--adapt[=min=#,max=#]
zstd will dynamically adapt compression level to perceived I/O conditions. Compression level adaptation can be observed live by using command -v. Adaptation can be constrained between supplied
min and max levels. The feature works when combined with multi-threading and --long mode. It does not work with --single-thread. It sets window size to 8 MB by default (can be changed manu‐
ally, see wlog). Due to the chaotic nature of dynamic adaptation, compressed result is not reproducible.
