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[209.85.220.65]) by mx.google.com with SMTPS id d18sor5433078iod.98.2019.05.06.08.22.47 for (Google Transport Security); Mon, 06 May 2019 08:22:47 -0700 (PDT) Received-SPF: pass (google.com: domain of laoar.shao@gmail.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=OWGhjKZO; spf=pass (google.com: domain of laoar.shao@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=laoar.shao@gmail.com; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=GwjCs7waUjzCsD/Xg/lAVVPTMZTrnUgLhXYDBkanDSk=; b=OWGhjKZOzYRCB0rqRJDqPrmz5F9AWSwawjP25Bbt/pucKURSLbTYhfD2a12A+pl5sD wDdqSpoqnH3Xweec7SSAAK2vouVxjpKsFzjgwpFKd4mb+hdArTQcB3VJ5Gwmp5wt0dZy rwQo/ZBUBAn3H384/vCbKuhUa9iU+yrSA97XCzeZsaYow88m1ZNg8Th0u9Pbhumk/XJ8 x5kBXCaJo7IfXRbaOG/TT2UNt+6glsaFkhcJPCuBwwwgP7fC0FfBizVg7/+/5kSU+QBl h1Rq8Pg0qxfNLnye5FdPKDdbI9omyiZ+WECfpYenJMlp3cPdYhzhvA4nu29Gaz/xH9H8 i2Pw== X-Google-Smtp-Source: APXvYqzPlaPgkszSTGQfHRiI7VvMmDYTYeuVDMH6WOeUYuuNTH0sc8C0h78pwkJ5fWEzuDJx8adobhbfErCNeOONgdg= X-Received: by 2002:a6b:6d06:: with SMTP id a6mr1998461iod.11.1557156167597; Mon, 06 May 2019 08:22:47 -0700 (PDT) MIME-Version: 1.0 References: <1557038457-25924-1-git-send-email-laoar.shao@gmail.com> <20190506135954.GB31017@dhcp22.suse.cz> In-Reply-To: <20190506135954.GB31017@dhcp22.suse.cz> From: Yafang Shao Date: Mon, 6 May 2019 23:22:11 +0800 Message-ID: Subject: Re: [PATCH] mm/memcontrol: avoid unnecessary PageTransHuge() when counting compound page To: Michal Hocko Cc: Andrew Morton , Linux MM , shaoyafang@didiglobal.com Content-Type: text/plain; charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, May 6, 2019 at 9:59 PM Michal Hocko wrote: > > On Sun 05-05-19 14:40:57, Yafang Shao wrote: > > If CONFIG_TRANSPARENT_HUGEPAGE is not set, hpage_nr_pages() is always 1; > > if CONFIG_TRANSPARENT_HUGEPAGE is set, hpage_nr_pages() will > > call PageTransHuge() to judge whether the page is compound page or not. > > So we can use the result of hpage_nr_pages() to avoid uneccessary > > PageTransHuge(). > > The changelog doesn't describe motivation. Does this result in a better > code/performance? > It is a better code, I think. Regarding the performance, I don't think it is easy to measure. Thanks Yafang