On Fri, Jun 17, 2022 at 10:18:43AM +0200, Matthias Klose wrote: >... > The proposal is to turn on LTO by default on most 64bit release > architectures. >...
By what factor does -ffat-lto-objects increase disk space usage during package builds? Please coordinate with DSA to ensure that the buildds on these architectures have sufficient diskspace. amd64 buildds have/had(?) only 74 GB of diskspace, which has even without LTO already forced some packages to do manual cleanup steps during the build to stay within the limited disk space. >... > Link time > optimizations are also at least turned on in other distros like Fedora, > OpenSuse (two years) and Ubuntu (one year). >... > The idea is to file wishlist bug reports for those 373 packages and then see > how far we get, and if it's feasible to already turn on LTO for bookworm. > If not, it should be turned on by default for the following release. I assume these 373 packages have already been fixed/workarounded in Ubuntu? Submitting 373 bugs with patches should settle the feasibility question. A bigger worry is the schedule of such a change. A major toolchain change shortly before the freeze means the vast majority of packages will be shipped with non-LTO builds in the release, with security updates or point release updates triggering a change to an LTO built package. This means few packages actually benefitting from LTO, but a higher regression risk when fixing bugs in stable. The best timing for such a change would be immediately after the release of bookworm. > Matthias cu Adrian
