From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 42659C433DB for ; Sat, 20 Feb 2021 01:24:21 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id D23EB64E54 for ; Sat, 20 Feb 2021 01:24:20 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D23EB64E54 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 4A3806B0005; Fri, 19 Feb 2021 20:24:20 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 42D2C6B006C; Fri, 19 Feb 2021 20:24:20 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 2F4A16B006E; Fri, 19 Feb 2021 20:24:20 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0233.hostedemail.com [216.40.44.233]) by kanga.kvack.org (Postfix) with ESMTP id 113326B0005 for ; Fri, 19 Feb 2021 20:24:20 -0500 (EST) Received: from smtpin10.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id CABBF87DE for ; Sat, 20 Feb 2021 01:24:19 +0000 (UTC) X-FDA: 77836900638.10.27D7E51 Received: from mail-ej1-f45.google.com (mail-ej1-f45.google.com [209.85.218.45]) by imf11.hostedemail.com (Postfix) with ESMTP id 76B2A2000381 for ; Sat, 20 Feb 2021 01:24:12 +0000 (UTC) Received: by mail-ej1-f45.google.com with SMTP id d8so17232201ejc.4 for ; Fri, 19 Feb 2021 17:24:18 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=intel-com.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=OI5diTT0Rk6aefWjwmf2Q0VLq/9wnZnAvXpY8uK5nUQ=; b=zJfceaRPvyJ6XZa2IRAPEjVVrbFYpp8LYpGQ3my7yGihQIEhzjOCVxmTiO2uw4T73u 2jk3Kb3huR1HG20iemJlm8FOxMT9lJ2P4dszGflF0jW0bKFGsS4TA2Vxw0kW9N2uCoBj F6aoBFfaGVoP+nnQ8z6hWWxZgRIDNLm144edAxTalfKaXHfJvOGEHzG5SWx/xU0GA4aM TUlLVu1u53Vf65vMDCwbLfLR/XGx/sSDa7ifiTleuevxNChFpoI8RbX76fnrHEvI5QU/ xR2Qyp51J8IaK4ZyiCfWPQ61mkF00O41wSjPMXtviS5Ak/qyvtQjPYO5gbBEALVImwEF to2g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=OI5diTT0Rk6aefWjwmf2Q0VLq/9wnZnAvXpY8uK5nUQ=; b=Fdmyl4xEe5Vk8WT1aWS2EOqg5BEJkEqyUaurLhkuZ5gkGG196kx5nAUmBHQlWt8c1J YrTl6y7yTLBoh5iMJXD4v4HJc3wL+S0rsE1j+so8OfQosPBa3F1sZNj8Yt6r9lnSmRfw TFOOX0KYHBzBhb67CRLYaZXUws6x1lzrUgBFNj/liFPhPoD+caGVmUEw6WMu6oFu9voI SVO4hzMb69Kj7CaHNhU100Txi964hvFD8g4lNokmIrhb+uvKqTQ7P9xNLO6ie75ZsTR2 AJ2EeVvpOOBHwIKp9rVM+bycI9EIEt+bu5ajF8518R5zJ54NvC8yaJ32B/Vggti9rpJ2 komQ== X-Gm-Message-State: AOAM532Z3xxOHgHYtKKGii/VQS0aDPKwN9gYgQJvtXcsorAClN8XXTKo 2+ZWv4KsvsnqQ0H5HxJmB4ZrgUuycXvpYJAsYINw1A== X-Google-Smtp-Source: ABdhPJyjHZZthx7MXPgxEnYR0n72AWETmXUIaUMfKn+DeqJXKwrmkbsGa/sIRoVbcrPAlQ6imr1TpcrwgPxKoAq3ajU= X-Received: by 2002:a17:906:cc91:: with SMTP id oq17mr10915211ejb.45.1613784257719; Fri, 19 Feb 2021 17:24:17 -0800 (PST) MIME-Version: 1.0 References: <20201208172901.17384-1-joao.m.martins@oracle.com> <20201208172901.17384-2-joao.m.martins@oracle.com> In-Reply-To: <20201208172901.17384-2-joao.m.martins@oracle.com> From: Dan Williams Date: Fri, 19 Feb 2021 17:24:09 -0800 Message-ID: Subject: Re: [PATCH RFC 1/9] memremap: add ZONE_DEVICE support for compound pages To: Joao Martins Cc: Linux MM , Ira Weiny , linux-nvdimm , Matthew Wilcox , Jason Gunthorpe , Jane Chu , Muchun Song , Mike Kravetz , Andrew Morton Content-Type: text/plain; charset="UTF-8" X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 76B2A2000381 X-Stat-Signature: m96p86mj3zfrt73ygaqb5bzyib4nwray Received-SPF: none (intel.com>: No applicable sender policy available) receiver=imf11; identity=mailfrom; envelope-from=""; helo=mail-ej1-f45.google.com; client-ip=209.85.218.45 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1613784252-354990 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 Tue, Dec 8, 2020 at 9:32 AM Joao Martins wrote: > > Add a new flag for struct dev_pagemap which designates that a a pagemap > is described as a set of compound pages or in other words, that how > pages are grouped together in the page tables are reflected in how we > describe struct pages. This means that rather than initializing > individual struct pages, we also initialize these struct pages, as > compound pages (on x86: 2M or 1G compound pages) > > For certain ZONE_DEVICE users, like device-dax, which have a fixed page > size, this creates an opportunity to optimize GUP and GUP-fast walkers, > thus playing the same tricks as hugetlb pages. > > Signed-off-by: Joao Martins > --- > include/linux/memremap.h | 2 ++ > mm/memremap.c | 8 ++++++-- > mm/page_alloc.c | 7 +++++++ > 3 files changed, 15 insertions(+), 2 deletions(-) > > diff --git a/include/linux/memremap.h b/include/linux/memremap.h > index 79c49e7f5c30..f8f26b2cc3da 100644 > --- a/include/linux/memremap.h > +++ b/include/linux/memremap.h > @@ -90,6 +90,7 @@ struct dev_pagemap_ops { > }; > > #define PGMAP_ALTMAP_VALID (1 << 0) > +#define PGMAP_COMPOUND (1 << 1) Why is a new flag needed versus just the align attribute? In other words there should be no need to go back to the old/slow days of 'struct page' per pfn after compound support is added.