From: Shile Zhang <shile.zhang@xxxxxxxxxxxxxxxxx> Hi, I found the unwind_init taken long time (more than 90ms) in kernel booting, mainly spent on sorting the two ORC unwind tables, orc_unwind and orc_unwind_ip. I also noticed that this issued has reported and discussed last year: https://lkml.org/lkml/2018/10/8/342 But seems no final solution until now, I tried to sort the ORC tables at build time, followed the helpful hints from Josh and Ingo in that thread. And mainly referred the implementation of 'sortextable' tool: https://lore.kernel.org/linux-mips/1334872799-14589-1-git-send-email-ddaney.cavm@xxxxxxxxx/ What I did: - Add a Kconfig to control build-time sorting or runtime sorting; - Referred 'sortextable', create a similar helper tool 'sortorctable', help to sort the ORC unwind tables at vmlinux link process. One potential improvement is to sort the module ORC tables in future. Thanks! Shile Zhang (4): scripts: Add sortorctable to sort ORC unwind tables kbuild: Sort ORC unwind tables in vmlinux link process x86/unwind/orc: Skip sorting if BUILDTIME_ORCTABLE_SORT is configured x86/Kconfig: Add a Kconfig option to sort ORC tables at build time arch/x86/Kconfig.debug | 9 ++ arch/x86/kernel/unwind_orc.c | 2 + scripts/.gitignore | 1 + scripts/Makefile | 2 + scripts/link-vmlinux.sh | 10 ++ scripts/sortorctable.c | 246 +++++++++++++++++++++++++++++++++++ scripts/sortorctable.h | 25 ++++ 7 files changed, 295 insertions(+) create mode 100644 scripts/sortorctable.c create mode 100644 scripts/sortorctable.h -- 2.24.0.rc2
