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From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
To: Michael Ellerman <michael@ellerman.id.au>
Subject: Re: [PATCH -V5 06/25] powerpc: Reduce PTE table memory wastage
In-Reply-To: <20130410071453.GB24786@concordia>
References: <1365055083-31956-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com>
 <1365055083-31956-7-git-send-email-aneesh.kumar@linux.vnet.ibm.com>
 <20130410071453.GB24786@concordia>
Date: Wed, 10 Apr 2013 13:24:59 +0530
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Michael Ellerman <michael@ellerman.id.au> writes:

> On Thu, Apr 04, 2013 at 11:27:44AM +0530, Aneesh Kumar K.V wrote:
>> From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
>> 
>> We allocate one page for the last level of linux page table. With THP and
>> large page size of 16MB, that would mean we are wasting large part
>> of that page. To map 16MB area, we only need a PTE space of 2K with 64K
>> page size. This patch reduce the space wastage by sharing the page
>> allocated for the last level of linux page table with multiple pmd
>> entries. We call these smaller chunks PTE page fragments and allocated
>> page, PTE page.
>
> This is not compiling for me:
>
> arch/powerpc/mm/mmu_context_hash64.c:118:3: error: implicit declaration of function 'reset_page_mapcount'
>

can you share the .config ? I have the git tree at 

git://github.com/kvaneesh/linux.git ppc64-thp-7

-aneesh