CODEWITHSUNDEEP
cudacublas
SkyWalker
SkyWalker

Reputation: 14317

Should we reuse the cublasHandle_t across different calls?

I'm using the latest version CUDA 5.5 and the new CUBLAS has a stateful taste where every function needs a cublasHandle_t e.g.

  cublasHandle_t handle;
  cublasCreate_v2(&handle);
  cublasDgemm_v2(handle, A_trans, B_trans, m, n, k, &alpha, d_A, lda, d_B, ldb, &beta, d_C, ldc);
  cublasDestroy_v2(handle);

Is it a good practice to reuse this handle instance as much as possible like some sort of a Session or the performance impact would be so small that it makes more sense to lower code complexity by having short-living handle instances and therefore create/destroy it continuously?

Upvotes: 7

Views: 2897

Answers (2)

Chelaru Viorel
Chelaru Viorel

Reputation: 11

As the CUDA Toolkit states in here

The application must initialize the handle to the cuBLAS library context by calling the cublasCreate() function. Then, the context is explicitly passed to every subsequent library function call. Once the application finishes using the library, it must call the function cublasDestory() to release the resources associated with the cuBLAS library context.

Upvotes: 1

Vitality
Vitality

Reputation: 21505

I think it is a good practice for two reasons:

  1. From the cuBLAS Library User Guide, "cublasCreate() [...] allocates hardware resources on the host", which makes me think that there is some overhead on its call.
  2. Multiple cuBLAS handle creation/destruction can break concurrency by unneeded context synchronizations.

Upvotes: 8

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