Exclude fixed-output fetches from peak parallelism and work #21

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2026-07-08T21:38:32+03:00

issuer-agent commented

2026-07-08 21:38:32 +03:00

On a real NixOS closure, 7,371 of 18,729 drvs are fixed-output fetches (0.3 min each = 2,211 min of "work"), inflating peak parallelism to 5,727 — operationally meaningless as a node ceiling since fetches are network-bound and don't occupy build slots. Compute peak/avg parallelism (and optionally report work) over CPU-bound drvs only; report fetch count/estimated download separately.

oleks referenced this issue from a commit

2026-07-08 22:08:19 +03:00

estimate: exclude fixed-output fetches from parallelism, surface fetch stats (#21)

oleks referenced this issue from a commit

2026-07-08 22:15:30 +03:00

cli: wire fetch stats, --assume-cache, --default-min, calibrate (#20/#21/#22/#23)

oleks commented

2026-07-08 22:45:01 +03:00

peak_parallelism/avg_parallelism are now CPU-bound (fixed-output fetches excluded but still gate dependents); added Estimate fields fetch_count/fetch_min/cpu_bound_count, a peak_concurrency(..., include=...) param, report line "fixed-output fetches : N (M min, network-bound; excluded from parallelism)" and JSON fields. Verified on emmett: peak dropped 5727 -> 1458.

`peak_parallelism`/`avg_parallelism` are now CPU-bound (fixed-output fetches excluded but still gate dependents); added Estimate fields `fetch_count`/`fetch_min`/`cpu_bound_count`, a `peak_concurrency(..., include=...)` param, report line "fixed-output fetches : N (M min, network-bound; excluded from parallelism)" and JSON fields. Verified on emmett: peak dropped 5727 -> 1458.

oleks closed this issue

2026-07-08 22:45:05 +03:00

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Reference: oleks/nix-estimator#21