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[209.132.180.67]) by mx.google.com with ESMTP id b10-v6si22561310pla.282.2018.05.24.19.34.13; Thu, 24 May 2018 19:34:28 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20161025 header.b=BK9HFd0Q; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1034198AbeEXR2b (ORCPT + 99 others); Thu, 24 May 2018 13:28:31 -0400 Received: from mail-it0-f66.google.com ([209.85.214.66]:37803 "EHLO mail-it0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1031100AbeEXR22 (ORCPT ); Thu, 24 May 2018 13:28:28 -0400 Received: by mail-it0-f66.google.com with SMTP id 70-v6so3414583ity.2 for ; Thu, 24 May 2018 10:28:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=XXNMwNh6nXwZtxzd1ikKBo5st23P7xGSkr/EOG3ZQis=; b=BK9HFd0QvinyY6mVbDdTEaNcF2Z1pXkeCe4BpgbJD/SmeaJDo4b1+oK/8iBaAMhKyI u07ItQ1bRUw0O7t4lPXZtmMXnFyHK66GarqtEKmbYntUjTwUoETQ9k2VGg3RU8kbk5+A KuKMw2UvZ0atkYXlgXlMMs3eIUAbrfk8JR/Qi1j+lvE4UHpcxBmDZTFApivyD/WYC532 p/eVXd/ggNl4HAVv9oB0ikyuSh9MezJzBkvlv8EZLUq9QvWyj90pDEuHF8wzTSBa8RGq FCy56Zu00bg/PAcapBEUHT8zhu40V0ApnqPM8NRqONIesaEIM7jTEHuEJkMvg7rnYabM 0TyQ== 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=XXNMwNh6nXwZtxzd1ikKBo5st23P7xGSkr/EOG3ZQis=; b=NoQB4nOp4Y/f5mKmVl/NC2D/glRDGNL0Tin1IKiPOC/U4ESaYlvCIsgum/hRGLiA1k /N1ikxUGxV3QrdQN2nl9fJ4fAobIajH+tp6kdVg9IymM2NLg3ZOtoK83NyekP5gWBoIN yNL7jM8U/ymylUdlwDIdiKauC+kPyWf4sTD/4fX4RWcOOM0TMFpDvchG+a8FndDMWufC 6Ax0Kahbto9FOeWbeSIrknDQOUY8mPAX5vSj2F0afgVn0hwnMqh42riyYXSaUklgzeh9 CZ1e8LBobgJuHT8u+O6lkxfav21LPI71L4q3DklONzxs+Bto6qZq38ozsk/5nRnz8aHr SAqw== X-Gm-Message-State: ALKqPwcHeZrK4xsoPc+e+aKHxCQEqq0g2i3Igk5z4YXI5AhRgUmosvSA +gqGceRHY8/ex+2JGaFWHxRlSFmRNXF3dFiTfZaQrQ== X-Received: by 2002:a24:5091:: with SMTP id m139-v6mr10144664itb.50.1527182907235; Thu, 24 May 2018 10:28:27 -0700 (PDT) MIME-Version: 1.0 References: <20180524093159.286472249@linuxfoundation.org> <20180524093204.290399449@linuxfoundation.org> <20180524105011.jkmjrmoyqtogtgnn@quack2.suse.cz> <20180524110546.GA16171@kroah.com> <20180524112841.GA17626@kroah.com> In-Reply-To: <20180524112841.GA17626@kroah.com> From: Hugh Dickins Date: Thu, 24 May 2018 10:27:59 -0700 Message-ID: Subject: Re: [PATCH 4.4 50/92] mm: filemap: avoid unnecessary calls to lock_page when waiting for IO to complete during a read To: Greg KH Cc: Jan Kara , linux-kernel , stable , Mel Gorman , Andrew Morton , Linus Torvalds , Mel Gorman Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, May 24, 2018 at 4:28 AM Greg KH wrote: > On Thu, May 24, 2018 at 04:17:12AM -0700, Hugh Dickins wrote: > > Thu, May 24, 2018 at 4:06 AM Greg Kroah-Hartman > > > > wrote: > > > > > On Thu, May 24, 2018 at 12:50:11PM +0200, Jan Kara wrote: > > > > On Thu 24-05-18 11:38:27, Greg Kroah-Hartman wrote: > > > > > 4.4-stable review patch. If anyone has any objections, please let me > > know. > > > > > > > > Just one objection: Why does stable care about this (and the previous > > > > patch)? I've checked the stable queue and I don't see anything that > > would > > > > have these patches as a prerequisite. And on their own, they are only > > > > cleanups without substantial gains. > > > > > There's a small gain here: > > > > > > > paralleldd > > > > > 4.4.0 4.4.0 > > > > > vanilla avoidlock > > > > > Amean Elapsd-1 5.28 ( 0.00%) 5.15 ( 2.50%) > > > > > Amean Elapsd-4 5.29 ( 0.00%) 5.17 ( 2.12%) > > > > > Amean Elapsd-7 5.28 ( 0.00%) 5.18 ( 1.78%) > > > > > Amean Elapsd-12 5.20 ( 0.00%) 5.33 ( -2.50%) > > > > > Amean Elapsd-21 5.14 ( 0.00%) 5.21 ( -1.41%) > > > > > Amean Elapsd-30 5.30 ( 0.00%) 5.12 ( 3.38%) > > > > > Amean Elapsd-48 5.78 ( 0.00%) 5.42 ( 6.21%) > > > > > Amean Elapsd-79 6.78 ( 0.00%) 6.62 ( 2.46%) > > > > > Amean Elapsd-110 9.09 ( 0.00%) 8.99 ( 1.15%) > > > > > Amean Elapsd-128 10.60 ( 0.00%) 10.43 ( 1.66%) > > > > > > > > > > The impact is small but intuitively, it makes sense to avoid > > unnecessary > > > > > calls to lock_page. > > > > > Yes, it's small, but it's marked in the SLES kernel as "needs to be > > > merged into stable", so obviously it matters to someone :) > > > > Hmm. I had the same reaction to these two as Jan, but assumed that they > > made applying later patches easier, and didn't take the trouble he did to > > find that's not so. > > > > I've no wish to be disputatious, but it does seem that the definition of > > "stable" has changed, and not necessarily for the better, if it's now a > > home for small gains: I thought we left those to upstream. > This is in the SLES kernel for a reason, and again, it's in the section > that says "this should be pushed to stable". So if it's good enough for > the SLES kernel, why isn't it good enough for all users of this kernel > tree? > If you all think it should be dropped in both places, that's fine with > me :) I think they are perfectly fine in SLES: folding in good work is a part of what distros are about. But I cannot find anything in stable-kernel-rules.rst that would admit them - perhaps that's just out of date? If -stable is to be a compendium of "this looks nice, you might like to include it", so be it: but the rules should then be updated. Hugh