Occupancy calculator

Accelerated Computing CUDA CUDA Programming and Performance
1

Hi, all guys.

I want to find the maximum block number. So I used the occupancy calculator
But I don’t know the meaning of it.

  1. What is Warps? It is same with Blocks?

  2. I am using GTX480. Seeing the spec for GTX480, there are 480 cores. Is core equal to multiprocessor? Or is there a difference?

  3. This is my occupancy calculator result

GPU Occupancy Data is displayed here and in the graphs:
Active Threads per Multiprocessor 1536
Active Warps per Multiprocessor 48
Active Thread Blocks per Multiprocessor 3
Occupancy of each Multiprocessor 100%

Then I can make 3 blocks maximum?? And What is occupancy mean? it is the percentage for utilization?

I am sorry for my poor English and many questions. Plz answer to my question :)

2

[list=1]

[*]A warp is a set of 32 threads and is the basic unit in which threads are scheduled.

[*]For a compute capability 2.0 device like your GTX 480, a multiprocessor has 32 cores. For other devices the number varies between 8 (1.x devices) and 48 (2.1 devices).

[*]t means that at your parameters you can have three blocks per multiprocessor at one time. More blocks can execute sequentially once these blocks have finished execution.

Have a look at the Programming Guide. It is essential reading for doing any Cuda programming and answers all your questions.

3

Thanks for your answer :) Thanks!