2 docs tagged with "roofline"

Every kernel is limited by one of two things before it is limited by anything else: how fast the device can do arithmetic, or how fast the device can move bytes from DRAM. Which one applies is a property of the kernel's own math, computable on paper before you write a line of CUDA, and it determines almost everything about how you should spend optimization effort afterward. The roofline model is the tool that turns "which one applies" into a single number you can compute and a single plot you can place it on.

Arithmetic Intensity and the Roofline Model builds the model from datasheet peaks and a paper estimate of FLOPs and bytes — a first-order filter you can apply before a kernel even runs. This page replaces every number in that estimate with one measured from a real execution: the FLOPs a kernel actually issued, the bytes it actually moved, and the roofs the hardware actually achieves rather than what its spec sheet claims.