Re: [PATCH 8/8] Convert PDA into the percpu section

From: Ingo Molnar
Date: Tue Mar 06 2007 - 08:11:48 EST



* Rusty Russell <rusty@xxxxxxxxxxxxxxx> wrote:

> Currently x86 (similar to x84-64) has a special per-cpu structure
> called "i386_pda" which can be easily and efficiently referenced via
> the %fs register. An ELF section is more flexible than a structure,
> allowing any piece of code to use this area. Indeed, such a section
> already exists: the per-cpu area.
>
> So this patch
> (1) Removes the PDA and uses per-cpu variables for each current member.

hmm ... i very much like this, but its needs performance and kernel-size
testing before it can move from -mm into mainline. We are now exposing
wide ranges of the kernel to segment prefixes again. (Btw., i'd expect
there to be a kernel size reduction.)

Ingo
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