Okay now this is weird.
I can reproduce it just fine ... but only when compressing all PDFs simultaneously.
To utilize all cores, I ran:
$ for x in *.pdf; do zstd <"$x" >"$x.zst" --ultra -22 & done; wait
(and similar for the other formats).
I ran this again and it produced the same 2M file from the source 1.1M file. However when I run without paralellization:
$ for x in *.pdf; do zstd <"$x" >"$x.zst" --ultra -22; done
That one file becomes 1.1M, and the total size of *.zst is 37M (competitive with Brotli, which is impressive given how much faster it is to decompress).
What's going on here? Surely '-22' disables any adaptive compression stuff based on system resource availability and just uses compression level 22?
I can reproduce it just fine ... but only when compressing all PDFs simultaneously.
To utilize all cores, I ran:
(and similar for the other formats).I ran this again and it produced the same 2M file from the source 1.1M file. However when I run without paralellization:
That one file becomes 1.1M, and the total size of *.zst is 37M (competitive with Brotli, which is impressive given how much faster it is to decompress).What's going on here? Surely '-22' disables any adaptive compression stuff based on system resource availability and just uses compression level 22?