netpmon command

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The netpmon command uses the trace facility to obtain a detailed picture of network activity during a time interval. Because it uses the trace facility, the netpmon command can be run only by a root user or by a member of the system group.

The netpmon command cannot run together with any of the other trace-based performance commands such as tprof and filemon. In its usual mode, the netpmon command runs in the background while one or more application programs or system commands are being executed and monitored.

The netpmon command focuses on the following system activities:

  • CPU usage
    • By processes and interrupt handlers
    • How much is network-related
    • What causes idle time
  • Network device driver I/O
    • Monitors I/O operations through all Ethernet, Token-Ring, and Fibre-Distributed Data Interface (FDDI) network device drivers.
    • In the case of transmission I/O, the command monitors utilizations, queue lengths, and destination hosts. For receive ID, the command also monitors time in the demux layer.
  • Internet socket calls
    • Monitors send(), recv(), sendto(), recvfrom(), sendmsg(), read(), and write() subroutines on Internet sockets.
    • Reports statistics on a per-process basis for the Internet Control Message Protocol (ICMP), Transmission Control Protocol (TCP), and the User Datagram Protocol (UDP).
  • NFS I/O
    • On client: RPC requests, NFS read/write requests.
    • On server: Per-client, per-file, read/write requests.

The following will be computed:

  • Response times and sizes associated with transmit and receive operations at the device driver level.
  • Response times and sizes associated with all types of Internet socket read and write system calls.
  • Response times and sizes associated with NFS read and write system calls.
  • Response times associated with NFS remote procedure call requests.
To determine whether the netpmon command is installed and available, run the following command: 
# lslpp -lI perfagent.tools

Tracing is started by the netpmon command, optionally suspended with the trcoff subcommand and resumed with the trcon subcommand. As soon as tracing is terminated, the netpmon command writes its report to standard output.