[Bug ld/32584] New: ld.bfd slowdown linking some linux kernels

[arnd at arndb dot de]

https://sourceware.org/bugzilla/show_bug.cgi?id=32584

            Bug ID: 32584
           Summary: ld.bfd slowdown linking some linux kernels
           Product: binutils
           Version: 2.39
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: ld
          Assignee: unassigned at sourceware dot org
          Reporter: arnd at arndb dot de
  Target Milestone: ---

I noticed a slowdown in link times between linux kernels 6.12 and 6.13,
bisected it to a commit that changed the section ordering, as well as
binutils-2.39 and higher, see my report on the kernel mailing list, see
https://lore.kernel.org/lkml/20250120212839.1675696-1-arnd@kernel.org/.

Rong Xu further narrowed down the cause of the problem on the binutils side to
to commit fba1ac87dcb7 ("Fix the sorting algorithm for reloc entries").

I created a smaller test case for reproducing the issue, but it still exceeds
the 10MB limit for binutils bugzilla, so I uploaded the file to
https://drive.google.com/file/d/1M_ccr8RINzfjpU1qA5qA0rhRIGgDOFix/view?usp=sharing

time x86_64-linux-gnu-ld  -m elf_x86_64 -z noexecstack  --emit-relocs
--discard-none -z max-page-size=0x200000 --gc-sections --build-id=sha1
--orphan-handling=warn --script=./arch/x86/kernel/vmlinux.lds --strip-debug -o
.tmp_vmlinux1 --whole-archive vmlinux.a init/version-timestamp.o
--no-whole-archive --start-group lib/lib.a arch/x86/lib/lib.a --end-group
.tmp_vmlinux0.kallsyms.o
real    0m31.128s
user    0m30.472s
sys     0m0.277s

time x86_64-linux-ld-2.36  -m elf_x86_64 -z noexecstack  --emit-relocs
--discard-none -z max-page-size=0x200000 --gc-sections --build-id=sha1
--orphan-handling=warn --script=./arch/x86/kernel/vmlinux.lds --strip-debug -o
.tmp_vmlinux1 --whole-archive vmlinux.a init/version-timestamp.o
--no-whole-archive --start-group lib/lib.a arch/x86/lib/lib.a --end-group
.tmp_vmlinux0.kallsyms.o 
real    0m1.142s
user    0m0.898s
sys     0m0.237s

-- 
You are receiving this mail because:
You are on the CC list for the bug.