mirror of https://github.com/golang/go.git
1fb4e4de26
This makes compress/flate's version of Snappy diverge from the upstream golang/snappy version, but the latter has a goal of matching C++ snappy output byte-for-byte. Both C++ and the asm version of golang/snappy can use a smaller N for the O(N) zero-initialization of the hash table when the input is small, even if the pure Go golang/snappy algorithm cannot: "var table [tableSize]uint16" zeroes all tableSize elements. For this package, we don't have the match-C++-snappy goal, so we can use a different (constant) hash table size. This is a small win, in terms of throughput and output size, but it also enables us to re-use the (constant size) hash table between encodeBestSpeed calls, avoiding the cost of zero-initializing the hash table altogether. This will be implemented in follow-up commits. This package's benchmarks: name old speed new speed delta EncodeDigitsSpeed1e4-8 72.8MB/s ± 1% 73.5MB/s ± 1% +0.86% (p=0.000 n=10+10) EncodeDigitsSpeed1e5-8 77.5MB/s ± 1% 78.0MB/s ± 0% +0.69% (p=0.000 n=10+10) EncodeDigitsSpeed1e6-8 82.0MB/s ± 1% 82.7MB/s ± 1% +0.85% (p=0.000 n=10+9) EncodeTwainSpeed1e4-8 65.1MB/s ± 1% 65.6MB/s ± 0% +0.78% (p=0.000 n=10+9) EncodeTwainSpeed1e5-8 80.0MB/s ± 0% 80.6MB/s ± 1% +0.66% (p=0.000 n=9+10) EncodeTwainSpeed1e6-8 81.6MB/s ± 1% 82.1MB/s ± 1% +0.55% (p=0.017 n=10+10) Input size in bytes, output size (and time taken) before and after on some larger files: 1073741824 57269781 ( 3183ms) 57269781 ( 3177ms) adresser.001 1000000000 391052000 ( 11071ms) 391051996 ( 11067ms) enwik9 1911399616 378679516 ( 13450ms) 378679514 ( 13079ms) gob-stream 8558382592 3972329193 ( 99962ms) 3972329193 ( 91290ms) rawstudio-mint14.tar 200000000 200015265 ( 776ms) 200015265 ( 774ms) sharnd.out Thanks to Klaus Post for the original suggestion on cl/21021. Change-Id: Ia4c63a8d1b92c67e1765ec5c3c8c69d289d9a6ce Reviewed-on: https://go-review.googlesource.com/22604 Reviewed-by: Russ Cox <rsc@golang.org> |
||
|---|---|---|
| .. | ||
| bzip2 | ||
| flate | ||
| gzip | ||
| lzw | ||
| testdata | ||
| zlib | ||