Re: [PATCH 9/15] misc: Make sysenter support optional

Andrew Morton
2005-11-12T05:58:08Z

Matt Mackall <mpm@selenic.com> wrote:
>
> his adds configurable sysenter support on x86. This saves about 5k on
> small systems.
>
> text data bss dec hex
> 3330172 529036 190556 4049764 3dcb64 baseline
> 3329604 524164 190556 4044324 3db624 sysenter
>
> $ bloat-o-meter vmlinux{-baseline,}
> add/remove: 0/2 grow/shrink: 0/3 up/down: 0/-316 (-316)
> function old new delta
> __restore_processor_state 76 62 -14
> identify_cpu 520 500 -20
> create_elf_tables 923 883 -40
> sysenter_setup 113 - -113
> enable_sep_cpu 129 - -129
>
> Most of the savings is not including the vsyscall DSO which doesn't
> show up with bloat-o-meter:
>
> $ size arch/i386/kernel/vsyscall.o
> text data bss dec hex filename
> 0 4826 0 4826 12da arch/i386/kernel/vsyscall.o
>
> $ nm arch/i386/kernel/vsyscall.o
> 00000961 T vsyscall_int80_end
> 00000000 T vsyscall_int80_start
> 000012da T vsyscall_sysenter_end
> 00000961 T vsyscall_sysenter_start

Similarly, stub out sysenter_setup() and enable_sep_cpu() and we lose a
bunch of ifdefs.