Message-ID: <55560963.30106@intel.com>
Date: Fri, 15 May 2015 07:57:39 -0700
From: Dave Hansen <dave.hansen@intel.com>
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To: "Kirill A. Shutemov" <kirill@shutemov.name>,
        Vlastimil Babka <vbabka@suse.cz>
CC: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Andrea Arcangeli <aarcange@redhat.com>,
        Hugh Dickins <hughd@google.com>, Mel Gorman <mgorman@suse.de>,
        Rik van Riel <riel@redhat.com>, Christoph Lameter <cl@gentwo.org>,
        Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>,
        Steve Capper <steve.capper@linaro.org>,
        "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>,
        Johannes Weiner <hannes@cmpxchg.org>, Michal Hocko <mhocko@suse.cz>,
        Jerome Marchand <jmarchan@redhat.com>,
        Sasha Levin <sasha.levin@oracle.com>, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org
Subject: Re: [PATCHv5 03/28] memcg: adjust to support new THP refcounting
References: <1429823043-157133-1-git-send-email-kirill.shutemov@linux.intel.com> <1429823043-157133-4-git-send-email-kirill.shutemov@linux.intel.com> <5555A3D1.3010108@suse.cz> <20150515111828.GC6250@node.dhcp.inet.fi>
In-Reply-To: <20150515111828.GC6250@node.dhcp.inet.fi>
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On 05/15/2015 04:18 AM, Kirill A. Shutemov wrote:
>> > But same question about whether it should be using hpage_nr_pages() instead
>> > of a constant.
> No. Compiler woundn't be able to optimize HPAGE_PMD_NR away for THP=n,
> since compound value cross compilation unit barrier.

What code are you talking about here, specifically?  This?

static inline int hpage_nr_pages(struct page *page)
{
        if (unlikely(PageTransHuge(page)))
                return HPAGE_PMD_NR;
        return 1;
}

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