Using cudaStreamBeginCapture()

Accelerated Computing CUDA CUDA Programming and Performance
1

Hi
Is there a way to check if a kernel is called inside a stream capture mode?
There is an example from the manual:

cudaStreamBeginCapture(stream);

kernel_A<<< ..., stream >>>(...);
kernel_B<<< ..., stream >>>(...);
libraryCall(stream);
kernel_C<<< ..., stream >>>(...);

cudaStreamEndCapture(stream, &graph);

Assume there are cases in other part of the program that call kernel_A without capture mode. When kernel_A is called, I want to know if it is called after the beginCapture or not.
Any idea about that?

2

In the programming guide, it says below your quoted example: " When a stream is being captured, work launched into the stream is not enqueued for execution."

kernel_A will not be executed if stream capture is in progress for the kernel’s stream.

3

I am a bit confused about the functionality of that. If kernel_A is not executed because of cudaStreamBeginCapture, then when is it going to be executed? After cudaStreamEndCapture?

4

The kernel is executed when you launch the executable graph that needs to be constructed from the captured sequence.