Comment 8 for bug 1931725

@cborntra

v5.13 ubuntu kernel's s390 configuration with zstd -22 --ultra compression is 8.5 MB, whereas gzip -9 is 11M.

Thus for gzip to win at bootspeed the decompression speed has to compensate for 2.5M of i/o and be faster than zstd.

Unaccelerated decompression comparison still gives me faster decompression with less i/o with zstd compressed kernel image.

At Canonical we still do not have z15 mainframe available for us to benchmark this.