Commit Graph

3234 Commits

Author SHA1 Message Date
Angel Li
3681312ce0 varlen api (#164502)
**Summary**

Today, the only way to have variable sequence length support in PyTorch attention is through nested tensors [here](https://docs.pytorch.org/tutorials/intermediate/scaled_dot_product_attention_tutorial.html#nestedtensor-and-dense-tensor-support). We also want to add an explicit lower-level API that provides variable sequence length support without padding/masking in SDPA.

This PR builds out `varlen_attn`, the public API that users can call for the forward method, and `_varlen_attn`, the private API that calls into the Flash Attention/cuDNN backend.

**Benchmarking**

To benchmark, we compare runtime and TFLOPs against the current SDPA approach with padding.

Settings:

- 1 H100 machine
- `batch_size=8`, `max_seq_len=2048`, `embed_dim=1024`, `num_heads=16`
- dtype `torch.bfloat16`
- `is_causal=False`
- for variable length, we set sequences to be random multiples of 64 up to `max_seq_len`
- 100 runs

|        | Variable Length API | SDPA     |
|--------|--------------------|----------|
| Runtime | 0.21750560760498047 ms       | 0.43171775817871094 ms  |
| TFLOPs | 231.812         | 320.840  |

The sparsity is 0.453 which we can see matches the speedup we get from Varlen (approx 50%). TFLOPs remains around the same, with SDPA slightly larger due to potential higher overhead and total flops scaling with sequence length.

**Testing**

Run `python test/test_varlen_attention.py` for unit tests where we verify basic functionality and confirm numerical match between varlen outputs vs SDPA.

**Next steps**

Next steps from this PR (higher in the stack) include registering the private API `_varlen_attn` as a custom op, implementing backward support, and enabling cuDNN with correct numerics.

(This stack builds on top of #162326)

Pull Request resolved: https://github.com/pytorch/pytorch/pull/164502
Approved by: https://github.com/v0i0, https://github.com/drisspg
2025-10-15 00:45:06 +00:00
sekyonda
c467e59cb0 dynamo configs to torch.compiler (#163517)
Moving some dynamo configs to torch.compiler

Pull Request resolved: https://github.com/pytorch/pytorch/pull/163517
Approved by: https://github.com/williamwen42, https://github.com/anijain2305

Co-authored-by: Svetlana Karslioglu <svekars@meta.com>
2025-10-14 22:44:53 +00:00
Sean McGovern
8c60f4ae08 [Distributed] update table in docs (#165009)
Fixes #162248

Pull Request resolved: https://github.com/pytorch/pytorch/pull/165009
Approved by: https://github.com/ezyang
2025-10-14 18:17:22 +00:00
Wei Feng
6918f17114 [FSDP2] provide public API to share cuda streams across roots (#165024)
for pipeline parallel, we can have multiple FSDP roots (chunks)
```
model = nn.Sequential([chunk0, chunk1])
fully_shard(model.chunk0)
fully_shard(model.chunk1)
```

we can call `share_comm_ctx` to share all-gather, reduce-scatter, all-reduce cuda streams. this avoids inter-stream memory fragmentation
```
from torch.distributed.fsdp import share_comm_ctx
share_comm_ctx([model.chunk0, model.chunk1])
```

unit test: `pytest -s test/distributed/_composable/fsdp/test_fully_shard_training.py -k test_share_comm_context`

Summary:

Test Plan:

Reviewers:

Subscribers:

Tasks:

Tags:

Pull Request resolved: https://github.com/pytorch/pytorch/pull/165024
Approved by: https://github.com/mori360
2025-10-14 17:50:46 +00:00
Animesh Jain
f3683453ae [compile] Regional inductor compilation with fx.annotate (#164776)
This PR introduces a way to compile a region of FX graph using `fx.traceback.annotate`.

### UX

1) In the user code, mark the region that you want to be compiled with inductor using `with fx_traceback.annotate({"compile_with_inductor": 0})`. As of now, we just rely on the string `compile_with_inductor` and ignore the integer. As the needs arise, we can update the logic.

Example

```
        def fn(x, y):
            sin = torch.sin(x)

            with fx_traceback.annotate({"compile_with_inductor": 0}):
                mul = sin * y
                add = mul + 1

            return torch.sin(add)
```

2) You have to instruct the compiler to use the annotations with `compile_fx_annotated_nodes_with_inductor` transformation. This is somewhat controversial, and a user might expect that just setting annotation is enough. But for now to control the blast radius, we need to explicitly do this. One such example is

```

# Set the fw and bw compiler of aot_autograd to `compile_fx_annotated_nodes_with_inductor`
def aot_eager_regional_inductor():
    return aot_autograd(
        fw_compiler=compile_fx_annotated_nodes_with_inductor,
        bw_compiler=compile_fx_annotated_nodes_with_inductor,
    )

```

3) Fixable in short-term - You have to wrap the user code in `torch.fx.traceback.preserve_node_meta` to ensure that annotations are propagated to the compiler. This is fixable, just need to make CI happy.

