1 /* Copyright 2018 The TensorFlow Authors. All Rights Reserved. 2 3 Licensed under the Apache License, Version 2.0 (the "License"); 4 you may not use this file except in compliance with the License. 5 You may obtain a copy of the License at 6 7 http://www.apache.org/licenses/LICENSE-2.0 8 9 Unless required by applicable law or agreed to in writing, software 10 distributed under the License is distributed on an "AS IS" BASIS, 11 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 See the License for the specific language governing permissions and 13 limitations under the License. 14 ==============================================================================*/ 15 16 #ifndef TENSORFLOW_COMPILER_XLA_SERVICE_OWNING_DEVICE_MEMORY_H_ 17 #define TENSORFLOW_COMPILER_XLA_SERVICE_OWNING_DEVICE_MEMORY_H_ 18 19 #include "tensorflow/compiler/xla/statusor.h" 20 #include "tensorflow/compiler/xla/types.h" 21 #include "tensorflow/core/platform/macros.h" 22 #include "tensorflow/core/platform/stream_executor_no_cuda.h" 23 24 namespace xla { 25 26 // Break circular dependency between this file and device_memory_allocator.h. 27 class DeviceMemoryAllocator; 28 29 // Owning pointer for memory on a device. 30 // 31 // OwningDeviceMemory is an owning pointer like std::unique_ptr, but it can 32 // point to memory that resides on a "device" (e.g. a GPU). When an 33 // OwningDeviceMemory goes out of scope, it frees the memory it owns. 34 // 35 // We say that an instance of OwningDeviceMemory is "active" if it currently 36 // owns a (possibly empty) slice of memory on the device. Moving, Forget()'ing, 37 // Free()'ing, and other actions can deactive an active object. 38 // 39 // Note that we can't simply use stream_executor::ScopedDeviceMemory instead of 40 // OwningDeviceMemory, because ScopedDeviceMemory frees its pointer via a 41 // StreamExecutor. This class needs to free via a xla::DeviceMemoryAllocator. 42 class OwningDeviceMemory { 43 public: OwningDeviceMemory()44 OwningDeviceMemory() : device_ordinal_(-1), allocator_(nullptr) {} 45 OwningDeviceMemory(se::DeviceMemoryBase mem,int device_ordinal,DeviceMemoryAllocator * allocator)46 explicit OwningDeviceMemory(se::DeviceMemoryBase mem, int device_ordinal, 47 DeviceMemoryAllocator* allocator) 48 : mem_(mem), device_ordinal_(device_ordinal), allocator_(allocator) { 49 CHECK(allocator != nullptr) << "allocator cannot be null."; 50 } 51 OwningDeviceMemory(OwningDeviceMemory && other)52 OwningDeviceMemory(OwningDeviceMemory&& other) 53 : mem_(other.mem_), 54 device_ordinal_(other.device_ordinal_), 55 allocator_(other.allocator_) { 56 other.mem_ = se::DeviceMemoryBase(); 57 other.allocator_ = nullptr; 58 } 59 60 OwningDeviceMemory& operator=(OwningDeviceMemory&& other) { 61 if (allocator_ != nullptr) { 62 Free(); 63 } 64 mem_ = other.mem_; 65 device_ordinal_ = other.device_ordinal_; 66 allocator_ = other.allocator_; 67 68 other.mem_ = se::DeviceMemoryBase(); 69 other.allocator_ = nullptr; 70 return *this; 71 } 72 73 // Deactivates this instance if it's active. Nop if it's not active. 74 OwningDeviceMemory& operator=(std::nullptr_t) { 75 if (allocator_ != nullptr) { 76 Free(); 77 } 78 return *this; 79 } 80 ~OwningDeviceMemory()81 ~OwningDeviceMemory() { 82 if (allocator_ != nullptr) { 83 Free(); 84 } 85 } 86 87 // The returned allocator is nonnull iff this object is active. allocator()88 DeviceMemoryAllocator* allocator() const { return allocator_; } 89 device_ordinal()90 int device_ordinal() const { return device_ordinal_; } 91 92 // Gets the device memory pointer. opaque()93 const void* opaque() const { return mem_.opaque(); } opaque()94 void* opaque() { return mem_.opaque(); } 95 size()96 uint64 size() const { return mem_.size(); } 97 98 // Determines whether this wraps a null pointer. 99 // 100 // !is_null() is sufficient but not necessary to imply `this` is active. is_null()101 bool is_null() const { return mem_.is_null(); } 102 AsDeviceMemoryBase()103 se::DeviceMemoryBase AsDeviceMemoryBase() { 104 return se::DeviceMemoryBase(opaque(), size(), /*is_sub_buffer=*/false); 105 } 106 107 // Returns the wrapped DeviceMemoryBase without freeing it, and deactivates 108 // this object. Precondition: `this` is active. Forget()109 TF_MUST_USE_RESULT se::DeviceMemoryBase Forget() { 110 CHECK(allocator_ != nullptr) 111 << "Can't call Forget() on an inactive (i.e. moved from, Forget()'ten, " 112 "or Free()'ed) instance."; 113 allocator_ = nullptr; 114 se::DeviceMemoryBase mem(mem_); 115 mem_ = se::DeviceMemoryBase(); 116 return mem; 117 } 118 119 // Frees the wrapped DeviceMemoryBase and deactivates this object. 120 // Precondition: `this` is active. 121 void Free(); 122 123 private: 124 se::DeviceMemoryBase mem_; 125 int device_ordinal_; 126 DeviceMemoryAllocator* allocator_; // Null if this object is inactive. 127 }; 128 129 } // namespace xla 130 131 #endif // TENSORFLOW_COMPILER_XLA_SERVICE_OWNING_DEVICE_MEMORY_H_ 132