The microblog: 2022.06.05 03:39:55

2022.06.05 03:39:55 (1533262309555965952) from Daniel J. Bernstein, replying to "Ruben Kelevra (@RubenKelevra)" (1533217109274140672):

Intel Xeon E3-1220 v5, pinned at 3GHz. Turbo Boost (which would be 3.5GHz) disabled. No evidence of any AVX2 throttling. Reasonable cooling, no evidence of thermal throttling, plus these were very short single-core runs. Both of the pieces of code being benchmarked were AVX2.


2022.06.04 23:39:13 (1533201734369103872) from Daniel J. Bernstein:

Tried Google's new vectorized quicksort code vqsort on Skylake, and timed Sorter() as ~8000 cycles for int32[256] (big chunk of code for a size-specific sorting network), ~19000 cycles for int32[1024] (non-constant-time). djbsort is 1230, 6286 (ct). Did I misuse vqsort somehow?

2022.06.05 00:40:19 (1533217109274140672) from "Ruben Kelevra (@RubenKelevra)":

Which type of processor did you use? Some Intel processors reduce their clock speed if you use a lot of AVX instructions for a short while which may show up as wrong numbers.