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From: "Chen, Kenneth W" <kenneth.w.chen@intel.com>
To: "'Dave McCracken'" <dmccr@us.ibm.com>, "Andrew Morton" <akpm@osdl.org>
Cc: "Linux Kernel" <linux-kernel@vger.kernel.org>,
	"Linux Memory Management" <linux-mm@kvack.org>
Subject: RE: [PATCH 1/1] Implement shared page tables
Date: Thu, 1 Sep 2005 21:26:27 -0700	[thread overview]
Message-ID: <200509020427.j824R0g01601@unix-os.sc.intel.com> (raw)
In-Reply-To: <7C49DFF721CB4E671DB260F9@[10.1.1.4]>

Dave McCracken wrote on Tuesday, August 30, 2005 3:13 PM
> This patch implements page table sharing for all shared memory regions that
> span an entire page table page.  It supports sharing at multiple page
> levels, depending on the architecture.

In function pt_share_pte():

> +		while ((svma = next_shareable_vma(vma, svma, &iter))) {
> +			spgd = pgd_offset(svma->vm_mm, address);
> +			if (pgd_none(*spgd))
> +				continue;
> +
> +			spud = pud_offset(spgd, address);
> +			if (pud_none(*spud))
> +				continue;
> +
> +			spmd = pmd_offset(spud, address);
> +			if (pmd_none(*spmd))
> +				continue;
....
> +			page = pmd_page(*spmd);
> +			pt_increment_share(page);
> +			pmd_populate(vma->vm_mm, pmd, page);
> +		}


Do you really have to iterate through all the vma?  Can't you just break
out of the while loop on first successful match and populating the pmd?
I would think you will find them to be the same pte page. Or did I miss
some thing?


--- ./mm/ptshare.c.orig	2005-09-01 21:16:35.311915518 -0700
+++ ./mm/ptshare.c	2005-09-01 21:18:24.629296992 -0700
@@ -200,6 +200,7 @@ pt_share_pte(struct vm_area_struct *vma,
 			page = pmd_page(*spmd);
 			pt_increment_share(page);
 			pmd_populate(vma->vm_mm, pmd, page);
+			break;
 		}
 	}
 	pte = pte_alloc_map(vma->vm_mm, pmd, address);


      parent reply	other threads:[~2005-09-02  4:27 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-08-30 22:13 [PATCH 1/1] Implement shared page tables Dave McCracken
2005-08-31 11:44 ` Hugh Dickins
2005-08-31 11:51   ` Arjan van de Ven
2005-08-31 13:42     ` Hugh Dickins
2005-08-31 14:31       ` Martin J. Bligh
2005-08-31 14:41         ` Arjan van de Ven
2005-08-31 15:06         ` Hugh Dickins
2005-08-31 15:39           ` Martin J. Bligh
2005-08-31 16:40   ` Dave McCracken
2005-09-02  1:58 ` Chen, Kenneth W
2005-09-02 16:40   ` Dave McCracken
2005-09-02  4:26 ` Chen, Kenneth W [this message]

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