### Implementation

1) Relies on `CapabilityBasedPartitioner` to "scoop" out regions based on annotations, and then create subgraphs in the main graph.
2) Call `torch._inductor.standalone_compile` on these subgraphs, and jam the returned callable into the FX graph at the place of call_module

Resulting graph looks something like this - search for `torch__inductor_standalone_compile_inner`

Forward graph
```
class GraphModule(torch.nn.Module):
    def forward(self, primals_1: "f32[10]", primals_2: "f32[10]"):
         # File: /data/users/anijain/pytorch2/test/dynamo/test_regional_inductor.py:64 in fn, code: sin = torch.sin(x)
        sin: "f32[10]" = torch.ops.aten.sin.default(primals_1)

        # No stacktrace found for following nodes
        inner = torch__inductor_standalone_compile_inner(sin, primals_2)

         # File: /data/users/anijain/pytorch2/test/dynamo/test_regional_inductor.py:68 in fn, code: add = mul + 1
        getitem: "f32[10]" = inner[0];  inner = None

         # File: /data/users/anijain/pytorch2/test/dynamo/test_regional_inductor.py:70 in fn, code: return torch.sin(add)
        sin_1: "f32[10]" = torch.ops.aten.sin.default(getitem)
        return (sin_1, primals_1, primals_2, sin, getitem)
```

Backward graph
```
class GraphModule(torch.nn.Module):
    def forward(self, primals_1: "f32[10]", primals_2: "f32[10]", sin: "f32[10]", add: "f32[10]", tangents_1: "f32[10]"):
         # File: /data/users/anijain/pytorch2/test/dynamo/test_regional_inductor.py:64 in fn, code: sin = torch.sin(x)
        cos_1: "f32[10]" = torch.ops.aten.cos.default(primals_1);  primals_1 = None

         # File: /data/users/anijain/pytorch2/test/dynamo/test_regional_inductor.py:70 in fn, code: return torch.sin(add)
        cos: "f32[10]" = torch.ops.aten.cos.default(add);  add = None
        mul_1: "f32[10]" = torch.ops.aten.mul.Tensor(tangents_1, cos);  tangents_1 = cos = None

        # No stacktrace found for following nodes
        inner = torch__inductor_standalone_compile_inner(mul_1, sin, primals_2);  mul_1 = sin = primals_2 = None

         # File: /data/users/anijain/pytorch2/test/dynamo/test_regional_inductor.py:67 in fn, code: mul = sin * y
        getitem: "f32[10]" = inner[0]
        getitem_1: "f32[10]" = inner[1];  inner = None

         # File: /data/users/anijain/pytorch2/test/dynamo/test_regional_inductor.py:64 in fn, code: sin = torch.sin(x)
        mul_4: "f32[10]" = torch.ops.aten.mul.Tensor(getitem_1, cos_1);  getitem_1 = cos_1 = None
        return (mul_4, getitem)
```

### Some issue raised in the HOP meeting
1) CSE will not differentiate different meta custom nodes and do wrong thing.
2) SAC - The recomputed forward will be smaller than the forward. Will we compile a smaller region than?
3) What happens if you have a op in the middle which does not disturb the topology, is it still 1 subgraph?
4) What happens with the nesting of `fx_traceback.annotate`? Are there any ordering requirements?
5) What are we going to use the annotations for?
   a) compile flex
   b) streams
   c) nn.Module info to organize MoE components for pipelining
   d) PP stages
   e) Rename graph nodes for more debugging
   f) No nested regional compile

Pull Request resolved: https://github.com/pytorch/pytorch/pull/164776
Approved by: https://github.com/SherlockNoMad
ghstack dependencies: #165188
2025-10-13 22:22:20 +00:00
Angel Li
fa95882093 [BE] document distributed apis (#165194)
This PR documents some `torch.distributed.distributed_c10d` APIs. Below are some screenshots of the rendered docs.

<img width="909" height="527" alt="Screenshot 2025-10-10 at 10 18 40 PM" src="https://github.com/user-attachments/assets/555ae886-bead-47f3-8c67-9bc91c14bd11" />
<img width="885" height="548" alt="Screenshot 2025-10-10 at 10 18 47 PM" src="https://github.com/user-attachments/assets/1d6f7af1-db28-40f9-927e-5c47668a1a88" />

Pull Request resolved: https://github.com/pytorch/pytorch/pull/165194
Approved by: https://github.com/janeyx99
2025-10-13 20:13:59 +00:00
Mark Saroufim
7c015334a3 Remove FIXME comment about reset_max_memory_reserved (#165249)
The function doesn't actually exist https://github.com/pytorch/pytorch/blob/main/torch/cuda/__init__.py#L1816

Fixes https://github.com/pytorch/pytorch/issues/27785

Pull Request resolved: https://github.com/pytorch/pytorch/pull/165249
Approved by: https://github.com/svekars
2025-10-13 19:44:40 +00:00
Angel Li
70ec464c16 [BE] document some quantization public apis (#165160)
This PR documents some apis in `torch.ao.quantization.utils`

<img width="885" height="296" alt="Screenshot 2025-10-10 at 4 38 10 PM" src="https://github.com/user-attachments/assets/4323a6f5-ac3a-4f2e-ba00-35f3b208bef4" />
<img width="876" height="319" alt="Screenshot 2025-10-10 at 4 38 14 PM" src="https://github.com/user-attachments/assets/164822c3-9740-46f9-953d-bb20c77bcf69" />

Pull Request resolved: https://github.com/pytorch/pytorch/pull/165160
Approved by: https://github.com/janeyx99
2025-10-13 17:24:42 +00:00
Yu, Guangye
3a110c9bb2 Add a new API torch.xpu.is_tf32_supported for Intel GPU (#163141)
# Motivation
Aligned with other backends, this PR introduces a new API `torch.xpu.is_tf32_supported`, which should be used before `torch.backends.mkldnn.allow_tf32=True` or provide hardware capability information to the Triton

# Additional Context
On Intel Xe architecture and newer, TF32 operations can be accelerated through DPAS (Dot Product Accumulate Systolic) instructions. Therefore, TF32 support can be determined by checking whether the device supports subgroup matrix multiply-accumulate operations.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/163141
Approved by: https://github.com/EikanWang
2025-10-12 12:11:57 +00:00
PyTorch MergeBot
8d49cd5b26 Revert "[compile] Regional inductor compilation with fx.annotate (#164776)"
This reverts commit 1e4c7dffa3.

