kaivalnp commented on PR #15341: URL: https://github.com/apache/lucene/pull/15341#issuecomment-3427956084
> I wasn't aligning the output inside [this merge function](https://github.com/apache/lucene/blob/eb27b14eaa09c53496a50c5944160b4989910882/lucene/core/src/java/org/apache/lucene/codecs/lucene99/Lucene99FlatVectorsWriter.java#L252-L253) Hmm this did not help for some reason (merge time increased).. `main` (4-byte-alignment) ``` recall latency(ms) netCPU avgCpuCount nDoc topK fanout maxConn beamWidth quantized visited index(s) index_docs/s force_merge(s) num_segments index_size(MB) vec_disk(MB) vec_RAM(MB) indexType 0.891 1.895 1.887 0.996 1000000 100 50 32 250 no 5408 72.35 13822.46 101.30 1 3014.54 2929.688 2929.688 HNSW ``` This PR (64-byte-alignment) ``` recall latency(ms) netCPU avgCpuCount nDoc topK fanout maxConn beamWidth quantized visited index(s) index_docs/s force_merge(s) num_segments index_size(MB) vec_disk(MB) vec_RAM(MB) indexType 0.893 1.868 1.860 0.996 1000000 100 50 32 250 no 5426 69.55 14378.97 127.48 1 3015.40 2929.688 2929.688 HNSW ``` I'll still add a commit + revert, so people can see what I tried, and comment if I'm missing something! --- > Is the alignment also (or maybe less) important for the quantized cases? I think alignment is less important for quantized vectors (which are stored as byte vectors on disk) -- because none of the JMH benchmarks show non-trivial variation with padding? (see `VectorScorerBenchmark.binaryDotProductMemSeg`) > Your results above are for `float32` vectors? Yeah, those benchmarks^ are for float vectors > Maybe at least `luceneutil` could somehow warn if vectors are unaligned during its perf testing? I added some print statements to complain if non-64-byte-aligned addresses were used (`MemorySegment#address % 64 == 0`) -- and it complained in (only) baseline benchmarks.. Not committing because it may not be needed after this PR? -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
