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zstd compression levels

2018-02-19
2019-02-14
  • Little Vulpix

    Little Vulpix - 2018-02-19

    Hello!

    I am glad to see zstd implemented. However because its compression speed is so high, would it perhaps make sense to allow for an easy way of setting a higher compression preset? Currently it seems we are using " -3 " ( "extra_zstd_opt" and for the multithreaded one, "extra_pzstd_opt" ). On modern CPUs this barely uses any cpu time at all, unless you're maybe cloning an SSD onto another SSD :D . I wanted to do some testing to see where the best level lies, but I'm not sure how to do this, and how to incorporate it into the live clonezilla once I do find such setting. Any tips? The current manual doesn't tell me much, seems to lead to an invalid link.

     
  • Little Vulpix

    Little Vulpix - 2018-02-22

    I managed to find a somewhat simple way somewhere in old documentation to remake the squashfs filesystem and I'm experimenting with the compression levels now.

     
  • ValdikSS

    ValdikSS - 2019-02-14

    On modern CPUs this barely uses any cpu time at all, unless you're maybe cloning an SSD onto another SSD

    It's fast indeed, but on highly compressible data (text) it may go as low as 48,6 MiB/s on my laptop (zstd v.1.3.8 with "-3" on 390 MB text file). Non-compressible or low-compressible data may hit as high as 500 MiB/s on average.

     

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