Reverted https://github.com/pytorch/pytorch/pull/164776 on behalf of https://github.com/malfet due to Looks like this one broke everything, not the top of the stack ([comment](https://github.com/pytorch/pytorch/pull/164776#issuecomment-3393725466))
2025-10-11 23:14:23 +00:00
Animesh Jain
1e4c7dffa3 [compile] Regional inductor compilation with fx.annotate (#164776)
This PR introduces a way to compile a region of FX graph using `fx.traceback.annotate`.

### UX

1) In the user code, mark the region that you want to be compiled with inductor using `with fx_traceback.annotate({"compile_with_inductor": 0})`. As of now, we just rely on the string `compile_with_inductor` and ignore the integer. As the needs arise, we can update the logic.

Example

```
        def fn(x, y):
            sin = torch.sin(x)

            with fx_traceback.annotate({"compile_with_inductor": 0}):
                mul = sin * y
                add = mul + 1

            return torch.sin(add)
```

2) You have to instruct the compiler to use the annotations with `compile_fx_annotated_nodes_with_inductor` transformation. This is somewhat controversial, and a user might expect that just setting annotation is enough. But for now to control the blast radius, we need to explicitly do this. One such example is

```

# Set the fw and bw compiler of aot_autograd to `compile_fx_annotated_nodes_with_inductor`
def aot_eager_regional_inductor():
    return aot_autograd(
        fw_compiler=compile_fx_annotated_nodes_with_inductor,
        bw_compiler=compile_fx_annotated_nodes_with_inductor,
    )

```

3) Fixable in short-term - You have to wrap the user code in `torch.fx.traceback.preserve_node_meta` to ensure that annotations are propagated to the compiler. This is fixable, just need to make CI happy.

### Implementation

1) Relies on `CapabilityBasedPartitioner` to "scoop" out regions based on annotations, and then create subgraphs in the main graph.
2) Call `torch._inductor.standalone_compile` on these subgraphs, and jam the returned callable into the FX graph at the place of call_module

Resulting graph looks something like this - search for `torch__inductor_standalone_compile_inner`

Forward graph
```
class GraphModule(torch.nn.Module):
    def forward(self, primals_1: "f32[10]", primals_2: "f32[10]"):
         # File: /data/users/anijain/pytorch2/test/dynamo/test_regional_inductor.py:64 in fn, code: sin = torch.sin(x)
        sin: "f32[10]" = torch.ops.aten.sin.default(primals_1)

        # No stacktrace found for following nodes
        inner = torch__inductor_standalone_compile_inner(sin, primals_2)

         # File: /data/users/anijain/pytorch2/test/dynamo/test_regional_inductor.py:68 in fn, code: add = mul + 1
        getitem: "f32[10]" = inner[0];  inner = None

         # File: /data/users/anijain/pytorch2/test/dynamo/test_regional_inductor.py:70 in fn, code: return torch.sin(add)
        sin_1: "f32[10]" = torch.ops.aten.sin.default(getitem)
        return (sin_1, primals_1, primals_2, sin, getitem)
```

Backward graph
```
class GraphModule(torch.nn.Module):
    def forward(self, primals_1: "f32[10]", primals_2: "f32[10]", sin: "f32[10]", add: "f32[10]", tangents_1: "f32[10]"):
         # File: /data/users/anijain/pytorch2/test/dynamo/test_regional_inductor.py:64 in fn, code: sin = torch.sin(x)
        cos_1: "f32[10]" = torch.ops.aten.cos.default(primals_1);  primals_1 = None

         # File: /data/users/anijain/pytorch2/test/dynamo/test_regional_inductor.py:70 in fn, code: return torch.sin(add)
        cos: "f32[10]" = torch.ops.aten.cos.default(add);  add = None
        mul_1: "f32[10]" = torch.ops.aten.mul.Tensor(tangents_1, cos);  tangents_1 = cos = None

        # No stacktrace found for following nodes
        inner = torch__inductor_standalone_compile_inner(mul_1, sin, primals_2);  mul_1 = sin = primals_2 = None

         # File: /data/users/anijain/pytorch2/test/dynamo/test_regional_inductor.py:67 in fn, code: mul = sin * y
        getitem: "f32[10]" = inner[0]
        getitem_1: "f32[10]" = inner[1];  inner = None

         # File: /data/users/anijain/pytorch2/test/dynamo/test_regional_inductor.py:64 in fn, code: sin = torch.sin(x)
        mul_4: "f32[10]" = torch.ops.aten.mul.Tensor(getitem_1, cos_1);  getitem_1 = cos_1 = None
        return (mul_4, getitem)
```

### Some issue raised in the HOP meeting
1) CSE will not differentiate different meta custom nodes and do wrong thing.
2) SAC - The recomputed forward will be smaller than the forward. Will we compile a smaller region than?
3) What happens if you have a op in the middle which does not disturb the topology, is it still 1 subgraph?
4) What happens with the nesting of `fx_traceback.annotate`? Are there any ordering requirements?
5) What are we going to use the annotations for?
   a) compile flex
   b) streams
   c) nn.Module info to organize MoE components for pipelining
   d) PP stages
   e) Rename graph nodes for more debugging
   f) No nested regional compile

Pull Request resolved: https://github.com/pytorch/pytorch/pull/164776
Approved by: https://github.com/SherlockNoMad
2025-10-11 15:49:42 +00:00
PyTorch MergeBot
f975bd58af Revert "Warn if AccumulateGrad stream does not match producer node stream (#165065)"
This reverts commit a70ef954b9.

