# Week 8: Preparatory Refactoring and Deeper Optimizations Following the foundational work from last week, I continued executing the step-by-step Multi-Scalar Multiplication (MSM) optimization plan. This week was less about big performance wins and more about strategic refactoring and implementing subtle, low-level improvements that prepare the codebase for more advanced changes. As always, the full technical details are in the main report, and the code is in the dedicated GitHub fork. * **Full Technical Report**: [MSM Stepwise Optimization Implementation Report](https://hackmd.io/@only4sim/HJkww6XYel) * **Optimization Code**: [https://github.com/only4sim/rust-kzg](https://github.com/only4sim/rust-kzg) ## Encapsulating Window Size Logic (Step 02) The first task was a strategic refactor. I encapsulated the logic for selecting the "window size" for the Pippenger algorithm into a dedicated helper function. This change wasn't intended to provide an immediate speedup. Instead, its purpose is to pave the way for a future, more advanced optimization (Step 17) that will allow for *adaptive* window sizes based on the input. As expected, this change was performance-neutral on its own. However, an important discovery was that when combined with last week's "fast-path" optimization, it caused a slight performance degradation, highlighting the complex interactions between different micro-optimizations. ## Inlining Zero-Value Checks (Step 03) The second task was a more traditional micro-optimization. I replaced a check for zero-value points in a hot path with a new, dedicated function marked with `#[inline(always)]`. This eliminates function call overhead. The new function also uses a short-circuiting trick to check two adjacent fields, which improves cache locality. The benefits of this kind of change are typically only visible in large-scale workloads, so its impact wasn't strongly felt in the existing small-scale benchmarks. However, it's a valuable improvement for the overall efficiency of the algorithm. ## Week 8 Achievements This week was about making careful, forward-looking changes: * **Completed Strategic Refactoring (Step 02):** The window selection logic is now encapsulated, preparing the code for future adaptive optimizations. * **Implemented a Targeted Micro-Optimization (Step 03):** The zero-value check is now more efficient, which should provide benefits in larger-scale computations. * **Uncovered Optimization Complexity:** A key insight from this week was seeing how combining individually sensible optimizations can sometimes lead to unexpected (though minor) performance regressions. ## Next Steps With these preparatory steps complete, the plan for next week is to: 1. Implement **Step 04: Bucket Memory Reuse**, which is a more significant optimization aimed at reducing memory allocations in repeated MSM calls. 2. Begin a **comprehensive performance analysis** of all the steps implemented so far (01-04) to understand their combined effects and formulate a recommendation for the best configuration. *** ## References and Further Reading 1. **MSM Stepwise Optimization Implementation Report**: The detailed technical report covering the work of weeks 7, 8, and 9. [https://hackmd.io/@only4sim/HJkww6XYel](https://hackmd.io/@only4sim/HJkww6XYel) 2. **`rust-kzg` Optimization Fork**: The GitHub repository where all the optimization code is being developed. [https://github.com/only4sim/rust-kzg](https://github.com/only4sim/rust-kzg) 3. **Grandine Official Website**: The production-grade execution client the optimization research is focused on. [https://grandine.io/](https://grandine.io/)