On Sun, Apr 10, 2022 at 2:44 PM Thomas Munro <thomas.mu...@gmail.com> wrote: > David Rowley privately reported a performance regression when sorting > single ints with a lot of duplicates, in a case that previously hit > qsort_ssup() but now hits qsort_tuple_int32() and then has to call the > tiebreaker comparator.
That's not good. The B&M quicksort implementation that we adopted is generally extremely fast for that case, since it uses 3 way partitioning (based on the Dutch National Flag algorithm). This essentially makes sorting large groups of duplicates take only linear time (not linearithmic time). -- Peter Geoghegan
