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optimization: bail out faster in presence of incompressible data

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This commit is contained in:
Yann Collet
2024-02-26 13:27:59 -08:00
parent ef82b214ad
commit 86db60752d
1 changed files with 4 additions and 1 deletions
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lib/compress/zstd_compress_superblock.c
+4 -1
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@@ -521,6 +521,9 @@ static size_t ZSTD_compressSubBlock_multi(const seqStore_t* seqStorePtr,
DEBUGLOG(5, "estimated fullblock size=%u bytes ; avgLitCost=%.2f ; avgSeqCost=%.2f ; targetCBlockSize=%u, nbSubBlocks=%u ; avgBlockBudget=%.0f bytes", DEBUGLOG(5, "estimated fullblock size=%u bytes ; avgLitCost=%.2f ; avgSeqCost=%.2f ; targetCBlockSize=%u, nbSubBlocks=%u ; avgBlockBudget=%.0f bytes",
(unsigned)ebs.estBlockSize, (double)avgLitCost/BYTESCALE, (double)avgSeqCost/BYTESCALE, (unsigned)ebs.estBlockSize, (double)avgLitCost/BYTESCALE, (double)avgSeqCost/BYTESCALE,
(unsigned)targetCBlockSize, (unsigned)nbSubBlocks, (double)avgBlockBudget/BYTESCALE); (unsigned)targetCBlockSize, (unsigned)nbSubBlocks, (double)avgBlockBudget/BYTESCALE);
/* simplification: if estimates states that the full superblock doesn't compress, just bail out immediately
* this will result in the production of a single uncompressed block covering @srcSize.*/
if (ebs.estBlockSize > srcSize) return 0;
/* compress and write sub-blocks */ /* compress and write sub-blocks */
for (n=0; n+1 < nbSubBlocks; n++) { for (n=0; n+1 < nbSubBlocks; n++) {
@@ -568,7 +571,7 @@ static size_t ZSTD_compressSubBlock_multi(const seqStore_t* seqStorePtr,
sp += seqCount; sp += seqCount;
blockBudgetSupp = 0; blockBudgetSupp = 0;
} } } }
/* otherwise : do not compress yet, coalesce current block with next one */ /* otherwise : do not compress yet, coalesce current sub-block with following one */
} }
} /* if (nbSeqs > 0) */ } /* if (nbSeqs > 0) */