From: Ulrich Weigand <weigand@immd1.informatik.uni-erlangen.de>
Message-Id: <200211120108.CAA05101@faui11.informatik.uni-erlangen.de>
Subject: Re: [PATCH] flush_cache_page while pte valid
To: manfred@colorfullife.com
Date: Tue, 12 Nov 2002 02:08:46 +0100 (MET)
Cc: linux-kernel@vger.kernel.org, uweigand@de.ibm.com, schwidefsky@de.ibm.com
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Manfred Spraul wrote:

>Is it correct that this are 3 arch hooks that must appear back to back?
>What about one hook with all parameters?
>
>        pte = ptep_get_and_clear_and_flush(ptep, vma, address);

This interface would help us on s390 very much.  We have a hardware
instruction (INVALIDATE PAGE TABLE ENTRY) that implements the combination 
of 
        pte = ptep_get_and_clear(ptep);
        flush_tlb_page(vma, address);

very efficiently, but we cannot use it to implement flush_tlb_page
alone, because it requires the pte to be valid.

This is why our current in-tree flush_tlb_page is quite inefficient
(it always flushes the complete TLB) ...

If we had a combined hook, we could use our IPTE instruction.

Bye,
Ulrich

-- 
  Dr. Ulrich Weigand
  weigand@informatik.uni-erlangen.de
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