docs(audits): ReorderBuffer cache behavior static analysis (#1854)#3707
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Static-analysis half of #1854: predicts cache-line residency, branch behavior, and working-set size of BoundedReorderBuffer at 100K, 1M, and 10M items. Compares the BTreeMap-backed buffer with the ring-based alternative already shipped in engine::concurrent_delta::ReorderBuffer (#1734) and lists the perf counters and decision criteria the runtime half must capture.
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…3707) Static-analysis half of #1854: predicts cache-line residency, branch behavior, and working-set size of BoundedReorderBuffer at 100K, 1M, and 10M items. Compares the BTreeMap-backed buffer with the ring-based alternative already shipped in engine::concurrent_delta::ReorderBuffer (#1734) and lists the perf counters and decision criteria the runtime half must capture.
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Summary
docs/audits/reorderbuffer-cache-behavior-static.md(513 lines), the static-analysis half of Add amd64 tarball artifact and guard packaging alternatives #1854.BoundedReorderBuffer<T>at file-list scales of 100K, 1M, and 10M, derived from theBTreeMap<u64, T>shape and the insert/drain cycle incrates/transfer/src/reorder_buffer.rs.BTreeMapform with theVecDeque + indexalternative from Improve CLI binary lookup for tests #1853 and reconciles with the ring-basedengine::concurrent_delta::ReorderBufferalready shipped under Add zlib accessor tests to improve coverage #1734.perf stat,cachegrind,perf c2c, and FlameGraph invocations the runtime half of Add amd64 tarball artifact and guard packaging alternatives #1854 must capture, plus the four decision criteria that justify migrating to the ring form.docs/design/reorderbuffer-metrics-and-bypass.md) for the metrics-counter hooks the runtime side reuses.Headline finding
At the default window of 64 the buffer's working set is bounded by
W * sizeof(T)plus a singleBTreeMapleaf, regardless of file-list length. Saturated working set is roughly 4.8 KiB - L1 resident on every shipping x86_64 and aarch64 part.Ndoes not enter the cache analysis.Test plan
markdownlintclean on the new doc