Linux Performance Observability Tools:
vmstat – monitoring tool that collects and displays summary information about operating system memory, processes, interrupts, paging and block I/O.
Users of vmstat can specify a sampling interval that permits observing system activity in near-real time.
iostat – monitor tool used to collect and show operating system storage input and output statistics. It is often used to identify performance issues with storage devices, including local disks, or remote disks accessed over network file systems such as NFS
netstat – command-line network utility that displays network connections for Transmission Control Protocol, routing tables, and a number of network interface and network protocol statistics
lsof – lists open files of the current system.
pidstat – monitors the utilization of system resources by all or
specified processes, including CPU, memory, device IO, task
switching, threads, etc.
The top command includes many of the metrics we checked earlier. It can be handy to run it to see if anything looks wildly different from the earlier commands, which would indicate that load is variable.
Advanced Observability Tools
Socket Statistics
The “ss” command is available to get socket statistics. This command is a replacement available for the “netstat” as the usage of “netstat” is now deprecated. This command is also faster and capable of displaying more information than the “netstat” command.
The “ss” command by default lists all open non-listening established TCP, UDP and UNIX socket connections.
Following are some important options:
- -r, — resolve: “Try to resolve numeric address/ports.”
- -a, — all: “Display both listening and non-listening (for TCP this means established connections) sockets.”
- -l, — listening: “Display only listening sockets (these are omitted by default).”
- -o, — options: “Show timer information.”
- -e, — extended: “Show detailed socket information”
- -m, — memory: “Show socket memory usage.”
- -p, — processes: “Show process using socket.”
- -i, — info: “Show internal TCP information.”
- -s, — summary: “Print summary statistics.”
- -t, — tcp: “Display TCP sockets.”
- -u, — udp: “Display UDP sockets.”
- -d, — dccp: “Display DCCP sockets.”
- -w, — raw: “Display RAW sockets.”
- -x, — unix: “Display Unix domain sockets (alias for -f unix).”
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