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=-0.7 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,HTML_MESSAGE,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no 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 BE7D1FA372A for ; Thu, 17 Oct 2019 14:11:58 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 7FDDA20854 for ; Thu, 17 Oct 2019 14:11:58 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="BXf6H2Za" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7FDDA20854 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 1B1078E0005; Thu, 17 Oct 2019 10:11:58 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 1610C8E0003; Thu, 17 Oct 2019 10:11:58 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0776E8E0005; Thu, 17 Oct 2019 10:11:58 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0152.hostedemail.com [216.40.44.152]) by kanga.kvack.org (Postfix) with ESMTP id DA5A58E0003 for ; Thu, 17 Oct 2019 10:11:57 -0400 (EDT) Received: from smtpin02.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with SMTP id 6B720181AEF32 for ; Thu, 17 Oct 2019 14:11:57 +0000 (UTC) X-FDA: 76053465474.02.linen15_4b39a2282fb2f X-HE-Tag: linen15_4b39a2282fb2f X-Filterd-Recvd-Size: 3283 Received: from mail-qt1-f169.google.com (mail-qt1-f169.google.com [209.85.160.169]) by imf46.hostedemail.com (Postfix) with ESMTP for ; Thu, 17 Oct 2019 14:11:56 +0000 (UTC) Received: by mail-qt1-f169.google.com with SMTP id c21so3704143qtj.12 for ; Thu, 17 Oct 2019 07:11:56 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:from:date:message-id:subject:to; bh=xERHjlRH2bdoigHKQX8XzL/osfTXlovF88YRA4L8vqw=; b=BXf6H2ZaT4OScbVFLz1rXh/Tlue3e1Rc728qPyhjuhD96AKXn6deUxS0ugnCxtUOZK dPWwQDrvLLhbUM2wGKm06KDxfPu6k/+OVIGx371+T+6AL3LptAPINxjl4ykT2fOLykih Juu13WatrAoYqb3uT3h1IKv/4ec6f3BtYZt/UPy1VqSIUN4KEhxTWi/cEV/RSzc6rAqx UpO6C1If+RdS9a+AuPPq6+lCFnKlVq4+eC5Ku9Wr7pl7d2tDVrV6Xv8L8/oXEX2YKrPc W9P+Cc7y1uKH/hjICbkc5hdjCTB2Hkt9KNDfYXwlplhDdpr5Wbk0jw9K0iwNXu6BR5AG daPg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:from:date:message-id:subject:to; bh=xERHjlRH2bdoigHKQX8XzL/osfTXlovF88YRA4L8vqw=; b=gzb8ye4mYxo9EWGBNLtbPRSBLV06mmTvsoSCzmWjwk7cqrZyPsMNZFcVpySEQGftDG UQUyyp4XVWSlSBatVCFkBX+XMsfrKeUNt+ZjSbcqqWouh6+iZWEcfPr3/DUZITP0qZ4t 47RKZtF95DGPZa5fENVwqKs29nEh+i53EstuYgmb1AMIOQMpQkKuSP4xNEuLzJ6pjYpn nUj4TRbgy0arxdQrDeDw+80fOX4/3WN+XmCpugzpXGebHK26A1tdQGzv2XU9W2Pk2MCJ FKTz0aQqYulFpG9f+v2oFkz+xlC521D4fU3JImaCR3RlEhVDYxPufu6vjWuAeKEYyZEV GVsQ== X-Gm-Message-State: APjAAAUja0JRuPpB8u4q7zpPODxUsWsqaQShk7JB8b5dCjueuu+E94XN zLIec65s4DjCkO+M+RsPr3tNFeZQ9hXLAuVtvkSQ6Y42 X-Google-Smtp-Source: APXvYqzDDTrr3cWBFsDhlnAlx20xxBvYRXkQbNzd3YoPTkIhvt8mWhy86cGMS/dllcZVDNgVtcau9LB2/koZMWrV+ks= X-Received: by 2002:ac8:13c6:: with SMTP id i6mr3973798qtj.265.1571321516167; Thu, 17 Oct 2019 07:11:56 -0700 (PDT) MIME-Version: 1.0 From: Hao Lee Date: Thu, 17 Oct 2019 22:11:41 +0800 Message-ID: Subject: [Question] Can PageReferenced() be replaced by reverse-mapping and pte_young()? To: linux-mm@kvack.org Content-Type: multipart/alternative; boundary="000000000000cc9beb05951bcccf" X-Bogosity: Ham, tests=bogofilter, spamicity=0.124871, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: --000000000000cc9beb05951bcccf Content-Type: text/plain; charset="UTF-8" PG_referenced means "The page has been recently accessed." I think we can also check if a page has been accessed recently using reverse-mapping and pte_young(), though using PG_referenced is more efficient. I don't know if performance is the only reason we use PG_referenced flag. Thanks. Regards, Hao Lee --000000000000cc9beb05951bcccf Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
PG_referenced means "The page has been recently acces= sed." I think we can also check if a page has been accessed recently u= sing reverse-mapping and pte_young(), though using PG_referenced is more ef= ficient. I don't know if performance is the only reason we use PG_refer= enced flag. Thanks.

Regards,
Hao Lee
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