From aea3f640ea59d91f7ca9b193acfcc3e26740318b Mon Sep 17 00:00:00 2001 From: eunhhu Date: Sun, 27 Sep 2026 14:46:31 +0100 Subject: Give a compacted file the zeros of its whole cycle (085) Commits grew the tree store's tail 256 KiB at a time, each growth a sync that also committed the ext4 journal for the new size and blocks. A file installed by compaction now carries written zeros up to where the next compaction will come (4 x live + slack, plus a commit's margin), capped at the size of the file it replaces, so a store never takes more space than before and shrinks when its live data does. The cycle's commits then only overwrite blocks the file has. Store commits: 317.5 -> 385.5 a second, ext4 journal commits 109 -> 45 for 4,000 commits; durable app posts +5.3%, their p99 the same within this SD card's noise. The new cycles test keeps sizes still between compactions once the live data is whole, and shows the file shrinking with it. --- .../2026-09-27-journal-ext4-linux-aarch64.jsonl | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) create mode 100644 research/experiments/013-parallel-syncs/2026-09-27-journal-ext4-linux-aarch64.jsonl (limited to 'research/experiments/013-parallel-syncs/2026-09-27-journal-ext4-linux-aarch64.jsonl') diff --git a/research/experiments/013-parallel-syncs/2026-09-27-journal-ext4-linux-aarch64.jsonl b/research/experiments/013-parallel-syncs/2026-09-27-journal-ext4-linux-aarch64.jsonl new file mode 100644 index 0000000..0c14f32 --- /dev/null +++ b/research/experiments/013-parallel-syncs/2026-09-27-journal-ext4-linux-aarch64.jsonl @@ -0,0 +1,20 @@ +{"round": 0, "store": "as it is", "commits_per_second": 411, "p50_ms": 1.27, "p90_ms": 3.96, "p99_ms": 25.68, "journal_commits": 52} +{"round": 0, "store": "no compaction", "commits_per_second": 449, "p50_ms": 1.27, "p90_ms": 3.99, "p99_ms": 23.52, "journal_commits": 46} +{"round": 0, "store": "no compaction, no growth", "commits_per_second": 519, "p50_ms": 1.27, "p90_ms": 3.14, "p99_ms": 5.55, "journal_commits": 4} +{"round": 0, "store": "tail grown as commits need it", "commits_per_second": 346, "p50_ms": 1.29, "p90_ms": 4.01, "p99_ms": 26.25, "journal_commits": 117} +{"round": 1, "store": "no compaction", "commits_per_second": 360, "p50_ms": 1.28, "p90_ms": 3.94, "p99_ms": 32.97, "journal_commits": 42} +{"round": 1, "store": "no compaction, no growth", "commits_per_second": 413, "p50_ms": 1.28, "p90_ms": 4.07, "p99_ms": 26.58, "journal_commits": 18} +{"round": 1, "store": "tail grown as commits need it", "commits_per_second": 270, "p50_ms": 1.28, "p90_ms": 4.34, "p99_ms": 50.93, "journal_commits": 110} +{"round": 1, "store": "as it is", "commits_per_second": 382, "p50_ms": 1.25, "p90_ms": 3.99, "p99_ms": 26.49, "journal_commits": 40} +{"round": 2, "store": "no compaction, no growth", "commits_per_second": 463, "p50_ms": 1.27, "p90_ms": 3.96, "p99_ms": 22.29, "journal_commits": 21} +{"round": 2, "store": "tail grown as commits need it", "commits_per_second": 289, "p50_ms": 1.27, "p90_ms": 3.99, "p99_ms": 32.56, "journal_commits": 104} +{"round": 2, "store": "as it is", "commits_per_second": 356, "p50_ms": 1.27, "p90_ms": 3.93, "p99_ms": 37.21, "journal_commits": 46} +{"round": 2, "store": "no compaction", "commits_per_second": 393, "p50_ms": 1.26, "p90_ms": 4.08, "p99_ms": 32.96, "journal_commits": 41} +{"round": 3, "store": "tail grown as commits need it", "commits_per_second": 406, "p50_ms": 1.27, "p90_ms": 4.12, "p99_ms": 26.45, "journal_commits": 108} +{"round": 3, "store": "as it is", "commits_per_second": 389, "p50_ms": 1.27, "p90_ms": 4.06, "p99_ms": 27.31, "journal_commits": 44} +{"round": 3, "store": "no compaction", "commits_per_second": 392, "p50_ms": 1.26, "p90_ms": 3.4, "p99_ms": 52.8, "journal_commits": 44} +{"round": 3, "store": "no compaction, no growth", "commits_per_second": 469, "p50_ms": 1.27, "p90_ms": 3.88, "p99_ms": 22.84, "journal_commits": 15} +{"store": "as it is", "commits": 4000, "commits_per_second": 385.5, "p50_ms": 1.27, "p90_ms": 3.975, "p99_ms": 26.9, "journal_commits": 45.0} +{"store": "no compaction", "commits": 4000, "commits_per_second": 392.5, "p50_ms": 1.2650000000000001, "p90_ms": 3.965, "p99_ms": 32.965, "journal_commits": 43.0} +{"store": "no compaction, no growth", "commits": 4000, "commits_per_second": 466.0, "p50_ms": 1.27, "p90_ms": 3.92, "p99_ms": 22.564999999999998, "journal_commits": 16.5} +{"store": "tail grown as commits need it", "commits": 4000, "commits_per_second": 317.5, "p50_ms": 1.275, "p90_ms": 4.0649999999999995, "p99_ms": 29.505000000000003, "journal_commits": 109.0} -- cgit v1.2.3