From b4250489cf558100c863716a7b3c4cf7ef343a89 Mon Sep 17 00:00:00 2001 From: Yann Collet Date: Sun, 13 May 2018 01:53:38 -0700 Subject: [PATCH 1/5] update compression levels for large inputs --- lib/compress/zstd_compress.c | 28 ++++++++++++++-------------- 1 file changed, 14 insertions(+), 14 deletions(-) diff --git a/lib/compress/zstd_compress.c b/lib/compress/zstd_compress.c index 08dc7db28..a979335a1 100644 --- a/lib/compress/zstd_compress.c +++ b/lib/compress/zstd_compress.c @@ -3423,25 +3423,25 @@ static const ZSTD_compressionParameters ZSTD_defaultCParameters[4][ZSTD_MAX_CLEV { 19, 13, 14, 1, 7, 1, ZSTD_fast }, /* level 1 */ { 19, 15, 16, 1, 6, 1, ZSTD_fast }, /* level 2 */ { 20, 16, 17, 1, 5, 8, ZSTD_dfast }, /* level 3 */ - { 20, 17, 18, 1, 5, 8, ZSTD_dfast }, /* level 4 */ - { 20, 17, 18, 2, 5, 16, ZSTD_greedy }, /* level 5 */ - { 21, 17, 19, 2, 5, 16, ZSTD_lazy }, /* level 6 */ - { 21, 18, 19, 3, 5, 16, ZSTD_lazy }, /* level 7 */ - { 21, 18, 20, 3, 5, 16, ZSTD_lazy2 }, /* level 8 */ - { 21, 19, 20, 3, 5, 16, ZSTD_lazy2 }, /* level 9 */ - { 21, 19, 21, 4, 5, 16, ZSTD_lazy2 }, /* level 10 */ - { 22, 20, 22, 4, 5, 16, ZSTD_lazy2 }, /* level 11 */ + { 20, 18, 18, 1, 5, 8, ZSTD_dfast }, /* level 4 */ + { 20, 18, 18, 2, 5, 16, ZSTD_greedy }, /* level 5 */ + { 21, 18, 19, 2, 5, 16, ZSTD_lazy }, /* level 6 */ + { 21, 18, 19, 3, 5, 16, ZSTD_lazy2 }, /* level 7 */ + { 21, 19, 19, 3, 5, 16, ZSTD_lazy2 }, /* level 8 */ + { 21, 19, 20, 4, 5, 16, ZSTD_lazy2 }, /* level 9 */ + { 21, 20, 21, 4, 5, 16, ZSTD_lazy2 }, /* level 10 */ + { 21, 21, 22, 4, 5, 16, ZSTD_lazy2 }, /* level 11 */ { 22, 20, 22, 5, 5, 16, ZSTD_lazy2 }, /* level 12 */ { 22, 21, 22, 4, 5, 32, ZSTD_btlazy2 }, /* level 13 */ { 22, 21, 22, 5, 5, 32, ZSTD_btlazy2 }, /* level 14 */ { 22, 22, 22, 6, 5, 32, ZSTD_btlazy2 }, /* level 15 */ { 22, 21, 22, 4, 5, 48, ZSTD_btopt }, /* level 16 */ - { 23, 22, 22, 4, 4, 48, ZSTD_btopt }, /* level 17 */ - { 23, 22, 22, 5, 3, 64, ZSTD_btopt }, /* level 18 */ - { 23, 23, 22, 7, 3,128, ZSTD_btopt }, /* level 19 */ - { 25, 25, 23, 7, 3,128, ZSTD_btultra }, /* level 20 */ - { 26, 26, 24, 7, 3,256, ZSTD_btultra }, /* level 21 */ - { 27, 27, 25, 9, 3,512, ZSTD_btultra }, /* level 22 */ + { 23, 22, 22, 4, 4, 64, ZSTD_btopt }, /* level 17 */ + { 23, 23, 22, 6, 3,256, ZSTD_btopt }, /* level 18 */ + { 23, 24, 22, 7, 3,256, ZSTD_btultra }, /* level 19 */ + { 25, 25, 23, 7, 3,256, ZSTD_btultra }, /* level 20 */ + { 26, 26, 24, 7, 