A few days after reviews of Intel's Core Ultra 7 270K Plus and Core Ultra 5 250K Plus rolled out, Geekbench said it would invalidate all results recorded with the two CPUs. That's because it's the only non-gaming application that currently supports Intel Binary Optimization Tool, or iBOT, which modifies a binary to optimize it for a specific Intel architecture. A week later, Geekbench has published its findings after investigating what iBOT is doing behind the scenes, and attributed an uplift of up to 30% in certain workloads to newly-vectorized instructions.
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With iBOT enabled, Geekbench saw a 14% reduction in overall instructions and a 62% drop in scalar instructions. However, it saw a 1,366% increase in vector instructions. To see which instructions were executing, Geekbench used Intel's Software Development Emulator, or SDE.
With iBOT disabled and after 100 runs of the HDR subtest, Geekbench saw a total of 220 billion scalar instructions and 1.25 billion vector instructions. With iBOT on, that went to 84.6 billion scalar and 18.3 billion vector. By vectorizing a large number of the instructions in this subtest, iBOT is able to significantly improve performance, relying on SIMD (single instruction, multiple data) rather than a linear pipeline (single instruction, single data, or SISD) of scalar instructions.
The change in instruction mix is what's interesting here. Geekbench's conclusion is what you probably expect; it doesn't appreciate an optimization that only applies in a small list of applications. "[iBOT] undermines this by replacing that varied code with processor-tuned, fully optimized binaries, measuring peak rather than typical performance."
Geekbench's view is rather negative, and understandably so, but the peek behind the curtain here has a lot of implications for the future of iBOT. Vectorized instructions on modern CPU architectures can vastly improve performance with a relatively small hit to power consumption — just look at Zen 5's performance in an AVX-512 workload like Y-Cruncher. This investigation shows that Intel is able to do that on the backend with a shipping binary.
There are downsides here, however. Geekbench noted a 40-second startup delay in its initial testing with iBOT, which shrunk to a consistent two-second delay on subsequent passes. There was no delay with iBOT disabled. Additionally, it found no performance improvement with Geekbench 6.7. iBOT computes a checksum against the executable, which means it's trying to find out if a specific binary is optimized.
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