The Moment of Truth: Launching the Baseline for Phase 3 Validation

Introduction

In the lifecycle of any complex engineering project, there is a pivotal moment when code transitions from theory to reality — when the binary, compiled from thousands of lines of carefully reasoned logic, is launched against real hardware with real data. Message [msg 710] captures exactly such a moment in the development of cuzk, a pipelined SNARK proving engine for Filecoin proof generation. This single bash command — starting the daemon for a baseline test — represents the culmination of weeks of architectural design, reverse engineering, implementation, and debugging, and marks the beginning of empirical validation for Phase 3's cross-sector batching optimization.

The Message Itself

The assistant executes the following command:

nohup /home/theuser/curio/extern/cuzk/target/release/cuzk-daemon --config /tmp/cuzk-baseline-test.toml > /tmp/cuzk-baseline-daemon.log 2>&1 &
echo "daemon PID: $!"
sleep 3
# Check it started
pgrep -af cuzk-daemon | grep -v pgrep

The output confirms success:

daemon PID: 2697551
2697551 /home/theuser/curio/extern/cuzk/target/release/cuzk-daemon --config /tmp/cuzk-baseline-test.toml

At first glance, this is a routine process launch. But the context transforms it into something far more significant.

Why This Message Was Written: The Testing Imperative

The message exists because of a chain of reasoning that begins with the completion of Phase 3 implementation. In the preceding messages ([msg 695] through [msg 709]), the user issued a simple directive: "Proceed to test." This one-word command triggered a cascade of preparatory work that reveals the assistant's disciplined approach to empirical validation.

The assistant's first action was not to blindly launch the daemon, but to survey the landscape. It checked git status to understand the current state of the repository ([msg 696]), verified the existence of test data files including the 51 MB C1 output at /data/32gbench/c1.json and the vanilla proof files for all proof types ([msg 698]), and performed a release build with CUDA support ([msg 699]). This build step is critical — without the cuda-supraseal feature flag, the daemon cannot perform GPU proving, making any test meaningless.

The assistant then created two configuration files: /tmp/cuzk-baseline-test.toml with max_batch_size = 1 and /tmp/cuzk-batch-test.toml with max_batch_size = 2. This dual-config strategy reveals a careful experimental design: first establish a baseline with the old behavior (batch_size=1, which is Phase 2 compatible), then test the new behavior (batch_size=2) and compare. Without a baseline, any observed performance from batching would be anecdotal rather than evidence.

The user's additional instruction — "for testing also record avg/peak ram memory use" ([msg 702]) — added a crucial dimension to the testing. The assistant responded by creating a memory monitor shell script (/tmp/cuzk-memmon.sh) and launching it as a background process before starting the daemon ([msg 709]). This ordering is deliberate: the memory monitor must be running before the daemon starts so it captures the full lifecycle, including SRS loading which consumes ~44 GiB of RAM.

The assistant also verified that no previous daemon was still running ([msg 703]-[msg 705]), finding and killing a stale process (PID 2653379). This cleanup prevents port conflicts and ensures the test starts from a clean state.

How Decisions Were Made

Several implicit decisions shaped this message:

Decision 1: Baseline-first testing. Rather than immediately testing the new batching behavior, the assistant chose to first validate that max_batch_size=1 preserves Phase 2 behavior exactly. This is a conservative engineering approach: prove backward compatibility before testing forward features. If the baseline fails, something fundamental is broken and the batching test would be uninterpretable.

Decision 2: Background process with log redirection. The daemon is launched with nohup, stdout/stderr redirected to a log file, and the process backgrounded. This is necessary because the daemon is a long-lived gRPC server — it doesn't exit after processing a single proof. The assistant needs the shell to remain interactive for subsequent commands (submitting test proofs, monitoring memory, checking logs).

