netpmon Command

Commands Reference, Volume 4

netpmon Command

Purpose

Monitors activity and reports statistics on network I/O and network-related CPU usage.

Syntax

netpmon [ -o File ] [ -d ] [ -T n ] [ -P ] [ -t ] [ -v ] [ -O ReportType ... ]

Description

The netpmon command monitors a trace of system events, and reports on network activity and performance during the monitored interval. By default, the netpmon command runs in the background while one or more application programs or system commands are being executed and monitored. The netpmon command automatically starts and monitors a trace of network-related system events in real time. By default, the trace is started immediately; optionally, tracing may be deferred until the user issues a trcon command. When tracing is stopped by a trcstop command, the netpmon command generates all specified reports and exits.

The netpmon command reports on the following system activities:

Note: The netpmon command does not work with NFS3(ONC+)

CPU Usage

The netpmon command monitors CPU usage by all threads and interrupt handlers. It estimates how much of this usage is due to network-related activities.

Network Device-Driver I/O

The netpmon command monitors I/O operations through Micro-Channel Ethernet, token-ring, and Fiber-Distributed Data Interface (FDDI) network device drivers. In the case of transmission I/O, the command also monitors utilizations, queue lengths, and destination hosts. For receive ID, the command also monitors time in the demux layer.

Internet Socket Calls

The netpmon command monitors all send , recv , sendto , recvfrom , read , and write subroutines on Internet sockets. It reports statistics on a per-process basis, for each of the following protocol types:

Internet Control Message Protocol (ICMP)
Transmission Control Protocol (TCP)
User Datagram Protocol (UDP)

NFS I/O

The netpmon command monitors read and write subroutines on client Network File System (NFS) files, client NFS remote procedure call (RPC) requests, and NFS server read or write requests. The command reports subroutine statistics on a per-process or optional per-thread basis and on a per-file basis for each server. The netpmon command reports client RPC statistics for each server, and server read and write statistics for each client.

Any combination of the preceding report types can be specified with the command line flags. By default, all the reports are produced.

Notes: The reports produced by the netpmon command can be quite long. Consequently, the -o flag should usually be used to write the report to an output file. The netpmon command obtains performance data using the AIX system trace facility. The trace facility only supports one output stream. Consequently, only one netpmon or trace process can be active at a time. If another netpmon or trace process is already running, the netpmon command responds with the message:
/dev/systrace: Device busy
While monitoring very network-intensive applications, the netpmon command may not be able to consume trace events as fast as they are produced in real time. When that happens, the error message:
Trace kernel buffers overflowed, N missed entries
will be displayed on standard error, indicating how many trace events were lost while the trace buffers were full. The netpmon command will continue monitoring network activity, but the accuracy of the report will be diminished by some unknown degree. One way to avoid overflow is to increase the trace buffer size using the -T flag, to accommodate larger bursts of trace events before overflow.

When running in memory-constrained environments (where demand for memory exceeds supply), the -P flag can be used to pin the text and data pages of the real-time netpmon process in memory so the pages cannot be swapped out. If the -P flag is not used, allowing the netpmon process to be swapped out, the progress of the netpmon command may be delayed such that it cannot process trace events fast enough to prevent trace buffer overflow.

If the /unix file and the running kernel are not the same, the kernel addresses will be incorrect, causing the netpmon command to exit.

Flags

-o File	Writes the reports to the specified File, instead of to standard output.
-d	Starts the netpmon command, but defers tracing until the trcon command has been executed by the user. By default, tracing is started immediately.
-O ReportType ...	Produces the specified report types. Valid report type values are: cpu CPU usage dd Network device-driver I/O so Internet socket call I/O nfs NFS I/O all All reports are produced. This is the default value.
-P	Pins monitor process in memory. This flag will cause the netpmon text and data pages to be pinned in memory for the duration of the monitoring period. This flag can be used to ensure that the real-time netpmon process does not run out of memory space when running in a memory-constrained environment.
-T n	Sets the kernel's trace buffer size to n bytes. The default size is 64000 bytes. The buffer size can be increased to accommodate larger bursts of events, if any.(A typical event record size is on the order of 30 bytes.)
	Note: The trace driver in the kernel uses double buffering, so actually two buffers of size n bytes will be allocated. These buffers are pinned in memory, so they are not subject to paging.
-t	Prints CPU reports on a per-thread basis.
-v	Prints extra information in the report. All processes and all accessed remote files are included in the report instead of only the 20 most active processes and files.

