Hi, On 6/16/21 10:28 AM, Daniel P. Berrangé wrote: > On Tue, Jun 15, 2021 at 05:34:02PM -0400, Neal Gompa wrote: >> Hey all, >> >> Earlier this week, I was helping with processing features for openSUSE >> Leap 15.4[1] and I discovered that they're planning on introducing >> x86_64-v2 to openSUSE soon. The reference for this change was that >> RHEL 9 is going to use x86_64-v2[2]. Additionally, other distributions >> have been considering bumping up to v2 or v3[3][4]. >> >> Some cursory examination of the new x86_64 sublevels seem to indicate >> that x86_64-v2 goes back to roughly 2007~2008, merely cutting off the >> first couple of generations of x86_64 CPUs from Intel and AMD. I >> personally don't have any computers that don't have support for >> x86_64-v2 anymore. > > Yes, you loose primarily Intel Conroe and Penryn generations and > AMD Opteron Gen 1 -> Gen 3. I doubt this is a significant portion > of Fedora installs. > > Slight tangent but I find Fedora's approach to hardware somewhat > at odds with our approach to software. > > On the one hand we portray our project as a place for cutting > edge Linux software & innovation. > > On the other hand we hold back our software by trying to keep > supporting long obsolete hardware. > > There is of course always a balance between bumping min hardware > specs and the impact on maintainers & users, but I'm not convinced > that we have the balance right in targeting our x86_64 baseline at > the very first generation of 64-bit CPUs from 15 years ago. I can't > imagine such old CPUs makes up a significant portion of our users. I don't know about that, all I can offer is my own anecdotal to the contrary. Of the 7 PCs/laptops which are in more or less daily use in our houshold 3 of them are still core2 duo systems. Once the core2 duo / amd64 machines came out we really started hitting the point of diminishing returns wrt PC performance for day 2 day use. For a lot of simple day2 day use there really is no reason to replace and x86_64-v1 capable machines unless they are actually broken. Perhaps more importantly though, is that there we are also very much at the point where bumping the processor architecture requirements also leads to strongly diminishing returns. Also see Mateusz Jończyk excellent reply in this thread, how rebuilding packages for x86_64-v2 vs x86_64 results in a barely measurable performance improvement. Of course there are some specific algorithms which greatly benefit from sse4.2, but those typically benefit even more from avx/avx2 which are not included in x86_64-v2; and often libraries already contain avx optimized code-paths for this which they automatically use where possible. You talk about we "hold back our software by trying to keep supporting long obsolete hardware". Let me flip the question can you provide hard proof, as in concrete numbers showing significant improvements, that switching to x86_64-v2 actually buys us anything meaningful ? Because this whole switch to x86_64-v2 sounds to me like it is mostly being pursued because it is a higher number so it must be better... Dropping 32 bit x86 support was a good thing to do because the virtual memory space offered by 32 bits was simply becoming too small for many desktop applications like web-browsers; and things were starting to become noticeably broken there because upstream where no longer testing on it. Forcing all Fedora PC users to move to x86_64 users as such was a good thing to do and also had a significant benefits in the form of lessening maintainer loads. Switching to x86_64-v2 OTOH simply does not seem to give any significant benefits. Regards, Hans _______________________________________________ devel mailing list -- devel@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe send an email to devel-leave@xxxxxxxxxxxxxxxxxxxxxxx Fedora Code of Conduct: https://docs.fedoraproject.org/en-US/project/code-of-conduct/ List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines List Archives: https://lists.fedoraproject.org/archives/list/devel@xxxxxxxxxxxxxxxxxxxxxxx Do not reply to spam on the list, report it: https://pagure.io/fedora-infrastructure