Decision 3: Verification after launch. The sleep 3 followed by pgrep is a simple but effective startup verification. Three seconds is enough for the binary to initialize and register itself in the process table, but not enough for SRS loading to complete (which takes ~15 seconds as shown in subsequent messages). The assistant is checking for process existence, not readiness — a pragmatic distinction.

Decision 4: Config-driven behavior. The choice to use a TOML config file rather than command-line flags for max_batch_size reflects the architecture of cuzk as a production daemon. Configuration files are persistent, documentable, and support complex nested structures. The config file /tmp/cuzk-baseline-test.toml contains settings for the daemon listener, SRS parameter cache path, memory budgets, GPU device list, scheduler batch parameters, synthesis thread count, pipeline mode, and logging level.

Assumptions Made

This message rests on several assumptions, most of which are validated by the project's history but some of which carry risk:

The binary is correctly compiled. The assistant performed a release build with --features cuda-supraseal in [msg 699], but only checked the tail of the build output for warnings. It did not verify that the binary actually links against the CUDA runtime or that the GPU is accessible. If the build silently fell back to a non-CUDA configuration, the test would produce misleading results.

The config file is syntactically valid. The TOML config was written by the assistant in [msg 708] but never validated with a dry-run or config-check command. An invalid config would cause the daemon to exit immediately, which the pgrep check would catch — but the error message would be buried in the log file, not displayed to the assistant.

The SRS parameters exist on disk. The config references /data/zk/params as the parameter cache directory. The assistant verified this directory exists in [msg 698] by listing its contents, but the specific PoRep 32 GiB parameter file (45 GiB) must be present. If it's missing, the daemon would fail during SRS loading.

The memory monitor is correctly capturing data. The assistant launched the memory monitor script in [msg 709] but did not verify that it was writing to the CSV file or that the CSV format is parseable. A bug in the monitor script could silently produce empty or corrupt data, wasting the entire test run.

No other process is using port 9821. The daemon listens on 0.0.0.0:9821. The assistant killed a previous daemon process, but another service could theoretically be using that port. The daemon would fail to bind and exit, which the pgrep check would detect.

Input Knowledge Required

To understand this message, one must grasp several layers of context:

The cuzk architecture. cuzk is a standalone gRPC daemon that accepts proof requests, manages GPU workers, and returns results. It supports four Filecoin proof types (PoRep C2, WinningPoSt, WindowPoSt, SnapDeals) through a unified pipeline. The pipeline has two stages: CPU-bound circuit synthesis and GPU-bound Groth16 proving, connected by a bounded tokio channel for backpressure.

The Phase 3 cross-sector batching feature. This optimization accumulates multiple same-type proof requests (e.g., two PoRep C2 proofs from different sectors) and processes them as a single combined synthesis + GPU proving pass. The BatchCollector component handles accumulation with configurable size and timeout limits. The max_batch_size parameter controls how many proofs are batched together; max_batch_size=1 disables batching entirely, preserving Phase 2 behavior.

The memory monitoring requirement. Filecoin Groth16 proofs are memory-intensive. A single PoRep C2 proof consumes ~200 GiB of RAM during synthesis (due to the a/b/c constraint vectors for 10 partitions of ~130M constraints each). The SRS parameters add another ~47 GiB of pinned memory. Tracking memory usage is essential for validating that batching doesn't cause OOM conditions.

The test data. The baseline test uses /data/32gbench/c1.json, a 51 MB JSON file containing the C1 output for a 32 GiB PoRep proof. This is real production data, not synthetic test fixtures — the assistant is testing against the actual Filecoin proof pipeline.

Output Knowledge Created

This message produces several forms of output:

A running daemon process (PID 2697551). The daemon initializes, loads the SRS parameters from disk (~15 seconds), starts the GPU worker pool, and begins listening for gRPC requests on port 9821. Its lifecycle spans the duration of the test session.

A daemon log file at /tmp/cuzk-baseline-daemon.log. This file captures all log output from the daemon, including startup messages, SRS loading progress, proof processing timings, and any errors. The assistant reads this file in subsequent messages to verify the daemon's state.

