DIE PHOTOS SHOW CORTEX-A78 SHORTFALL: New-Generation Arm CPUs Are Larger Than Expected

摘要

The latest mobile SoCs include the debut of Arm's Cortex-X family, creating three heterogenous CPU tiers comprising Cortex-X1, Cortex-A78, and Cortex-A55. Although this structure was supposed to bring new efficiencies to smartphone processors, our die-photo analysis shows that the initial implementations of the X1 and A78 are larger than expected, reducing performance per square millimeter. In analyzing the first 5nm processors, we also determined that the density gain from 7nm is underwhelming and far short of TSMC's goal.For our die analysis, we selected five chips: Apple's A14, Huawei's Kirin 9000, Intel's Lakefield, Qualcomm's Snapdragon 888, and Samsung's Exynos 2100. Except Lake-field, all compete in the flagship-smartphone market and are optimized for performance; the Intel product instead targets thin tablet PCs with similar power constraints. We included this attempt at a heterogeneous x86-CPU design to see how it stacks up against multi-tier Arm solutions. Intel has committed to the hybrid route with Alder Lake, and Lakefield provides insight on its progress.