Re: PTE aging, ptep_test_and_clear_young() and TLB

[Russell King <rmk@arm.linux.org.uk>]

On Sun, Apr 18, 2004 at 01:36:11PM +0100, Hugh Dickins wrote:
> On Sun, 18 Apr 2004, Russell King wrote:
> > 
> > So, I think we definitely need the flush there.  The available data
> > so far from Marc appears to confirm this, and the theory surrounding
> > ASID-based MMUs (which are coming on ARM) also require it.
> 
> I agree that we need to flush TLB more, that if we keep on ignoring a
> hint forever then things go awry.  I disagree that it needs to be done
> so immediately, in the young/referenced/accessed case.  But go ahead,
> we can always optimize some of it out later on.

Well, having struggled with the kernels include mess to try to get at
the information I need to flush the TLB from an asm-arm header file,
I'm just considering whether to just say "fuck it" and add

#ifdef __arm__
		flush_tlb_mm_page(ptep_to_mm(pte), ptep_to_address(pte));
#endif

directly into page_referenced() and be done with it.

Basically, to be able to use either ptep_to_mm() or ptep_to_address()
in asm/pgtable.h, you need to:

1. remove linux/mm.h from asm-generic/rmap.h
2. somehow work around linux/highmem.h which includes linux/mm.h so
   asm-generic/rmap.h can have a definition of kmap_atomic_to_page()
3. remove asm/pgtable.h from linux/mm.h and linux/page-flags.h

I've managed to get so far with that, but the real killer seems to
be (2).

-- 
Russell King
 Linux kernel    2.6 ARM Linux   - http://www.arm.linux.org.uk/
 maintainer of:  2.6 PCMCIA      - http://pcmcia.arm.linux.org.uk/
                 2.6 Serial core
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