From 84d5f6dd4987bb78f85a706b0fc689d5b51bbba0 Mon Sep 17 00:00:00 2001 From: Tobias Klauser Date: Wed, 15 May 2013 11:00:09 +0200 Subject: man: trafgen: Minor fixes Replace "on default" by "by default", make it a bit more clear what the seed in the -E/--seed option is for and mention exit after display of information on --version and --help. Signed-off-by: Tobias Klauser --- ifpps.8 | 44 ++++++++++++++++++++++---------------------- 1 file changed, 22 insertions(+), 22 deletions(-) (limited to 'ifpps.8') diff --git a/ifpps.8 b/ifpps.8 index 8f802e9..46088dd 100644 --- a/ifpps.8 +++ b/ifpps.8 @@ -15,24 +15,24 @@ ifpps \- top-like networking and system statistics ifpps is a small utility which periodically provides top-like networking and system statistics from the kernel. ifpps gathers its data directly from procfs files and does not apply any user space monitoring libraries -which could falsify statistics on high load. +which would falsify statistics on high load. For instance, consider the following scenario: two directly connected -Linux machines, each with an Intel Core 2 Quad Q6600 2.40GHz CPUs, 4 GB -RAM, and an Intel 82566DC-2 Gigabit Ethernet NIC, are used for performance -evaluation. One machine generates 64 byte network packets by using the -kernel space packet generator, pktgen, with a maximum possible packet rate. -The other machine displays statistics about incoming network packets by -using i) iptraf(8) and ii) ifpps. - -iptraf which incorporates pcap(3) shows an average packet rate of -246,000 pps, while on the other hand, ifpps shows an average packet rate -of 1,378,000 pps. Hence, due to packet copies and deferring statistical -calculations to user space, a measurement error of approx. 460 per cent +Linux machines with Intel Core 2 Quad Q6600 2.40GHz CPUs, 4 GB RAM, and +an Intel 82566DC-2 Gigabit Ethernet NIC are used for performance evaluation. +One machine generates 64 byte network packets by using the kernel space +packet generator pktgen with a maximum possible packet rate. The other +machine displays statistics about incoming network packets by using i) +iptraf(8) and ii) ifpps. + +iptraf that incorporates pcap(3) shows an average packet rate of +246,000 pps while on the other hand ifpps shows an average packet rate of +1,378,000 pps. Hence, due to copying packets and deferring statistics +creation into user space, measurement error of approx. 460 per cent occurs. Tools like iptraf might display much more information such as TCP per flow statistics (therefore the use of the pcap library), which -is not implemented in ifpps, because overall networking statistics is -our focus; statistics, which are also fairly reliable under high packet +is not implemented in ifpps, because overall networking statistics are +in our focus; statistics, which are also fairly reliable under high packet load. .SH OPTIONS @@ -41,7 +41,7 @@ load. Networking device to fetch statistics from, e.g. eth0, wlan0. .SS -t