Reverted https://github.com/pytorch/pytorch/pull/165065 on behalf of https://github.com/izaitsevfb due to breaks lint ([comment](https://github.com/pytorch/pytorch/pull/165065#issuecomment-3391387386))
2025-10-10 17:29:29 +00:00
soulitzer
a70ef954b9 Warn if AccumulateGrad stream does not match producer node stream (#165065)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/165065
Approved by: https://github.com/ngimel
ghstack dependencies: #162815
2025-10-10 16:46:01 +00:00
Mikayla Gawarecki
9c057d9863 [BE] Refresh documentation for stable ABI / API (#163899)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/163899
Approved by: https://github.com/janeyx99
2025-10-10 03:26:28 +00:00
Simon Layton
6a7f5c0d21 Add scaled_mm python API, test (#164142)
Summary:

* Add `torch.nn.functional.scaled_mm` as an abstraction around the C++
  methods
* Wraps `torch._scaled_mm_v2` API by default, but user can force use of
  the older `torch._scaled_mm` interface.
* Scaled MM tests now run on the new API

Test Plan:

`pytest test/test_scaled_matmul_cuda.py`

Reviewers:

Subscribers:

Tasks:

Tags:
Signed-off-by: Simon Layton <simonlaytonmeta.com>

Pull Request resolved: https://github.com/pytorch/pytorch/pull/164142
Approved by: https://github.com/drisspg
ghstack dependencies: #164141
2025-10-09 12:43:18 +00:00
Natalia Gimelshein
37c6087334 Add split-K control to cuBLAS reduced-precision settings (#164766)
## Summary
- add a CuBLASReductionOption enum so the CUDA context can track reduced-precision and split-K options
- extend the Python bindings, backend helpers, and docs to accept an optional allow_splitk argument for fp16/bf16 matmul controls
- update cuBLAS/cuBLASLt call sites plus dynamo guards and tests to respect the new combinations

## Testing
- python test/test_cuda.py TestCuda.test_cublas_allow_fp16_reduced_precision_reduction_get_set -v *(fails: ModuleNotFoundError: No module named 'psutil')*

------
https://chatgpt.com/codex/tasks/task_e_68e404623178832f8a3e1d34e1e175da

Pull Request resolved: https://github.com/pytorch/pytorch/pull/164766
Approved by: https://github.com/malfet, https://github.com/albanD
2025-10-08 18:48:45 +00:00
bobrenjc93
91b9484264 [ez] fix small doc error (#164915)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/164915
Approved by: https://github.com/svekars
2025-10-08 18:27:44 +00:00
PyTorch MergeBot
fd4bde430a Revert "list_stored_sd_metadata API. (#160610)"
This reverts commit da903b6a8b.

Reverted https://github.com/pytorch/pytorch/pull/160610 on behalf of https://github.com/jeffdaily due to broke ROCm CI, but flaky also on CUDA CI https://hud.pytorch.org/failure?name=periodic%20%2F%20linux-jammy-rocm-py3.10%20%2F%20test%20(distributed%2C%202%2C%203%2C%20linux.rocm.gpu.mi250.4%2C%20module%3Arocm%2C%20oncall%3Adistributed)&jobName=undefined&failureCaptures=distributed%2Fcheckpoint%2Ftest_list_stored_state_dict.py%3A%3ATestListStateDict%3A%3Atest_list_stored_sd_metadata ([comment](https://github.com/pytorch/pytorch/pull/160610#issuecomment-3382023022))
2025-10-08 15:10:38 +00:00
Pradeep Fernando
da903b6a8b list_stored_sd_metadata API. (#160610)
Summary:
1\ Certain checkpoint load use cases are not aware of the properties of the data/tensors they want to load.
2\ These usecases include data loader checkpoints, reading data for post processing (when the original model definition is not available).
3\ There, we have to use saved checkpoint  (metadata) as our source of truth.
4\ This RFC proposal exposes the checkpoint metadata using a public API.

In this proposal we expose the stored state-dict metadata  (minus associated storage/chunk metadata).

Chunk/storage details should not be exposed to the users and is a impl detail of the storage writer/reader.

Test Plan:
UT.

Rollback Plan:

Differential Revision: D80231457

Pull Request resolved: https://github.com/pytorch/pytorch/pull/160610
Approved by: https://github.com/saumishr
2025-10-08 04:33:51 +00:00
PyTorch MergeBot
1e42fde45e Revert "[CUDA] Add experimental green context support for SM carveout (#159104)"
This reverts commit 746fe78ecd.

Reverted https://github.com/pytorch/pytorch/pull/159104 on behalf of https://github.com/malfet due to Breaks Windows CD build ([comment](https://github.com/pytorch/pytorch/pull/159104#issuecomment-3378675515))
2025-10-07 20:51:22 +00:00
Eddie Yan
746fe78ecd [CUDA] Add experimental green context support for SM carveout (#159104)
Low-level PyTorch APIs should be usable/stable enough at this point but we might move the underlying driver API usage a bit from here...

Built on top of @drisspg 's branch

Pull Request resolved: https://github.com/pytorch/pytorch/pull/159104
Approved by: https://github.com/ngimel

Co-authored-by: drisspg <drisspguessous@gmail.com>
2025-10-06 23:11:23 +00:00
PyTorch MergeBot
8ec8c14ace Revert "[CUDA] Add experimental green context support for SM carveout (#159104)"
This reverts commit 3c59351c6e.

