Glibc Git Lands Another FMA-Optimized Function - 24% Mean Improvement

Written by Michael Larabel in GNU on 14 August 2023 at 09:23 PM EDT. Add A Comment
A few days ago Intel compiler expert H.J. Lu landed an FMA-optimized log2 function for the GNU C Library that could yield up to a 69% performance improvement on tested Intel Skylake processors. Merged today to Glibc Git was another FMA-optimized function.

H.J. Lu has continued his recent FMA optimization push for the GNU C Library by optimizing expm1, the function to return a value of an exponential minus 1.

While the expm1 function may not be as common, testing again on Intel Skylake showed some nice improvements. The mean improvement was 24% better than the prior Glibc behavior before introducing this Fused Multiply Add (FMA) optimized code for benefiting modern Intel and AMD CPUs.

Glibc FMA optimization improvement

This commit lands the code and not a bad improvement for x86_64 CPUs with the next Glibc release. Great as always to Intel and their relentless open-source contributions for further tuning the performance potential of Linux x86_64 systems.
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