The costs of the i386 to x86-64 upgrade

The article discusses the transition from i386 (32-bit) to x86-64 (64-bit) architecture, focusing on the implications of this upgrade on code density, memory usage, and performance. It highlights the historical context of computing, where earlier 16-bit machines had significant limitations in memory and processing capabilities. The author explains the differences between Complex Instruction Set Computing (CISC) and Reduced Instruction Set Computing (RISC), emphasizing how code density affects the efficiency of programs. The transition to 32-bit architecture allowed for greater memory addressing capabilities, leading to the adoption of the ILP32 model, where integers, longs, and pointers were all 32 bits. However, as software demands grew, the shift to 64-bit architecture became necessary, introducing the LP64 model, which increased pointer sizes and allowed for larger memory addressing. While this transition enabled more sophisticated applications, it also raised concerns about code density and potential performance issues due to larger binary sizes and L1 cache thrashing. The author concludes by noting the unexpected size differences in installation images for FreeBSD, prompting further investigation into the implications of these architectural changes.

- The transition from 32-bit to 64-bit architecture has significant implications for code density and performance.

- CISC and RISC architectures present trade-offs in instruction complexity and memory usage.

- The ILP32 model was adopted for 32-bit systems, while LP64 became the standard for 64-bit systems.

- Larger binaries in 64-bit systems can lead to performance issues, particularly with L1 cache utilization.

- The article highlights the evolving demands of software and the need for corresponding hardware capabilities.