Moving DTensor to be in the public namespace, to formally add the
documentation page that includes all the public APIs. This includes:
* many path renames and path import fixes
* a dedicated doc page without too much content yet (adding in the next
PRs)
* To preserve the BC for users still using the `torch.distributed._tensor`,
I added a shim script to redirect old path calls to the new module
The BC preserving is evidented by the fact that all DTensor tests are still
working without changing the public imports. So it's safe to land the
changes
Pull Request resolved: https://github.com/pytorch/pytorch/pull/133113
Approved by: https://github.com/XilunWu
ghstack dependencies: #133305, #133306
Instead of having a separate context variable for SymDispatchMode, we
now simply delegate to the current active proxy tensor mode when we
need to trace a SymInt. We maintain a separate `__sym_dispatch__` magic
method as the calling convention is different than `__torch_dispatch__`.
Consolidating the modes in this ways means that we can consistently
disable both of these modes in tandem simply by removing the mode
from the proxy mode infra slot.
Signed-off-by: Edward Z. Yang <ezyang@meta.com>
Pull Request resolved: https://github.com/pytorch/pytorch/pull/132674
Approved by: https://github.com/zou3519, https://github.com/bdhirsh
Instead of having a separate context variable for SymDispatchMode, we
now simply delegate to the current active proxy tensor mode when we
need to trace a SymInt. We maintain a separate `__sym_dispatch__` magic
method as the calling convention is different than `__torch_dispatch__`.
Consolidating the modes in this ways means that we can consistently
disable both of these modes in tandem simply by removing the mode
from the proxy mode infra slot.
Signed-off-by: Edward Z. Yang <ezyang@meta.com>
Pull Request resolved: https://github.com/pytorch/pytorch/pull/132674
Approved by: https://github.com/zou3519, https://github.com/bdhirsh
When caching is enabled, an internal model fails with
```
assert_size_stride(bmm_9, (17, s0, 512), (54784, 512, 1))
AssertionError: expected size 17==17, stride 57344==54784 at dim=0
```
looking at this model, the exact problem is when the cache is hit on the forward graph, the generated code for backward fails since the strides of the outputs of forward, passed to backward as inputs, are not what we expected.
This PR changes the evaluation logic so that we defer evaluation of output stride exprs to load path as opposed to eagerly doing it on save path.
I have not been able to come up with a unit test repro for this problem.
Differential Revision: [D58796503](https://our.internmc.facebook.com/intern/diff/D58796503)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/128997
Approved by: https://github.com/ezyang
Summary:
This makes barrier and rank operations linear instead of quadratic with the number of workers. This drastically improves performance for rendezvous when running with over 1000 hosts.
This uses 2 approaches for different areas:
* local rank assignment: each worker does 1 set and 1 get, local ranks are assigned on the rank 0 host in a O(n) operation which reduces total store operations to be linear with number of workers.
* exit_barrier: use a counter and a final flag so each worker has to do max 1 set, 1 get and 1 add.
At 4000 hosts we see torchelastic be able to run in as little as 10 seconds down from 373 seconds.
Test Plan:
This is testing using many small tests running on a remote cluster.
{D56549942}
```
torchx run --scheduler mast -- --image=torchelastic_benchmark --j=4000x1
```
Differential Revision: D56605193
Pull Request resolved: https://github.com/pytorch/pytorch/pull/124982
Approved by: https://github.com/kiukchung, https://github.com/kurman
Loss parallel is the last piece of sequence parallelism to enable. It enables efficient distributed cross entropy computation when the input is sharded on the class dimension (in a classification problem with many classes). The implementation is via a context manager `loss_parallel`, after enabling which users can directly use `torch.nn.functional.cross_entropy` or `torch.nn.CrossEntropyLoss` without modifying other parts of their code.
Here are the underlying rationales why we are going through these op replacements:
1. `nn.functional.cross_entropy` is the common method that OSS user is using for things like transformer training, to avoid changing user code, we want user to still use this function for loss calculation if they are already using it.
