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Paddle/paddle/fluid/memory/allocation/allocator.h

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4.7 KiB

// Copyright (c) 2018 PaddlePaddle Authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#pragma once
#include <memory>
#include <string>
#include "paddle/fluid/platform/place.h"
namespace paddle {
namespace memory {
namespace allocation {
// Exception when `Alloc`/`AllocShared` failed
class BadAlloc : public std::exception {
public:
explicit BadAlloc(std::string msg) : msg_(std::move(msg)) {}
const char* what() const noexcept override;
private:
std::string msg_;
};
class Allocation;
class AllocationDeleter {
public:
void operator()(Allocation* allocation) const;
};
class Allocator;
// Allocation is the object holding the actually pointer. Use
// `Allocation::ptr()` will returns the pointer that allocated.
//
// NOTE: this is the base class of Allocation. Each allocator can use its own
// allocation object.
// NOTE: the `Allocation::ptr()` could be nullptr, if the allocation size is 0
class Allocation {
public:
Allocation(void* ptr, size_t size, platform::Place place)
: allocator_(nullptr), ptr_(ptr), size_(size), place_(place) {}
Allocation(const Allocation& o) = delete;
Allocation& operator=(const Allocation& o) = delete;
// Returns the holding pointer.
// NOTE: For performance consideration, it is better not to make this method
// as a virtual method. If we want to implement a `defragmentation` later,
// we might need to make `ptr_` field as a protected field, and add a virtual
// method like `defragmentation` to change `ptr_`.
void* ptr() const { return ptr_; }
// Returns the size of this memory buffer, i.e., ptr() + size() - 1 is the
// last valid element.
//
// NOTE: Some allocator might alloc more memory than request. The size
// could larger than its request. For example,
// the AlignedAllocator will always allocate memory as size + kAlignment.
// The raw pointer might not aligned, so an offset might be added to raw
// the pointer. The size of this allocation will be
// `size + kAlignemnt - offset`.
size_t size() const { return size_; }
const platform::Place& place() const { return place_; }
Allocator* allocator() { return allocator_; }
void set_allocator(Allocator* allocator) { allocator_ = allocator; }
virtual ~Allocation();
private:
Allocator* allocator_;
void* ptr_;
size_t size_;
platform::Place place_;
};
using AllocationPtr = std::unique_ptr<Allocation, AllocationDeleter>;
// Base interface class of memory Allocator.
// To allocate a memory, allocator needs two parameters:
// 1. size of bytes.
// 2. Attribute of memory.
// NOTE: the attribute of memory might be ignored if the allocator does not
// care it.
class Allocator {
public:
enum Attr {
kDefault = 0, // Default attribute. Uses the fast or stablest allocation
// algorithm.
kFixedHuge = 1, // The allocation may not be freed until the program
// ends. e.g., `Parameters` and `Momentum`.
kFluxHuge = 2, // The allocation may create and freed frequently and the
// allocation is considerable huge. Like `activations`
// and gradients.
kScratchpad =
3, // The `Scratchpad` memory is allocated and freed very soon,
// usually within an operator or aux memory.
// Like CUDNN workspace, AUX memory in batch norm, etc.
//
// https://en.wikipedia.org/wiki/Scratchpad_memory
kCrossDevice =
4, // The memory used cross-device memory copy/communication.
// For example:
// 1. it can use an `pinned` memory for CPU-GPU
// communication.
// 2. it can use an `registered` memory for RDMA
// communication.
NumOfAttrs = 5 // The number of all attributes. It is used internally.
};
virtual ~Allocator();
// Allocate an allocation.
AllocationPtr Allocate(size_t size, Allocator::Attr attr = kDefault);
// True if the `Allocate` is thread safe.
virtual bool IsAllocThreadSafe() const;
protected:
virtual void Free(Allocation* allocation);
virtual Allocation* AllocateImpl(size_t size, Allocator::Attr attr) = 0;
private:
friend class AllocationDeleter;
};
} // namespace allocation
} // namespace memory
} // namespace paddle