/* Copyright 2015 The TensorFlow Authors. All Rights Reserved.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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==============================================================================*/
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#ifndef TENSORFLOW_STREAM_EXECUTOR_SCRATCH_ALLOCATOR_H_
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#define TENSORFLOW_STREAM_EXECUTOR_SCRATCH_ALLOCATOR_H_
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#include <memory>
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#include "tensorflow/stream_executor/device_memory.h"
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#include "tensorflow/stream_executor/lib/statusor.h"
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#include "tensorflow/stream_executor/platform/port.h"
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#include "tensorflow/stream_executor/temporary_device_memory.h"
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namespace stream_executor {
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class Stream;
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// Interface that allows stream operations (e.g.
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// Stream::ThenConvolveWithScratch) to optionally request scratch space be
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// allocated in order to speed up the operation being enqueued.
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//
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// Note that the caller is responsible for deallocating the scratch space at a
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// known-safe point, when all scratch-memory-consuming kernels are known for
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// sure to have finished; e.g. at stream synchronization time. This is different
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// from a traditional C++ object allocator, where the client is responsible for
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// releasing. (Conceptually, scratch memory is a form of "temporary" device
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// memory allocation.)
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class ScratchAllocator {
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public:
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virtual ~ScratchAllocator();
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// Returns a limit of memory this scratch allocator wants to produce, in
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// bytes. This information may be used to help select an algorithm.
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//
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// Returns values < 0 to indicate that there is no recommended limit.
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virtual int64 GetMemoryLimitInBytes(Stream* stream) = 0;
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// Returns an allocation on byte_size bytes for use in an operation on stream.
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//
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// This is a temporary allocation, and the caller is responsible for
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// deallocating at some known-safe point. See the class comment above.
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virtual port::StatusOr<DeviceMemory<uint8>> AllocateBytes(
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Stream* stream, int64 byte_size) = 0;
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};
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// Allocates a single temporary memory allocation -- this memory is deallocated
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// at the next stream synchronization point after this object has gone out of
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// scope. This satisfies the lifetime and deallocation properties given in the
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// class comment above.
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//
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// Thread-compatible, but not thread-safe (use in scenarios where only one
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// thread will request the scratch allocation).
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class OneTimeScratchAllocator : public ScratchAllocator {
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public:
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OneTimeScratchAllocator();
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~OneTimeScratchAllocator() override;
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int64 GetMemoryLimitInBytes(Stream* stream) override;
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port::StatusOr<DeviceMemory<uint8>> AllocateBytes(Stream* stream,
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int64 byte_size) override;
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private:
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std::unique_ptr<TemporaryDeviceMemory<uint8>> temporary_;
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SE_DISALLOW_COPY_AND_ASSIGN(OneTimeScratchAllocator);
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};
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} // namespace stream_executor
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#endif // TENSORFLOW_STREAM_EXECUTOR_SCRATCH_ALLOCATOR_H_
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