Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
MIME-Version: 1.0
References: <1557447392-61607-1-git-send-email-yang.shi@linux.alibaba.com>
 <87y33fjbvr.fsf@yhuang-dev.intel.com> <20190510163612.GA23417@bombadil.infradead.org>
In-Reply-To: <20190510163612.GA23417@bombadil.infradead.org>
From:   Yafang Shao <laoar.shao@gmail.com>
Date:   Sat, 11 May 2019 12:09:57 +0800
Message-ID: <CALOAHbCs62ynCEeTqAr7wx2TerFmK1ZBp_9r5jh-oP36tGMXDg@mail.gmail.com>
Subject: Re: [PATCH] mm: vmscan: correct nr_reclaimed for THP
To:     Matthew Wilcox <willy@infradead.org>
Cc:     "Huang, Ying" <ying.huang@intel.com>,
        Yang Shi <yang.shi@linux.alibaba.com>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Michal Hocko <mhocko@suse.com>, mgorman@techsingularity.net,
        kirill.shutemov@linux.intel.com, Hugh Dickins <hughd@google.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Linux MM <linux-mm@kvack.org>,
        LKML <linux-kernel@vger.kernel.org>
Content-Type: text/plain; charset="UTF-8"
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Sat, May 11, 2019 at 12:36 AM Matthew Wilcox <willy@infradead.org> wrote:
>
> On Fri, May 10, 2019 at 10:12:40AM +0800, Huang, Ying wrote:
> > > +           nr_reclaimed += (1 << compound_order(page));
> >
> > How about to change this to
> >
> >
> >         nr_reclaimed += hpage_nr_pages(page);
>
> Please don't.  That embeds the knowledge that we can only swap out either
> normal pages or THP sized pages.

Agreed.
compound_order() is more general than hpage_nr_pages().
It seems to me that hpage_nr_pages() is a little  abuse in lots of places.

Thanks
Yafang