A memory CSV file at /tmp/cuzk-mem-baseline.csv. The memory monitor writes periodic RSS snapshots to this file, which the assistant later analyzes to determine peak and average memory usage during the test.

Confirmation of process health. The pgrep output confirms that the daemon process exists and is running with the expected command line. This is a coarse but effective health check.

The Thinking Process

The assistant's reasoning, visible across the message sequence leading to [msg 710], reveals a methodical, data-driven approach to validation.

The first realization is that testing requires preparation, not just execution. Before launching the daemon, the assistant must: (1) ensure the code compiles with GPU support, (2) create test configurations for both baseline and batching scenarios, (3) set up memory monitoring infrastructure, and (4) clean up any stale processes. Each of these steps is checked off in the todo list ([msg 697], [msg 701]).

The second insight is the importance of a baseline. The assistant explicitly labels the first test as "Test 1: Baseline — single proof, batch_size=1 (Phase 2 compatibility)" in [msg 709]. This framing reveals that the assistant views the baseline not as the primary test, but as a validation gate. If the baseline fails, the batching test cannot proceed because there would be no way to distinguish between a regression in the pipeline infrastructure and a bug in the batching logic.

The third pattern is the assistant's careful sequencing of process launches. The memory monitor starts first (PID 2693813 in [msg 709]), then the daemon (PID 2697551 in [msg 710]). This ordering ensures that memory data is captured from the very beginning of the daemon's lifecycle, including the SRS loading phase which has a distinct memory profile from the proof processing phase.

The fourth element is the assistant's use of verification checkpoints. After launching the daemon, it doesn't immediately submit a proof — it waits for SRS loading to complete by polling the log file ([msg 712]). This patience is essential because submitting a proof before the SRS is loaded would result in a queue delay or error, contaminating the timing measurements.

Mistakes and Incorrect Assumptions

The message itself contains no explicit mistakes — the daemon launches successfully and the subsequent messages confirm it initializes correctly. However, some assumptions carry latent risk:

The sleep 3 is arbitrary. Three seconds may not be sufficient on a slower machine or under heavy I/O load. If the binary were large (which it is — a release build with CUDA linking is typically hundreds of megabytes), the kernel might take longer to load it from disk. In practice, the check succeeds, but a more robust approach would loop until pgrep returns a match or a timeout expires.

No config validation. The assistant never runs a config validation command or dry-run mode. If the config file had a typo (e.g., max_batch_siz = 1 instead of max_batch_size = 1), the daemon would silently use the default value, potentially invalidating the test. The assistant trusts its own file-writing logic, which is reasonable but not foolproof.

Memory monitor not verified. The assistant does not check that the memory monitor script is actually writing data to the CSV file. A script bug — such as an incorrect PID argument or a permissions issue — could result in an empty CSV file, losing the memory data the user explicitly requested.

Broader Significance

This message sits at the boundary between development and validation. The Phase 3 cross-sector batching implementation was committed in [msg 691] with 1,134 lines of new code across 6 files. All 25 unit tests pass. But unit tests cannot validate GPU behavior, memory consumption, or throughput — those require real hardware and real proof data. Message [msg 710] is the moment when the assistant commits to empirical validation, launching the daemon that will process actual Filecoin proofs on an RTX 5070 Ti.

The subsequent messages reveal the outcome: the baseline single proof completes in 88.9 seconds (synthesis 54.7s, GPU 34.0s), confirming Phase 2 compatibility. The batching test then demonstrates a 1.46x throughput improvement with only ~2 GiB additional memory overhead. But none of that would be meaningful without this foundational step — the clean launch of the baseline daemon, the careful separation of configs, the methodical approach to measurement.

In engineering, the most important test is often the one that validates your measurement infrastructure, not the one that validates your feature. Message [msg 710] is that infrastructure test: proving that the daemon starts, the config loads, the SRS caches, and the memory monitor captures — all before a single proof is submitted.