Re: PTE aging, ptep_test_and_clear_young() and TLB

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

On Sat, Apr 17, 2004 at 01:43:02PM -0700, William Lee Irwin III wrote:
> On Sat, Apr 17, 2004 at 09:15:06PM +0100, Russell King wrote:
> > This in turn means that we need to replace ptep_test_and_clear_young()
> > with ptep_clear_flush_young(), which in turn means we need the VMA and
> > address.  However, this implies introducing more code into
> > page_referenced().
> > Comments?
> 
> The address and mm should already be recoverable via the pte page
> tagging technique. The vma is recoverable from that, albeit at some
> cost (mm->page_table_lock acquisition + find_vma() call). OTOH unless
> kswapd's going wild it should largely count as a slow path anyway.

Actually, we don't actually need the VMA - if you look at flush_tlb_page()
in include/asm-arm/tlbflush.h, we only really need the MM.  Therefore,
it's pointless digging up the VMA.  (I did think that we didn't flush
the I-TLB if VM_EXEC wasn't set, but I think that was a previous
incarnation.)

-- 
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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