![]() UPDATE: LWN article "Better than POSIX?" has a title ending with a question mark - an old journalistic trick! I realize he only talks about files that application deems permanent, but in reality it's cancer that's going to poison every application through the cargo cult programming practices and will stay with us forever (necessitating ruining fsync for everyone, which is exactly his plan, apparently). The only acceptable criterium is the reasonable use. Hey, manpage says we can! This doesn't make the argument any more relevant. Doing just that is the favourite trick of morons who insist on returning an error from close(2), too. Next step: fcntl(F_FULLFSYNC).Īlso, hiding behind the letter of a manpage is plain wrong. Įspecially fabulous is how, in the same breath, he proposes disabling fsync() in kernel. ![]() If you want to include another interface in the analysis, you can either pass in only this interface ( Listing 1, line 1) or all interfaces ( Listing 1, line 2).Requesting all applications to add fsync() before close() is madness. For example, the program listens on the first interface (typically eth0), and it refreshes the display every second. When launched without additional parameters, Nethogs simply assumes meaningful defaults. Pressing Ctrl+C, or alternatively q, quits the program again. The second to last column, labeled SENT, shows the outgoing bandwidth, and the last column, RECEIVED, shows the incoming traffic in kilobytes per second. The fourth column, labeled DEV points to the interface currently handling the data traffic. Because many programs in Linux use different tools or modules, you can't always automatically see the program you launched in this column. ![]() The third column, PROGRAM, points to the executable file – in Figure 1, apt-get update turns out to be hiding behind the program /usr/lib/apt/methods/http. The data displays in six columns: the first column, labeled PID, contains a process ID of the displayed processors the column labeled USER lists the corresponding users who launched the processes. Figure 1 shows how Nethogs broke down the bandwidth in our lab.įigure 1: Nethogs shows that a Wget process and an Apt process are currently using some bandwidth. Before the tool can create its first analyses, you need a few network packets across the wire. Once you launch Nethogs, you'll need to wait for a while before you start to see meaningful results onscreen. You can launch Nethogs directly as root or use sudo on Ubuntu or Debian: $ sudo nethogs If you do decide to build Nethogs from the source code, make sure you resolve the Libpcap and Ncurses dependencies in advance – on Debian/Ubuntu, you'll need the packages libncurses5-dev and libpcap0.8-dev. $ sudo apt-get install libncurses5 libpcap0.8 On the Ubuntu 14.04 64-bit version in our lab, I was able to install the package with the following commands: $ sudo apt-get update Nethogs has found its way by now into the official package repositories for more popular distributions. ![]() Also, Nethogs analyzes the network usage for a single system and doesn't attempt to study all the traffic on the network. Currently, Nethogs only shows you the TCP data flow other protocols, such as ICMP or UDP, are not supported. You will find the official source code at the project website. Nethogs, which is licensed under the GPL, relies on the virtual proc filesystem for the analysis (relying on /proc/net/tcp and /proc/net/tcp6, among others). A view of the network by process is particularly useful if you want to know which application is currently involved in a particularly intensive communication. Nethogs is a little-known utility that breaks down network bandwidth by process. For more than 10 years, Arnout Engelen has worked on his Nethogs tool.
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