[yakubin]

That appears to be systemd being slow.

  $ dd if=/dev/urandom of=test bs=1G count=1 iflag=fullblock
  $ gzip -k test
  $ zcat test.gz | pv -a >/dev/null
  [ 228MiB/s]

  $ sudo journalctl -r | pv -a >/dev/null
  [13.1MiB/s]

UPDATE: Gzip with more real-world data[1]:

  $ gzip -k adventures-of-huckleberry-finn.txt
  $ zcat adventures-of-huckleberry-finn.txt.gz | pv -a >/dev/null
  [ 151MiB/s]

[1]: <https://gutenberg.org/files/76/76-0.txt>

[klauspost]

By "compressing" random data you are bypassing gzip, since it will just store your data as uncompressed blocks, making "decompression" a memcopy.

With real data, deflate maxes out somewhere around there either way, but that is a bit coincidental.

With modern CPUs getting increasingly smaller IPC improvements this will likely be pretty much the max decompression speed we can expect from gzip going forward.

[yakubin]

It actually made the file bigger (1.1G from 1.0G) :)

I was getting the same numbers with text data I have scattered on my disk, but those were small, so I decided to generate a bigger file. But, yes, I agree a more robust benchmark would use a Mark Twain novel e.g.