> https://fedoraproject.org/wiki/Changes/fno-omit-frame-pointer > [...] > === Unwinding === > [...] > * Kernel 4.8 frame pointer benchmarks by Suse showed 5%-10% > regressions in some benchmarks > (https://lore.kernel.org/all/20170602104048.jkkzssljsompj...@suse.de/T/#u)
Regressions of such magnitude can veto such changes, especially when they hit everyone, not just those who are highly dependent on the profiling tools the proposal is concerned about. > === Alternatives to frame pointers === > > There are a few alternative ways to unwind stacks instead of using the > frame pointer: > * [https://dwarfstd.org DWARF] data - The compiler can emit extra > [...] The problem is that we need to unwind the stack in kernel space (Are you referring to a novel kernel-resident tool?) > To summarize, if we want complete stacks with reasonably low overhead > (which we do, there's no other way to get accurate profiling data from > running services), frame pointers are currently the best option. The proposal doesn't characterize the "reasonably low overhead" that this operation targets. That makes it hard to judge the tradeoffs. > [...] > Fedora users will be more likely to have a streamlined experience when > trying to debug/profile system executables/libraries. Tools such as > perf will work out of the box instead of requiring to users to provide > extra options (e.g. --call-graph=dwarf/LBR) [...] If typing that option were a hardship, it could be made default on Fedora. With broad debuginfod auto-downloading capability, maybe it's worth considering. - FChE _______________________________________________ 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 Do not reply to spam on the list, report it: https://pagure.io/fedora-infrastructure