2. `nn.functional.cross_entropy` boils down into `aten.log_softmax` and `aten.nll_loss_foward/backward`, and DTensor now supports those ops already (#117723#119255#118917#119256). They are doing computation with input *replicated* on the class dimension.
3. However when the input of this loss calculation is **sharded on the class dimension**, to run sharded computation efficiently, we need to run both `aten.log_softmax` and `aten.nll_loss_foward` with multiple all-reduce collectives **in the middle of** those aten ops. This is not possible if we are just overriding these two ops, so we need to have some way to **decompose** these two ops into smaller ops to have collectives run in the middle of these two ops.
4. We explored the existing decompositions (#118950). It seems working, except that `log_softmax_backward` and `nll_loss_backward` combined together in aten are implemented in a inefficient way, which would trigger an additional expensive collective. Recently some user also reported similar issues https://github.com/pytorch/pytorch/issues/119261.
5. Therefore, currently we are doing our own decomposition inside a context manager for sequence parallelism specifically. Once we have a better decomposition in core, we can possibly take that instead of reinventing the wheels here.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/119877
Approved by: https://github.com/wanchaol
This PR adds the bare minimum functionality to get torchbind working in an e2e testable way on PT2.
It implements:
* ProxyTensor support
* Simple torch.export support (proxytensor-only path, e.g. non-strict).
* add some tests exercising the path.
Because all this is not fully baked, I hide the functionality behind a feature flag (`enable_torchbind_tracing()`) so it does not affect regular users for now.
Still on the agenda:
* Dynamo support
* Actual FakeMode support
* Mutability support
Hoping to get this first bit in as a standalone, as it will unblock some more extensive experimentation/testing going on internally.
Differential Revision: [D51825372](https://our.internmc.facebook.com/intern/diff/D51825372/)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/117697
Approved by: https://github.com/SherlockNoMad
This adds a function `statically_known_true` for `SymBool` that works
like inductor's `is_expr_static_and_true`. That is, it tries to simplify the
expression to a constant or returns `False` if it cannot be simplified.
This is useful in cases that can be optimized if the condition is met,
otherwise it doesn't effect correctness so we can avoid adding guards.
I also use this new function in inductor for `FakeTensorUpdater` and
`remove_noop_pass` which both generated unexpected guards previously.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/117359
Approved by: https://github.com/lezcano
Continuation of #112185, following the design in this [doc](https://docs.google.com/document/d/1ipSxcTzEMMOAPvxP-YJlD5JBZZmIGgh8Q34ixtOUCRo).
Summary:
* Introduce `SubclassSymbolicPolicy` containing separate dynamic dim / constraint policies for the outer and inner tensors
* Expand the automatic dynamic algorithm to recurse into inner tensors and produce one of these for a subclass instance
* Maintain legacy behavior for subclasses by recursively calling `mark_dynamic()` on inner tensors *of the same dim as outer* when `mark_dynamic(outer, ...)` is called
* Addresses this: 6a86cf00ad/torch/_dynamo/variables/builder.py (L1750)
* Add `outer_size` and `outer_stride` arguments to `__tensor_unflatten__()` so that you can find out what symbols were allocated for the outer size / stride (you are expected to return a tensor that compares equal to the outer symbols)
* Signatures now:
```python
# attrs is a list of inner tensor attributes on x; inner_tensor = getattr(x, attr)
# ctx is anything useful for rebuilding the class we want to guard on
attrs, ctx = x.__tensor_flatten__()
...
