Improve ByteBufUtil#lastIndexOf
#13942
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jchrys
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Benchmark result on below env shows max 83% performance boost. |
jchrys
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| for (int i = 0; i < longCount; i++) { | ||
| // use the faster available getLong | ||
| final long word = useLE? buffer._getLongLE(offset - Long.BYTES) | ||
| : buffer._getLong(offset - Long.BYTES); |
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While searching backward, we need to check the last occurrence of the needle in the long batch, which means basically working with the opposite endianness. I don't see any mention about it (in a comment too)
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@franz1981
I added the comment.
if (result != 0) {
// used the oppoiste endianness since we are looking for the last index.
return offset - 1 - SWARUtil.getIndex(result, !isNative);
}
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| private static int unrolledLastIndexOf(final AbstractByteBuf buffer, final int fromIndex, final int byteCount, |
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Did you compare this unrolledLastIndexOf to calling linearLastIndexOf with adjusted range?
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Previous research has shown that manually unrolled loops improves performance for size=7 benchmark case(#10737 (comment)).
I will add an updated comparison.
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Manual unrolling results in better performance compared to a linear approach. (size > 1)
1X10X2, Intel(R) Xeon(R) Silver 4210 CPU @ 2.20GHz, openjdk 17.0.8 2023-07-18, Ubuntu 22.04.3 LTS, tuend network low-latency, no turbo boost.
benchmark
linear benchmark source code
manual unroll benchmark source code
Motivation: The performance of `#lastIndexOf` could be enhanced by applying SWAR. Modification: Utilized `SWARUtil` for byte search. Result: Enhanced performance.
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Motivation: The performance of `#lastIndexOf` could be enhanced by applying SWAR. Modification: Utilized `SWARUtil` for byte search. Result: Enhanced performance.
Motivation:
The performance of
#lastIndexOfcould be enhanced by applying SWAR.Modification:
Utilized
SWARUtilfor byte search.Result:
Enhanced performance.