linux-kernel - Re: [patch 3/5] remove ptep_test_and_clear_dirty and ptep_clear_flush

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Message-ID: <4689A691.9090908@vmware.com>
Date:	Mon, 02 Jul 2007 18:29:53 -0700
From:	Zachary Amsden <zach@...are.com>
To:	Martin Schwidefsky <schwidefsky@...ibm.com>
CC:	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	Hugh Dickins <hugh@...itas.com>
Subject: Re: [patch 3/5] remove ptep_test_and_clear_dirty and ptep_clear_flush_dirty.

Martin Schwidefsky wrote:
> From: Martin Schwidefsky <schwidefsky@...ibm.com>
>
> Nobody is using ptep_test_and_clear_dirty and ptep_clear_flush_dirty.
> Remove the functions from all architectures.
>
>
> -static inline int
> -ptep_test_and_clear_dirty (struct vm_area_struct *vma, unsigned long addr, pte_t *ptep)
> -{
> -#ifdef CONFIG_SMP
> -	if (!pte_dirty(*ptep))
> -		return 0;
> -	return test_and_clear_bit(_PAGE_D_BIT, ptep);
> -#else
> -	pte_t pte = *ptep;
> -	if (!pte_dirty(pte))
> -		return 0;
> -	set_pte_at(vma->vm_mm, addr, ptep, pte_mkclean(pte));
> -	return 1;
> -#endif
> -}

I've not followed all the changes lately - what is the current protocol 
for clearing dirty bit?  Is it simply pte_clear followed by set or is it 
not done at all?  At least for i386 and virtualization, we had several 
optimizations to the test_and_clear path that are not possible with a 
pte_clear / set_pte approach.

Zach
-
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