IBM z15: Physical design improvements to significantly increase content in the same technology
The IBM Z processor continues to improve over previous System Z processors, but for the first time it does so without a technology improvement as the baseline enabler. The IBM z15 was designed in the same 14-nm High-Performance GLOBALFOUNDRIES technology as the IBM z14 and yet still added 20% more cores, doubled the L3 cache, and increased the L2 cache by a third while also adding a third peripheral component interconnect express (PCIe) port to the chip and an elliptic curve cryptography engine into each core. This article discusses the design, tool, and methodology enhancements required to increase the design content so significantly while maintaining the chip size and power limits from the previous z14 design. This article also discusses other design and methodology improvements that were made possible via the deeper understanding of the technology and how to more fully leverage it in a second generation.