Reports

The reports generated by the netpmon command begin with a header, which identifies the date, the machine ID, and the length of the monitoring period in seconds. This is followed by a set of summary and detailed reports for all specified report types.

CPU Usage Reports

Process CPU Usage Statistics: Each row describes the CPU usage associated with a process. Unless the verbose option is specified, only the 20 most active processes are listed. At the bottom of the report, CPU usage for all processes is totaled, and CPU idle time is reported.

Process: Process name
PID: Process ID number
CPU Time: Total amount of CPU time used by this process
CPU %: CPU usage for this process as a percentage of total time
Network CPU %: Percentage of total time that this process spent executing network-related code
Thread CPU Usage Statistics: If the -t flag is used, each process row described above is immediately followed by rows describing the CPU usage of each thread owned by that process. The fields in these rows are identical to those for the process, except for the name field. (Threads are not named.)

First-Level Interrupt Handler Usage Statistics: Each row describes the CPU usage associated with a first-level interrupt handler (FLIH). At the bottom of the report, CPU usage for all FLIHs is totaled.

FLIH: First-level interrupt handler description
CPU Time: Total amount of CPU time used by this FLIH
CPU %: CPU usage for this interrupt handler as a percentage of total time
Network CPU %: Percentage of total time that this interrupt handler executed on behalf of network-related events

Second-Level Interrupt Handler Usage Statistics: Each row describes the CPU usage associated with a second-level interrupt handler (SLIH). At the bottom of the report, CPU usage for all SLIHs is totaled.

SLIH: Second-level interrupt handler description
CPU Time: Total amount of CPU time used by this SLIH
CPU %: CPU usage for this interrupt handler as a percentage of total time
Network CPU %: Percentage of total time that this interrupt handler executed on behalf of network-related events

Summary Network Device-Driver Reports

Network Device-Driver Statistics (by Device): Each row describes the statistics associated with a network device.

Device: Path name of special file associated with device
Xmit Pkts/s: Packets per second transmitted through this device
Xmit Bytes/s: Bytes per second transmitted through this device
Xmit Util: Busy time for this device, as a percent of total time
Xmit Qlen: Number of requests waiting to be transmitted through this device, averaged over time, including any transaction currently being transmitted
Recv Pkts/s: Packets per second received through this device
Recv Bytes/s: Bytes per second received through this device
Recv Demux: Time spent in demux layer as a fraction of total time

Network Device-Driver Transmit Statistics (by Destination Host): Each row describes the amount of transmit traffic associated with a particular destination host, at the device-driver level.

Host: Destination host name. An * (asterisk) is used for transmissions for which no host name can be determined.
Pkts/s: Packets per second transmitted to this host
Xmit Bytes/s: Bytes per second transmitted to this host

Summary Internet Socket Reports

Socket Call Statistics for Each Internet Protocol (by Process): Each row describes the amount of read/write subroutine activity on sockets of this protocol type associated with a particular process. Unless the verbose option is specified, only the top 20 processes are listed. At the bottom of the report, all socket calls for this protocol are totaled.

Process: Process name
PID: Process ID number
Read Calls/s: Number of read , recv , and recvfrom subroutines per second made by this process on sockets of this type
Read Bytes/s: Bytes per second requested by the above calls
Write Calls/s: Number of write , send , and sendto subroutines per second made by this process on sockets of this type
Write Bytes/s: Bytes per second written by this process to sockets of this protocol type

Summary NFS Reports

NFS Client Statistics for Each Server (by File): Each row describes the amount of read/write subroutine activity associated with a file mounted remotely from this server. Unless the verbose option is specified, only the top 20 files are listed. At the bottom of the report, calls for all files on this server are totaled.

File: Simple file name
Read Calls/s: Number of read subroutines per second on this file
Read Bytes/s: Bytes per second requested by the above calls
Write Calls/s: Number of write subroutines per second on this file
Write Bytes/s: Bytes per second written to this file

NFS Client RPC Statistics (by Server): Each row describes the number of NFS remote procedure calls being made by this client to a particular NFS server. At the bottom of the report, calls for all servers are totaled.

