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CopyUtils.cuh
1 /**
2 * Copyright (c) 2015-present, Facebook, Inc.
3 * All rights reserved.
4 *
5 * This source code is licensed under the BSD+Patents license found in the
6 * LICENSE file in the root directory of this source tree.
7 */
8
9 // Copyright 2004-present Facebook. All Rights Reserved.
10
11 #pragma once
12
13 #include "DeviceTensor.cuh"
14 #include "HostTensor.cuh"
15
16 namespace faiss { namespace gpu {
17
18 /// Ensure the memory at `p` is either on the given device, or copy it
19 /// to the device in a new allocation.
20 /// If `resources` is provided, then we will perform a temporary
21 /// memory allocation if needed. Otherwise, we will call cudaMalloc if
22 /// needed.
23 template <typename T, int Dim>
24 DeviceTensor<T, Dim, true> toDevice(GpuResources* resources,
25 int dstDevice,
26 T* src,
27 cudaStream_t stream,
28 std::initializer_list<int> sizes) {
29 int dev = getDeviceForAddress(src);
30
31 if (dev == dstDevice) {
32 // On device we expect
33 return DeviceTensor<T, Dim, true>(src, sizes);
34 } else {
35 // On different device or on host
36 DeviceScope scope(dstDevice);
37
38 Tensor<T, Dim, true> oldT(src, sizes);
39
40 if (resources) {
41 DeviceTensor<T, Dim, true> newT(resources->getMemoryManager(dstDevice),
42 sizes,
43 stream);
44
45 newT.copyFrom(oldT, stream);
46 return newT;
47 } else {
48 DeviceTensor<T, Dim, true> newT(sizes);
49
50 newT.copyFrom(oldT, stream);
51 return newT;
52 }
53 }
54 }
55
56 /// Copies a device array's allocation to an address, if necessary
57 template <typename T>
58 inline void fromDevice(T* src, T* dst, size_t num, cudaStream_t stream) {
59 // It is possible that the array already represents memory at `p`,
60 // in which case no copy is needed
61 if (src == dst) {
62 return;
63 }
64
65 int dev = getDeviceForAddress(dst);
66
67 if (dev == -1) {
68 CUDA_VERIFY(cudaMemcpyAsync(dst,
69 src,
70 num * sizeof(T),
71 cudaMemcpyDeviceToHost,
72 stream));
73 } else {
74 CUDA_VERIFY(cudaMemcpyAsync(dst,
75 src,
76 num * sizeof(T),
77 cudaMemcpyDeviceToDevice,
78 stream));
79 }
80 }
81
82 /// Copies a device array's allocation to an address, if necessary
83 template <typename T, int Dim>
84 void fromDevice(Tensor<T, Dim, true>& src, T* dst, cudaStream_t stream) {
85 FAISS_ASSERT(src.isContiguous());
86 fromDevice(src.data(), dst, src.numElements(), stream);
87 }
88
89 } } // namespace