# inner_tensors is a dict of {attr -> tensor}
# ctx is taken unmodified from flattening and (eventually) guarded on
# outer_size is the expected size of the output; possibly symbolic
# outer_stride is the expected strides of the output; possibly symbolic
y = MySubclass.__tensor_unflatten__(inner_tensors, ctx, outer_size, outer_stride)
# at the __tensor_unflatten__() call-site in PT2, we assert y.shape == outer_size and y.stride() == outer_stride
# the assert simplifies symbols when there are relationships between outer and inner symbols
```
* Size info needed for `NestedTensor` at least, stride info needed for `DTensor` at least
* Punting on `outer_storage_offset` because storage_offset handling is horribly broken in PT2 right now
* ~~Add new `__tensor_mark_dynamic__()` to allow overriding the behavior of mark_dynamic on a per-subclass basis~~ (booted to future work)
* ~~Add guards for tensor subclasses by calling `__tensor_flatten__()` in the guard to test equality on `ctx`~~
* Now handled in #114469
* Next PR: add TENSOR_MATCH guards on inner tensors
Pull Request resolved: https://github.com/pytorch/pytorch/pull/114311
Approved by: https://github.com/ezyang, https://github.com/drisspg, https://github.com/voznesenskym, https://github.com/bdhirsh
Summary:
The primary problem we are setting out to solve here is fake tensor freshness. Before this PR, fake tensors after dynamo represented fake tensors *at the end* of trace, so subsequent retraces like aot_autograd would start off with fake tensors in the wrong (end result) state, rather than their expected fresh state. The solution here is to start a fresh fake mode, and re-fakify the tensors. The nuance comes from ensuring that symbols are uniformly created for the symbolic sizes and strides of the tensor.
This PR is the result of *a lot* of back and forth with ezyang and eellison. Initially, the first pass at this was not super different from what we have in the PR - the broad strokes were the same:
1) We cache source->symbol in shape_env
2) We pass policy objects around, stored at dynamo fakificaiton time, and reused for later fakification
3) We create a new fake mode for backends
(from https://github.com/pytorch/pytorch/pull/113605/files)
This is ugly, and has some layering violations. We detoured our decision making through a few other alternatives. Immutable/mutable fake tensor mode was the most interesting alternative, https://github.com/pytorch/pytorch/pull/113653, and was struck down on concerns of complexity in fake mode combined with it not covering all edge cases. We also detoured on what to do about tensor memoization returning back potentially different tensors than requested, and if that was an anti pattern (it is) we want to hack in with the symbol cache (we don't).
We went back to the drawing board here, but with a few concessions:
1) the cache for source->symbol must live outside of shape_env, for both lifecycle, and layering reasons
2) A good amount of work needs to be done to pipe policy around fake_mode and meta_utils correctly, to cover all the cases (ezyang did this)
cc penguinwu EikanWang jgong5 Guobing-Chen XiaobingSuper zhuhaozhe blzheng wenzhe-nrv jiayisunx chenyang78 aakhundov kadeng
imported-using-ghimport
Test Plan: Imported from OSS
Reviewed By: huydhn, Chillee
Differential Revision: D51566250
Pulled By: voznesenskym
Pull Request resolved: https://github.com/pytorch/pytorch/pull/114526
Approved by: https://github.com/Chillee, https://github.com/huydhn
The primary problem we are setting out to solve here is fake tensor freshness. Before this PR, fake tensors after dynamo represented fake tensors *at the end* of trace, so subsequent retraces like aot_autograd would start off with fake tensors in the wrong (end result) state, rather than their expected fresh state. The solution here is to start a fresh fake mode, and re-fakify the tensors. The nuance comes from ensuring that symbols are uniformly created for the symbolic sizes and strides of the tensor.
This PR is the result of *a lot* of back and forth with @ezyang and @eellison. Initially, the first pass at this was not super different from what we have in the PR - the broad strokes were the same:
1) We cache source->symbol in shape_env
2) We pass policy objects around, stored at dynamo fakificaiton time, and reused for later fakification
3) We create a new fake mode for backends
(from https://github.com/pytorch/pytorch/pull/113605/files)
This is ugly, and has some layering violations. We detoured our decision making through a few other alternatives. Immutable/mutable fake tensor mode was the most interesting alternative, https://github.com/pytorch/pytorch/pull/113653, and was struck down on concerns of complexity in fake mode combined with it not covering all edge cases. We also detoured on what to do about tensor memoization returning back potentially different tensors than requested, and if that was an anti pattern (it is) we want to hack in with the symbol cache (we don't).
