Date: Fri, 16 Mar 2018 12:07:05 -0600 From: Ian Lepore <ian@freebsd.org> To: Patrick Kelsey <pkelsey@freebsd.org>, freebsd-hackers@freebsd.org Subject: Re: option TCP_RFC7413 is not in GENERIC Message-ID: <1521223625.99081.61.camel@freebsd.org> In-Reply-To: <CAD44qMU7jMKtzeWzwQxMiWz1BQMNdtkQ516RbcOoXMnJzMs5Sw@mail.gmail.com> References: <1521062028.2511351.1303413736.6960BF4F@webmail.messagingengine.com> <20180314233811.GA35025@mail.bsd4all.net> <CAD44qMUR_bKOzaWLMatGT3xXWdovWm3Abv8zwu=NCVm6YjEkiQ@mail.gmail.com> <1521216713.99081.55.camel@freebsd.org> <CAD44qMU7jMKtzeWzwQxMiWz1BQMNdtkQ516RbcOoXMnJzMs5Sw@mail.gmail.com>
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On Fri, 2018-03-16 at 16:42 +0000, Patrick Kelsey wrote: > On Fri, Mar 16, 2018 at 12:12 PM Ian Lepore <ian@freebsd.org> 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 Oh, then I assume it's because TCP_FASTOPEN is in the default options when the package gets built. -- Ian
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