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Date: Wed, 9 Feb 2011 10:27:39 +0100 From: Anders Berggren <anders@...on.se> To: Joe Perches <joe@...ches.com> Cc: "Ronciak, John" <john.ronciak@...el.com>, "Kirsher, Jeffrey T" <jeffrey.t.kirsher@...el.com>, e1000-devel@...ts.sourceforge.net, netdev@...r.kernel.org Subject: Re: [E1000-devel] [PATCH] fixing hw timestamping in igb On Feb 9, 2011, at 9:56 AM, Joe Perches wrote: > On Wed, 2011-02-09 at 09:24 +0100, Anders Berggren wrote: >> Our hardware ping, using Intel 82580 NICs, >> have an accuracy of 8 nanoseconds. > > Perhaps you mean 8 nanosecond resolution? > Is documentation available for this claim? Well, both. 8 ns is the accuracy when performing RTT (round-trip time) measurements using our hardware ping tool. We tested it by connecting a 10 m (European meters ;) CAT6 copper and measuring the jitter. The RTT is always 1240 ns or 1248 ns, hence the accuracy of 8 ns. $ sudo ./probed -c 10.10.10.3 -i eth2 -p 666 SLA-NG probed 0.1 probed: Binding port 666 probed: Using hardware timestamps probed: client: ::ffff:10.10.10.3: Connecting to port 666 probed: client: ::ffff:10.10.10.3: Connected Response 1 from 0 in 1240 ns Response 2 from 0 in 1248 ns Response 3 from 0 in 1248 ns Response 4 from 0 in 1248 ns ^C 4 ok, 0 ts err, 0 lost pong, 0 timeout, 0 dup, 0.000000% loss max: 1248 ns, avg: 1246 ns, min: 1240 ns This is our tool: $ ./probed SLA-NG probed 0.1 usage: probed [-saqd] [-c addr] [-t type] [-i iface] [-p port] [-f file] MODES OF OPERATION -c addr Client mode: PING 'addr', fetch UDP timestamps -s Server mode: respond to PING, send UDP timestamps -d Daemon mode: both server and client, output to pipe OPTIONS -k Create timestamps in kernel driver instead of hardware -u Create timestamps in userland instead of hardware -i iface Network interface used for hardware timestamping -p port UDP port, both source and destination -w usecs Client mode wait time between PINGs, in microseconds -v Output more debugging -q Be quiet, log error to syslog only -f file Path to configuration file -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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