shell-softnet-stat-cpu-hotplug-rollover-accounting
Done. Here's what I delivered.
~/SOLUTION.md — the full diagnosis + fix + verification report (905 lines).~/softnet-meter.sh — the working, self-contained bash tool (589 lines, executable).The report embeds the tool verbatim; I extracted the embedded copy and confirmed it is byte-identical to the tested script and passes its self-test.
%08x. Naive new - old goes negative/inflated. Correct delta is (new-old) mod 2^32; a modular delta ≥ 2^31 is a reset, not a wrap./proc/net/softnet_stat has no CPU id, only positional lines. A line-count change can silently remap an index. The meter re-baselines on any topology change and marks rows reused/hotplugged/removed with partial:true.processed, dropped, time_squeeze) are stable; this host reports 15 columns. The rest are named from a configurable map, unknown → colN, and non-hex rows are skipped.awks/frame (1.7 s), inflating the measured interval. Fixed with integer-microsecond timestamps and precomputed names → ~0.08 s/sample and true --interval tracking.selftest: all pass (rollover 512 from 0xffffff00→0x00000100, reset suppression, hotplug, 3/6/15-column parsing)./proc samples 1.04 s apart (topology_change=false, zero negative deltas).jq/python3; root-object brace bug caught and fixed.# Evidence - Problem class: shell-softnet-stat-cpu-hotplug-rollover-accounting - Model: openrouter/deepseek/deepseek-v4.1-flash - Solved: 2026-09-17T10:14:48.211Z - Verification: solution produced by pi in sandbox; see signatures.json
{"description": "Build a per-CPU network softirq drop/backlog meter that samples /proc/net/softnet_stat on an interval and reports exact cumulative and per-second counters. It must survive the 32-bit field wraparound (a drop counter can wrap between samples and must never yield a negative or inflated delta), CPUs appearing or disappearing mid-run (CPU hotplug changes both line count and CPU numbering), and column-layout drift across kernel versions where the documented column order (processed, dropped, time_squeeze, cpu_collision, received_rps, flow_limit_count) differs. Emit a stable JSON snapshot per CPU plus a documented partial result when a CPU index is reused or its counters reset, and a self-test mode with synthetic rollover and hotplug traces.", "environment": "bash", "language": "shell", "model": "openrouter/deepseek/deepseek-v4.1-flash", "problem_class": "shell-softnet-stat-cpu-hotplug-rollover-accounting", "provider": "openrouter", "solved_at": "2026-09-17T10:14:48.212Z", "version": "5.2"}Done. Here's what I delivered.
~/SOLUTION.md — the full diagnosis + fix + verification report (905 lines).~/softnet-meter.sh — the working, self-contained bash tool (589 lines, executable).The report embeds the tool verbatim; I extracted the embedded copy and confirmed it is byte-identical to the tested script and passes its self-test.
%08x. Naive new - old goes negative/inflated. Correct delta is (new-old) mod 2^32; a modular delta ≥ 2^31 is a reset, not a wrap./proc/net/softnet_stat has no CPU id, only positional lines. A line-count change can silently remap an index. The meter re-baselines on any topology change and marks rows reused/hotplugged/removed with partial:true.processed, dropped, time_squeeze) are stable; this host reports 15 columns. The rest are named from a configurable map, unknown → colN, and non-hex rows are skipped.awks/frame (1.7 s), inflating the measured interval. Fixed with integer-microsecond timestamps and precomputed names → ~0.08 s/sample and true --interval tracking.selftest: all pass (rollover 512 from 0xffffff00→0x00000100, reset suppression, hotplug, 3/6/15-column parsing)./proc samples 1.04 s apart (topology_change=false, zero negative deltas).jq/python3; root-object brace bug caught and fixed.# Evidence - Problem class: shell-softnet-stat-cpu-hotplug-rollover-accounting - Model: openrouter/deepseek/deepseek-v4.1-flash - Solved: 2026-09-17T10:14:48.211Z - Verification: solution produced by pi in sandbox; see signatures.json
{"description": "Build a per-CPU network softirq drop/backlog meter that samples /proc/net/softnet_stat on an interval and reports exact cumulative and per-second counters. It must survive the 32-bit field wraparound (a drop counter can wrap between samples and must never yield a negative or inflated delta), CPUs appearing or disappearing mid-run (CPU hotplug changes both line count and CPU numbering), and column-layout drift across kernel versions where the documented column order (processed, dropped, time_squeeze, cpu_collision, received_rps, flow_limit_count) differs. Emit a stable JSON snapshot per CPU plus a documented partial result when a CPU index is reused or its counters reset, and a self-test mode with synthetic rollover and hotplug traces.", "environment": "bash", "language": "shell", "model": "openrouter/deepseek/deepseek-v4.1-flash", "problem_class": "shell-softnet-stat-cpu-hotplug-rollover-accounting", "provider": "openrouter", "solved_at": "2026-09-17T10:14:48.212Z", "version": "5.2"}