>>>> "PM" == Panu Matilainen
<pmatilai(a)redhat.com> writes:
PM> Note that rpm doesn't support parallel zstd compression, and while
PM> it does for xz, that's not even utilized in Fedora.
Doing parallel xz compression has a surprising cost in compression ratio
which gets worse as the thread count increases (because it just splits
the input into independent blocks and compresses them separately). I
did start on a feature to have it enabled but then abandoned that after
realizing that it didn't really work as I'd hoped.
That said, I do wonder how difficult it would be to do parallel zstd
compression/decompression within RPM. If it were possible then that
might help to obviate some of the downsides.
PM> To me the sweet spot between compression efficiency and speed seems
PM> closer to 10 than 19 - yes at a minor loss in space but huge speedup
PM> in both compress and decompress times.
One problem is that I don't think anyone wants to see any quantifiable
regression in overall package size. Spins still struggle to fit within
fixed media sizes as the package set grows ever larger.
- J<