Date: Fri, 19 Jul 2013 17:33:32 +0200
From: Andi Kleen <andi@firstfloor.org>
To: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
        Mel Gorman <mgorman@suse.de>, Hugh Dickins <hughd@google.com>,
        KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
        Andi Kleen <andi@firstfloor.org>, Hillf Danton <dhillf@gmail.com>,
        Michal Hocko <mhocko@suse.cz>, Rik van Riel <riel@redhat.com>,
        "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>,
        linux-kernel@vger.kernel.org,
        Naoya Horiguchi <nao.horiguchi@gmail.com>
Subject: Re: [PATCH v3 0/8] extend hugepage migration
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On Thu, Jul 18, 2013 at 05:34:24PM -0400, Naoya Horiguchi wrote:
> Here is the 3rd version of hugepage migration patchset.
> I rebased it onto v3.11-rc1 and applied most of your feedbacks.
> 
> Some works referred to in previous discussion (shown below) are not included
> in this patchset, but likely to be done after this work.
>  - using page walker in check_range
>  - split page table lock for pmd/pud based hugepage (maybe applicable to thp)

I did a quick read through the patchkit and it looks all good to me.
It also closes a long standing gap. Thanks!

Acked-by: Andi Kleen <ak@linux.intel.com>

> Hugepage migration of 1GB hugepage is not enabled for now, because
> I'm not sure whether users of 1GB hugepage really want it.
> We need to spare free hugepage in order to do migration, but I don't
> think that users want to 1GB memory to idle for that purpose
> (currently we can't expand/shrink 1GB hugepage pool after boot).

I think we'll need 1GB migration sooner or later. As memory sizes
go up 1GB use will be more common, and the limitation of not
expanding/shrinking 1GB will be eventually fixed.

It would be just a straight forward extension of your patchkit,
right?

-Andi
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