From owner-freebsd-hackers@freebsd.org Fri Mar 16 16:47:39 2018 Return-Path: Delivered-To: freebsd-hackers@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 782B5F5D149 for ; Fri, 16 Mar 2018 16:47:39 +0000 (UTC) (envelope-from pkelsey@gmail.com) Received: from mail-pf0-f172.google.com (mail-pf0-f172.google.com [209.85.192.172]) (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 EEF5C68CB5 for ; Fri, 16 Mar 2018 16:47:38 +0000 (UTC) (envelope-from pkelsey@gmail.com) Received: by mail-pf0-f172.google.com with SMTP id q13so4365709pff.0 for ; Fri, 16 Mar 2018 09:47:38 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to; bh=owqApDWUV6Vni4/aZ9glClQ7+EcpNTM+BXqEHCKDlVE=; b=qzZWfY3V7Uw9PnFp+iXK0GyT7/GQB0CYRNddPVtK20LxUqE8i/m2bKBLL1or0ho6i0 +D+pKN4f5RAvjNpX38QhGjEHBwC12VoOFDMFMwVR9g0SzG/1AQ4b5C6pFs4hhfOBrWBU hBWP8N8iJ6FqFqFYbMBvI49xiWeSE3nOlHwPV7q9WDBiEC+qZDx1B3bZI2FU0nZ+2U7m JXh6SD7v0MX2knErK8Pb9AcP1jzbE6x++Gp1Ew/4VSYXZmO9eHil+cUHIWua3t4qwhc1 Gtl+y8CqtdqFQuX8LUlpW+oJZUWsRB9k6CnmSlOpMkpTNuMkrDTPPY4+Ji+sIOZxGvwW moDA== X-Gm-Message-State: AElRT7FwbUaKqhEowQA7RanKzsTpWFniGsIx/zfXxoXs8ility722QdB mx5pZGfcNWp6mPUrrJ5+xl5Aw2UimVlH/VlGVEg= X-Google-Smtp-Source: AG47ELudBhBRaRrhi1AktdgYO3PPYSX9fazdD/6xV1ZkFBO5+3mv2olhytyK4Q/cyIj86/Q18e1PMz4jjIHPgwudQOM= X-Received: by 10.99.112.92 with SMTP id a28mr1921176pgn.17.1521218541005; Fri, 16 Mar 2018 09:42:21 -0700 (PDT) MIME-Version: 1.0 References: <1521062028.2511351.1303413736.6960BF4F@webmail.messagingengine.com> <20180314233811.GA35025@mail.bsd4all.net> <1521216713.99081.55.camel@freebsd.org> In-Reply-To: <1521216713.99081.55.camel@freebsd.org> From: Patrick Kelsey Date: Fri, 16 Mar 2018 16:42:10 +0000 Message-ID: Subject: Re: option TCP_RFC7413 is not in GENERIC To: freebsd-hackers@freebsd.org Content-Type: text/plain; charset="UTF-8" X-Content-Filtered-By: Mailman/MimeDel 2.1.25 X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.25 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 16 Mar 2018 16:47:39 -0000 On Fri, Mar 16, 2018 at 12:12 PM Ian Lepore wrote: > On Fri, 2018-03-16 at 16:04 +0000, Patrick Kelsey wrote: > > The current thinking is that users who care > > about such performance differences are dealing with extreme workloads > that > > already motivate them to compile their own kernels, or are working with > > very resource-constrained platforms, so the way forward is to keep the > > TCP_RFC7413 kernel option around and enable it by default for the > > server-class platforms (armd64 and arm64). > > I have no idea what TCP_RFC7413 even is, but I know I was forced to add > it to my kernel config when I installed the bind911 package during a > recent upgrade. This is on a tiny NUC for which saturating even one of > its gbe interfaces would count as "extreme workload". :) > > RFC7413 is TCP Fast Open (TFO), which is a way to short-circuit TCP handshakes if conditions are met. I'm curious as to why you were forced to add the option to your kernel config when you installed bind911. Maybe that version of bind was assuming something like 'if the TCP_FASTOPEN sockopt is defined in a header, then all setsockopt(TCP_FASTOPEN) should succeed or else die'? That would be a very weird assumption, as the MacOS, Linux, and FreeBSD implementations all have a sysctl that can be used to disable the feature system-wide at any point in time. -Patrick