Date: Sun, 20 Mar 2011 12:47:27 +0900 From: George Neville-Neil <gnn@neville-neil.com> To: Navdeep Parhar <nparhar@gmail.com> Cc: arch@freebsd.org Subject: Re: Updating our TCP and socket sysctl values... Message-ID: <281E39E0-55D0-4B52-9CD9-F437442B67EC@neville-neil.com> In-Reply-To: <AANLkTi=ptv617t0KhgNrcxTUzLmQd0eLFBf2x4%2BP7EAL@mail.gmail.com> References: <132388F1-44D9-45C9-AE05-1799A7A2DCD9@neville-neil.com> <AANLkTi=ptv617t0KhgNrcxTUzLmQd0eLFBf2x4%2BP7EAL@mail.gmail.com>
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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On Mar 20, 2011, at 08:13 , Navdeep Parhar wrote: > On Fri, Mar 18, 2011 at 11:37 PM, George Neville-Neil > <gnn@neville-neil.com> wrote: >> -----BEGIN PGP SIGNED MESSAGE----- >> Hash: SHA1 >> >> Howdy, >> >> I believe it's time for us to upgrade our sysctl values for TCP sockets so that >> they are more in line with the modern world. At the moment we have these limits on >> our buffering: >> >> kern.ipc.maxsockbuf: 262144 >> net.inet.tcp.recvbuf_max: 262144 >> net.inet.tcp.sendbuf_max: 262144 >> >> I believe it's time to up these values to something that's in line with higher speed >> local networks, such as 10G. Perhaps it's time to move these to 2MB instead of 256K. >> >> Thoughts? > > 256KB seems adequate for 10G (as long as the consumer can keep > draining the socket rcv buffer fast enough). If you consider 2 x > bandwidth delay product to be a reasonable socket buffer size then > 256K allows for 10G networks with ~100ms delays. Normally the delay > is _way_ less than this for 10G and even 256K may be an overkill (but > this is ok, the kernel has tcp_do_autorcvbuf on by default) > > While we're here discussing defaults, what about nmbclusters and > nmbjumboXX? Now those haven't kept up with modern machines (imho). > Yes we should also up the nmbclusters, IMHO, but I wasn't going to put that in the same bucket with the TCP buffers just yet. On 64 bit/large memory machines you could make the nmbclusters far higher than our current default. I know people who just set that to 1,000,000 by default. If people are also happy to up nmbclusters I'm willing to conflate that with this. Best, George -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (Darwin) iEYEARECAAYFAk2FeM8ACgkQYdh2wUQKM9KPZgCgy9AcsoowTLk+sAaFHx52VSkW mGEAn22eOTi3yqweMrOKsVkZ2XOWi9kX =22fZ -----END PGP SIGNATURE-----help
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