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Introducing the vector api. 1s faster on 4 core i7 (#506)

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Co-authored-by: Ian Preston <ianopolous@protonmail.com>
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Dr Ian Preston 2024-01-20 19:09:40 +00:00 committed by GitHub
parent 114ba76d20
commit 062f2bbecf
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2 changed files with 50 additions and 54 deletions
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2
calculate_average_ianopolousfast.sh
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@ -15,5 +15,5 @@
# limitations under the License.
#
JAVA_OPTS="--enable-preview"
JAVA_OPTS="--enable-preview --add-modules=jdk.incubator.vector"
java $JAVA_OPTS --class-path target/average-1.0.0-SNAPSHOT.jar dev.morling.onebrc.CalculateAverage_ianopolousfast

102
src/main/java/dev/morling/onebrc/CalculateAverage_ianopolousfast.java
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@ -15,6 +15,10 @@
*/
package dev.morling.onebrc;
import jdk.incubator.vector.ByteVector;
import jdk.incubator.vector.VectorOperators;
import jdk.incubator.vector.VectorSpecies;
import java.lang.foreign.Arena;
import java.lang.foreign.MemorySegment;
import java.nio.ByteOrder;
@ -30,19 +34,23 @@ import static java.lang.foreign.ValueLayout.*;
/* A fast implementation with no unsafe.
* Features:
* * memory mapped file using preview Arena FFI
* * semicolon finding using incubator vector api
* * read chunks in parallel
* * minimise allocation
* * no unsafe
*
* Timings on 4 core i7-7500U CPU @ 2.70GHz:
* average_baseline: 4m48s
* ianopolous: 16s
* ianopolous: 15s
*/
public class CalculateAverage_ianopolousfast {
public static final int MAX_LINE_LENGTH = 107;
public static final int MAX_STATIONS = 1 << 14;
private static final OfLong LONG_LAYOUT = JAVA_LONG_UNALIGNED.withOrder(ByteOrder.BIG_ENDIAN);
private static final VectorSpecies<Byte> BYTE_SPECIES = ByteVector.SPECIES_PREFERRED.length() >= 32
? ByteVector.SPECIES_256
: ByteVector.SPECIES_128;
public static void main(String[] args) throws Exception {
Arena arena = Arena.global();
@ -165,58 +173,40 @@ public class CalculateAverage_ianopolousfast {
}
}
public static long hasSemicolon(long d) {
// from Hacker's Delight page 92
d = d ^ 0x3b3b3b3b3b3b3b3bL;
long y = (d & 0x7f7f7f7f7f7f7f7fL) + 0x7f7f7f7f7f7f7f7fL;
return ~(y | d | 0x7f7f7f7f7f7f7f7fL);
}
public static int getSemicolonIndex(long y) {
// from Hacker's Delight page 92
return Long.numberOfLeadingZeros(y) >> 3;
}
static long maskHighBytes(long d, int nbytes) {
return d & (-1L << ((8 - nbytes) * 8));
}
public static Stat parseStation(long lineStart, MemorySegment buffer, List<List<Stat>> stations) {
// find semicolon and update hash as we go, reading a long at a time
long d = buffer.get(LONG_LAYOUT, lineStart);
long hasSemi = hasSemicolon(d);
if (hasSemi != 0) {
int semiIndex = getSemicolonIndex(hasSemi);
d = maskHighBytes(d, semiIndex);
return dedupeStation8(lineStart, lineStart + semiIndex, d, d, buffer, stations);
}
long first8 = d;
long hash = d;
ByteVector line = ByteVector.fromMemorySegment(BYTE_SPECIES, buffer, lineStart, ByteOrder.nativeOrder());
int keySize = line.compare(VectorOperators.EQ, ';').firstTrue();
d = buffer.get(LONG_LAYOUT, lineStart + 8);
hasSemi = hasSemicolon(d);
if (hasSemi != 0) {
int semiIndex = getSemicolonIndex(hasSemi);
if (semiIndex == 0)
return dedupeStation8(lineStart, lineStart + 8, first8, first8, buffer, stations);
