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zstdmt cli and API allow selection of section sizes

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By default, section sizes are 4x window size.
This new setting allow manual selection of section sizes.
The larger they are, the (slightly) better the compression ratio,
but also the higher the memory allocation cost,
and eventually the lesser the nb of possible threads,
since each section is compressed by a single thread.

It also introduces a prototype to set generic parameters,
ZSTDMT_setMTCtxParameter()

The idea is that it's possible to add enums
to extend the list of parameters that can be set this way.
This is more long-term oriented than a fixed-size struct.
Consider it as a test.
This commit is contained in:
Yann Collet
2017-01-24 17:02:26 -08:00
parent 3488a4a473
commit 512cbe8c10
5 changed files with 67 additions and 13 deletions
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2
programs/zstdcli.c
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@ -118,6 +118,7 @@ static int usage_advanced(const char* programName)
DISPLAY( "--[no-]check : integrity check (default:enabled) \n");
#ifdef ZSTD_MULTITHREAD
DISPLAY( " -T# : use # threads for compression (default:1) \n");
DISPLAY( " -B# : select size of independent sections (default:0==automatic) \n");
#endif
#endif
#ifndef ZSTD_NODECOMPRESS
@ -625,6 +626,7 @@ int main(int argCount, const char* argv[])
if (operation==zom_compress) {
#ifndef ZSTD_NOCOMPRESS
FIO_setNbThreads(nbThreads);
FIO_setBlockSize((U32)blockSize);
if ((filenameIdx==1) && outFileName)
operationResult = FIO_compressFilename(outFileName, filenameTable[0], dictFileName, cLevel, &compressionParams);
else