From owner-svn-src-all@freebsd.org Tue Feb 2 20:35:48 2016 Return-Path: Delivered-To: svn-src-all@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id A2C2DA98808; Tue, 2 Feb 2016 20:35:48 +0000 (UTC) (envelope-from alfred@freebsd.org) Received: from elvis.mu.org (elvis.mu.org [192.203.228.196]) by mx1.freebsd.org (Postfix) with ESMTP id 82D8B30B; Tue, 2 Feb 2016 20:35:48 +0000 (UTC) (envelope-from alfred@freebsd.org) Received: from Alfreds-MacBook-Pro-2.local (unknown [IPv6:2601:645:8001:cee1:c76:2f7d:b92b:76e4]) by elvis.mu.org (Postfix) with ESMTPSA id DED71345A97C; Tue, 2 Feb 2016 12:35:47 -0800 (PST) Subject: Re: svn commit: r295136 - in head: sys/kern sys/netinet sys/sys usr.bin/netstat To: Xin LI References: <201602020557.u125vxCP084718@repo.freebsd.org> <36439709.poT7RgRunK@ralph.baldwin.cx> <56B10D67.4050602@freebsd.org> Cc: John Baldwin , "src-committers@freebsd.org" , "svn-src-all@freebsd.org" , "svn-src-head@freebsd.org" From: Alfred Perlstein Organization: FreeBSD Message-ID: <56B11323.70905@freebsd.org> Date: Tue, 2 Feb 2016 12:35:47 -0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.11; rv:38.0) Gecko/20100101 Thunderbird/38.5.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-Content-Filtered-By: Mailman/MimeDel 2.1.20 X-BeenThere: svn-src-all@freebsd.org X-Mailman-Version: 2.1.20 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: Tue, 02 Feb 2016 20:35:48 -0000 On 2/2/16 12:23 PM, Xin LI wrote: > > > On Tuesday, February 2, 2016, Alfred Perlstein > wrote: > > > > On 2/2/16 11:39 AM, John Baldwin wrote: > > On Tuesday, February 02, 2016 05:57:59 AM Alfred Perlstein wrote: > > Author: alfred > Date: Tue Feb 2 05:57:59 2016 > New Revision: 295136 > URL: https://svnweb.freebsd.org/changeset/base/295136 > > Log: > Increase max allowed backlog for listen sockets > from short to int. > PR: 203922 > Submitted by: White Knight > MFC After: 4 weeks > > You do realize that this breaks the ABI of the sysctls used to > fetch > connection lists (and so will break existing binaries like > ucd-snmpd, etc.) > and thus can't be MFC'd right? > > OK, I will not MFC it. > > Is it worthwhile to extend the xsocket to have padding so that in > 11.x and beyond we can allow for some changes in the structure? > > Another idea I had was to include a version number with the sysctl > request so that we can send back versioned structures, let me know > what you think about that. > > The first idea will take not more than a few days for me to > accomplish, the second (versioning the sysctl) probably a few more > days than that. > > > We have similar construction (versioned ioctl) in FreeBSD ZFS but the > main goal is to keep system bootable, not to support all > functionalities. Do we change the structure often and is it important > enough to warrant the complexity? I think kmem interface have a > simple size check to guard against world/kernel inconsistency. > > I would second John's comment on the necessity of the change though, > if one already have 32K of *backlogged* connections, it's probably not > very useful to allow more coming in. It sounds like the application > itself is seriously broken, and unless expanding the field have some > performance benefit, I don't think it should stay. Imagine a hugely busy image board like 2ch.net, if there is a single hiccup, it's very possible to start dropping connections. I stand by the scalability improvement offered here even though it is an edge case. Linux appears to offer 32 bits of backlog and so should we. -Alfred