we introduced a new test case to verify that when the user provides an empty FQN list, Muon correctly falls back to AdamW behavior.~~
As discussed, in order not to complicate the codebase, we prefer not to include reference implementation into PyTorch. We also updated the interface so we don't need to test the FQN based filtering. Muon is covered by the existing `test_optim.py` unit test.
2. End-to-end test: we added a training script that pre-trains a QWEN-like model on `openwebtext-100k` dataset. We trained for one epoch and the resulting loss curve is compared against the Moonshot implementation to confirm behavioral consistency.
<img width="1102" height="472" alt="Screenshot 2025-07-29 at 1 04 12 AM" src="https://github.com/user-attachments/assets/ceab0733-497d-4070-8032-02ae7995c64c" />
**Numerics**
We evaluate our implementation with existing implementation to confirm numerical consistency.
As discussed, our implementation closely follows the algorithm described in [Keller's post](https://kellerjordan.github.io/posts/muon/), while incorporating the learning rate adjustment from [Moonlight](https://github.com/MoonshotAI/Moonlight/blob/master/Moonlight.pdf). This captures a key insight that allows users to reuse hyper-parameters tuned for `adamW`, making Muon a drop-in swap.
As expected, the numerics difference mainly comes from `adjust_lr`, a max of ~5% relative diff in an example unit test setup below.
```python
# dummy model and data
model0 = Linear(10, 10, bias=False)
model1 = copy.deepcopy(model0)
inputs = torch.randn(8, 10)
targets = torch.randn(8, 10)
loss = MSELoss()
lr = 1e-3
wd = 0.1
momentum = 0.95
opt_ref_muon = KellySingleDeviceMuon(
params=model0.parameters(),
lr=lr,
weight_decay=wd,
momentum=momentum,
)
opt_exp_muon = Muon(
params=model1.parameters(),
lr=lr,
weight_decay=wd,
momentum=momentum,
)
out_ref = model0(inputs)
loss_ref = loss(out_ref, targets)
opt_ref_muon.zero_grad()
loss_ref.backward()
opt_ref_muon.step()
out_exp = model1(inputs)
loss_exp = loss(out_exp, targets)
opt_exp_muon.zero_grad()
loss_exp.backward()
opt_exp_muon.step()
for p_ref, p_exp in zip(model0.parameters(), model1.parameters()):
torch.testing.assert_close(p_ref, p_exp)
```
As explained above, including this `adjust_lr` is preferable. This is validated by an e2e training runs on training a qwen-2-like 0.5b model, where the curves show that training with `adjust_lr` converges more effectively than without.
<img width="1179" height="464" alt="Screenshot 2025-08-18 at 10 12 33 AM" src="https://github.com/user-attachments/assets/e797d3da-c2f0-4187-b99e-5d48b7437c3c" />
**Performance**
Training for one epoch of openwebtext-100k on eight H100 GPUs with DDP:
- adamw_ddp finishes in 13.12 min
- pytorch_muon_ddp finishes in 13.45 min
Muon runs ~20s slower compared to AdamW. Assuming no other changes, Muon is *2.5%* slower than AdamW.
AdamW: Optimizer.step() takes ~13.5 ms, step time ~930 ms
<img width="726" height="590" alt="Screenshot 2025-07-29 at 1 56 14 AM" src="https://github.com/user-attachments/assets/ebcd7e1c-d129-4b20-9396-39f568edf03d" />
Muon: Optimizer.step() takes ~54 ms, step time ~960 ms
<img width="751" height="597" alt="Screenshot 2025-07-29 at 2 02 20 AM" src="https://github.com/user-attachments/assets/72f5b904-ebd5-4502-a6ff-d3e9e5a6da81" />
**Note**
We restrict the implementation to accept only 2D parameters.
An alternative approach is to allow parameters with more than two dimensions and apply orthogonalization over the last two dimensions. We opt not to go with this approach as it can be error-prone. For example, with a kernel shaped `[in_channel, height, width, out_channel]`, applying orthogonalization to the last two dimensions is not meaningful.
Since Muon is designed to operate orthogonalization on 2D matrices, preserving this assumption keeps the implementation clean and sound.
