Date: Sun, 20 Mar 2011 12:15:20 -0700 From: Gordon Tetlow <gordon@tetlows.org> To: Navdeep Parhar <nparhar@gmail.com> Cc: arch@freebsd.org, George Neville-Neil <gnn@neville-neil.com> Subject: Re: Updating our TCP and socket sysctl values... Message-ID: <AANLkTimnNoquvsE9AiNKFnErWwR81vugCkK2EabDebc9@mail.gmail.com> In-Reply-To: <AANLkTi=QRBj-u3rPaw37bLJ9yF4Qv1B11PQP-ybjkg16@mail.gmail.com> References: <132388F1-44D9-45C9-AE05-1799A7A2DCD9@neville-neil.com> <AANLkTi=ptv617t0KhgNrcxTUzLmQd0eLFBf2x4%2BP7EAL@mail.gmail.com> <AANLkTimOaVwy-ne6JWtaHqjtN3v6fEwbnasaRVi8M7gW@mail.gmail.com> <AANLkTi=QRBj-u3rPaw37bLJ9yF4Qv1B11PQP-ybjkg16@mail.gmail.com>
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On Sat, Mar 19, 2011 at 6:19 PM, Navdeep Parhar <nparhar@gmail.com> wrote: > I meant 100us (microseconds), sorry. My point still stands - 10G > networks have much less one way delay than this. The worst I can > find in the lab right now has around ~30us delay. A socket rcv > bufsize of 64K maxes out the link in some casual testing with netperf > (with autosizing disabled). 256K is already more than what's needed. Let's look at something much more realistic on the internet. How about a 100Mbps link with 100ms delay. That's downloading something from Europe from the US. I do this at work all of the time. The BDP for such a link is ~1.2MB. This is a pretty common scenario today and it's not even close to what is reasonably capable (a reliable 1Gbps link over the same delay distance). Looking at other operating systems: Linux (CentOS 5.4): Read window: Initial: 87380 Max: 4194304 Write window: Initial: 16384 Max: 4194304 Solaris 10: Read window: Initial: 49152 Max: 1048576 Write window: Initial: 49152 Max: 1048576 What is the FreeBSD initial setting? Is that sendspace (32k) and recvspace (64k)? Should we look at changing those too or just discuss the maximum window sizes? Gordonhome | help
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