Re: [RFC 00/15] x86_64: Optimize percpu accesses

From: Ingo Molnar
Date: Wed Jul 09 2008 - 15:42:11 EST



* Jeremy Fitzhardinge <jeremy@xxxxxxxx> wrote:

>> What is remaining is the task to rename
>>
>> pda.Y -> Z
>>
>> in order to make variable references the same under both arches.
>> Presumably the Z is the corresponding 32 bit variable. There are
>> likely a number of cases where the transformation is trivial if we
>> just identify the corresponding 32 bit equivalent.
>
> Yes, I understand that, but it's still pointless churn. The
> intermediate step is no improvement over what was there before, and
> isn't any closer to the desired final result.
>
> Once you've made the pda a percpu variable, and redefined all the
> X_pda macros in terms of x86_X_percpu, then there's no need to touch
> all the usage sites until you're *actually* going to unify something.
> Touching them all just because you find "X_pda" unsightly doesn't help
> anyone. Ideally every site you touch will remove a #ifdef
> CONFIG_X86_64, or make two as-yet unified pieces of code closer to
> unification.

that makes sense. Does everyone agree on #1-#2-#3 and then gradual
elimination of most pda members (without going through an intermediate
renaming of pda members) being the way to go?

Ingo
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