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=-13.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL 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 CB371C433E0 for ; Wed, 24 Feb 2021 23:51:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7485264F10 for ; Wed, 24 Feb 2021 23:51:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234006AbhBXXvb (ORCPT ); Wed, 24 Feb 2021 18:51:31 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34986 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232491AbhBXXv1 (ORCPT ); Wed, 24 Feb 2021 18:51:27 -0500 Received: from mail-io1-xd33.google.com (mail-io1-xd33.google.com [IPv6:2607:f8b0:4864:20::d33]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D9589C061574 for ; Wed, 24 Feb 2021 15:50:46 -0800 (PST) Received: by mail-io1-xd33.google.com with SMTP id i8so3974189iog.7 for ; Wed, 24 Feb 2021 15:50:46 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=HHAMxwO0RN5Il90ir5Bo3fGze6LKQGtEHSeat0z2uIo=; b=cRo4toHeGxpVexHF/YAEG+uIWzAyWs1pK2mIlg962ut4/vVoLntcPQZC6JdtFf92zU oxIx+Ht1M/6QSNgA2r3AX1dDXz8MpQQz/PmYwze5GeydKZIi7V7NcH+ogPC1DCtzQ/0S +WXL8pZzow/0r5Z7THeNawXu1DpSqsGgzl/RhKoerkFM0/cTbArlm6qP5eq4Zw3Vfsoh 7txgTpuf0ogRJxJhRzuGsdiJlgs3qqkQInLSgRC7YlemI7P9CzSHS6tMMYaH882XuLuF yDxXOnuWZeD62+EvMooff1tpbv6gy4lfZFFmUhRZ2rp2l8CsZUg1LiuFH352Jb2x0Ch6 VwBA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=HHAMxwO0RN5Il90ir5Bo3fGze6LKQGtEHSeat0z2uIo=; b=Fr7e+7/2RjCx7e6/OWAiXTz5bnBEPFkySAFl7sjbfvhnTQupCugea/W0SUzDVwMQ6q R33UnFcFeR2SxDlOwhzIZ/CbJahxPaT01BTns1FtM98bWz8rQRYalwrNYP2UhPdZePhe MNSnRc5012pa07ot9oUfJEF4wuG71aoTTkhh9IjWoULyR7K2XrKW4liobiGjASRqaBwf Vu+/45HSSz/JcOI9CO8sOG0nWYmgd5VfVYh9R1k+WU1cxPMRlsX1ooZNe8zmxTF1EPKP hKWnvNeFnBcnB5rTh6rtjDBx/I0YZ4Ds4iWUto8UBUHpfHnvEHVTTSwEl1jEeUV3W9F0 UBaw== X-Gm-Message-State: AOAM533fMBGh4279X065wlDB+9i4fXdxHwzmg3c1jBjkRLq2TOdDuxPw Tf58Uvh0QtALG3tNXQVpigyF8g== X-Google-Smtp-Source: ABdhPJy6X/K39lgbmIovoZg4d8Uzw4vQJBZK8Vdk65weda6qzcWjI3+wRrtBRKSBq3o7hAr0ZAy/rg== X-Received: by 2002:a5d:9f4a:: with SMTP id u10mr310855iot.186.1614210646231; Wed, 24 Feb 2021 15:50:46 -0800 (PST) Received: from google.com ([2620:15c:183:200:c037:ba21:bf5e:4d1f]) by smtp.gmail.com with ESMTPSA id o8sm2248030ilu.55.2021.02.24.15.50.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 24 Feb 2021 15:50:45 -0800 (PST) Date: Wed, 24 Feb 2021 16:50:39 -0700 From: Yu Zhao To: Matthew Wilcox Cc: Andrew Morton , vbabka@suse.cz, alex.shi@linux.alibaba.com, guro@fb.com, hannes@cmpxchg.org, hughd@google.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, mhocko@kernel.org, vdavydov.dev@gmail.com Subject: Re: [PATCH] mm: test page->flags directly in page_lru() Message-ID: References: <20210122220600.906146-11-yuzhao@google.com> <20210224084807.2179942-1-yuzhao@google.com> <20210224051558.79e31c60eea2c088f4a1b300@linux-foundation.org> <20210224215639.GT2858050@casper.infradead.org> <20210224224846.GU2858050@casper.infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210224224846.GU2858050@casper.infradead.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Feb 24, 2021 at 10:48:46PM +0000, Matthew Wilcox wrote: > On Wed, Feb 24, 2021 at 03:34:16PM -0700, Yu Zhao wrote: > > > If only somebody were working on a patch series to get rid of > > > all those calls to compound_head()! Some reviews on > > > https://lore.kernel.org/linux-mm/20210128070404.1922318-2-willy@infradead.org/ > > > would be nice. > > > > I'm on board with the idea and have done some research in this > > direction. We've found that the ideal *anon* page size for Chrome OS > > is not 4KB or 2MB, but 32KB. I hope we could leverage the folio to > > support flexible anon page size to reduce the number of page faults > > (vs 4KB) or internal fragmentation (vs 2MB). > > > > That being said, it seems to me this is a long term plan and right > > now we need something smaller. So if you don't mind, I'll just go > > ahead and remove compound_head() from Page{LRU,Active,Unevictable, > > SwapBacked} first? > > It's really not a big change I'm suggesting here. You need > https://lore.kernel.org/linux-mm/20210128070404.1922318-2-willy@infradead.org/ > https://lore.kernel.org/linux-mm/20210128070404.1922318-5-willy@infradead.org/ > https://lore.kernel.org/linux-mm/20210128070404.1922318-8-willy@infradead.org/ > and then the patch I sent above to create folio_lru(). > > Then any changes you want to make to use folios more broadly will > incrementally move us towards your goal of 32kB anon pages. Well, these patches introduce a new concept which I'm on board with. Assume everybody else is too, it still seems to me it's an overkill to employee folio to just get rid of unnecessary compound_head() in page_lru() -- this is not a criticism but a compliment. Let me work out something *conceptually* smaller first, and if you think folio is absolutely more suitable even for this specific issue, I'll go review and test the four patches you listed. Sounds good?