d = maskHighBytes(d, semiIndex);
return dedupeStation16(lineStart, lineStart + 8 + semiIndex, first8 ^ d, first8, d, buffer, stations);
if (keySize == BYTE_SPECIES.vectorByteSize()) {
while (buffer.get(JAVA_BYTE, lineStart + keySize) != ';') {
keySize++;
}
long first8 = buffer.get(LONG_LAYOUT, lineStart);
if (keySize < 8)
return dedupeStation8(lineStart, lineStart + keySize, first8, first8, buffer, stations);
long second8 = buffer.get(LONG_LAYOUT, lineStart + 8);
if (keySize < 16)
return dedupeStation16(lineStart, lineStart + keySize, first8 ^ second8, first8, second8, buffer, stations);
long hash = first8 ^ second8; // todo include other bytes
return dedupeStation(lineStart, lineStart + keySize, hash, first8, second8, buffer, stations);
}
int index = 8;
long second8 = d;
while (hasSemi == 0) {
hash = hash ^ d;
index += 8;
d = buffer.get(LONG_LAYOUT, lineStart + index);
hasSemi = hasSemicolon(d);
long first8 = buffer.get(LONG_LAYOUT, lineStart);
if (keySize <= 8) {
first8 = maskHighBytes(first8, keySize & 0x07);
return dedupeStation8(lineStart, lineStart + keySize, first8, first8, buffer, stations);
}
int semiIndex = getSemicolonIndex(hasSemi);
d = maskHighBytes(d, semiIndex);
if (semiIndex > 0) {
hash = hash ^ d;
long second8 = buffer.get(LONG_LAYOUT, lineStart + 8);
if (keySize < 16) {
second8 = maskHighBytes(second8, keySize & 0x07);
return dedupeStation16(lineStart, lineStart + keySize, first8 ^ second8, first8, second8, buffer, stations);
}
return dedupeStation(lineStart, lineStart + index + semiIndex, hash, first8, second8, buffer, stations);
long hash = first8 ^ second8; // todo include later bytes
return dedupeStation(lineStart, lineStart + keySize, hash, first8, second8, buffer, stations);
}
public static int getDot(long d) {
@ -266,24 +256,30 @@ public class CalculateAverage_ianopolousfast {
for (int i = 0; i < MAX_STATIONS; i++)
stations.add(null);
// Handle reading the very last line in the file
// this allows us to not worry about reading a long beyond the end
// Handle reading the very last few lines in the file
// this allows us to not worry about reading beyond the end
// in the inner loop (reducing branches)
// We only need to read one because the min record size is 6 bytes
// so 2nd last record must be > 8 from end
// We need at least the vector lane size bytes back
if (endByte == buffer.byteSize()) {
endByte -= 2; // skip final new line
while (endByte > 0 && buffer.get(JAVA_BYTE, endByte) != '\n')
endByte -= 1; // skip final new line
// reverse at least vector lane width
while (endByte > 0 && buffer.byteSize() - endByte < BYTE_SPECIES.vectorByteSize()) {
endByte--;
while (endByte > 0 && buffer.get(JAVA_BYTE, endByte) != '\n')
endByte--;
}
if (endByte > 0)
endByte++;
// copy into a 8n sized buffer to avoid reading off end
MemorySegment end = Arena.global().allocate(MAX_LINE_LENGTH + 4);
// copy into a larger buffer to avoid reading off end
MemorySegment end = Arena.global().allocate(MAX_LINE_LENGTH + BYTE_SPECIES.vectorByteSize());
for (long i = endByte; i < buffer.byteSize(); i++)
end.set(JAVA_BYTE, i - endByte, buffer.get(JAVA_BYTE, i));
Stat station = parseStation(0, end, stations);
processTemperature(station.name.length + 1, end, station);
int index = 0;
while (endByte + index < buffer.byteSize()) {
Stat station = parseStation(index, end, stations);
index = (int) processTemperature(index + station.name.length + 1, end, station);
}
}
while (startByte < endByte) {