Quick sort: Replace recursion with custom stack, small improvements #84
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Instead of recursing just roll a custom stack with low/high bounds
of the next region.
Also tune some of the logic a bit.
- Simpler (and faster) median + setup for partition
- Remove some unnecessary branches in hot control flow.
Results in roughly 10% perf improvement on the project benchmarks:
(See PR for full run data)
4027959.8 / 4258144.7 -> 0.9459
Quick_sort 100000 x86_64 249 4027959.8 ns/op
Quick_sort 100000 x86_64 235 4258144.7 ns/op
Running tests with random numbers: 902582.0 / 940650.0 -> 0.9595
sort.h quick_sort - ok, 902582.0 usec
sort.h quick_sort - ok, 940650.0 usec
Running tests with same number: 8986.0 / 9059.0 -> 0.9919
sort.h quick_sort - ok, 8986.0 usec
sort.h quick_sort - ok, 9059.0 usec
Running tests with sorted numbers: 148790.0 / 160015.0 -> 0.9299
sort.h quick_sort - ok, 148790.0 usec
sort.h quick_sort - ok, 160015.0 usec
Running tests with sorted blocks of length 10: 872430.0 / 915431.0 -> 0.953
sort.h quick_sort - ok, 872430.0 usec
sort.h quick_sort - ok, 915431.0 usec
Running tests with sorted blocks of length 100: 751763.0 / 791987.0 -> 0.9492
sort.h quick_sort - ok, 751763.0 usec
sort.h quick_sort - ok, 791987.0 usec
Running tests with sorted blocks of length 10000: 461118.0 / 514853.0 -> 0.8956
sort.h quick_sort - ok, 461118.0 usec
sort.h quick_sort - ok, 514853.0 usec
Running tests with swapped size/2 pairs: 812161.0 / 854230.0 -> 0.9508
sort.h quick_sort - ok, 812161.0 usec
sort.h quick_sort - ok, 854230.0 usec
Running tests with swapped size/8 pairs: 522638.0 / 575848.0 -> 0.9076
sort.h quick_sort - ok, 522638.0 usec
sort.h quick_sort - ok, 575848.0 usec
Running tests with known evil data: 146601.0 / 196450.0 -> 0.7463
sort.h quick_sort - ok, 146601.0 usec
sort.h quick_sort - ok, 196450.0 usec
So roughly a 5-10% for most cases with the outliers being no-change
for same-number and 25% improvement for "evil data".
|
Results from running |
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Instead of recursing just roll a custom stack with low/high bounds of the next region.
Also tune some of the logic a bit.
- Simpler (and faster) median + setup for partition
- Remove some unnecessary branches in hot control flow.
Results in roughly 10% perf improvement on the project benchmarks: (See PR for full run data)
4027959.8 / 4258144.7 -> 0.9459
Quick_sort 100000 x86_64 249 4027959.8 ns/op
Quick_sort 100000 x86_64 235 4258144.7 ns/op
Running tests with random numbers: 902582.0 / 940650.0 -> 0.9595
sort.h quick_sort - ok, 902582.0 usec
sort.h quick_sort - ok, 940650.0 usec
Running tests with same number: 8986.0 / 9059.0 -> 0.9919
sort.h quick_sort - ok, 8986.0 usec
sort.h quick_sort - ok, 9059.0 usec
Running tests with sorted numbers: 148790.0 / 160015.0 -> 0.9299
sort.h quick_sort - ok, 148790.0 usec
sort.h quick_sort - ok, 160015.0 usec
Running tests with sorted blocks of length 10: 872430.0 / 915431.0 -> 0.953
sort.h quick_sort - ok, 872430.0 usec
sort.h quick_sort - ok, 915431.0 usec
Running tests with sorted blocks of length 100: 751763.0 / 791987.0 -> 0.9492
sort.h quick_sort - ok, 751763.0 usec
sort.h quick_sort - ok, 791987.0 usec
Running tests with sorted blocks of length 10000: 461118.0 / 514853.0 -> 0.8956
sort.h quick_sort - ok, 461118.0 usec
sort.h quick_sort - ok, 514853.0 usec
Running tests with swapped size/2 pairs: 812161.0 / 854230.0 -> 0.9508
sort.h quick_sort - ok, 812161.0 usec
sort.h quick_sort - ok, 854230.0 usec
Running tests with swapped size/8 pairs: 522638.0 / 575848.0 -> 0.9076
sort.h quick_sort - ok, 522638.0 usec
sort.h quick_sort - ok, 575848.0 usec
Running tests with known evil data: 146601.0 / 196450.0 -> 0.7463
sort.h quick_sort - ok, 146601.0 usec
sort.h quick_sort - ok, 196450.0 usec
So roughly a 5-10% for most cases with the outliers being no-change for same-number and 25% improvement for "evil data".