Commit 7e08688e authored by Neil Gershenfeld's avatar Neil Gershenfeld

wip

parent c28495fc
Pipeline #5102 passed with stage
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//
// cudapit.cu
// Neil Gershenfeld 3/1/20
// calculation of pi by a CUDA multi-GPU thread sum
// pi = 3.14159265358979323846
//
#include <iostream>
#include <chrono>
#include <thread>
#include <vector>
#include <cstdint>
uint64_t blocks = 1024;
uint64_t threads = 1024;
uint64_t nloop = 1000000;
uint64_t npts = blocks*threads;
std::vector<double> results;
__global__ void init(double *arr,uint64_t nloop,uint64_t npts,int index) {
uint64_t i = blockIdx.x*blockDim.x+threadIdx.x;
uint64_t start = nloop*i+npts*nloop*index+1;
uint64_t end = nloop*(i+1)+npts*nloop*index+1;
arr[i] = 0;
for (uint64_t j = start; j < end; ++j)
arr[i] += 0.5/((j-0.75)*(j-0.25));
}
__global__ void reduce_sum(double *arr,uint64_t len) {
uint64_t i = blockIdx.x*blockDim.x+threadIdx.x;
if (i < len)
arr[i] += arr[i+len];
}
void reduce(double *arr) {
uint64_t len = npts >> 1;
while (1) {
reduce_sum<<<blocks,threads>>>(arr,len);
len = len >> 1;
if (len == 0)
return;
}
}
void sum(int index) {
cudaSetDevice(index);
double harr[1],*darr;
cudaMalloc(&darr,npts*sizeof(double));
init<<<blocks,threads>>>(darr,nloop,npts,index);
reduce(darr);
cudaDeviceSynchronize();
cudaMemcpy(harr,darr,8,cudaMemcpyDeviceToHost);
results[index] = harr[0];
cudaFree(darr);
}
int main(void) {
int ngpus;
cudaGetDeviceCount(&ngpus);
std::thread threads[ngpus];
double pi = 0;
auto tstart = std::chrono::high_resolution_clock::now();
for (int i = 0; i < ngpus; ++i) {
results.push_back(0);
threads[i] = std::thread(sum,i);
}
for (int i = 0; i < ngpus; ++i) {
threads[i].join();
pi += results[i];
}
auto tend = std::chrono::high_resolution_clock::now();
auto dt = std::chrono::duration_cast<std::chrono::microseconds>(tend-tstart).count();
auto gflops = npts*nloop*ngpus*5.0/dt/1e3;
std::cout << "npts: " << npts << " nloop: " << nloop << " ngpus: " << ngpus << " pi: " << pi << '\n';
std::cout << "time: " << 1e-6*dt << " estimated GFlops: " << gflops << '\n';
return 0;
}
......@@ -4,6 +4,7 @@
|estimated GFlops|code|description|system|date|
|---|---|---|---|---|
|88,333|[mpimppi.c](hybrid/mpimppi.c)|C, MPI+OpenMP, 1024 nodes, 64 cores/node, 4 threads/core<br>cc mpimppi.c -o mpimppi -O3 -ffast-math -fopenmp|Argonne ALCF Theta<br>Cray XC40|Oct 9, 2019|
|5,738.|[cudapit.cu](CUDA/cudapit.cu)|C++, CUDA, 4 GPUs, 5120 cores/GPU|NVIDIA V100|March 1, 2020|
|2,117|[mpipi2.c](MPI/mpipi2.c)|C, MPI, 10 nodes, 96 cores/node<br>mpicc mpipi2.c -o mpipi2 -O3 -ffast-math|Intel 2x Xeon Platinum 8175M|Oct 24, 2019|
|2,102|[mpipi2.py](Python/mpipi2.py)|Python, Numba, MPI<br>10 nodes, 96 cores/node|Intel 2x Xeon Platinum 8175M|Feb 6, 2020|
|1,635|[cudapi.cu](CUDA/cudapi.cu)|C++, CUDA, 5120 cores|NVIDIA V100|March 1, 2020|
......
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