From owner-svn-src-head@FreeBSD.ORG Mon Dec 1 15:49:21 2014 Return-Path: Delivered-To: svn-src-head@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id D752D150; Mon, 1 Dec 2014 15:49:21 +0000 (UTC) Received: from bigwig.baldwin.cx (bigwig.baldwin.cx [IPv6:2001:470:1f11:75::1]) (using TLSv1 with cipher DHE-RSA-CAMELLIA256-SHA (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id ACA82F17; Mon, 1 Dec 2014 15:49:21 +0000 (UTC) Received: from ralph.baldwin.cx (pool-173-70-85-31.nwrknj.fios.verizon.net [173.70.85.31]) by bigwig.baldwin.cx (Postfix) with ESMTPSA id 10981B94E; Mon, 1 Dec 2014 10:49:20 -0500 (EST) From: John Baldwin To: Alfred Perlstein Subject: Re: svn commit: r275136 - in head/sys: dev/e1000 dev/ixgbe kern sys Date: Mon, 01 Dec 2014 10:49:16 -0500 Message-ID: <1762770.yx1cv63jp7@ralph.baldwin.cx> User-Agent: KMail/4.14.2 (FreeBSD/10.1-STABLE; KDE/4.14.2; amd64; ; ) In-Reply-To: <872C180A-6ADD-469F-A801-3728DF134EEC@mu.org> References: <201411262019.sAQKJaw4043557@svn.freebsd.org> <39377603.10OyiSzjWY@ralph.baldwin.cx> <872C180A-6ADD-469F-A801-3728DF134EEC@mu.org> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.2.7 (bigwig.baldwin.cx); Mon, 01 Dec 2014 10:49:20 -0500 (EST) Cc: "svn-src-head@freebsd.org" , "svn-src-all@freebsd.org" , Alfred Perlstein , "src-committers@freebsd.org" X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 01 Dec 2014 15:49:22 -0000 On Monday, December 01, 2014 07:19:13 AM Alfred Perlstein wrote: > John, > > Will work on a new revision based on feedback. > > Two things to note however: > > Already explored the idea of using kernel_sysctlbyname but rejected due to > following: > > It makes little sense to have a rw sysctl that only takes effect "some > times". This violates POLA at the expense of making code appear cleaner. > Expectation is that writable sysctls take effect or are read only. They are > not to be "write sometimes" unless we are to introduce a new flag. Instead > of going to a confusing model we consider some form of rw sysctl that can > set itself ro somehow. Otherwise people will be confused as to why nic > queues says N while actually M. What the rw->ro api would look like I have > no idea. Suggestions? This is only somewhat true. In the near distant future we will have a devctl tool which would let you do 'devctl detach igb0 && devctl attach igb0' which would honor your post-boot setting of hw.igb.num_queues. Instead what is important to understand about this particular sysctl node is that it only takes affect when a device is attached. However, there are other control knobs that also only affect future operations and not existing instances of objects, so I don't think this is that big of a leap. -- John Baldwin