On Sat, 2019-12-21 at 10:52 -0500, Josh Boyer wrote: > On Thu, Dec 19, 2019 at 5:48 PM Jeff Law <l...@redhat.com> wrote: > > On Thu, 2019-12-19 at 16:24 -0600, Neal Gompa wrote: > > > On Thu, Dec 19, 2019 at 4:14 PM Jeff Law <l...@redhat.com> wrote: > > > > On Thu, 2019-12-19 at 21:56 +0000, devel- > > > > requ...@lists.fedoraproject.org wrote: > > > > > > > > Neal, > > > > > > > > > > > > > I'm generally happy with this idea. I'm one of the maintainers of > > > > > rpm-config-SUSE (the equivalent of redhat-rpm-config for SUSE > > > > > distributions) and I somewhat saw the development of this feature > > > > > across rpm, rpm-config-SUSE, and the implementation in openSUSE > > > > > Tumbleweed. > > > > Understood. FWIW, I work closely with Martin L, Martin J, Jan and > > > > Richi @ SuSE. Martin L and I in particular coordinate on mass build > > > > testing & related failure analysis and bugfixing. > > > > > > > > > > Martin Liška is the one I've primarily interfaced with throughout the > > > implementation. > > > > > > I don't know if you know about this, but there's a tracker bug for > > > LTO-related failures: https://bugzilla.opensuse.org/1133084 > > I am aware of it and have referenced it several times in my own work. > > > > > We should probably make sure this is cross-referenced as LTO is > > > implemented in Fedora. > > Sure. That's easy enough to do. Some of the information is dated, but > > there still useful nuggets in there. > > > > They punted lots of stuff though. In particular they punted the > > configure problem and middle-end issued diagnostics, which was terribly > > unfortunate. > > > > > > > However, the implementation of LTO in openSUSE caused major problems > > > > > for "weaker" architectures like ARM and RISC-V. In Fedora, ARM is > > > > > co-primary with the rest of the architectures (ARM is allowed to be > > > > > broken in openSUSE from time to time). The major problems we > > > > > encountered was increased miscompilation errors and timeouts due to > > > > > builds taking even longer with LTO straining ARM build environments. > > > > Yes. The 32bit architectures in particular are expected to be slightly > > > > problematical due to the limited address space. Even with Jan's work > > > > in this area, I expect things like firefox to simply be too big to > > > > compile/link using LTO on the 32bit platforms. > > > > > > > > When I discussed this with Martin L and one of the Ubuntu engineers > > > > (Matthias) back in Sept, the general plan we agreed on was to first get > > > > the Fedora test builds in reasonable shape on x86_64 that we could use > > > > as a baseline (and we're just about there). Then do an i686 build for > > > > comparison purposes. > > > > > > > > For packages we find problematical on the 32bit platforms, we'll be > > > > able to trivially opt-out of LTO for that package on those 32bit > > > > platforms. It's a one-liner in the .spec file. > > > > > > > > > > > > > > Are we going to use the same %_lto_cflags mechanism that was > > > implemented in openSUSE, or are we going to do something different? > > Ideally the same. I don't own redhat-rpm-config, but certainly my > > preference is use the same mechanisms. > > > > > > > > I'd like to see at *least* AArch64 spun to see how well this goes. I'm > > > reasonably confident that POWER8+ would be fine, since we don't have > > > ppc64be anymore (and I *know* that one was broken, since I reported it > > > years ago: https://bugzilla.redhat.com/1515934). > > Obviously aarch64 will be built and any issues resolved as is the case > > with other architectures. We do this every spring cycle with the > > introduction of a major GCC release and we work closely with the GCC > > engineers at ARM and IBM along the way. > > > > Building 9000 packages 3X each (gcc-10+LTO, gcc-10, gcc-9 baseline) > > takes significant hardware. If there's hardware I can use (and you > > should be thinking on the order of dozens of dedicated machines), then > > I'm happy to use them. I mentioned ppc64le simply because I can get > > access to a goodly number of them. > > Is there a reason you couldn't use aarch64 AWS instances? I've actually applied for aws credits which could be used for this. THe instances in the free tier are too small to really be useful.
jeff > _______________________________________________ devel mailing list -- devel@lists.fedoraproject.org To unsubscribe send an email to devel-le...@lists.fedoraproject.org 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@lists.fedoraproject.org
