On 3/24/19 9:18 PM, Baptiste Jonglez wrote: > Just one detail: your results for -19, -20 and -21 are identical because > apparently zstd needs an additional flag (--ultra) to "unlock" the higher > compression levels: > > zstd -c -T0 -20 - > Warning : compression level higher than max, reduced to 19 > > Also, I see you did not test zstd with a small number of cores: can you > add e.g. -T1, -T2 and -T4 to the comparison? It would give a more > realistic idea of what to expect when building on a typical machine, as > opposed to dragon ;) > In my tests, using less threads also decreased memory usage when > compressing (35% less memory when switching from -T2 to -T1). >
Damn, i knew i must've missed something - archange had already mentioned on IRC that these results look weird, but i shrugged it off. Should've double-checked. I'll get you a new table with the higher levels fixed and a second set with -T2 for comparison later. Regardless, IIRC preliminary testing showed that these gains are not worth it, as they were quite small in the tests we ran a while ago. > For decompression, it seems that both xz and zstd run single-threaded, so > there's not much to think about (zstd is just incredibly fast). > Correct Rob
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