On Sat, Nov 7, 2015 at 9:24 PM, Reindl Harald <h.reindl@xxxxxxxxxxxxx> wrote: > > > Am 07.11.2015 um 20:36 schrieb drago01: >> >> On Sat, Nov 7, 2015 at 7:40 PM, Reindl Harald <h.reindl@xxxxxxxxxxxxx> >> wrote: >>> >>> 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. > > > for which one? > that don't show the impact on a complete distribution anyways There is no such thing as "the complete distribution" ... the flags used to compile libreoffice won't affect http or firefox. >>> 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 > > > i know that Then don't cite unrelated links. >> 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). > > > enable SSE3 don't diable SSE2 > so "gain you more" is impossible I meant "i686 + SSE2" (which we don't do for the same reason) gains more than "x86_64 + sse3". >> 2. Runtime detection does not have the cost of dropping support for >> specific hardware > > > runtime detection needs to be implemented in every relevant software at it's > own and hence has a *high cost* Not really its a common practice for software that does matter; even glibc does it. > add -msse3 to the default falgs have no costs at all but only an impact of a > unknown amount f *very* outdated hardware which is unlikely running a > bleeding edge distribution As you just wrote in that very paragraph the cost is dropping support for a set of hardware. We have no numbers on how much if at all it would help. > frankly whatever somebody has run on a 10 years old machine can be easily > virtualized and i doubt that many people have a 10 years old computer as > their only device, as far there is something with a core2 or newer in the > house you can virtualize the other machine and save a lot of energy Depends on the device. Virtualizing a laptop for instance won't make much sense. -- devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxxx https://admin.fedoraproject.org/mailman/listinfo/devel Fedora Code of Conduct: http://fedoraproject.org/code-of-conduct
