On Sat, Nov 7, 2015 at 7:40 PM, Reindl Harald <h.reindl@xxxxxxxxxxxxx> wrote: > > > Am 07.11.2015 um 19:27 schrieb drago01: >> >> On Sat, Nov 7, 2015 at 7:23 PM, Reindl Harald <h.reindl@xxxxxxxxxxxxx> >> wrote: >>> >>> maybe you did not get "not that i say Fedora should go ahead and build >>> with >>> -mavx" but we talk about SSE3 >> >> >> Compiling everything with sse3 does have a cost (dropping support for >> some hardware) but what does it gain us? >> Better performance in theory? To convince anyone you have to at least >> provide numbers. Otherwise the discussion is a waste of time > > > how do you expect to get such numbers? > > even if you test whatever application with -msse2 versus -msse3 mosdt parts > of the operating system and the whole libraries are still built with only > SSE2 support > > the point is compile a single application with new features won#t gain that > muc 8until you do the same with most libraries used by the software) but > having the whole distribution is a summary with a completly different > behavior than a single test of software xyz Uh no you just have to compile the software any libraries used by the hot paths of the software you are trying to test. > if there would be no difference kernel upstream won't invest that much time > for runtime-cpu-detection (look at the bootlog on different hardware) > > here are examples http://www.phoronix.com/scan.php?page=news_item&px=MTU0MTY > http://www.phoronix.com/scan.php?page=news_item&px=MTI1Njc You missed the point completely. 1. AVX != (S)SSE3 There are lots of workloads that would benefit from AVX but SSE3 doesn't add that much (enabling SSE2 on i686 would gain you more for instance). 2. Runtime detection does not have the cost of dropping support for specific hardware. -- devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxxx https://admin.fedoraproject.org/mailman/listinfo/devel Fedora Code of Conduct: http://fedoraproject.org/code-of-conduct
