On Wed, Sep 13, 2017 at 12:38:56PM +0200, Adam Borowski wrote: > On Wed, Sep 13, 2017 at 04:12:46PM +0900, Minchan Kim wrote: > > On Tue, Sep 12, 2017 at 02:00:05PM +0900, Sergey Senozhatsky wrote: > > > ZSTD tends to outperform deflate/inflate, thus we remove > > > zlib from the list of recommended algorithms and recommend > > > zstd instead. > > > > I did test with my sample data and compared zstd with deflate. > > zstd's compress ratio is lower a little bit but compression > > speed is much faster 3 times more and decompress speed is too > > 2 times more. With different data, it is different but overall, > > zstd would be better for speed at the cost of a little lower compress > > ratio(about 5%) so I believe it's worth to replace deflate. > > Both zlib and zstd have the compression level adjustable, zstd in a far > greater range (from lzo-like at lowest levels to mid-range lzma at the > highest). Thus, any such comparison needs to mention the used level. > Ie, if you selected a setting where speed is same, compression ratio > will be a lot better.
Unfortunately, it seems crypto doesn't support configurable level yet so when I read the source properly, zstd default level is 3 while deflate is 6. > > For compressing RAM it's reasonable to keep to fastest levels, and a > non-adjustable level reduces complexity, but if your use case wants high but > slow compression, now is a good time to mention this. What I expect zstd is same comp ratio with zlib but much faster speed. And lastly, predefined dictionary for 4K comp/decomp. :) Thanks.