3,512, ZSTD_btultra }, /* level 21 */ + { 27, 27, 25, 9, 3,999, ZSTD_btultra }, /* level 22 */ }, { /* for srcSize <= 256 KB */ /* W, C, H, S, L, T, strat */ From c9227ee16bfc95ec99aeb4ca8ddf1217f9129482 Mon Sep 17 00:00:00 2001 From: Yann Collet Date: Sun, 13 May 2018 17:15:07 -0700 Subject: [PATCH 2/5] update table for 128 KB blocks --- lib/compress/zstd_compress.c | 30 +++++++++++++++--------------- 1 file changed, 15 insertions(+), 15 deletions(-) diff --git a/lib/compress/zstd_compress.c b/lib/compress/zstd_compress.c index a979335a1..622b069be 100644 --- a/lib/compress/zstd_compress.c +++ b/lib/compress/zstd_compress.c @@ -3471,26 +3471,26 @@ static const ZSTD_compressionParameters ZSTD_defaultCParameters[4][ZSTD_MAX_CLEV }, { /* for srcSize <= 128 KB */ /* W, C, H, S, L, T, strat */ - { 17, 12, 12, 1, 5, 1, ZSTD_fast }, /* level 0 - not used */ + { 17, 12, 12, 1, 5, 1, ZSTD_fast }, /* base for negative levels */ { 17, 12, 13, 1, 6, 1, ZSTD_fast }, /* level 1 */ - { 17, 13, 16, 1, 5, 1, ZSTD_fast }, /* level 2 */ - { 17, 16, 16, 2, 5, 8, ZSTD_dfast }, /* level 3 */ - { 17, 13, 15, 3, 4, 8, ZSTD_greedy }, /* level 4 */ - { 17, 15, 17, 4, 4, 8, ZSTD_greedy }, /* level 5 */ - { 17, 16, 17, 3, 4, 8, ZSTD_lazy }, /* level 6 */ - { 17, 15, 17, 4, 4, 8, ZSTD_lazy2 }, /* level 7 */ + { 17, 13, 15, 1, 5, 1, ZSTD_fast }, /* level 2 */ + { 17, 15, 16, 2, 5, 8, ZSTD_dfast }, /* level 3 */ + { 17, 17, 17, 2, 4, 8, ZSTD_dfast }, /* level 4 */ + { 17, 16, 17, 3, 4, 8, ZSTD_greedy }, /* level 5 */ + { 17, 17, 17, 3, 4, 8, ZSTD_lazy }, /* level 6 */ + { 17, 17, 17, 3, 4, 8, ZSTD_lazy2 }, /* level 7 */ { 17, 17, 17, 4, 4, 8, ZSTD_lazy2 }, /* level 8 */ { 17, 17, 17, 5, 4, 8, ZSTD_lazy2 }, /* level 9 */ { 17, 17, 17, 6, 4, 8, ZSTD_lazy2 }, /* level 10 */ { 17, 17, 17, 7, 4, 8, ZSTD_lazy2 }, /* level 11 */ - { 17, 17, 17, 8, 4, 8, ZSTD_lazy2 }, /* level 12 */ - { 17, 18, 17, 6, 4, 8, ZSTD_btlazy2 }, /* level 13.*/ - { 17, 17, 17, 7, 3, 8, ZSTD_btopt }, /* level 14.*/ - { 17, 17, 17, 7, 3, 16, ZSTD_btopt }, /* level 15.*/ - { 17, 18, 17, 7, 3, 32, ZSTD_btopt }, /* level 16.*/ - { 17, 18, 17, 7, 3, 64, ZSTD_btopt }, /* level 17.*/ - { 17, 18, 17, 7, 3,256, ZSTD_btopt }, /* level 18.*/ - { 17, 18, 17, 8, 3,256, ZSTD_btopt }, /* level 19.*/ + { 17, 18, 17, 6, 4, 16, ZSTD_btlazy2 }, /* level 12 */ + { 17, 18, 17, 8, 4, 16, ZSTD_btlazy2 }, /* level 13.*/ + { 17, 18, 17, 4, 4, 32, ZSTD_btopt }, /* level 14.*/ + { 17, 18, 17, 6, 3, 64, ZSTD_btopt }, /* level 15.