On Wed, Dec 25, 2019 at 4:25 PM Richard Hipp <d...@sqlite.org> wrote:
> > The video provided details on what they did. I could not find any > performance improvement by making mutexes direct calls instead of > indirect calls. This kind of optimization improves performance by reducing pressure on the CPU's branch branch-target address caching and prediction. > Maybe they are measuring performance differently than > me. (I use CPU cycle counts measured by valgrind.) > By default, valgrind doesn't model either branch predictors or branch-target address caches. Its model is somewhat primitive[0], but it is available through command-line option `--branch-sim` [1,2]. When you performance tested this change, did you enable that option? tool/run-speed-test.sh certainly doesn't. Of course, since those structures are shared globally, the performance benefit for de-virtualizing any given function call is highly context dependent. Sincerely, -- Jonathan Brandmeyer [0]: https://valgrind.org/docs/manual/cg-manual.html#branch-sim [1]: https://www.valgrind.org/docs/manual/cl-manual.html#cl-manual.options.simulation [2]: https://valgrind.org/docs/manual/cg-manual.html#cg-manual.cgopts _______________________________________________ sqlite-users mailing list sqlite-users@mailinglists.sqlite.org http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
