Link Copied
Yes, I'm sorry, I didn't copy the "include file".
Anyway, I tried your version of code, and also if it works, the result seem to be wrong.
This is the output, and the vector is not sorted correctly, as you can see. It is as it was before the sorting; instead it should have values in a different order.
Maybe this is different from the output you obtained...
Thank you.
Hi Eugenio,
We are also getting the wrong results using CPU whereas with GPU it's giving correct results. We don't the exact reason for this behavior yet but we are debugging it meanwhile you can use GPU to execute your code.
We will get back to you as soon as we get the exact reason for this behavior.
Warm Regards,
Abhishek
Ok. In the meanwhile I post another related question:
is it normal that the sort on GPU is much slower than the sequential one, for sorting a vector<int>?
I'm talking about the same sort function, executed with an execution policy (on GPU) and without policy.
Here the output of the program, and the code:
#include <CL/sycl.hpp>
#include <iostream>
#include <chrono>
#include <vector>
#include <dpstd/iterator>
#include <dpstd/algorithm>
#include <dpstd/execution>
using namespace std;
int main(int argc, char **argv) {
auto asyncHandler = [&](cl::sycl::exception_list eL) {
for (auto& e : eL) {
try {
std::rethrow_exception(e);
}catch (cl::sycl::exception& e) {
std::cout << e.what() << std::endl;
std::cout << "fail" << std::endl;
// std::terminate() will exit the process, return non-zero, and output a
// message to the user about the exception std::terminate();
}
}
};
auto start=std::chrono::system_clock::now();
auto end=std::chrono::system_clock::now();
long time=0;
sycl::queue q(sycl::default_selector{}, asyncHandler);
const int n = 500000000;
{// TEST simple integer
std::vector<int> keys(n);
int i=1;
// Initialization
for_each(keys.begin(), keys.end(),[&](int& value){
value=n-i;
i++;
});
cout<<"Input array dimension: "<<n<<std::endl;
cout<<"First 10 values of input array: "<<std::endl;
for_each(keys.begin(), keys.begin()+10,[&](int& value){
std::cout<<value<<std::endl;
});
cout<<"-------------------------------------------------- "<<std::endl<<std::endl;
cout<<"Sequential sorting... "<<std::endl;
// Sequential std::sort
start=std::chrono::system_clock::now();
std::sort(keys.begin(), keys.end());
end=std::chrono::system_clock::now();
time=std::chrono::duration_cast<std::chrono::milliseconds>(end-start).count();
for_each(keys.begin(), keys.begin()+10,[&](int& value){
std::cout<<value<<std::endl;
});
std::cout<<"Time: "<<(float)time/1000<<std::endl;
cout<<"-------------------------------------------------- "<<std::endl<<std::endl;
// Parallel std::sort
auto policy = dpstd::execution::make_device_policy(q);
std::cout << "Parallel sort running on: " << q.get_device().get_info<sycl::info::device::name>() << "\n";
start=std::chrono::system_clock::now();
std::sort(policy, keys.begin(), keys.end(), [](int i1, int i2){
return i1 < i2;
});
end=std::chrono::system_clock::now();
time=std::chrono::duration_cast<std::chrono::milliseconds>(end-start).count();
for_each(keys.begin(), keys.begin()+10,[&](int& value){
std::cout<<value<<std::endl;
});
std::cout<<"Time: "<<(float)time/1000<<std::endl;
}
return 0;
}
