From owner-svn-src-stable-10@freebsd.org Mon Dec 28 03:15:47 2015 Return-Path: Delivered-To: svn-src-stable-10@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 DE97EA4D62C; Mon, 28 Dec 2015 03:15:47 +0000 (UTC) (envelope-from pkelsey@gmail.com) Received: from mail-yk0-x230.google.com (mail-yk0-x230.google.com [IPv6:2607:f8b0:4002:c07::230]) (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 A5BE81B35; Mon, 28 Dec 2015 03:15:47 +0000 (UTC) (envelope-from pkelsey@gmail.com) Received: by mail-yk0-x230.google.com with SMTP id x67so92139936ykd.2; Sun, 27 Dec 2015 19:15:47 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:sender:in-reply-to:references:date:message-id:subject :from:to:cc:content-type; bh=+hAi1Pc+fR5n+2e/u+UgqH4ndvAoWIMwAN83HW7OgzU=; b=pwnFx5aHBeeurmRyajIcRJoKlKnQO8IO/n84Qhy0uppogt2rhLECtQ6ioZ5X2vaQ79 tHd6xecFWmMlihB7wENRut4mtTEJOx1pUIvSdjRCb0jtemvWrC3T++Z4COAI8MnFRGbs mtkQe2cATH3d+4Hi/MARUGjEAuIILX8yeRUByXv96jxt9iy5IlxOl97NWnVXQmURAPeB elhoWMqpopbw8owoQENayBxPYyG3i//GMhjITM13dQ1qxhPeQ2oNa17nQf74lfCVNXS4 be/RM0nz3MwMYgOkxTgqKx5OSKZmG8ykEkloqn1/iBQKqoq9yLfvGZD2cV/jCtN3uxPc 6XkA== MIME-Version: 1.0 X-Received: by 10.129.117.132 with SMTP id q126mr2206980ywc.184.1451272546949; Sun, 27 Dec 2015 19:15:46 -0800 (PST) Sender: pkelsey@gmail.com Received: by 10.13.211.65 with HTTP; Sun, 27 Dec 2015 19:15:46 -0800 (PST) In-Reply-To: <5680A574.9050002@freebsd.org> References: <201512280243.tBS2hD7X008202@repo.freebsd.org> <5680A574.9050002@freebsd.org> Date: Sun, 27 Dec 2015 22:15:46 -0500 X-Google-Sender-Auth: J5rtvYA0-J9AysdF77aII9cfOZs Message-ID: Subject: Re: svn commit: r292823 - in stable/10/sys: conf netinet From: Patrick Kelsey To: Andrey Chernov Cc: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-10@freebsd.org Content-Type: text/plain; charset=UTF-8 X-Content-Filtered-By: Mailman/MimeDel 2.1.20 X-BeenThere: svn-src-stable-10@freebsd.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: SVN commit messages for only the 10-stable src tree List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 28 Dec 2015 03:15:48 -0000 On Sun, Dec 27, 2015 at 9:59 PM, Andrey Chernov wrote: > On 28.12.2015 5:43, Patrick Kelsey wrote: > > Author: pkelsey > > Date: Mon Dec 28 02:43:12 2015 > > New Revision: 292823 > > URL: https://svnweb.freebsd.org/changeset/base/292823 > > > > Log: > > MFC r292706: > > > > Implementation of server-side TCP Fast Open (TFO) [RFC7413]. > > > > TFO is disabled by default in the kernel build. See the top comment > > in sys/netinet/tcp_fastopen.c for implementation particulars. > > Why it is disabled by default? Do we need some rc.conf knobs to not deal > directly with it, like tcp_extensions? OMG, why it is kernel config and > not boot-time sysctl? > This is explained in the top comment in sys/netinet/tcp_fastopen.c, but I will repeat it here and elaborate a little. It is disabled by default in the kernel build as a conservative measure until it is exercised more widely, given the modifications it introduces to the TCP state machine code, syncache code, etc. When you do enable it in the kernel build (and after some point in the future when it is enabled by default), there is still a sysctl that governs its availability in the system that must be enabled before it can be used. -Patrick