CODEWITHSUNDEEP
cudanpp
Artur Ispiriants
Artur Ispiriants

Reputation: 108

NPP: Overlapping computation and data transfer

CUDA allows to overlap computation and data transfer using cuMemcpy async functions and streams. But is it possible with NPP(Performance Primitives)?

A little background. I am trying to utilize GPU using NPP image resize functions (in our case it is nppiResize_8u_C3R). I am using pinned memory and successfully transfer data to GPU using cuMemcpy2DAsync_v2 and per thread stream. The problem is that nppiResize_8u_C3R and all other computation functions do not accept streams.

When I run Nvidia Visual Profiler I see the next:

  1. Pinned memory allows me to transfer data faster - ~6.524 GB/s.
  2. The percentage of time when memcpy is being performed in parallel with compute is 0%.

Upvotes: 1

Views: 913

Answers (1)

talonmies
talonmies

Reputation: 72348

The problems [sic] is that nppiResize_8u_C3R and all other computation functions do not accept streams.

NPP is fundamentally a stateless API. However, to use streams with NPP, you use nppSetStream to set the default stream for subsequent operations. There are several caveats noted on page 2 of the documentation about using NPP with streams and recommended synchronization practices when switching streams.

Upvotes: 2

Related Questions