jpountz commented on code in PR #13636: URL: https://github.com/apache/lucene/pull/13636#discussion_r1712554332
########## lucene/core/src/java21/org/apache/lucene/internal/vectorization/MemorySegmentPostingDecodingUtil.java: ########## @@ -0,0 +1,109 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. + * The ASF licenses this file to You under the Apache License, Version 2.0 + * (the "License"); you may not use this file except in compliance with + * the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ +package org.apache.lucene.internal.vectorization; + +import java.io.IOException; +import java.lang.foreign.MemorySegment; +import java.nio.ByteOrder; +import jdk.incubator.vector.LongVector; +import jdk.incubator.vector.VectorOperators; +import jdk.incubator.vector.VectorSpecies; +import org.apache.lucene.store.IndexInput; + +final class MemorySegmentPostingDecodingUtil extends PostingDecodingUtil { + + private static final VectorSpecies<Long> LONG_SPECIES = + PanamaVectorConstants.PRERERRED_LONG_SPECIES; + + private final IndexInput in; + private final MemorySegment memorySegment; + + MemorySegmentPostingDecodingUtil(IndexInput in, MemorySegment memorySegment) { + this.in = in; + this.memorySegment = memorySegment; + } + + @Override + public void readLongs(int count, long[] b) throws IOException { + if (count < LONG_SPECIES.length()) { + in.readLongs(b, 0, count); + } else { + long offset = in.getFilePointer(); + long endOffset = offset + count * Long.BYTES; + int loopBound = LONG_SPECIES.loopBound(count - 1); + for (int i = 0; + i < loopBound; + i += LONG_SPECIES.length(), offset += LONG_SPECIES.length() * Long.BYTES) { + LongVector.fromMemorySegment(LONG_SPECIES, memorySegment, offset, ByteOrder.LITTLE_ENDIAN) Review Comment: This method is only used when decoding 8 or 16 bits per value. I am not sure why, but the micro benchmark sees a small but consistent speedup by copying memory this way rather than using readLongs. If you don't like it, I can remove it. -- 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: issues-unsubscr...@lucene.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: issues-unsubscr...@lucene.apache.org For additional commands, e-mail: issues-h...@lucene.apache.org
