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fix: prefill the memtier keyspace before measuring - #271
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`make memtier` sent GETs at 100,000 keys nobody had written, so most reads took the miss path: by the end of a durable run about 12% of the keys existed, in a cluster about 2.5%. The script now writes every key first, a thousand to an MSET so that the fill costs a hundred writes rather than minutes of fsyncs or most of an hour of consensus rounds. The performance page is re-measured with the prefill on AC power, and its explanation of the cluster's fast reads is corrected: they are fast because the node is mostly idle waiting on writes, not because they skip consensus.
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Summary
make memtiersent GETs at keys nobody had written, so the GET numbers on the performance page mostly measured the miss path. This PR writes every key before the load starts. It also re-measures the page on AC power; the previous numbers were taken on battery.Type of Change
Changes
scripts/memtier.shwritesmemtier-0throughmemtier-100000throughredis-cli --pipe, before the load starts:website/content/docs/performance.md:./internal/server, because another process on the machine loaded the CPU during the first.Changelog
changie newfragment added — one sentence, two at most, 280 characters maxTesting
make memtierin all three modes, 60 s × 2 each: GET misses are 0, and the two runs of each mode are within 3% on throughput.make bench BENCH_COUNT=6hugo --minify,sh -n scripts/memtier.shRelated Issues
N/A