linux-kernel - Re: [PATCH] mm: vmscan: correct nr

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Message-ID: <CALOAHbCs62ynCEeTqAr7wx2TerFmK1ZBp_9r5jh-oP36tGMXDg@mail.gmail.com>
Date:   Sat, 11 May 2019 12:09:57 +0800
From:   Yafang Shao <laoar.shao@...il.com>
To:     Matthew Wilcox <willy@...radead.org>
Cc:     "Huang, Ying" <ying.huang@...el.com>,
        Yang Shi <yang.shi@...ux.alibaba.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Michal Hocko <mhocko@...e.com>, mgorman@...hsingularity.net,
        kirill.shutemov@...ux.intel.com, Hugh Dickins <hughd@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linux MM <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mm: vmscan: correct nr_reclaimed for THP

On Sat, May 11, 2019 at 12:36 AM Matthew Wilcox <willy@...radead.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