[RFC PATCH 3/3] powerpc/64s/radix: optimise TLB flush with precise TLB ranges in mmu_gather

[Linus Torvalds]

On Tue, Jun 12, 2018 at 12:16 AM Nicholas Piggin <npiggin at gmail.com> wrote:
>
> This brings the number of tlbiel instructions required by a kernel
> compile from 33M to 25M, most avoided from exec->shift_arg_pages.

And this shows that "page_start/end" is purely for powerpc and used
nowhere else.

The previous patch should have been to purely powerpc page table
walking and not touch asm-generic/tlb.h

I think you should make those changes to
arch/powerpc/include/asm/tlb.h. If that means you can't use the
generic header, then so be it.

Or maybe you can embed the generic case in some ppc-specific
structures, and use 90% of the generic code just with your added
wrappers for that radix invalidation on top.

But don't make other architectures do pointless work that doesn't
matter - or make sense - for them.

               Linus