We went back to the drawing board here, but with a few concessions:
1) the cache for source->symbol must live outside of shape_env, for both lifecycle, and layering reasons
2) A good amount of work needs to be done to pipe policy around fake_mode and meta_utils correctly, to cover all the cases (@ezyang did this)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/113926
Approved by: https://github.com/ezyang, https://github.com/eellison
Thanks aakhundov for constructing the test case. This PR was constructed by running the failing test case, and then fixing problems until we got all the way to the end. There are a few distinct fixes:
* AOTAutograd performs equality tests on tensor metadata to determine if a metadata mutation had occurred. If we test i0 vs i1, we should report these are NOT equal, since obviously we have somehow resized the tensor from i0 to i1 (even if, on a particular run, it is possible i0 == i1).
* There's a sketchy fix for `test_aot_autograd_exhaustive_matmul_cpu_float32` where we check if the output shape equals the tangent shape. Unfortunately, the same `definitely_true` treatment does not work here, it still fails on the example. I piled an extra sketchy fix on top of it, where I just try my best to avoid doing the view. Maybe we should have some sort of logging here.
* Partitioner needs to get out a size for unbacked SymInt when partitioning. I just feed it a random heuristic value in this case, similar to how we've been dealing with this in Inductor.
Signed-off-by: Edward Z. Yang <ezyang@meta.com>
Pull Request resolved: https://github.com/pytorch/pytorch/pull/113159
Approved by: https://github.com/aakhundov, https://github.com/bdhirsh
We spend somewhere on the order 1% in `sympy.Expr.free_symbols` as it is called millions of times.
Most of the time we actually just want to know "is this a constant", however `e.is_constant()` is
horribly slow. It turns out though that there is another propery `is_number` that does what we want.
> property is_number:
>
> Returns True if self has no free symbols and no undefined functions (AppliedUndef, to be precise). It will be faster
> than if not self.free_symbols, however, since is_number will fail as soon as it hits a free symbol or undefined
> function.
Even further, we also avoid the overhead of building the unnecessary set object.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/112688
Approved by: https://github.com/lezcano
This PR:
- Moves TrueDiv, LShift, RShift, IsNonOverlappingAndDenseIndicator to `_sympy.functions.py`
- Moves SymNode to `fx.experimental.sym_node`.
- This file does not have any SymPy dependencies at import time
- It installs the magic methods in Sym{Bool,Int,Float}.
- N.b. With this split, we may be able to move Sym{Bool,Int,Float} to this file, and remove quite a few of the hacks around these classes
- Imports `sym_node` in `torch/__init__.py` rather than the whole `symbolic_shapes.py`.
This breaks the import-time dependency between torch and SymPy
Pull Request resolved: https://github.com/pytorch/pytorch/pull/112037
Approved by: https://github.com/peterbell10
ghstack dependencies: #112035, #112036
This PR supports sym_ite. This is useful for converting SymBool to SymInt in e.g. #109916. Internally, it uses sympy.Piecewise. We cannot use sympy.ITE because it expects the arguments and output all to be boolean type but we want return SymInt type when converting a SymBool to SymInt. So we use sympy.Piecewise to denote the symbolic relationship.
Note that this pr uses the range analysis for sympy.Piecewise implemented in https://github.com/pytorch/pytorch/blob/main/torch/utils/_sympy/value_ranges.py.
Test Plan:
See added test.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/111440
Approved by: https://github.com/ezyang
Add non-package python modules to the public API checks.
The original change is to remove the `ispkg` check in this line
https://github.com/pytorch/pytorch/blob/main/docs/source/conf.py#L518
Everything else is to add the appropriate modules to the rst files, make sure every module we provide can be imported (fixed by either making optional dependencies optional or just deleting files that have been un-importable for 3 years), make API that are both modules and functions (like torch.autograd.gradcheck) properly rendered on the docs website without confusion and add every non-documented API to the allow list (~3k of them).
Next steps will be to try and fix these missing docs
Pull Request resolved: https://github.com/pytorch/pytorch/pull/110568
Approved by: https://github.com/zou3519
As per title.
Note that the c++ side code for the minidumps part was removed. So trying to call any of these 3 functions today results in an error saying that `torch._C` doesn't have these attributes.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/105142
Approved by: https://github.com/janeyx99
