From owner-svn-src-all@FreeBSD.ORG Sat Mar 21 12:00:24 2015 Return-Path: Delivered-To: svn-src-all@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 29E7BDE6; Sat, 21 Mar 2015 12:00:24 +0000 (UTC) Received: from mail-pd0-x229.google.com (mail-pd0-x229.google.com [IPv6:2607:f8b0:400e:c02::229]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id E6B42D3C; Sat, 21 Mar 2015 12:00:23 +0000 (UTC) Received: by pdbcz9 with SMTP id cz9so134666177pdb.3; Sat, 21 Mar 2015 05:00:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=sender:reply-to:subject:references:to:from:message-id:date :user-agent:mime-version:in-reply-to:content-type :content-transfer-encoding; bh=PQ4daqP7uSJqMmDG8Z0+WGwlUpAhLKGyF6ONdDzGqAQ=; b=Siyq0qn9XC8GzHn8Uh7qVoJK7iaK0wlLrqTIP3l5Oo2JxOLKvCNcy/wnhZb6kHtzXT bS4nDMAKthtzReE2M/mbMd3nzp9JmU1ShZXKeypPYujxwk/NnAxbespMSp/F/5hyUVvA f/ikXtuGxSsuTi0/iEgQSki92YTQyYOwREm6s7rZqiuM1s/x1zocGMaFcLlWO8QrNJhi wqcePiPfjHjeF6b+7wkZUBMn7un2QPAtzGGdirt956GPATawz/o9n0KFPZLayUk9zE9X 7mlk0OugBrspao1Jmej6GUPm6kWFJ1x5nnKsLAw2eitQfgh6w4zO4nhwF602gCvi5OLT yOSw== X-Received: by 10.66.253.101 with SMTP id zz5mr167161702pac.143.1426939223414; Sat, 21 Mar 2015 05:00:23 -0700 (PDT) Received: from [192.168.1.104] (ppp59-167-128-11.static.internode.on.net. [59.167.128.11]) by mx.google.com with ESMTPSA id rk5sm11450606pab.37.2015.03.21.05.00.20 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sat, 21 Mar 2015 05:00:22 -0700 (PDT) Sender: Kubilay Kocak Reply-To: koobs@FreeBSD.org Subject: Re: svn commit: r280308 - head/sys/fs/devfs references: <201503210114.t2L1ECcB075556@svn.freebsd.org> To: Xin LI , src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org x-enigmail-draft-status: N1110 From: Kubilay Kocak message-id: <550D5D49.6020503@FreeBSD.org> Date: Sat, 21 Mar 2015 23:00:09 +1100 user-agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:37.0) Gecko/20100101 Thunderbird/37.0 mime-version: 1.0 in-reply-to: <201503210114.t2L1ECcB075556@svn.freebsd.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-BeenThere: svn-src-all@freebsd.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: "SVN commit messages for the entire src tree \(except for " user" and " projects" \)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 21 Mar 2015 12:00:24 -0000 On 21/03/2015 12:14 PM, Xin LI wrote: > Author: delphij > Date: Sat Mar 21 01:14:11 2015 > New Revision: 280308 > URL: https://svnweb.freebsd.org/changeset/base/280308 > > Log: > Disable timestamping on devfs read/write operations by default. > > Currently we update timestamps unconditionally when doing read or > write operations. This may slow things down on hardware where > reading timestamps is expensive (e.g. HPET, because of the default > vfs.timestamp_precision setting is nanosecond now) with limited > benefit. > > A new sysctl variable, vfs.devfs.dotimes is added, which can be > set to non-zero value when the old behavior is desirable. Perhaps *devfs_timestamp_update* is a better name. thoughts? If something shorter is desired: devfs_ts_update might be ok, though I prefer the former. Let's not forget these are user visible system control knobs, not just code variables, though I do understand the desire to shorten them, and that we do have descriptions for them ... mostly :) koobs