Re: When substitute download + decompression is CPU-bound

[Jonathan Brielmaier <jonathan.brielmaier@web.de>]

Super interesting findings!

On 14.12.20 23:20, Ludovic Courtès wrote:
>    2. Use Zstd like all the cool kids since it seems to have a much
>       higher decompression speed: <https://facebook.github.io/zstd/>.
>       630 MB/s on ungoogled-chromium on my laptop.  Woow.

Not only decompression speed is fast, compression is as well:

size	file			time for compression (lower is better)
335M	uc.nar

104M	uc.nar.gz
	 	  8
71M	uc.nar.lz.level9	120
74M	uc.nar.lz.level6
  	 80
82M	uc.nar.lz.level3	 30
89M	uc.nar.lz
.level1	 16
97M	uc.nar.zst	 	  1

So I am bought by zstd, as user and as substitution server care taker :)

For mobile users and users without internet flatrates the increased nar
size is a problem.
Although I think the problem here is not bewtween gzip, lzip and zstd.
It's the fact that we completely download the new package even if's just
some 100 lines of diffoscope diff[0]. And most of them is due to the
change /gnu/store name...

[0] diffoscope --max-diff-block-lines 0
/gnu/store/zvcn2r352wxnmq7jayz5myg23gh9s17q-icedove-78.5.1
/gnu/store/dzjym6y7b9z4apgvvydj9lf0kbaa8qbv-icedove-78.5.1
lines: 783
size: 64k