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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9D3E2C77B76 for ; Sun, 16 Apr 2023 19:52:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229547AbjDPTv7 (ORCPT ); Sun, 16 Apr 2023 15:51:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37212 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229593AbjDPTv6 (ORCPT ); Sun, 16 Apr 2023 15:51:58 -0400 Received: from mail-yw1-x1131.google.com (mail-yw1-x1131.google.com [IPv6:2607:f8b0:4864:20::1131]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2C7A2CA for ; Sun, 16 Apr 2023 12:51:57 -0700 (PDT) Received: by mail-yw1-x1131.google.com with SMTP id 00721157ae682-54ee0b73e08so401511317b3.0 for ; Sun, 16 Apr 2023 12:51:57 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20221208; t=1681674716; x=1684266716; h=mime-version:references:message-id:in-reply-to:subject:cc:to:from :date:from:to:cc:subject:date:message-id:reply-to; bh=+XV1SaR4oDj2LmHIYbtEP9BS2GzUn6i8QGpmiK2pWes=; b=35GxN9QmW2hjy0Dfkmb2w05f+ZtVlxILgN7uYJpNWJLcIPK3szAO7GVlFCTIxLRIFw ovaBhQJgVADB9Q6ICg7hyMv/NAh8j0wq800X9YdYJ/dDjbdghw8JokHMRoEQNsIdRkdC WLiQXpG4Q+TttdZCcEbXfxWBxXC2GFAHRO1LtQZQgEpcMxrKREN4Avy2QCWCb6+mN3qa FRLCFpSJV0ak+dFRGggbPcpzGTkIvZjikma5vN7FHtcFbl8p3SNMYoZ+VAOk0dtr67BG CWcPeQAuI2DkTnaae9/D0Af3q8cBuCh0xrhWT3C7wipnfK4eVsi6qPFipvyeb/FiaUE3 Z2Xg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1681674716; x=1684266716; h=mime-version:references:message-id:in-reply-to:subject:cc:to:from :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=+XV1SaR4oDj2LmHIYbtEP9BS2GzUn6i8QGpmiK2pWes=; b=JZUJBopgNR8QILASmPkdGwWoLUvkEjmq/8KBdu4HRrUDmr46pkN2GuQ1n50tIrT35H lNFd9h8VYowY2gCraxoSdmcJBk0af8Q2lpBqdKvxqfTrXfA8ACNo1vulvA2qMjPFDky7 8bmQrBd4+KNBUjoIDaaP21x18Q3SF4Chq25u4+RCGQHsUGipLsytwbtP19gJ7RjJG5gd lgb5kbH5vdFtthCXv1oK1mmsdAB0FMMRA4pVoIUExdTalWqP3ixx+xKwAIZkH5mWr1T+ J2MN5AH615OKDMyJi2vkNL7wxeD8o/DlwB8YjWEWh8ypgGw2kNldh77fgIit6Pm8+U8W jxvQ== X-Gm-Message-State: AAQBX9cI4kVHWiV5suZJDkOQhDkkv3sEIXQ3L0wwLZzcmg/4Su0dMImx qfR7DeJ+T+06BBCw2ThEFHbhVA== X-Google-Smtp-Source: AKy350aso6IEsDAN1exazMbmo6Wh+kHtNe004GaFkMaSD4/1/07yu0c9ScNQNbT2abH6NzKDCzhu7g== X-Received: by 2002:a81:a210:0:b0:54e:ffbd:7a7e with SMTP id w16-20020a81a210000000b0054effbd7a7emr13157859ywg.45.1681674716340; Sun, 16 Apr 2023 12:51:56 -0700 (PDT) Received: from ripple.attlocal.net (172-10-233-147.lightspeed.sntcca.sbcglobal.net. [172.10.233.147]) by smtp.gmail.com with ESMTPSA id 22-20020a810b16000000b0054fae5ed408sm2677063ywl.45.2023.04.16.12.51.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 16 Apr 2023 12:51:55 -0700 (PDT) Date: Sun, 16 Apr 2023 12:51:46 -0700 (PDT) From: Hugh Dickins X-X-Sender: hugh@ripple.attlocal.net To: Zi Yan cc: "Matthew Wilcox (Oracle)" , Yang Shi , Yu Zhao , linux-mm@kvack.org, "Kirill A . Shutemov" , Ryan Roberts , =?ISO-8859-15?Q?Michal_Koutn=FD?= , Roman Gushchin , Zach O'Keefe , Andrew Morton , linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: Re: [PATCH v3 6/7] mm: truncate: split huge page cache page to a non-zero order if possible. In-Reply-To: <9dd96da-efa2-5123-20d4-4992136ef3ad@google.com> Message-ID: <86864d6c-39d3-d26f-278f-b96e14884541@google.com> References: <20230403201839.4097845-1-zi.yan@sent.com> <20230403201839.4097845-7-zi.yan@sent.com> <9dd96da-efa2-5123-20d4-4992136ef3ad@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org > As this code stands, truncate a 2M huge page at 1M and you get two 1M > pieces (one then discarded) - nice; but truncate it at 1M+1 and you get > lots of order 2 (forced up from 1) pieces. Seems weird, and not worth > the effort. I've probably said that wrong: truncate at 1M+1 and you'd get lots of order 0 pieces. Hugh