**Next Steps**
1. Add `MuP`
2. Open-source optimized triton kernel for symmetric matmul. A preliminary benchmark found 1.23x - 1.48x speedup on small - large (n = 256 -> 16384) matrices.
3. Open-source unsharded Muon co-designed with FSDP2.
****
Pull Request resolved: https://github.com/pytorch/pytorch/pull/160213
Approved by: https://github.com/janeyx99
# Context
In #160163, we added support for NUMA binding for `Callable` entrypoints to `elastic_launch`. This requires special consideration, because they go through a different path to spawn subprocesses compared to `str` entrypoints, a path which does not provide a straightforward way to utilize `numactl` CLI. See #160006 for a full description of the challenges.
Although #160163 worked in initial local experiments, we ran into some linker errors in other environments when we tried to call `numactl`. This appeared to be due to interactions with how the `LD_PRELOAD` environment variable was being set.
# This PR
On further thought, the most straightforward, foolproof solution here is to use [the trick that @d4l3k suggested.](https://github.com/pytorch/pytorch/issues/160006#issuecomment-3162018836)
Specifically, for each local rank `i`:
1. The parent process sets its own CPU affinity to what local rank `i`'s should be.
2. Then, the parent spawns the subprocess for local rank `i`.
3. Finally, the parent resets its own CPU affinity to what it was originally.
There were other solutions that would work just for `Callable` entrypoints, but I believe this is the simplest one that can work for *both* `str` and `Callable`, and it's pretty simple.
This required a bit of refactoring:
1. Turn all the `_get_.*_numactl_options` into functions which return a set of logical CPUs to bind to, rather than options like `--cpunodebind=0`.
2. Instead of wrapping commands with `numactl`, use `os.sched_setaffinity` to bind to the CPUs from (1.).
3. Put this all inside a context manager which encapsulates applying and restoring the bindings in the parent process.
4. Use the context manager for both `str` and `Callable` paths
# Test Plan
## Automated
`$ pytest test/test_numa_binding.py`
## Manual
See [doc.](https://docs.google.com/document/d/1vxD-OKYBTT27jbBwtW9iz9g0tNM0u-i0tiTJg_ieQA8/edit?tab=t.0) Meta only, but TLDR tried out every combination of `str`, `Callable`, binding disabled, and binding enabled on the same model and saw 2x SM utilization for binding enabled.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/161183
Approved by: https://github.com/d4l3k
Remove enable_fake_mode and exporter_legacy entirely. Even though this is bc breaking, `enable_fake_mode` is no longer compatible with the latest version of transformers, and so it is no longer useful.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/161222
Approved by: https://github.com/titaiwangms
Previously, DTensor kept its own copy of the generator state after the
first time a random operator was called on a DTensor. This copy would
evolve independently from the generator outside of DTensor.
After adding support for users to pass a specific generator into
random operators (e.g. `uniform_(..., generator=)`), it was determined
(in discussion on #159991) to change the semantics so that any random
operations performed on DTensor would evolve the state of the publicly
visible generators (either the default one or user-passed one).
The upsides are (1) it is now possible to call torch.manual_seed() at
any point in the program and have a consistent effect on DTensor, (2)
DTensor ops have an observable effect on the generator. The downside is
that users are now responsible for seeding their generator before using
DTensor, ensuring all ranks use the same seed.
Fixes#159991
confirmed docs rendered OK
<img width="897" height="414" alt="image" src="https://github.com/user-attachments/assets/c082f0f0-5447-47aa-834f-65342eb237cd" />
Pull Request resolved: https://github.com/pytorch/pytorch/pull/160482
Approved by: https://github.com/wanchaol
TL;DR: Moving to ScalarType in user extensions and removing deprecated dtypes.
This change _modifies_ the from/to behavior between ScalarType and StableValue! Whereas before, user extensions could only in abstract pass around obfuscated dtypes appearing as int32_ts, now, users can confidently use torch::headeronly::ScalarType in their extensions for major scalar types. This PR enables ABI stability by adding a translation layer through the shim, so that even if the ScalarType enum values change in the future, user extensions need not fear.
Then we add a Tensor scalar_type API which reuses the from/to logic to return to the user a nice ScalarType (vs an abstracted int32_t).
