Default to a sensible zstd compression level

[probonopd]

Default to a sensible zstd compression level to improve application startup times. Data:

AppImage/AppImageKit#478 (comment)

[TheAssassin]

Define "sensible".

[probonopd]

A reasonably good tradeoff between

• Good compression
• Fast application startup times
• High zsync efficiency

Did I miss something?

[Samueru-sama]

I think this issue can be closed, it ended up being the issue of the default block size, even back then I noticed that there was something other than the compression level at play.

Now librewolf takes:

• 2.5 seconds with the original gzip that the official appimage comes with (111.1 MiB)
• 1.9 seconds with zstd level 20 (100.9 MiB)
• 1.7 seconds with zstd level 1 (124 MiB)

The difference between zstd 1 and 20 is 0.2 seconds, in other words it really isn't a big deal that zstd 15 is the default being used.

And native non appimage librewolf takes 0.9 seconds to start, so the overhead of the appimage is less than 1 second for my old broadwell cpu.

[probonopd]

Reference:

• Systematically benchmark compression algorithm, compression factor, block size AppImageSpec#44

[adrianinsaval]

I think this issue can be closed, it ended up being the issue of the default block size, even back then I noticed that there was something other than the compression level at play.

so how are you making your appimages now? Or has the default blocksize been changed in appimagetol?

[Samueru-sama]

I think this issue can be closed, it ended up being the issue of the default block size, even back then I noticed that there was something other than the compression level at play.

so how are you making your appimages now? Or has the default blocksize been changed in appimagetol?

It was changed here.