Reverted https://github.com/pytorch/pytorch/pull/159104 on behalf of https://github.com/clee2000 due to failed lint, pyfmt not caught pyi file, I think they need special handling since theyre not in the changed files list? ([comment](https://github.com/pytorch/pytorch/pull/159104#issuecomment-3367077208))
2025-10-03 20:15:56 +00:00
Eddie Yan
3c59351c6e [CUDA] Add experimental green context support for SM carveout (#159104)
Low-level PyTorch APIs should be usable/stable enough at this point but we might move the underlying driver API usage a bit from here...

Built on top of @drisspg 's branch

Pull Request resolved: https://github.com/pytorch/pytorch/pull/159104
Approved by: https://github.com/ngimel

Co-authored-by: drisspg <drisspguessous@gmail.com>
2025-10-03 18:59:12 +00:00
Banit Agrawal
f39789cdab [PyTorch Pinned Allocator] Add support of reserved pinned memory segment to avoid slow paths (#164501)
Summary:
This diff adds the feature of allocating a large pinned memory segment upfront based on the provided config. This large segment is then used to serve all the small pinned memory requests to avoid expensive device level APIs (slow paths).

Example:

PYTORCH_CUDA_ALLOC_CONF=pinned_reserve_segment_size_mb:2048

This reserves a 2GB pinned memory segment for the process and then all incoming small requests are just served from this segment and no cudaHostAlloc/cudaHostRegister apis are being called.

Differential Revision: D83779074

Pull Request resolved: https://github.com/pytorch/pytorch/pull/164501
Approved by: https://github.com/yangw-dev
2025-10-03 18:11:27 +00:00
Eddie Yan
f7082e92b3 [cuBLAS] update cuBLAS determinism docs, remove workspace requirement checks (#161749)
Since CUDA 11.x (need to update the docs for this, current PR is saying 12.2 which is incorrect) we've been allocating cuBLAS workspaces explicitly per handle/stream combination https://github.com/pytorch/pytorch/pull/85447

According to the cuBLAS documentation, this appears to be sufficient for determinism without any explicit workspace requirements to e.g., `:4096:8` or `:16:8` as was previously expressed in PyTorch docs https://docs.nvidia.com/cuda/cublas/#results-reproducibility

Planning to add an explicit determinism test as well...

Pull Request resolved: https://github.com/pytorch/pytorch/pull/161749
Approved by: https://github.com/ngimel
2025-10-03 00:09:47 +00:00
Parthava Adabala
e6d4b26776 Update torch.rst (#164408)
Corrected grammatical mistake

Fixes #ISSUE_NUMBER

Pull Request resolved: https://github.com/pytorch/pytorch/pull/164408
Approved by: https://github.com/mikaylagawarecki
2025-10-02 18:12:47 +00:00
Frank Lin
bec6541d84 [CUDA][CUDAGraph] Reduce capture overhead in CUDA Graph memory reuse (#162186)
Previous work #158352 delivered CUDAGraph memory footprint reduction with no replay-time impact, but capture time regressed (up to 20× slower) due to repeated full-graph traversals. See previous benchmark results [here](https://github.com/pytorch/pytorch/pull/158352#issuecomment-3215947565)

This PR removes capture/reply overhead while preserving the memory savings:

1. **Terminals as free markers**
   We stop inserting empty nodes and instead record the current stream terminals as free markers. This avoids mutating the user’s graph and keeps semantics unchanged.

2. **Incremental, cached reachability**
   We add a **per-graph reuse context** that caches reverse-traversal state:

   * `graph_reuse_context[graph].visited[stream]` tracks nodes already seen from that stream’s terminal frontier.
   * On each allocation during capture, we resume traversal from the latest terminals and only visit unseen nodes.
   * A block is freed when all its recorded markers are in the visited set of its allocation stream—i.e., all markers are proven predecessors of future work.

See [the performance results here](https://docs.google.com/spreadsheets/d/e/2PACX-1vRPvdd9Xa8W87ixbiA0da_qvOhrUAjUpFz0G-_j-MsDnoeRyhEa4_ut_W3rqcg1VVZVFJ-gucwov-3b/pubhtml?gid=1468302443&single=true), we sweep synthetic multi-stream CUDA Graphs built by `capture_benchmark.py` (same as before, we generate random interleaving of alloc/free/join with given probabilities, see [gist here](https://gist.github.com/eee4017/e2092d215b1d4bd46534148939af39e3)), and we compare median capture/replay times and memory. On an NVIDIA H100 PCIe across 24 configs, the optimization preserves reserved memory reduction at ~24–98%, leaves allocated memory unchanged, and brings capture time back to baseline (range 0.96–1.04× vs. baseline) with replay time unchanged (range 0.97–1.11×).

Pull Request resolved: https://github.com/pytorch/pytorch/pull/162186
Approved by: https://github.com/eqy, https://github.com/ngimel
2025-09-30 22:28:46 +00:00
Han Qi
60f0a356fd Update persons of interest for XLA. The previous one is out of date. (#158652)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/158652
Approved by: https://github.com/JackCaoG, https://github.com/albanD
2025-09-30 19:21:18 +00:00
zeshengzong
77354e22e1 [OpenReg] Add AMP Integration guide for accelerators (#162050)
Fix part of #158917

Add AMP integration document and OpenReg code as example to explain steps of integration.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/162050
Approved by: https://github.com/albanD

Co-authored-by: FFFrog <ljw1101.vip@gmail.com>
2025-09-30 12:27:11 +00:00
Rachel Guo
0b0ed6fd33 [doc] Add AOTInductor intermediate debug printer OSS user manual (#163794)
Summary: Add a OSS user manual for AOTI intermediate debug printer so we can link it in the Pytorch conference poster.

