From owner-cvs-src@FreeBSD.ORG Thu Dec 29 16:16:59 2005 Return-Path: X-Original-To: cvs-src@FreeBSD.ORG Delivered-To: cvs-src@FreeBSD.ORG Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id E924816A41F; Thu, 29 Dec 2005 16:16:59 +0000 (GMT) (envelope-from dds@aueb.gr) Received: from mx-out-01.forthnet.gr (mx-out.forthnet.gr [193.92.150.4]) by mx1.FreeBSD.org (Postfix) with ESMTP id 8667C43D8B; Thu, 29 Dec 2005 16:16:21 +0000 (GMT) (envelope-from dds@aueb.gr) Received: from mx-av-03.forthnet.gr (mx-av.forthnet.gr [193.92.150.27]) by mx-out-01.forthnet.gr (8.13.5/8.13.5) with ESMTP id jBTGGGUV017036; Thu, 29 Dec 2005 18:16:16 +0200 Received: from mx-in-02.forthnet.gr (mx-in-02.forthnet.gr [193.92.150.185]) by mx-av-03.forthnet.gr (8.13.5/8.13.5) with ESMTP id jBTGGGLQ022278; Thu, 29 Dec 2005 18:16:16 +0200 Received: from [192.168.136.16] (ppp46-adsl-254.ath.forthnet.gr [62.1.63.254]) by mx-in-02.forthnet.gr (8.13.5/8.13.5) with ESMTP id jBTGGFdO001091; Thu, 29 Dec 2005 18:16:15 +0200 Authentication-Results: mx-in-02.forthnet.gr from=dds@aueb.gr; sender-id=neutral; spf=neutral Message-ID: <43B40BD1.7020400@aueb.gr> Date: Thu, 29 Dec 2005 18:16:17 +0200 From: Diomidis Spinellis User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7.3) Gecko/20040910 X-Accept-Language: en, el, en-us, de MIME-Version: 1.0 To: Brian Fundakowski Feldman References: <200512261347.jBQDlKUB022385@repoman.freebsd.org> <20051229150819.GA27794@green.homeunix.org> In-Reply-To: <20051229150819.GA27794@green.homeunix.org> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Cc: cvs-src@FreeBSD.ORG, src-committers@FreeBSD.ORG, Diomidis Spinellis , cvs-all@FreeBSD.ORG Subject: Re: cvs commit: src/sys/kern kern_exec.c vfs_subr.c src/sys/sys vnode.h src/sys/ufs/ufs ufs_vnops.c src/sys/vm vm_mmap.c X-BeenThere: cvs-src@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: CVS commit messages for the src tree List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 29 Dec 2005 16:17:00 -0000 Brian Fundakowski Feldman wrote: > On Mon, Dec 26, 2005 at 01:47:20PM +0000, Diomidis Spinellis wrote: > >>dds 2005-12-26 13:47:20 UTC >> >> FreeBSD src repository >> >> Modified files: (Branch: RELENG_6) >> sys/kern kern_exec.c vfs_subr.c >> sys/sys vnode.h >> sys/ufs/ufs ufs_vnops.c >> sys/vm vm_mmap.c >> Log: >> MFC changes from 2005.10.26: >> Move execve's access time update functionality into a >> new vfs_mark_atime() function, and use the new function >> for performing efficient atime updates in mmap(). > > > Do you have any particular use cases that are improved a lot by > (seemingly) reducing gratuitous seeks for R/W file mappings? > Substantial improvement for the general case of not-noatime? > I have no comparative tests or use cases, because the base case was an earlier less-than-perfect change that only lived in HEAD for a week. The claimed "efficient atime updates in mmap()" are over an earlier change I committed to HEAD, but never MFCd (vm_mmap.c 1.202). I introduced that change to fix the behavior where reads through mmap(2)d files did not update the file's atime. As a result, for example, our implementation of cp(1) would copy files without updating the atime of the source. For that earlier change, bde@ complained: "This is a large pessimization for nfs and a usually-small pessimization for local file systems." The current implementation fixes that problem by following the existing approach in execve(2) (the then-named VA_EXECVE_ATIME flag), and is also cleaner than the earlier one. Diomidis