The Last Link: How Changing BENCH_PROOFS from 12 to 10 Completed a Benchmark Restructuring

In a coding session dedicated to deploying and tuning a GPU-accelerated zero-knowledge proving engine (CuZK) for Filecoin, one of the smallest changes imaginable—a single number in a shell script—represented the final piece of a much larger puzzle. The message reads in its entirety:

Now update entrypoint.sh — change BENCH_PROOFS=12 to BENCH_PROOFS=10: [edit] /tmp/czk/docker/cuzk/entrypoint.sh Edit applied successfully.

This is message <msg id=3754> in a long conversation spanning dozens of rounds. On its surface, it is almost trivial: a one-line edit that decrements a constant by two. But to understand why this change was made, what reasoning led to it, and what assumptions it encodes, one must trace the chain of decisions that preceded it—a chain that reveals deep thinking about benchmark methodology, pipeline behavior, and the practical challenges of measuring throughput in a distributed proving system.

The Problem: A Warmup That Cost Too Much

The story begins with the user's observation in <msg id=3744>: "Due to the much longer warmup we should adjust the benchmark." The "much longer warmup" refers to the time required for the CuZK daemon to load its Structured Reference Strings (SRS) into GPU memory—a process that could take many seconds or even minutes. In the previous benchmark design, the daemon was started twice: first in a "warmup mode" with synthesis_concurrency=1 to perform Pre-Compiled Constraint Evaluator (PCE) extraction on a single proof, then restarted with full concurrency settings for the actual benchmark run. This restart meant the SRS had to be loaded from scratch, wasting precious GPU memory bandwidth and adding significant overhead to every benchmark cycle.

The user's proposed solution was elegant: eliminate the restart entirely. Run the daemon once with full settings from the beginning, perform a single PCE warmup proof if needed, then immediately launch into a three-phase benchmark: 5 untimed warmup proofs to let the pipeline reach steady state, 10 timed proofs for actual throughput measurement, and 3 untimed cooldown proofs to let the pipeline drain gracefully. No restarts, no SRS reloading, no wasted time.

The Assistant's Reasoning: Wrestling with Pipeline Dynamics

The assistant's response in <msg id=3745> reveals an extended period of reasoning—nearly 1,500 words of internal deliberation—about how to implement this three-phase model. This reasoning is remarkable for its depth and for the way it grapples with a fundamental tension in benchmark design: how do you measure steady-state throughput when the act of measurement itself disturbs the system?

The assistant considered several approaches. One option was to dispatch all 18 proofs (5 warmup + 10 timed + 3 cooldown) in a single batch and measure only the middle 10 completions. This would give the truest steady-state measurement, since the pipeline would be continuously loaded from start to finish. However, the cuzk-bench batch tool did not support per-proof timing or selective measurement windows—it dispatched a fixed count at a given concurrency and reported only aggregate results.

A second option was to run three sequential batches: warmup, then timed, then cooldown. This was simpler to implement in shell script but introduced a problem: when the warmup batch completed, the pipeline would drain before the timed batch started. The first few proofs of the timed batch would therefore experience a "cold" pipeline, distorting the measurement. The assistant wrestled with this explicitly:

"if I run the warmup batch and wait for it to complete before starting the timed batch, the pipeline will be empty when timing begins. The whole point of the warmup is to have synthesis and GPU workers already busy so the timed batch runs under realistic load conditions. Running them sequentially defeats that purpose."

The assistant ultimately settled on the sequential approach, reasoning that with only 10 timed proofs, the pipeline would stabilize quickly after each batch transition, and the measurement would still capture mostly steady-state behavior. This was a pragmatic compromise—not theoretically perfect, but good enough for the practical purpose of comparing hardware configurations and tuning parameters.

The Entrypoint Change: Aligning the Interface

With the benchmark script restructured across six substantial edits (messages <msg id=3747> through <msg id=3753>), one final piece remained. The entrypoint.sh script—the container's initialization script that configures and launches the benchmark—contained a variable BENCH_PROOFS=12. This variable was passed as the positional argument to benchmark.sh, which in the old design represented the total number of proofs to run.

But in the new design, the positional argument to benchmark.sh had been redefined to represent only the number of timed proofs, with separate --warmup-proofs and --cooldown-proofs options for the other phases. The default timed count was 10. The entrypoint needed to pass 10, not 12, to align with this new semantics.

The change from 12 to 10 is therefore not arbitrary. It encodes a conceptual shift: the entrypoint no longer specifies "run this many proofs total"; it specifies "run this many proofs for timing." The warmup and cooldown phases are now implicit parts of the benchmark structure, configured separately and not exposed through the entrypoint's simple interface.

Assumptions and Knowledge Required

To understand this message, one must know several things that are not stated in the message itself. First, one must know that BENCH_PROOFS is a variable in entrypoint.sh that controls the number of proofs passed to benchmark.sh. Second, one must know that benchmark.sh was just restructured to use a three-phase model where the positional argument represents timed proofs only. Third, one must know that the old value of 12 represented the total proof count in the previous single-batch design.

These assumptions are reasonable within the context of the conversation—the assistant and user have been working on this benchmark for many rounds—but they highlight how even a trivial-looking change depends on a web of shared understanding about the system architecture.

Output Knowledge and Significance

This message creates one piece of output knowledge: entrypoint.sh now passes BENCH_PROOFS=10 instead of BENCH_PROOFS=12. But the significance goes deeper. This change completes the benchmark restructuring, tying together all the edits to benchmark.sh and making the system consistent. The Docker image can now be rebuilt with a coherent benchmark pipeline: no daemon restart, three-phase proof execution, and a clean separation between warmup, measurement, and cooldown.

The message also serves as a testament to the importance of interface alignment in complex systems. A single number changed in a single file, but that number only makes sense in the context of a redesigned benchmark methodology, a restructured shell script, and a deep understanding of GPU pipeline dynamics. In software engineering, the smallest changes often carry the heaviest context.