История изменений
Исправление greenman, (текущая версия) :
Помнится, ещё лет 10 назад в btrfs были эвристики, которые сами нормально решали, что жать, а что не жать.
Есть такое мнение об этом:
The «automatic compression detector» of btrfs is a total bullshit.
It just kills compression performance, almost at random.
The «detector» itself is very poorly done, and wrongly believes it can determine compressibility from some trivial-to-grab statistics.
That couldn’t be more wrong.Besides, and that’s the funny point, modern compressors such as LZ4, LZO and Zstandard have built-in skippers which know when things are not compressible and just intelligently skip past the bad section.
The only case for this external detector is zlib, but it’s wrongly applied to all !Try it on
zstd, it skips the incompressible parts at > 1 GB / s !
That’s faster than the processing of this «compressibility detector».Bottom line : on btrfs, always use «force compress» on any partition with anything else than zlib.
Исходная версия greenman, :
Помнится, ещё лет 10 назад в btrfs были эвристики, которые сами нормально решали, что жать, а что не жать.
Есть такое мнение об этом:
The «automatic compression detector» of btrfs is a total bullshit.
It just kills compression performance, almost at random.
The «detector» itself is very poorly done, and wrongly believes it can determine compressibility from some trivial-to-grab statistics.
That couldn’t be more wrong.Besides, and that’s the funny point, modern compressors such as LZ4, LZO and Zstandard have built-in skippers which know when things are not compressible and just intelligently skip past the bad section.
The only case for this external detector is zlib, but it’s wrongly applied to all !Try it on
zstd, it skips the incompressible parts at > 1 GB / s !
That’s faster than the processing of this «compressibility detector».