*/ + { 17, 18, 17, 7, 3,128, ZSTD_btopt }, /* level 16.*/ + { 17, 18, 17, 7, 3,256, ZSTD_btopt }, /* level 17.*/ + { 17, 18, 17, 8, 3,256, ZSTD_btopt }, /* level 18.*/ + { 17, 18, 17, 8, 3,256, ZSTD_btultra }, /* level 19.*/ { 17, 18, 17, 9, 3,256, ZSTD_btultra }, /* level 20.*/ { 17, 18, 17, 10, 3,256, ZSTD_btultra }, /* level 21.*/ { 17, 18, 17, 11, 3,512, ZSTD_btultra }, /* level 22.*/ From 63eeeaa1dd60022e657c95317bdd15aeae4436d9 Mon Sep 17 00:00:00 2001 From: Yann Collet Date: Wed, 16 May 2018 16:13:37 -0700 Subject: [PATCH 3/5] update table levels for blocks <= 16K also : allow hlog to be slighly larger than windowlog, as it's apparently good for both speed and compression ratio. --- lib/compress/zstd_compress.c | 58 ++++++++++++++++++------------------ 1 file changed, 29 insertions(+), 29 deletions(-) diff --git a/lib/compress/zstd_compress.c b/lib/compress/zstd_compress.c index 622b069be..d4e3462d2 100644 --- a/lib/compress/zstd_compress.c +++ b/lib/compress/zstd_compress.c @@ -743,7 +743,7 @@ ZSTD_compressionParameters ZSTD_adjustCParams_internal(ZSTD_compressionParameter ZSTD_highbit32(tSize-1) + 1; if (cPar.windowLog > srcLog) cPar.windowLog = srcLog; } - if (cPar.hashLog > cPar.windowLog) cPar.hashLog = cPar.windowLog; + if (cPar.hashLog > cPar.windowLog+1) cPar.hashLog = cPar.windowLog+1; { U32 const cycleLog = ZSTD_cycleLog(cPar.chainLog, cPar.strategy); if (cycleLog > cPar.windowLog) cPar.chainLog -= (cycleLog - cPar.windowLog); @@ -3422,11 +3422,11 @@ static const ZSTD_compressionParameters ZSTD_defaultCParameters[4][ZSTD_MAX_CLEV { 19, 12, 13, 1, 6, 1, ZSTD_fast }, /* base for negative levels */ { 19, 13, 14, 1, 7, 1, ZSTD_fast }, /* level 1 */ { 19, 15, 16, 1, 6, 1, ZSTD_fast }, /* level 2 */ - { 20, 16, 17, 1, 5, 8, ZSTD_dfast }, /* level 3 */ - { 20, 18, 18, 1, 5, 8, ZSTD_dfast }, /* level 4 */ - { 20, 18, 18, 2, 5, 16, ZSTD_greedy }, /* level 5 */ - { 21, 18, 19, 2, 5, 16, ZSTD_lazy }, /* level 6 */ - { 21, 18, 19, 3, 5, 16, ZSTD_lazy2 }, /* level 7 */ + { 20, 16, 17, 1, 5, 1, ZSTD_dfast }, /* level 3 */ + { 20, 18, 18, 1, 5, 1, ZSTD_dfast }, /* level 4 */ + { 20, 18, 18, 2, 5, 2, ZSTD_greedy }, /* level 5 */ + { 21, 18, 19, 2, 5, 4, ZSTD_lazy }, /* level 6 */ + { 21, 18, 19, 3, 5, 8, ZSTD_lazy2 }, /* level 7 */ { 21, 19, 19, 3, 5, 16, ZSTD_lazy2 }, /* level 8 */ { 21, 19, 20, 4, 5, 16, ZSTD_lazy2 }, /* level 9 */ { 21, 20, 21, 4, 5, 16, ZSTD_lazy2 }, /* level 10 */ @@ -3447,12 +3447,12 @@ static const ZSTD_compressionParameters ZSTD_defaultCParameters[4][ZSTD_MAX_CLEV /* W, C, H, S, L, T, strat */ { 18, 12, 13, 1, 5, 1, ZSTD_fast }, /* base for negative levels */ { 18, 13, 14, 1, 6, 1, ZSTD_fast }, /* level 1 */ - { 18, 14, 13, 1, 5, 8, ZSTD_dfast }, /* level 2 */ - { 18, 16, 15, 1, 5, 8, ZSTD_dfast }, /* level 3 */ - { 18, 15, 17, 1, 5, 8, ZSTD_greedy }, /* level 4.*/ - { 18, 16, 17, 4, 5, 8, ZSTD_greedy }, /* level 5.*/ - { 18, 16, 17, 3, 5, 8, ZSTD_lazy }, /* level 6.*/ - { 18, 17, 17, 4, 4, 8, ZSTD_lazy }, /* level 7 */ + { 18, 14, 13, 1, 5, 1, ZSTD_dfast }, /* level 2 */ + { 18, 16, 15, 1, 5, 1, ZSTD_dfast }, /* level 3 */ + { 18, 15, 17, 1, 5, 2, ZSTD_greedy }, /* level 4.*/ + { 18, 16, 17, 4, 5, 2, ZSTD_greedy }, /* level 5.*/ + { 18, 16, 17, 3, 5, 4, ZSTD_lazy }, /* level 6.*/ + { 18, 17, 17, 4, 4, 4, ZSTD_lazy }, /* level 7 */ { 18, 17, 17, 4, 4, 8, ZSTD_lazy2 }, /* level 8 */ { 18, 17, 17, 5, 4, 8, ZSTD_lazy2 }, /* level 9 */ { 18, 17, 17, 6, 4, 8, ZSTD_lazy2 }, /* level 10 */ @@ -3474,10 +3474,10 @@ static const ZSTD_compressionParameters ZSTD_defaultCParameters[4][ZSTD_MAX_CLEV { 17, 12, 12, 1, 5, 1, ZSTD_fast }, /* base for negative levels */ { 17, 12, 13, 1, 6, 1, ZSTD_fast }, /* level 1 */ { 17, 13, 15, 1, 5, 1, ZSTD_fast }, /* level 2 */ - { 17, 15, 16, 2, 5, 8, ZSTD_dfast }, /* level 3 */ - { 17, 17, 17, 2, 4, 8, ZSTD_dfast }, /* level 4 */ - { 17, 16, 17, 3, 4, 8, ZSTD_greedy }, /* level 5 */ - { 17, 17, 17, 3, 4, 8, ZSTD_lazy }, /* level 6 */ + { 17, 15, 16, 2, 5, 1, ZSTD_dfast }, /* level 3 */ + { 17, 17, 17, 2, 4, 1, ZSTD_dfast }, /* level 4 */ + { 17, 16, 17, 3, 4, 2, ZSTD_greedy }, /* level 5 */ + { 17, 17, 17, 3, 4, 4, ZSTD_lazy }, /* level 6 */ { 17, 17, 17, 3, 4, 8, ZSTD_lazy2 }, /* level 7 */ { 17, 17, 17, 4, 4, 8, ZSTD_lazy2 }, /* level 8 */ { 17, 17, 17, 5, 4, 8, ZSTD_lazy2 }, /* level 9 */ @@ -3498,25 +3498,25 @@ static const ZSTD_compressionParameters ZSTD_defaultCParameters[4][ZSTD_MAX_CLEV { /* for srcSize <= 16 KB */ /* W, C, H, S, L, T, strat */ { 14, 12, 13, 1, 5, 1, ZSTD_fast }, /* base for negative levels */ - { 14, 14, 14, 1, 6, 1, ZSTD_fast }, /* level 1 */ - { 14, 14, 14, 1, 4, 1, ZSTD_fast }, /* level 2 */ - { 14, 14, 14, 1, 4, 6, ZSTD_dfast }, /* level 3.*/ - { 14, 14, 14, 4, 4, 6, ZSTD_greedy }, /* level 4.*/ - { 14, 14, 14, 3, 4, 6, ZSTD_lazy }, /* level 5.