On 15 September 2011 19:46, Alexander Korotkov <aekorot...@gmail.com> wrote: > Proposed algorithm finds following splits by single pass on two arrays: one > sorted by lower bound of interval and another sorted by upper bound of > interval.
Have you considered if further performance improvements could come from providing a qsort implementation that allows for the inlining of the comparator? I find it curious that we go to the trouble of providing a custom qsort implementation in qsort.c, pg_qsort, but haven't gone one step further and considered inlining effects. Here's a macro-based inlining implementation: http://www.corpit.ru/mjt/qsort.html I wondered in passing if compiler vendors had got around to figuring out a way of solving the "inlining function pointer" problem that I first read about years ago, so I ran this code, which benchmarks the macro-based qsort above: http://www.lemoda.net/c/inline-qsort-example/index.html It's actually C++, but that isn't significant (c stdlib qsort() is called). When I built this code with GCC 4.5, the results were: C quick-sort time elapsed: 3.24 Inline C quick-sort time elapsed: 2.01 It looks like this is something that could be revisited. -- Peter Geoghegan http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training and Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
