CODEWITHSUNDEEP
c++cudagpu-shared-memory
Aliya Clark
Aliya Clark

Reputation: 131

dynamic allocation of shared memory for array of data and pointers to data in CUDA

I am beginner to CUDA and I am trying to allocate shared memory for double data type and pointers to double data types. I am allocating data using

extern __shared__ double dataShared[];

Here at I want pointers to this data at specific places

int v = threadIdx.x;
dataShared[v] = &dataShared[v + (v+1)*data.V];

I want a 2D double data array and 1D pointer array which points to each column of the 2D array in shared memory. Here I am avoiding dynamic allocation of the pointer array due to the performance implications. Here the pointer array is shifted and used to access the columns so that the 2D array would be column shifted as a result.

However this is not allowed and is there any other way I can achieve this. Currently I am working using CUDA 7.5 and it would be better if someone can suggest if there is anything new in CUDA 8.0 to achieve this.

Upvotes: -1

Views: 419

Answers (1)

ptrendx
ptrendx

Reputation: 326

You can use 2 different pointers, with different types, to point to the same block of shared memory:

extern __shared__ char dataShared[];
double ** columns = (double **) dataShared; //Here you can store pointers to columns
double * realData = (double *) (dataShared + N * sizeof(double *)); //N is the number of columns

Here you use one block of shared memory, but use different offsets for 2 regions of it (offset 0 for the pointers to columns and offset N * sizeof(double *) for your actual data).

Upvotes: 3

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