This was originally @jansel's PR:
https://github.com/pytorch/pytorch/pull/102625, which I've built upon.
This diff implements static memory planning. It's disabled by default
while we examine its performance.
We use a greedy-by-size approach. For dynamic shapes, the sizes of the
example inputs are used as estimates when making planning decisions. We
generate expressions to calculate the actual memory offsets and sizes at
runtime when the values of the dynamic shapes are known. In order to
simplify these calculations, we have organized the allocations into a
tree that branches on space (address offsets) and time (live ranges).
Finally, we need to align these offsets, so we have added an `align`
sympy Expr to express these calculations.
Some limitations:
1. It is only enabled during inference for now. Enabling it for training
increases peak memory usage as we allocate all the memory needed for
training upfront, before freeing the memory allocated during
inference. We can probably address this by doing planning for both
the inference and training passes together.
2. It doesn't work with PyTorch Distributed, because kernels like
AllGatherIntoTensor codegen strings which do memory operations. We
can fix this down the line by having them emit MemoryPlanningLines
instead.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/112178
Approved by: https://github.com/desertfire, https://github.com/jansel
This was originally @jansel's PR:
https://github.com/pytorch/pytorch/pull/102625, which I've built upon.
This diff implements static memory planning. It's disabled by default
while we examine its performance.
We use a greedy-by-size approach. For dynamic shapes, the sizes of the
example inputs are used as estimates when making planning decisions. We
generate expressions to calculate the actual memory offsets and sizes at
runtime when the values of the dynamic shapes are known. In order to
simplify these calculations, we have organized the allocations into a
tree that branches on space (address offsets) and time (live ranges).
Finally, we need to align these offsets, so we have added an `align`
sympy Expr to express these calculations.
Some limitations:
1. It is only enabled during inference for now. Enabling it for training
increases peak memory usage as we allocate all the memory needed for
training upfront, before freeing the memory allocated during
inference. We can probably address this by doing planning for both
the inference and training passes together.
2. It doesn't work with PyTorch Distributed, because kernels like
AllGatherIntoTensor codegen strings which do memory operations. We
can fix this down the line by having them emit MemoryPlanningLines
instead.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/112178
Approved by: https://github.com/desertfire, https://github.com/jansel
This cherrypicks the reinterpret_tensor change from #102625 in order to fix a subtle correctness bug when the graph inputs already have a storage_offset set.
The view change also fixes some issues with quantized models in torchbench.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/108168
Approved by: https://github.com/desertfire