Test Plan: N/A

Differential Revision: D83171374

Pull Request resolved: https://github.com/pytorch/pytorch/pull/163794
Approved by: https://github.com/yushangdi
2025-09-30 03:01:03 +00:00
Fabian
8701f18bc0 Adjust ...mark_unbacked() -> ...decorators.mark_unbacked() in logs. (#164131)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/164131
Approved by: https://github.com/albanD, https://github.com/Skylion007
2025-09-29 17:44:00 +00:00
Dev Sashidhar
5ff2387dbe Fix comment on broadcasting example to clarify dimension mismatch (#162177)
Fixes #162116

Updated the comment in the broadcasting example to clarify that tensors with mismatched dimension sizes (0 vs 2) are not broadcastable. Removed incorrect reference to missing dimensions.

Pull Request resolved: https://github.com/pytorch/pytorch/pull/162177
Approved by: https://github.com/soulitzer
2025-09-29 16:47:48 +00:00
Bin Bao
48a852b7ae [AOTI] Update AOTInductor tutorial (#163808)
Summary: Remove the BC breaking warning. Add inductor_config to the example code.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/163808
Approved by: https://github.com/yushangdi
2025-09-26 22:01:31 +00:00
Sherlock Huang
10e69a6e17 Preserve user annotation in graph (#163673)
```
import torch
import torch.fx.traceback as fx_traceback
import torch.export

class M(torch.nn.Module):
    def forward(self, x):
        with fx_traceback.annotate({"pp_stage": 0}):
            with fx_traceback.annotate({"fdsp_bucket": 0}):
                x = x + 1
            x = x - 2
            with fx_traceback.annotate({"cuda_stream": 2, "fsdp_bucket": 1}):
                x = x * 2
        x = x / 3
        return x

m = M()

with fx_traceback.preserve_node_meta():
    ep = torch.export.export(m, (torch.randn(10),))

for node in ep.graph.nodes:
    if node.op == "call_function":
        print(f"{node.target}, {node.meta.get("custom", {})}")

```

prints

```
aten.add.Tensor, {'pp_stage': 0, 'fdsp_bucket': 0}
aten.sub.Tensor, {'pp_stage': 0}
aten.mul.Tensor, {'pp_stage': 0, 'cuda_stream': 2, 'fsdp_bucket': 1}
aten.div.Tensor, {}
```

TODOs:
- run_decomposition is failing
- Need to test with the new full graph capture + aot_export_joint apis
- Need to make the annotation propagate through autograd engine to reach the bw nodes. Sample impl here: https://github.com/pytorch/pytorch/pull/83558
- Edward want to restrict the key in custom field to be top-level singleton objects only
- also need to take care of metadata merging when passes are fusing nodes

Thanks @angelayi  for contributing the dynamo fixes.

Pull Request resolved: https://github.com/pytorch/pytorch/pull/163673
Approved by: https://github.com/albanD, https://github.com/angelayi
2025-09-25 15:50:15 +00:00
PyTorch MergeBot
00059db034 Revert "[RELAND] Always build USE_DISTRIBUTED (#160449) and Make distributed modules importable even when backend not built (#159889) (#162594)"
This reverts commit 09cb34c1dc.

Reverted https://github.com/pytorch/pytorch/pull/162594 on behalf of https://github.com/malfet due to reverted internally and now can be safely reverted in OSS ([comment](https://github.com/pytorch/pytorch/pull/162594#issuecomment-3334176367))
2025-09-25 13:47:46 +00:00
Svetlana Karslioglu
8c8416b021 Update pytorch.org links in docs/conf.py (#163682)
Update links in conf.py to docs.pytorch.org

Fixes #ISSUE_NUMBER

Pull Request resolved: https://github.com/pytorch/pytorch/pull/163682
Approved by: https://github.com/sekyondaMeta, https://github.com/albanD
2025-09-23 21:40:11 +00:00
Sherlock Huang
95ac7d724e Rename to _debug_mode.py to make it private (#163534)
rename debug_mode.py to _debug_mode.py to make it private, per @alban's request.

Pull Request resolved: https://github.com/pytorch/pytorch/pull/163534
Approved by: https://github.com/albanD
2025-09-23 04:27:10 +00:00
Edward Yang
09cb34c1dc [RELAND] Always build USE_DISTRIBUTED (#160449) and Make distributed modules importable even when backend not built (#159889) (#162594)
Summary:
Original: D81957844 and D81957923

Also, https://github.com/pytorch/pytorch/pull/162142 is patched in as well

#buildall

Test Plan:
sandcastle and oss ci

Rollback Plan:

Reviewed By: H-Huang

Pull Request resolved: https://github.com/pytorch/pytorch/pull/162594
Approved by: https://github.com/H-Huang, https://github.com/dcci
2025-09-22 21:12:18 +00:00
Svetlana Karslioglu
8e62d01f7a Add dynamic shapes doc (#159428)
This PR adds new Dynamic Shapes documentation and expands on the existing one.
- Adds a new structure with Intro, Core Concepts, Troubleshooting

Pull Request resolved: https://github.com/pytorch/pytorch/pull/159428
Approved by: https://github.com/bobrenjc93

Co-authored-by: bobrenjc93 <bobren@meta.com>
2025-09-22 21:01:27 +00:00
PyTorch MergeBot
f0078941cf Revert "[RELAND] Always build USE_DISTRIBUTED (#160449) and Make distributed modules importable even when backend not built (#159889) (#162594)"
This reverts commit 6c334885d4.

Reverted https://github.com/pytorch/pytorch/pull/162594 on behalf of https://github.com/wdvr due to reverted internally - @ezyang see D82281294 ([comment](https://github.com/pytorch/pytorch/pull/162594#issuecomment-3317017530))
2025-09-22 05:39:07 +00:00
Jiannan Wang
6ac2b3ae35 [BE] Adding aliases for CUDA and XPU API documentation (#162984)
This PR reorganizes CUDA and XPU API documentation with additional aliases pages. Multiple entries of APIs under torch.cuda are thus removed.