*/ - { 14, 14, 14, 4, 4, 6, ZSTD_lazy2 }, /* level 6 */ - { 14, 14, 14, 5, 4, 6, ZSTD_lazy2 }, /* level 7 */ - { 14, 14, 14, 6, 4, 6, ZSTD_lazy2 }, /* level 8.*/ - { 14, 15, 14, 6, 4, 6, ZSTD_btlazy2 }, /* level 9.*/ - { 14, 15, 14, 3, 3, 6, ZSTD_btopt }, /* level 10.*/ - { 14, 15, 14, 6, 3, 8, ZSTD_btopt }, /* level 11.*/ + { 14, 14, 15, 1, 5, 1, ZSTD_fast }, /* level 1 */ + { 14, 14, 15, 1, 4, 1, ZSTD_fast }, /* level 2 */ + { 14, 14, 14, 2, 4, 1, ZSTD_dfast }, /* level 3.*/ + { 14, 14, 14, 4, 4, 2, ZSTD_greedy }, /* level 4.*/ + { 14, 14, 14, 3, 4, 4, ZSTD_lazy }, /* level 5.*/ + { 14, 14, 14, 4, 4, 8, ZSTD_lazy2 }, /* level 6 */ + { 14, 14, 14, 6, 4, 8, ZSTD_lazy2 }, /* level 7 */ + { 14, 14, 14, 8, 4, 8, ZSTD_lazy2 }, /* level 8.*/ + { 14, 15, 14, 5, 4, 8, ZSTD_btlazy2 }, /* level 9.*/ + { 14, 15, 14, 9, 4, 8, ZSTD_btlazy2 }, /* level 10.*/ + { 14, 15, 14, 3, 4, 12, ZSTD_btopt }, /* level 11.*/ { 14, 15, 14, 6, 3, 16, ZSTD_btopt }, /* level 12.*/ { 14, 15, 14, 6, 3, 24, ZSTD_btopt }, /* level 13.*/ { 14, 15, 15, 6, 3, 48, ZSTD_btopt }, /* level 14.*/ { 14, 15, 15, 6, 3, 64, ZSTD_btopt }, /* level 15.*/ { 14, 15, 15, 6, 3, 96, ZSTD_btopt }, /* level 16.*/ { 14, 15, 15, 6, 3,128, ZSTD_btopt }, /* level 17.*/ - { 14, 15, 15, 6, 3,256, ZSTD_btopt }, /* level 18.*/ - { 14, 15, 15, 7, 3,256, ZSTD_btopt }, /* level 19.*/ + { 14, 15, 15, 7, 3,256, ZSTD_btopt }, /* level 18.*/ + { 14, 15, 15, 6, 3,256, ZSTD_btultra }, /* level 19.*/ { 14, 15, 15, 8, 3,256, ZSTD_btultra }, /* level 20.*/ { 14, 15, 15, 9, 3,256, ZSTD_btultra }, /* level 21.*/ { 14, 15, 15, 10, 3,256, ZSTD_btultra }, /* level 22.*/ From 7cbb8bbbbf4d04b49b23267e461fcb4ac42a0c8f Mon Sep 17 00:00:00 2001 From: Nick Terrell Date: Fri, 18 May 2018 15:25:10 -0700 Subject: [PATCH 4/5] [cover] Small compression ratio improvement The cover algorithm selects one segment per epoch, and it selects the epoch size such that `epochs * segmentSize ~= dictSize`. Selecting less epochs gives the algorithm more candidates to choose from for each segment it selects, and then it will loop back to the first epoch when it hits the last one. The trade off is that now it takes longer to select each segment, since it has to look at more data before making a choice. I benchmarked on the following data sets using this command: ```sh $ZSTD -T0 -3 --train-cover=d=8,steps=256 $DIR -r -o dict && $ZSTD -3 -D dict -rc $DIR | wc -c ``` | Data set | k (approx) | Before | After | % difference | |--------------|------------|----------|----------|--------------| | GitHub | ~1000 | 738138 | 746610 | +1.14% | | hg-changelog | ~90 | 4295156 | 4285336 | -0.23% | | hg-commands | ~500 | 1095580 | 1079814 | -1.44% | | hg-manifest | ~400 | 16559892 | 16504346 | -0.34% | There is some noise in the measurements, since small changes to `k` can have large differences, which is why I'm using `steps=256`, to try to minimize the noise. However, the GitHub data set still has some noise. If I run the GitHub data set on my Mac, which presumably lists directory entries in a different order, so the dictionary builder sees the files in a different order, or I use `steps=1024` I see these results. | Run | Before | After | % difference | |------------|--------|--------|--------------| | steps=1024 | 738138 | 734470 | -0.50% | | MacBook | 738451 | 737132 | -0.18% | Question: Should we expose this as a parameter? I don't think it is necessary. Someone might want to turn it up to exchange a much longer dictionary building time in exchange for a slightly better dictionary. I tested `2`, `4`, and `16`, and `4` got most of the benefit of `16` with a faster running time. --- lib/dictBuilder/cover.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/lib/dictBuilder/cover.c b/lib/dictBuilder/cover.c index 6d473624d..448f71372 100644 --- a/lib/dictBuilder/cover.c +++ b/lib/dictBuilder/cover.c @@ -620,7 +620,7 @@ static size_t COVER_buildDictionary(const COVER_ctx_t *ctx, U32 *freqs, /* Divide the data up into epochs of equal size. * We will select at least one segment from each epoch. */ - const U32 epochs = (U32)(dictBufferCapacity / parameters.k); + const U32 epochs = MAX(1, (U32)(dictBufferCapacity / parameters.k / 4)); const U32 epochSize = (U32)(ctx->suffixSize / epochs); size_t epoch; DISPLAYLEVEL(2, "Breaking content into %u epochs of size %u\n", epochs, From b0b3fb517dba3ff3ed4f4d45652f2ff9cc94c3c6 Mon Sep 17 00:00:00 2001 From: Yann Collet Date: Fri, 18 May 2018 17:17:12 -0700 Subject: [PATCH 5/5] updated compression levels for blocks of 256KB --- lib/compress/zstd_compress.c | 42 ++++++++++++++++++------------------ 1 file changed, 21 insertions(+), 21 deletions(-) diff --git a/lib/compress/zstd_compress.c b/lib/compress/zstd_compress.c index d4e3462d2..faecad40f 100644 --- a/lib/compress/zstd_compress.c +++ b/lib/compress/zstd_compress.c @@ -3447,27 +3447,27 @@ static const ZSTD_compressionParameters ZSTD_defaultCParameters[4][ZSTD_MAX_CLEV /* W, C, H, S, L, T, strat */ { 18, 12, 13, 1, 5, 1, ZSTD_fast }, /* base for negative levels */ { 18, 13, 14, 1, 6, 1, ZSTD_fast }, /* level 1 */ - { 18, 14, 13, 1, 5, 1, ZSTD_dfast }, /* level 2 */ - { 18, 16, 15, 1, 5, 1, ZSTD_dfast }, /* level 3 */ - { 18, 15, 17, 1, 5, 2, ZSTD_greedy }, /* level 4.