I then changed the test to test the scalar_type API.
This code change required some refactoring because of circular dependencies.
## BC Breaking note
This commit is (narrowly) BC-breaking for unpopular dtypes: `quint*`s, `qint*`s, `Bits*`, `dummy_uint*`s, `dummy_int*`s, `Float8_e8m0fnu`, and `Float4_e2m1fn_x2` in the narrow use case where an extension retrieves a Tensor dtype of the above and passes it into `aoti_torch_call_dispatcher`. As of now, I believe there are 0 users of this use case, so the benefits of this change significantly justify BC-breaking this API.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/160557
Approved by: https://github.com/mikaylagawarecki, https://github.com/malfet
Existing documentation for torch.finfo().eps is as below:
| eps | float | The smallest representable number such that ``1.0 + eps != 1.0``. |
Proposed documentation for torch.finfo().eps is as below:
| eps | float | The difference between 1.0 and the next smallest representable float larger than 1.0. |
Fixes#160397
Pull Request resolved: https://github.com/pytorch/pytorch/pull/160502
Approved by: https://github.com/ngimel
Adds `OperatorEntry::getComputedKernelForDispatchKey` which returns the KernelFunction corresponding to `OperatorEntry.dispatchTable_[dispatch_ix]` for a given dispatch key
- Specifically it returns a `SafeKernelFunction` that holds a `KernelToken`. This `KernelToken` is registered to the `KernelFunction` in `OperatorEntry.kernels_` and will be invalidated when the `KernelFunction` is destructed (i.e. when the `AnnotatedKernel` that holds this `KernelFunction` is removed from `kernels_`, which happens when the corresponding impl is deregistered).
- `SafeKernelFunction` can be called via `callBoxed`, the validity of the token will be checked before this happens
- `SafeKernelFunction` is pybinded and `getComputedKernelForDispatchKey` is exposed to the frontend ia `torch.library.get_kernel`
Related to https://github.com/pytorch/pytorch/issues/155330
Pull Request resolved: https://github.com/pytorch/pytorch/pull/158393
Approved by: https://github.com/albanD
# Context
This is an extension of #149334.
# This PR
Add support for NUMA bindings with Callable entrypoints, such as `do_train` instead of `/usr/local/bin/python`.
Most notably, we utilize a hack in order to force `Process.start()` to use custom NUMA bindings for each subprocess. Please search for `HACK:` in the code to see a description of the implementation we chose, and #160006 for discussion of alternatives and why this is necessary.
Other changes:
* Remove unnecessary `--preferred` option from all binding strategies. By default, Linux already allocates memory to the NUMA node local to the CPU which triggered the allocation. (See [MPOL_LOCAL](https://man7.org/linux/man-pages/man2/set_mempolicy.2.html).)
* Refactor so that the main API is `maybe_wrap_command_with_numa_bindings`, which computes bindings for a single rank at a time, rather than `maybe_wrap_with_numa_bindings` which computed bindings for all ranks at once. This allowed for more code sharing between `Callable` and `str` entrypoints.
# Test Plan
## Automated
`$ pytest test/test_numa_binding.py`
## Manual
Using [this benchmark,](https://gist.github.com/pdesupinski/bbe01ade455d86e989794f2c612e2d91), ran
```
$ PYTHONUNBUFFERED=1 LOGLEVEL=INFO perf stat -e ls_dmnd_fills_from_sys.dram_io_far,ls_dmnd_fills_from_sys.dram_io_near -- python -m torch.distributed.run --standalone --nproc-per-node=8 --numa-binding=node --run-path mlp_train.py 2>&1 | tee node_callable.txt && PYTHONUNBUFFERED=1 LOGLEVEL=INFO perf stat -e ls_dmnd_fills_from_sys.dram_io_far,ls_dmnd_fills_from_sys.dram_io_near -- python -u -m torch.distributed.run --standalone --nproc-per-node=8 --run-path mlp_train.py 2>&1 | tee none_callable.txt
```
and observed
* 6.6% remote memory accesses with 'node' bindings
* 11.6% remote without bindings
I also ran similar with `str` entrypoints as before just to be sure it's still working.