Pull Request resolved: https://github.com/pytorch/pytorch/pull/162984
Approved by: https://github.com/janeyx99
2025-09-21 22:28:27 +00:00
windsonsea
4a96a6fa4a [Docs] Fix indentations in cond.md (#156147)
This is a follow-up PR to fix indentations mentioned by https://github.com/pytorch/pytorch/pull/155653#issuecomment-2971660356

Pull Request resolved: https://github.com/pytorch/pytorch/pull/156147
Approved by: https://github.com/svekars, https://github.com/cyyever
2025-09-21 05:50:50 +00:00
Pian Pawakapan
4c007073e6 [dynamic shapes] DynamicInts prototype (#162194)
Initial prototype for dynamic int inputs, allows users to run with `torch.compile(f)(DynamicInt(4))`, compiling dynamically and using the underlying hint at runtime.

Current behavior:
- Also works in eager (mostly by subclassing int), as scalar input to torch functions, or numpy/math/etc. For example, `x = DynamicInt(3); torch.randn(x); torch.add(y, z, alpha=x); np.arange(x)` all act as if x = 3.
- Behavior for arithmetic ops is to return new DynamicInts rather than static ints; `DynamicInt(3) * 2 = DynamicInt(6)`. This is via SymNode magic methods, but coverage might not be 100% - for example, I had to explicitly override floordiv to avoid int casting. This is not necessarily the case for non-magic method ops (e.g. `math.cos(x)`). The alternative here is to int cast on all operations, but I opted for this for dynamism propagation in non-compiled regions.
- Doesn't ban fullgraph=False; DynamicInt objects might be leaked back to the user, but I guess this is fine, because they can be casted to ints when needed?
- Dynamo only allocates one symbol per DynamicInt; specifying the same DynamicInt for multiple inputs leads to input deduplication, and a guard installed.
- We don't raise on int specialization (in allowlist/maybe_mark_dynamic style) - but an easy change if needed.
- DynamicInts as nn.Module attributes are handled.
- We don't guard on the DynamicInt id, e.g. users can do the following without recompiling (maybe we should guard?)
```python
x = DynamicInt(4)
f(x)
f(1)
f(DynamicInt(3))  # same as f(3)
```

Follow-up work:
- Specifying shape constraints, either at the int-level, e.g.
```python
DynamicInt(64, name="s0", constraints=["s0 % 32 == 0", "s0 <= 1024"]
```
or at the compilation level, e.g. something like
```python
s0 = DynamicInt(64, name="s0")
s1 = DynamicInt(128, name="s1")
with some_compiler_config.dynamic_int_constraints(["s1 == 2*s0", "s0 % 32 == 0"]):
    f(s0, s1)
```
This should subsume the need for specifying derived SymInts?
- SymFloat support - currently it seems backed floats are specialized by the tensorify float pass, and there's no handling in inductor.
- Propagating dynamism in tensor constructors, e.g. `x = DynamicInt(4); torch.randn(x)` could annotate `_dynamo_dynamic_indices`.

Differential Revision: D81698719

Pull Request resolved: https://github.com/pytorch/pytorch/pull/162194
Approved by: https://github.com/bobrenjc93
2025-09-18 23:26:28 +00:00
PaliC
c43ccfbc2d [BE] Remove bottleneck (#163210)
Some cleanup related to this RFC: https://github.com/pytorch/pytorch/issues/68742
Pull Request resolved: https://github.com/pytorch/pytorch/pull/163210
Approved by: https://github.com/ezyang
2025-09-18 12:08:13 +00:00
rzou
98ce93db0b [DTensor] Add guide for what to do about mixed torch.Tensor and DTensor operations (#162651)
Also updates the error message to point to the guide.

Pull Request resolved: https://github.com/pytorch/pytorch/pull/162651
Approved by: https://github.com/ezyang
ghstack dependencies: #162117, #162307
2025-09-18 06:41:02 +00:00
Shangdi Yu
69a5a5ac02 Add to inductor provenance tracking doc (#162975)
As title

Pull Request resolved: https://github.com/pytorch/pytorch/pull/162975
Approved by: https://github.com/desertfire, https://github.com/mlazos
2025-09-16 19:09:06 +00:00
Yu, Guangye
0819de412d Add a new API torch.xpu.can_device_access_peer for Intel GPU (#162705)
# Motivation
Aligned with other backends, this PR introduces an new API `torch.xpu.can_device_access_peer`, which is used in vllm distributed [scenarios](2048c4e379/vllm/distributed/device_communicators/custom_all_reduce.py (L37))

Pull Request resolved: https://github.com/pytorch/pytorch/pull/162705
Approved by: https://github.com/EikanWang, https://github.com/ezyang
2025-09-16 18:00:22 +00:00
jiannanWang
b6a48ff69f [BE] Add Documentation for Device APIs (#162834)
Added documentation for torch.cuda APIs.
Fixed docstring for xpu and mtia is_bf16_supported API.

Pull Request resolved: https://github.com/pytorch/pytorch/pull/162834
Approved by: https://github.com/janeyx99

Co-authored-by: Jane (Yuan) Xu <31798555+janeyx99@users.noreply.github.com>
2025-09-16 17:01:06 +00:00
Sherlock Huang
f8d379d29e [DTensor] Introduce DebugMode (#162665)
Introduce a lightweight TorchDispatchMode for understanding the magic behind DTensor.

