On Tue, Jan 24, 2017 at 07:00:03PM +0100, René Scharfe wrote: > > I do worry about having to support more implementations in the > > future that have different function signature for the comparison > > callbacks, which will make things ugly, but this addition alone > > doesn't look too bad to me. > > It is unfair of me to show a 5% speedup and then recommend to not > include it. ;-) That difference won't be measurable in real use cases > and the patch is not necessary. This patch is simple, but the overall > complexity (incl. #ifdefs etc.) will be lower without it.
I care less about squeezing out the last few percent performance and more that somebody libc qsort_r() might offer some other improvement. For instance, it could sort in-place to lower memory use for some cases, or do some clever thing that gives more than a few percent in the real world (something like TimSort). I don't know to what degree we should care about that. > But here's another one, with even higher performance and with an even > bigger recommendation to not include it! :) It veers off into another > direction: Parallel execution. It requires thread-safe comparison > functions, which might surprise callers. The value 1000 for the minimum > number of items before threading kicks in is just a guess, not based on > measurements. So it's quite raw -- and I'm not sure why it's still a > bit slower than sort(1). Fun, but probably insane for our not-very-threadsafe code base. :) -Peff
