Register pressure
Register pressure is the demand created by values that must remain live in registers at the same time. It influences resource allocation and possible spills.
How it works
Tiling, unrolling and fusion can keep more intermediate values alive. Crossing an allocation threshold can reduce resident blocks; exceeding the useful register budget can introduce local-memory traffic. The compiler may also change scheduling when constraints change.
Work through an example
A fused operation may remove a global-memory intermediate but need more live accumulators. Compare saved traffic, final register use, spills and measured duration before accepting the fusion.
Where the term can mislead
Lower register use is not an optimization goal by itself. Recomputing values or spilling them can cost more than the residency gained.
Connect the idea
Take it into practice
Continue with the existing concept, apply it to an interview problem, or follow a course lesson. Access requirements are shown before you open a page.
New to GPUs? Start with the free execution-model concept.
Sources and scope
Examples here are teaching calculations, not measured GPU performance. Consult the linked documentation for the exact device, instruction and tool version. Source review: 25 October 2026.