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    SubjectRe: [PATCH] i386-pda UP optimization
    Eric Dumazet wrote:
    > if !CONFIG_SMP, why even dereferencing boot_pda+PDA_cpu to get 0 ?
    > and as PER_CPU(cpu_gdt_descr, %ebx) in !CONFIG_SMP doesnt need the a value in
    > ebx, you can just do :
    >
    > #define CUR_CPU(reg) /* nothing */
    >

    Yep. On the other hand, I think that's an incredibly rare path anyway,
    so it won't make any difference either way.

    >> --- a/include/asm-i386/pda.h Tue Nov 21 18:54:56 2006 -0800
    >> +++ b/include/asm-i386/pda.h Wed Nov 22 02:35:24 2006 -0800
    >> @@ -22,6 +22,16 @@ extern struct i386_pda *_cpu_pda[];
    >>
    >>
    >
    > My patch was better IMHO : we dont need to force asm () instructions to
    > perform regular C variable reading/writing in !CONFIG_SMP case.
    >
    > Using plain C allows compiler to generate a better code.
    >

    Probably, but I'm interested in comparing apples with apples; how much
    do the actual segment prefixes make a difference?

    J
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