NOTE: [--run-path triggers the code to be run inside a `Callable`.](017259f9c6/torch/distributed/run.py (L870))
Pull Request resolved: https://github.com/pytorch/pytorch/pull/160163
Approved by: https://github.com/d4l3k
Refactors how the enablement/disablement of CK Gemms and SDPA works.
- Adds USE_ROCM_CK_GEMM compile flag for enabling CK gemms.
- USE_ROCM_CK_GEMM is set to True by default on Linux
- Updates USE_CK_FLASH_ATTENTION to USE_ROCM_CK_SDPA.
- USE_ROCM_CK_SDPA is set to False by default
- (USE_CK_FLASH_ATTENTION still works for now, but will be deprecated in a future release)
- Prevents these CK libraries from being used unless pytorch has been built specifically with the functionality AND is running on a system architecture that supports it.
- the getters for these library backends will also do some validity checking in case the user used an environment variable to change the backend. If invalid, (i.e. one of the cases mentioned above is false) the backend will be set as the current non-CK default
Pull Request resolved: https://github.com/pytorch/pytorch/pull/152951
Approved by: https://github.com/eqy, https://github.com/jeffdaily, https://github.com/m-gallus
Co-authored-by: Jeff Daily <jeff.daily@amd.com>
Co-authored-by: Jithun Nair <jithun.nair@amd.com>
Co-authored-by: Jane (Yuan) Xu <31798555+janeyx99@users.noreply.github.com>
Sphinx likes titles and complains about them when they are not there. So adding a title to address this Wartning in the build:
```
WARNING: toctree contains reference to document 'distributed._dist2' that doesn't have a title: no link will be generated
```
Pull Request resolved: https://github.com/pytorch/pytorch/pull/159385
Approved by: https://github.com/d4l3k
This PR removes the integration point torch.fx had with torch::deploy (and another minor change).
Note: This PR has some broken mypy errors, but I believe those should have been in the code base beforehand, and should be fixed in a separate PR
Pull Request resolved: https://github.com/pytorch/pytorch/pull/158291
Approved by: https://github.com/albanD
ghstack dependencies: #158290
Options to address the "undocumented python objects":
1. Reference the functions in the .rst via the torch.nn.modules namespace. Note that this changes the generated doc filenames / locations for most of these functions!
2. [Not an option] Monkeypatch `__module__` for these objects (broke several tests in CI due to `inspect.findsource` failing after this change)
3. Update the .rst files to also document the torch.nn.modules forms of these functions, duplicating docs.
#### [this is the docs page added](https://docs-preview.pytorch.org/pytorch/pytorch/158491/nn.aliases.html)
This PR takes option 3 by adding an rst page nn.aliases that documents the aliases in nested namespaces, removing all the torch.nn.modules.* entries from the coverage skiplist except
- NLLLoss2d (deprecated)
- Container (deprecated)
- CrossMapLRN2d (what is this?)
- NonDynamicallyQuantizableLinear
This mostly required adding docstrings to `forward`, `extra_repr` and `reset_parameters`. Since forward arguments are already part of the module docstrings I just added a very basic docstring.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/158491
Approved by: https://github.com/janeyx99
Options to address the "undocumented python objects":
1. Reference the functions in the .rst via the `torch.functional` namespace. Note that this changes the generated doc filenames / locations for most of these functions!
2. Document these functions by referencing them from the `torch.` namespace instead, in line with common usage. This would also require setting the `__module__` for these functions and moving entries from `torch.functional`'s `__all__` -> `torch`'s `__all__`, which is BC-breaking.
3. Update the .rst files to also document the `torch.functional` forms of these functions, duplicating docs.
This PR takes option (3) above and:
* Removes all 20 `torch.functional` entries from the doc ignore list
* Removes `torch.functional.align_tensors()` entirely, since we don't want to document it.
* This is technically BC-breaking, although the previous impl simply errored out. This change could be moved to a separate isolated PR for safety.
* Introduces `torch.aliases.md` as a hidden page for the `torch.functional` aliases to the `torch` analogue functions
Pull Request resolved: https://github.com/pytorch/pytorch/pull/158581
Approved by: https://github.com/janeyx99
