Fix comparison in ReinitializeTensor #16294
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Summary: In `ReinitializeTensor`, we compare `tensor->GetDevice()` and `options.device()`, but in the callsite, we actually just provide an option with `device_type`, which means the `device_id` will always be default(-1) for `options`, but for tensor, although it is passed a `device` with default `device_id`, when we allocate the data, the `device` of the `tensor` is the `device` of `Storage`, which is the `device` of underlying `DataPtr`, which is the same as the `device` of the `Context` of the operator, which has a non-default `device_id`. Therefore everytime we do `ReinitializeTensor`, we'll find the `device` does not match, and after the `ReinitializeTensor` call, the `device` still does not match. That's why everytime we'll allocate a new Tensor and cause perf regressions for ops that uses `ReinitializeTensor` on multiple GPUs. Reviewed By: BIT-silence Differential Revision: D13795635 fbshipit-source-id: d82f0e6e07e26e819010607ff3025e58556365c4
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Thanks for this fix! |
xiaomengy
approved these changes
Jan 24, 2019
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Summary:
In
ReinitializeTensor, we comparetensor->GetDevice()andoptions.device(), but in the callsite, we actually just provide an option withdevice_type, which means thedevice_idwill always be default(-1) foroptions, but for tensor, although it is passed adevicewith defaultdevice_id, when we allocate the data, thedeviceof thetensoris thedeviceofStorage, which is thedeviceof underlyingDataPtr, which is the same as thedeviceof theContextof the operator, which has a non-defaultdevice_id.Therefore everytime we do
ReinitializeTensor, we'll find thedevicedoes not match, and after theReinitializeTensorcall, thedevicestill does not match. That's why everytime we'll allocate a new Tensor and cause perf regressions for ops that usesReinitializeTensoron multiple GPUs.Reviewed By: BIT-silence
Differential Revision: D13795635