linux-kernel - Re: [PATCHv2 15/28] thp: handle file COW faults

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Message-ID: <56BE2629.90001@intel.com>
Date:	Fri, 12 Feb 2016 10:36:25 -0800
From:	Dave Hansen <dave.hansen@...el.com>
To:	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
	Hugh Dickins <hughd@...gle.com>,
	Andrea Arcangeli <aarcange@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Vlastimil Babka <vbabka@...e.cz>,
	Christoph Lameter <cl@...two.org>,
	Naoya Horiguchi <n-horiguchi@...jp.nec.com>,
	Jerome Marchand <jmarchan@...hat.com>,
	Yang Shi <yang.shi@...aro.org>,
	Sasha Levin <sasha.levin@...cle.com>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCHv2 15/28] thp: handle file COW faults

On 02/11/2016 06:21 AM, Kirill A. Shutemov wrote:
> File COW for THP is handled on pte level: just split the pmd.

More changelog.  More comments, please.

We don't want to COW THP's because we'll waste memory?  A COW that we
could handle with 4k, we would have to handle with 2M, and that's
inefficient and high-latency?

Seems like a good idea to me.  It would just be nice to ensure every
reviewer doesn't have to think their way through it.