Messages in this thread | | | Date | Wed, 13 Sep 2017 12:38:56 +0200 | From | Adam Borowski <> | Subject | Re: [PATCH 2/2] zram: remove zlib from the list of recommended algorithms |
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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.
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.
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