Evaluating Spec CPU2026

Summary

SPEC’s CPU benchmark suite has been a long established industry standard, and is almost impossible to miss when reading through various publications. Intel used SPEC CPU2000 to showcase Pentium 4’s improvements over Pentium III. Samsung used SPEC CPU2000 and SPEC CPU2006 traces to tune their Mongoose cores. SPEC CPU2017 formed part of Intel’s performance projections for Lion Cove. Now, SPEC has updated their CPU benchmark suite with SPEC CPU2026. The new suite consists of 52 workloads, up from 43 in SPEC CPU2017. Individual workloads consist of more source code lines, measured in KLOC (thousands of lines of code). SPEC’s goal is to modernize their CPU benchmark suite, while retaining the portability goals that characterized SPEC.Because of SPEC’s importance in the CPU performance world, I’ll be looking over the new suite’s workloads to examine the challenges that they serve up to CPUs. I’m interested in hardware rather than compiler comparisons, so I’ll be using GCC 14.2.0 with -O3 and native architecture/optimization targets. I did try GCC 15.2.0, but ran into various issues and decided to stick with GCC 14.2.0 to conserve time. I’m testing all of the systems below using Linux.SPEC CPU scores represent speedup ratios relative to a reference system. Each SPEC CPU update tends to update the reference system, though not always to one that’s a relevant comparison for recent hardware.An Ampere eMAG 8180 system provides the reference score of 1.0 for SPEC CPU2026. Ampere’s eMAG is faster than the Sun Fire V490 used for SPEC CPU2017, in much the same way that a Cessna 172 might be faster than a Sopwith Camel. Neither is a good comparison against modern airliners. Similarly, Ampere eMAG was not a widely deployed platform, and even systems that pre-date it by many years outperform it by a large margin. I’ve heard part of the motivation behind using a slower system was to let most systems achieve high scores, but that could have been accomplished by making the reference scor...