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[209.85.220.41]) by mx.google.com with SMTPS id n31sor2161631jac.0.2019.06.27.20.59.41 for (Google Transport Security); Thu, 27 Jun 2019 20:59:41 -0700 (PDT) Received-SPF: pass (google.com: domain of kernelfans@gmail.com designates 209.85.220.41 as permitted sender) client-ip=209.85.220.41; Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=Kkh8QnWI; spf=pass (google.com: domain of kernelfans@gmail.com designates 209.85.220.41 as permitted sender) smtp.mailfrom=kernelfans@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=Cs/BCNc/RCyeiUvf3Dd7XA6XNw70/7ZfOeMlzKTDfTw=; b=Kkh8QnWIzrZazVljg6hBsx7W/ZP0eBr1ejVjQyHZVuyvnJ6opqO1Z13W5iz5qwZfcj H0lYWcBOzr76HbMzjj9mSOh7bOMz8gIv2Mc8LAsLOX1h/MbSQcUX+u0P7/MCrytmMmf1 LP6QAlNDiOPI4CvLDKDvIhwWm+6F4zDZ/QIV2jsOeWikKn5H8nTXUpxnPFDi+tADdELb wftLrz7FO1ZOq0s5Vc8glGunRKW99QX4s7hsFHySk3XEKUzqbNXquuqnZrDKU6fKvAgc +PVk85g3fniAVaasVO0H0eME/b4zu2fMzz+50cj1nNgjd2/g2/SKXK8IT1YVcTH0vSHL pMXA== X-Google-Smtp-Source: APXvYqyY3ydiSQhtYGah1iASt/iBOIbXr1KVVwN5LrQiYQZl9AUwyMpJlNcyVhrRfjf43MZT+WCGvVS8crgLy/UEH1M= X-Received: by 2002:a02:c6b8:: with SMTP id o24mr9180808jan.80.1561694381133; Thu, 27 Jun 2019 20:59:41 -0700 (PDT) MIME-Version: 1.0 References: <1561612545-28997-1-git-send-email-kernelfans@gmail.com> <20190627162511.1cf10f5b04538c955c329408@linux-foundation.org> In-Reply-To: <20190627162511.1cf10f5b04538c955c329408@linux-foundation.org> From: Pingfan Liu Date: Fri, 28 Jun 2019 11:59:29 +0800 Message-ID: Subject: Re: [PATCHv5] mm/gup: speed up check_and_migrate_cma_pages() on huge page To: Andrew Morton Cc: Linux-mm@kvack.org, Ira Weiny , Mike Rapoport , "Kirill A. Shutemov" , Thomas Gleixner , John Hubbard , "Aneesh Kumar K.V" , Christoph Hellwig , Keith Busch , Mike Kravetz , LKML 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 Fri, Jun 28, 2019 at 7:25 AM Andrew Morton wrote: > > On Thu, 27 Jun 2019 13:15:45 +0800 Pingfan Liu wrote: > > > Both hugetlb and thp locate on the same migration type of pageblock, since > > they are allocated from a free_list[]. Based on this fact, it is enough to > > check on a single subpage to decide the migration type of the whole huge > > page. By this way, it saves (2M/4K - 1) times loop for pmd_huge on x86, > > similar on other archs. > > > > Furthermore, when executing isolate_huge_page(), it avoid taking global > > hugetlb_lock many times, and meanless remove/add to the local link list > > cma_page_list. > > > > Thanks, looks good to me. Have any timing measurements been taken? Not yet. It is a little hard to force huge page to be allocated CMA area. Should I provide the measurements? > > > ... > > > > --- a/mm/gup.c > > +++ b/mm/gup.c > > @@ -1336,25 +1336,30 @@ static long check_and_migrate_cma_pages(struct task_struct *tsk, > > struct vm_area_struct **vmas, > > unsigned int gup_flags) > > { > > - long i; > > + long i, step; > > I'll make these variables unsigned long - to match nr_pages and because > we have no need for them to be negative. OK, will fix it. Thanks, Pingfan > > > ...