Can graphics and present queues really be different?

Question

almost all examples and tutorials handle the situation when graphics queue index and present queue index are different. But after some testing on multiple gpus I found that they are always the same.

The questions are - what are the chances they will be different? Can it happen on old hardware only? Is it safe for future if I will not handle that situation?

Answer 1

Specification is clear in this regard - it allows graphics and present queues to be different. So if You want to be compliant with the specification, You should handle this situation.

In practice, on most common operating systems like Windows or Linux, I doubt it will be the case - graphics and present queues will usually be the same. But I also doubt You will find someone that will promise You it won't change in the future. Currently the situation looks as described, but how it will look in 1, 2 or 5 years in the future? I don't know. So, as I wrote, spec is clear. If You want to be sure Your code works correctly, You have to handle such situation.