Goodbye Slow Configuration: Parallelizing Build Configuration with Makefiles

2025-04-26

Author Tavian Barnes complains about the inefficiency of existing build systems (Autoconf, CMake, Meson, etc.) in the configuration phase, which takes far longer than the build phase. He proposes a parallelized solution based on Makefiles, significantly improving efficiency by breaking down the configuration process into multiple concurrently executable tasks. The core idea is to leverage make's parallel capabilities to parallelize the originally sequential compiler test tasks, ultimately reducing configuration time from 38 seconds to 0.4 seconds. The article details the implementation, including helper scripts, Makefile writing techniques, and parallelization strategies. This article is valuable for developers seeking faster build speeds.

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Development

Alder Lake SHLX Instruction Anomaly: A 3x Performance Mystery

2025-01-02

Blogger Tavian Barnes uncovered a strange performance quirk in Intel's Alder Lake processors concerning the SHLX instruction. Under certain conditions, this instruction runs significantly slower—three times slower than expected. Benchmarking revealed that initializing the shift count register using a 64-bit immediate value causes the slowdown, while 32-bit instructions or other initialization methods do not. This discrepancy is puzzling since SHLX only uses the lower 6 bits of the shift count register. The root cause remains a mystery, but this finding highlights a potential optimization oversight in the Alder Lake microarchitecture.

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