#roofline
2 articles
01
·Computer Architecture·★ MEMBER·PAPER·9 min read
The GPU Memory Hierarchy — HBM, SRAM, Registers, and Why Movement Wins
What sets a GPU's speed is not the arithmetic units but where the data sits — registers, shared memory, L2 or HBM — and how many times it is moved. Capacities and bandwidths by order of magnitude, arithmetic intensity and tiling, a roofline per level of the hierarchy, and finally FlashAttention: more FLOPs, less time.
02
·Computer Architecture·★ MEMBER·9 min read
The Memory Wall from Scratch — Why Moving Data Costs More Than Computing
Multiplying two numbers is cheap; delivering them is not. Starting from the physics of charging a wire, we get to why DRAM latency never shrank, the orders of magnitude in the memory hierarchy, Little's law, machine balance and the roofline — and end with a procedure for deciding whether your kernel is compute bound or bandwidth bound.