1[/
2          Copyright Oliver Kowalke 2017.
3 Distributed under the Boost Software License, Version 1.0.
4    (See accompanying file LICENSE_1_0.txt or copy at
5          http://www.boost.org/LICENSE_1_0.txt
6]
7
8[#hip]
9[section:hip ROCm/HIP]
10
11[@http://github.com/ROCm-Developer-Tools/HIP/tree/roc-1.6.0/ HIP] is part of the
12[@http://rocm.github.io/ ROC (Radeon Open Compute)] platform for parallel computing
13on AMD and NVIDIA GPUs. The application programming interface of HIP gives access to
14GPU's instruction set and computation resources (Execution of compute kernels).
15
16
17[heading Synchronization with ROCm/HIP streams]
18
19HIP operation such as compute kernels or memory transfer (between host and
20device) can be grouped/queued by HIP streams. are executed on the GPUs.
21Boost.Fiber enables a fiber to sleep (suspend) till a HIP stream has completed
22its operations. This enables applications to run other fibers on the CPU without
23the need to spawn an additional OS-threads. And resume the fiber when the HIP
24streams has finished.
25
26        __global__
27        void kernel( int size, int * a, int * b, int * c) {
28            int idx = threadIdx.x + blockIdx.x * blockDim.x;
29            if ( idx < size) {
30                int idx1 = (idx + 1) % 256;
31                int idx2 = (idx + 2) % 256;
32                float as = (a[idx] + a[idx1] + a[idx2]) / 3.0f;
33                float bs = (b[idx] + b[idx1] + b[idx2]) / 3.0f;
34                c[idx] = (as + bs) / 2;
35            }
36        }
37
38        boost::fibers::fiber f([&done]{
39            hipStream_t stream;
40            hipStreamCreate( & stream);
41            int size = 1024 * 1024;
42            int full_size = 20 * size;
43            int * host_a, * host_b, * host_c;
44            hipHostMalloc( & host_a, full_size * sizeof( int), hipHostMallocDefault);
45            hipHostMalloc( & host_b, full_size * sizeof( int), hipHostMallocDefault);
46            hipHostMalloc( & host_c, full_size * sizeof( int), hipHostMallocDefault);
47            int * dev_a, * dev_b, * dev_c;
48            hipMalloc( & dev_a, size * sizeof( int) );
49            hipMalloc( & dev_b, size * sizeof( int) );
50            hipMalloc( & dev_c, size * sizeof( int) );
51            std::minstd_rand generator;
52            std::uniform_int_distribution<> distribution(1, 6);
53            for ( int i = 0; i < full_size; ++i) {
54                host_a[i] = distribution( generator);
55                host_b[i] = distribution( generator);
56            }
57            for ( int i = 0; i < full_size; i += size) {
58                hipMemcpyAsync( dev_a, host_a + i, size * sizeof( int), hipMemcpyHostToDevice, stream);
59                hipMemcpyAsync( dev_b, host_b + i, size * sizeof( int), hipMemcpyHostToDevice, stream);
60                hipLaunchKernel(kernel, dim3(size / 256), dim3(256), 0, stream, size, dev_a, dev_b, dev_c);
61                hipMemcpyAsync( host_c + i, dev_c, size * sizeof( int), hipMemcpyDeviceToHost, stream);
62            }
63            auto result = boost::fibers::hip::waitfor_all( stream); // suspend fiber till HIP stream has finished
64            BOOST_ASSERT( stream == std::get< 0 >( result) );
65            BOOST_ASSERT( hipSuccess == std::get< 1 >( result) );
66            std::cout << "f1: GPU computation finished" << std::endl;
67            hipHostFree( host_a);
68            hipHostFree( host_b);
69            hipHostFree( host_c);
70            hipFree( dev_a);
71            hipFree( dev_b);
72            hipFree( dev_c);
73            hipStreamDestroy( stream);
74        });
75        f.join();
76
77
78[heading Synopsis]
79
80        #include <boost/fiber/hip/waitfor.hpp>
81
82        namespace boost {
83        namespace fibers {
84        namespace hip {
85
86        std::tuple< hipStream_t, hipError_t > waitfor_all( hipStream_t st);
87        std::vector< std::tuple< hipStream_t, hipError_t > > waitfor_all( hipStream_t ... st);
88
89        }}}
90
91
92[ns_function_heading hip..waitfor]
93
94    #include <boost/fiber/hip/waitfor.hpp>
95
96    namespace boost {
97    namespace fibers {
98    namespace hip {
99
100    std::tuple< hipStream_t, hipError_t > waitfor_all( hipStream_t st);
101    std::vector< std::tuple< hipStream_t, hipError_t > > waitfor_all( hipStream_t ... st);
102
103    }}}
104
105[variablelist
106[[Effects:] [Suspends active fiber till HIP stream has finished its operations.]]
107[[Returns:] [tuple of stream reference and the HIP stream status]]
108]
109
110
111[endsect]
112