- Tracks redistribution, see `redistribute_input(input_idx, from_placement, to_placement)`
- Optionally tracks torch-level functions, via `__torch_function__`
- Optionally tracks FakeTensor operations, which was needed for propagating tensor meta as a step of sharding propagation
- Optionally tracks real tensor operations, including functional c10d op, and regular ops
- Calls are shown in the hierarchical structure!
- shorthand representation
  - dt: DTesnor, ft: FakeTensor, t: Tensor
  - DM(2, 2) == DeviceMesh(shape = [2, 2])
  - [R, P, S(0)] == Placement[Replicate, Partial, Shard(0)]
  - f32[8,8] == float32 with shape[8, 8]

```
  debug_mode = DTensorDebugMode(record_faketensor=False, record_realtensor=True)
  with debug_mode:
      torch.mm(x_dtensor, y_dtensor)
  print(debug_mode.debug_string())
```
produces:
```
  torch.mm(dt: f32[8, 8][S(0)], dt: f32[8, 32][S(0)])
    aten::mm(dt: f32[8, 8][S(0)], dt: f32[8, 32][S(0)])
      redistribute_input(1, [S(0)], [R])
        _c10d_functional::all_gather_into_tensor(t: f32[1, 32], 8, 0)
        _c10d_functional::wait_tensor(t: f32[8, 32])
      aten::mm(t: f32[1, 8], t: f32[8, 32])
```

Another example, for torch.einsum
```
  torch.functional.einsum(bld,dnh->blnh, dt: f32[16, 6, 8][P, R], dt: f32[8, 4, 4][R, P])
    aten::unsqueeze(dt: f32[16, 6, 8][P, R], 3)
      aten::unsqueeze(t: f32[16, 6, 8], 3)
    aten::unsqueeze(dt: f32[16, 6, 8, 1][P, R], 4)
      aten::unsqueeze(t: f32[16, 6, 8, 1], 4)
    aten::permute(dt: f32[16, 6, 8, 1, 1][P, R], [0, 1, 3, 4, 2])
      aten::permute(t: f32[16, 6, 8, 1, 1], [0, 1, 3, 4, 2])
    aten::unsqueeze(dt: f32[8, 4, 4][R, P], 3)
      aten::unsqueeze(t: f32[8, 4, 4], 3)
    aten::unsqueeze(dt: f32[8, 4, 4, 1][R, P], 4)
      aten::unsqueeze(t: f32[8, 4, 4, 1], 4)
    aten::permute(dt: f32[8, 4, 4, 1, 1][R, P], [3, 4, 1, 2, 0])
      aten::permute(t: f32[8, 4, 4, 1, 1], [3, 4, 1, 2, 0])
    aten::permute(dt: f32[16, 6, 1, 1, 8][P, R], [0, 1, 4, 2, 3])
      aten::permute(t: f32[16, 6, 1, 1, 8], [0, 1, 4, 2, 3])
    aten::view(dt: f32[16, 6, 8, 1, 1][P, R], [1, 96, 8])
      aten::view(t: f32[16, 6, 8, 1, 1], [1, 96, 8])
    aten::permute(dt: f32[1, 1, 4, 4, 8][R, P], [4, 2, 3, 0, 1])
      aten::permute(t: f32[1, 1, 4, 4, 8], [4, 2, 3, 0, 1])
    aten::view(dt: f32[8, 4, 4, 1, 1][R, P], [1, 8, 16])
      aten::view(t: f32[8, 4, 4, 1, 1], [1, 8, 16])
    aten::bmm(dt: f32[1, 96, 8][P, R], dt: f32[1, 8, 16][R, P])
      redistribute_input(0, [P, R], [S(2), S(2)])
        aten::chunk(t: f32[1, 96, 8], 4, 2)
        aten::cat(['t: f32[1, 96, 2]', 't: f32[1, 96, 2]', 't: f32[1, 96, 2]', 't: f32[1, 96, 2]'])
        _c10d_functional::reduce_scatter_tensor(t: f32[4, 96, 2], sum, 4, 2)
        aten::clone(t: f32[1, 96, 1])
      redistribute_input(1, [R, P], [S(1), S(1)])
        aten::chunk(t: f32[1, 8, 16], 4, 1)
        aten::clone(t: f32[1, 2, 16])
        aten::chunk(t: f32[1, 2, 16], 2, 1)
        aten::cat(['t: f32[1, 1, 16]', 't: f32[1, 1, 16]'])
        _c10d_functional::reduce_scatter_tensor(t: f32[2, 1, 16], sum, 2, 3)
        _c10d_functional::wait_tensor(t: f32[1, 1, 16])
      aten::bmm(t: f32[1, 96, 1], t: f32[1, 1, 16])
    aten::view(dt: f32[1, 96, 16][P, P], [16, 6, 1, 4, 4])
      aten::view(t: f32[1, 96, 16], [16, 6, 1, 4, 4])
    aten::permute(dt: f32[16, 6, 1, 4, 4][P, P], [0, 1, 3, 4, 2])
      aten::permute(t: f32[16, 6, 1, 4, 4], [0, 1, 3, 4, 2])
    aten::view(dt: f32[16, 6, 4, 4, 1][P, P], [16, 6, 4, 4])
      aten::view(t: f32[16, 6, 4, 4, 1], [16, 6, 4, 4])
```

Pull Request resolved: https://github.com/pytorch/pytorch/pull/162665
Approved by: https://github.com/ezyang
2025-09-16 07:30:05 +00:00
drisspg
d08cabe314 [BC Breaking] Remove flex + njt code paths (#161734)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/161734
Approved by: https://github.com/jbschlosser
2025-09-16 00:13:56 +00:00