ZSTD_c_overlapLog constant

int const ZSTD_c_overlapLog

Control the overlap size, as a fraction of window size. The overlap size is an amount of data reloaded from previous job at the beginning of a new job. It helps preserve compression ratio, while each job is compressed in parallel. This value is enforced only when nbWorkers >= 1. Larger values increase compression ratio, but decrease speed. Possible values range from 0 to 9 :

  • 0 means "default" : value will be determined by the library, depending on strategy
  • 1 means "no overlap"
  • 9 means "full overlap", using a full window size. Each intermediate rank increases/decreases load size by a factor 2 : 9: full window; 8: w/2; 7: w/4; 6: w/8; 5:w/16; 4: w/32; 3:w/64; 2:w/128; 1:no overlap; 0:default default value varies between 6 and 9, depending on strategy

Implementation

static const int ZSTD_c_overlapLog = 402;