*/ - { 18, 16, 17, 4, 5, 2, ZSTD_greedy }, /* level 5.*/ - { 18, 16, 17, 3, 5, 4, ZSTD_lazy }, /* level 6.*/ - { 18, 17, 17, 4, 4, 4, ZSTD_lazy }, /* level 7 */ - { 18, 17, 17, 4, 4, 8, ZSTD_lazy2 }, /* level 8 */ - { 18, 17, 17, 5, 4, 8, ZSTD_lazy2 }, /* level 9 */ - { 18, 17, 17, 6, 4, 8, ZSTD_lazy2 }, /* level 10 */ - { 18, 18, 17, 6, 4, 8, ZSTD_lazy2 }, /* level 11.*/ - { 18, 18, 17, 5, 4, 8, ZSTD_btlazy2 }, /* level 12.*/ - { 18, 19, 17, 7, 4, 8, ZSTD_btlazy2 }, /* level 13 */ - { 18, 18, 18, 4, 4, 16, ZSTD_btopt }, /* level 14.*/ - { 18, 18, 18, 4, 3, 16, ZSTD_btopt }, /* level 15.*/ - { 18, 19, 18, 6, 3, 32, ZSTD_btopt }, /* level 16.*/ - { 18, 19, 18, 8, 3, 64, ZSTD_btopt }, /* level 17.*/ - { 18, 19, 18, 9, 3,128, ZSTD_btopt }, /* level 18.*/ - { 18, 19, 18, 10, 3,256, ZSTD_btopt }, /* level 19.*/ - { 18, 19, 18, 11, 3,512, ZSTD_btultra }, /* level 20.*/ - { 18, 19, 18, 12, 3,512, ZSTD_btultra }, /* level 21.*/ - { 18, 19, 18, 13, 3,512, ZSTD_btultra }, /* level 22.*/ + { 18, 14, 14, 1, 5, 1, ZSTD_dfast }, /* level 2 */ + { 18, 16, 16, 1, 4, 1, ZSTD_dfast }, /* level 3 */ + { 18, 16, 17, 2, 5, 2, ZSTD_greedy }, /* level 4.*/ + { 18, 18, 18, 3, 5, 2, ZSTD_greedy }, /* level 5.*/ + { 18, 18, 19, 3, 5, 4, ZSTD_lazy }, /* level 6.*/ + { 18, 18, 19, 4, 4, 4, ZSTD_lazy }, /* level 7 */ + { 18, 18, 19, 4, 4, 8, ZSTD_lazy2 }, /* level 8 */ + { 18, 18, 19, 5, 4, 8, ZSTD_lazy2 }, /* level 9 */ + { 18, 18, 19, 6, 4, 8, ZSTD_lazy2 }, /* level 10 */ + { 18, 18, 19, 5, 4, 16, ZSTD_btlazy2 }, /* level 11.*/ + { 18, 19, 19, 6, 4, 16, ZSTD_btlazy2 }, /* level 12.*/ + { 18, 19, 19, 8, 4, 16, ZSTD_btlazy2 }, /* level 13 */ + { 18, 18, 19, 4, 4, 24, ZSTD_btopt }, /* level 14.*/ + { 18, 18, 19, 4, 3, 24, ZSTD_btopt }, /* level 15.*/ + { 18, 19, 19, 6, 3, 64, ZSTD_btopt }, /* level 16.*/ + { 18, 19, 19, 8, 3,128, ZSTD_btopt }, /* level 17.*/ + { 18, 19, 19, 10, 3,256, ZSTD_btopt }, /* level 18.*/ + { 18, 19, 19, 10, 3,256, ZSTD_btultra }, /* level 19.*/ + { 18, 19, 19, 11, 3,512, ZSTD_btultra }, /* level 20.*/ + { 18, 19, 19, 12, 3,512, ZSTD_btultra }, /* level 21.*/ + { 18, 19, 19, 13, 3,999, ZSTD_btultra }, /* level 22.*/ }, { /* for srcSize <= 128 KB */ /* W, C, H, S, L, T, strat */