Summary: With autotune_at_compile_time enabled, AOTI now can perform CUDA codegen in one pass. CUDA kernel related code is generated in a deferred way, after autotuning is done. This one-pass implementation will eliminate any issue caused by disparity between passes in the previous two-pass implementation (which caused multiple bug reports in the past). One-pass implementation also avoids cloning mutated inputs needed in the two-pass implementation, which will reduce GPU memory consumption.
Differential Revision: [D66739414](https://our.internmc.facebook.com/intern/diff/D66739414)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/141980
Approved by: https://github.com/chenyang78
Summary: Avoid using expr_printer as an overriden class member for WrapperCodegen. Instead, use pexpr and cexpr explicitly for python and cpp expression print respectively. This is to prepare for one-pass AOTI CUDA codegen, where PythonWrapperCodegen is used to generate the autotune block and CppWrapperCodegen is used to generate the model code.
Differential Revision: [D66459992](https://our.internmc.facebook.com/intern/diff/D66459992)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/141388
Approved by: https://github.com/chenyang78
This PR adds caching for user defined triton kernels by putting the transitive closure of source code in node.meta along with constant arguments.
One HUGE hack we do here is a node looks like
```
triton_kernel_wrapper_functional_proxy = torch.ops.higher_order.triton_kernel_wrapper_functional(kernel_idx = 0, constant_args_idx = 1, grid = [(1, 1, 1)], tma_descriptor_
metadata = {}, kwargs = {'in_ptr0': arg0_1, 'in_ptr1': arg1_1, 'out_ptr': arg0_1}, tensors_to_clone = ['out_ptr']);
```
so we use regex to remove `kernel_idx = 0, constant_args_idx = 1` parts as they are not relevant to cache hash. This is horrible and I'd like to eventually not use pickle as a hashing alternative but this is a longer project.
Differential Revision: [D65895744](https://our.internmc.facebook.com/intern/diff/D65895744)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/140326
Approved by: https://github.com/zou3519
This PR adds support for the `restore_value` argument of the
`@triton.autotune` for the user-defined Triton kernels in PT2.
The `kernel.restore_idx` are extracted in the
`ir.UserDefinedTritonKernel` and the corresponding arg names are
placed into the `triton_meta["restore_value"]`. From there, those
are added to the existing `mutated_arg_names` in the caching autotuner
infra which already exists and leads to the listed argss being cloned.
This achieves the equivalent effect to the native `restore_value`.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/139851
Approved by: https://github.com/oulgen
Summary:
I think we can inplace a buffer if all of the users of said buffer are "inconsequential", defined as having been removed, being completed, or being part of the ancestors set. In particular, this allows LayerNorm to inplace its input buffer.
Implements:
https://github.com/pytorch/pytorch/issues/132826
Test Plan:
New unit test of matmul followed by LayerNorm, make sure there's an inplaced buffer.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/138383
Approved by: https://github.com/eellison
```
NOTE [lowering-time collective optimization]
In collective communication libraries such as NCCL, every rank maintains
communication buffers that are remotely accessible by some peers. Depending
on the underlying transport, remote accessibility may be established via
mechanisms such as ib_reg_mr, CUDA P2P, or CUDA multicast. Typically, these
buffers are private to the communication library by default, and
communication ops copy user data in and out of these buffers.
To prevent these copies, an optimization commonly known as "user buffer
registration" can be employed. This allows direct establishment of remote
accessibility on user buffers, eliminating the need for copying. However,
this optimization introduces stringent usage requirements, which are
typically hard to satisfy without being intrusive to the user code:
- Establishing remote accessibility is expensive and often done ahead of
time. In such implementations, all ranks must agree on the set of allocations
used for every collective op. Failing to meet this requirement can
lead to runtime errors or even silent correctness issues.
- Even if the collective communication library supports gracefully falling
back to "unregistered" implementations, the fallback mechanism would nullify
the optimization.
- Some communication mechanisms impose stricter requirements than others. For
example, CUDA's multicast + multi-mem instructions require all ranks to agree
not only on the allocations used for every collective but also on the offsets
within these allocations.
To support all different mechanisms with optimal results, we aim to satisfy
the strictest requirement for this family of optimizations - we ensures that
every collective op invocation is guaranteed to operate on the same
allocation, at the same offset, in every iteration.
For eligible collective ops, we identify communication buffers at lowering
time and optionally choose to lower the op to a different kernel
(ommunication libraries like NCCL handle both registered and non-registered
buffers transparently within the same op, though some may require different
ops for different cases). Later, the codegen will perform "persistent
allocation" to satisfy the aforementioned constraints, and optionally,
perform buffer planning to optimize overall memory usage.
```
### Changes
- Created `comm_lowering.py` for the lowerings of `_c10d_functional` ops. This is to prevent cluttering `lowering.py` as we add more lowering-time collective optimizations. This PR moved the lowerings for `all_reduce` and `all_reduce_` to the file.
- Added `comm_buffer_type: Dict[str, str]` to `GraphLowering` to track whether a buffer is a comm buffer and the type of the comm buffer.
- Added codegen allocation support for comm buffers of type "symm_mem".
- Added support for auto-lowering `_c10d_functional.all_reduce_` to `symm_mem.one_shot_all_reduce`.
- Added an Inductor config for collective optimizations in general (`config._collective`).
### Limitation
Currently, each persistently allocated comm buffer is dedicated to a single callsite. This is not viable in terms of memory usage. However, this is a neccesary intermediate state before we tackle memory planning for comm buffers.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/138029
Approved by: https://github.com/Chillee
ghstack dependencies: #138028
Here's a markdown summary for the PR:
# Add workspace buffer support for Triton templates
## Summary
Adds support for templates to allocate and use temporary workspace buffers
## Key Changes
- Add `WorkspaceArg` support in Triton template system
- Automatic workspace allocation/deallocation around kernel execution
- Zero-initialization support for workspace buffers
- Seamless integration with existing tensor management
## Example Usage
```python
def generate(self, ...):
workspace_arg = WorkspaceArg(
count=1024*1024, # 1MB workspace
zero_fill=True # Zero-initialized
)
return TritonTemplateCaller(..., workspace_arg=workspace_arg)
```
Pull Request resolved: https://github.com/pytorch/pytorch/pull/138050
Approved by: https://github.com/Chillee, https://github.com/eellison
