Can we move data from global to constant memory in host function?

[202476410arsmart]

Hi! Previously one expert in this forum told me can not use “device function” to move data from global memory to constant memory. And now I am wondering, can we use “host function” to somehow achieve that??

Thank you!!!

I tired this guy’s idea, and failed…

copy device memory to constant memory

I got a hint! Definition after includes… __contant__ float constant_device_variable Host code… float *device_pointer cudaMalloc( (void**)&device_pointer, device_pointer_size ); [...] cudaMemcpyToSymbol( "constant_device_variable", device_pointer, sizeof( float ), 0, cudaMemcpyDeviceToDevice ); This version works. Important is to set a 0-offset. Perhaps cudaMemcpyDeviceToDevice is misinterpreted by nvcc as an offset, when there are three arguments in the function call. edit: perhaps cud…

[Robert_Crovella]

It seems to work for me:

$ cat t2081.cu
#include <cstdio>

__constant__ float f = 0.0f;

__global__ void k(){

  printf("%f\n", f);

}

int main(){

  float *d_f, *h_f = new float(1.234f);
  cudaMalloc(&d_f, sizeof(float));
  cudaMemcpy(d_f, h_f, sizeof(float), cudaMemcpyHostToDevice);
  cudaMemcpyToSymbol(f, d_f, sizeof(float), 0, cudaMemcpyDeviceToDevice);
  k<<<1,1>>>();
  cudaDeviceSynchronize();
}
$ nvcc -o t2081 t2081.cu
$ compute-sanitizer ./t2081
========= COMPUTE-SANITIZER
1.234000
========= ERROR SUMMARY: 0 errors
$

CUDA 11.4, V100, CentOS7

[202476410arsmart]

Thank you!! It works!!!