[英]Pass a vector of custom structs by reference to a boost::compute closure or function
I'm somewhat new to opencl and am trying to learn to use boost::compute properly. 我是opencl的新手,正在尝试学习正确使用boost :: compute。 Consider the following code: 考虑以下代码:
#include <iostream>
#include <vector>
#include <boost/compute.hpp>
const cl_int cell_U_size{ 4 };
#pragma pack (push,1)
struct Cell
{
cl_double U[cell_U_size];
};
#pragma pack (pop)
BOOST_COMPUTE_ADAPT_STRUCT(Cell, Cell, (U));
int main(int argc, char* argv[])
{
using namespace boost;
auto device = compute::system::default_device();
auto context = compute::context(device);
auto queue = compute::command_queue(context, device);
std::vector<Cell> host_Cells;
host_Cells.reserve(10);
for (auto j = 0; j < host_Cells.capacity(); ++j) {
host_Cells.emplace_back(Cell());
for (auto i = 0; i < cell_U_size; ++i) {
host_Cells.back().U[i] = static_cast<cl_double>(i+j);
}
}
std::cout << "Before:\n";
for (auto const& hc : host_Cells) {
for (auto const& u : hc.U)
std::cout << " " << u;
std::cout << "\n";
}
compute::vector<Cell> device_Cells(host_Cells.size(), context);
auto f = compute::copy_async(host_Cells.begin(), host_Cells.end(), device_Cells.begin(), queue);
try {
BOOST_COMPUTE_CLOSURE(Cell, Step1, (Cell cell), (cell_U_size), {
for (int i = 0; i < cell_U_size; ++i) {
cell.U[i] += 1.0;
}
return cell;
});
f.wait(); // Wait for data to finish being copied
compute::transform(device_Cells.begin(), device_Cells.end(), device_Cells.begin(), Step1, queue);
//BOOST_COMPUTE_CLOSURE(void, Step2, (Cell &cell), (cell_U_size), {
// for (int i = 0; i < cell_U_size; ++i) {
// cell.U[i] += 1.0;
// }
//});
//compute::for_each(device_Cells.begin(), device_Cells.end(), Step2, queue);
compute::copy(device_Cells.begin(), device_Cells.end(), host_Cells.begin(), queue);
}
catch (std::exception &e) {
std::cout << e.what() << std::endl;
throw;
}
std::cout << "After:\n";
for (auto const& hc : host_Cells) {
for (auto const& u : hc.U)
std::cout << " " << u;
std::cout << "\n";
}
}
I have a vector of custom structs (actually much more complicated than shown here) that I want to process on the GPU. 我有一个要在GPU上处理的自定义结构向量(实际上比这里显示的要复杂得多)。 In the uncommented BOOST_COMPUTE_CLOSURE the compute::transform
passes the structs by value, processes them and then copies them back. 在未注释的BOOST_COMPUTE_CLOSURE中, compute::transform
按值传递结构,对其进行处理,然后将其复制回。
I would like to pass these by reference as shown in the commented out BOOST_COMPUTE_CLOSURE with compute::for_each
, but the kernel fails to compile ( Build Program Failure
) when the program is run and I have not found any documentation mentioning how this should be achieved. 我想以引用的方式传递这些内容,如带注释的BOOST_COMPUTE_CLOSURE和compute::for_each
,但是当程序运行时内核无法编译( Build Program Failure
),并且我还没有找到任何文档说明如何实现。
I know I can achieve passing by reference (pointers actually, since it's C99) by using BOOST_COMPUTE_STRINGIZE_SOURCE
and passing a pointer to the entire vector of structs, but I'd like to use the compute::...
functions as these seem more elegant. 我知道我可以通过使用BOOST_COMPUTE_STRINGIZE_SOURCE
并传递指向整个结构向量的指针来实现按引用传递(实际上是指针,因为它是C99),但是我想使用compute::...
函数,因为这些函数看起来更优雅。
If you define BOOST_COMPUTE_DEBUG_KERNEL_COMPILATION
macro and building OpenCL program fails, the program source and the build log will be written to stdout. 如果您定义BOOST_COMPUTE_DEBUG_KERNEL_COMPILATION
宏而构建OpenCL程序失败,则该程序源和构建日志将被写入stdout。
You can't pass by reference in OpenCL C, which you are trying to do in the BOOST_COMPUTE_CLOSURE
. 您不能在OpenCL C中按引用传递,而要在BOOST_COMPUTE_CLOSURE
中尝试这样做。 I understand that you would like to pass a __global
pointer to your closure and modify values of the variable in global memory, not of the local copy of that value. 我知道您想将__global
指针传递给您的闭包,并修改全局内存中变量的值,而不是该值的本地副本。 I don't think it's supported in Boost.Compute, because in for_each
(and other algorithms) Boost.Compute always passes value to your function/closure. 我认为Boost.Compute不支持它,因为在for_each
(和其他算法)中,Boost.Compute始终将值传递给函数/闭包。
Of course you can always implement a workaround - add unary &
operator, or implement custom device iterator. 当然,您始终可以实施变通方法-添加一元&
运算符,或实施自定义设备迭代器。 However, in presented example it would just decrease performance, because it would lead to non-coalesced memory reads and writes. 但是,在给出的示例中,这只会降低性能,因为这将导致非逐级读取和写入内存。 If you have very array of complex structures (AoS), try to change it structure of arrays (SoA) or/and break your structure. 如果您有非常复杂的数组(AoS),请尝试更改其数组结构(SoA)或/和破坏您的结构。
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