Server: Host name of server. An * (asterisk) is used for RPC calls for which no hostname could be determined.
Calls/s: Number of NFS RPC calls per second being made to this server.

NFS Client Statistics (by Process): Each row describes the amount of NFS read/write subroutine activity associated with a particular process. Unless the verbose option is specified, only the top 20 processes are listed. At the bottom of the report, calls for all processes are totaled.

Process: Process name
PID: Process ID number
Read Calls/s: Number of NFS read subroutines per second made by this process
Read Bytes/s: Bytes per second requested by the above calls
Write Calls/s: Number of NFS write subroutines per second made by this process
Write Bytes/s: Bytes per second written to NFS mounted files by this process

NFS Server Statistics (by Client): Each row describes the amount of NFS activity handled by this server on behalf of particular client. At the bottom of the report, calls for all clients are totaled.

Client: Host name of client
Read Calls/s: Number of remote read requests per second processed on behalf of this client
Read Bytes/s: Bytes per second requested by this client's read calls
Write Calls/s: Number of remote write requests per second processed on behalf of this client
Write Bytes/s: Bytes per second written by this client
Other Calls/s: Number of other remote requests per second processed on behalf of this client

Detailed Reports

Detailed reports are generated for any of the specified report types. For these report types, a detailed report is produced for most of the summary reports. The detailed reports contain an entry for each entry in the summary reports with statistics for each type of transaction associated with the entry.

Transaction statistics consist of a count of the number of transactions of that type, followed by response time and size distribution data (where applicable). The distribution data consists of average, minimum, and maximum values, as well as standard deviations. Roughly two-thirds of the values are between average - standard deviation and average + standard deviation. Sizes are reported in bytes. Response times are reported in milliseconds.

Detailed Second Level Interrupt Handler CPU Usage Statistics:

SLIH: Name of second-level interrupt handler
Count: Number of interrupts of this type
CPU Time (Msec): CPU usage statistics for handling interrupts of this type

Detailed Network Device-Driver Statistics (by Device):

Device: Path name of special file associated with device
Recv Packets: Number of packets received through this device
Recv Sizes (Bytes): Size statistics for received packets
Recv Times (msec): Response time statistics for processing received packets
Xmit Packets: Number of packets transmitted to this host
Demux Times (msec): Time statistics for processing reveived packets in the demux layer
Xmit Sizes (Bytes): Size statistics for transmitted packets
Xmit Times (Msec): Response time statistics for processing transmitted packets

Detailed Network Device-Driver Transmit Statistics (by Host):

Host: Destination host name
Xmit Packets: Number of packets transmitted through this device
Xmit Sizes (Bytes): Size statistics for transmitted packets
Xmit Times (Msec): Response time statistics for processing transmitted packets

Detailed Socket Call Statistics for Each Internet Protocol (by Process):

Process: Process name
PID: Process ID number
Reads: Number of read , recv , recvfrom , and recvmsg subroutines made by this process on sockets of this type
Read Sizes (Bytes): Size statistics for read calls
Read Times (Msec): Response time statistics for read calls
Writes: Number of write , send , sendto , and sendmsg subroutines made by this process on sockets of this type
Write Sizes (Bytes): Size statistics for write calls
Write Times (Msec): Response time statistics for write calls

Detailed NFS Client Statistics for Each Server (by File):

File: File path name
Reads: Number of NFS read subroutines for this file
Read Sizes (Bytes): Size statistics for read calls
Read Times (Msec): Response time statistics for read calls
Writes: Number of NFS write subroutines for this file
Write Sizes (Bytes): Size statistics for write calls
Write Times (Msec): Response time statistics for write calls

Detailed NFS Client RPC Statistics (by Server):

Server: Server host name
Calls: Number of NFS client RPC calls made to this server
Call Times (Msec): Response time statistics for RPC calls

Detailed NFS Client Statistics (by Process):

Process: Process name
PID: Process ID number
Reads: Number of NFS read subroutines made by this process
Read Sizes (Bytes): Size statistics for read calls
Read Times (Msec): Response time statistics for read calls
Writes: Number of NFS write subroutines made by this process
Write Sizes (Bytes): Size statistics for write calls
Write Times (Msec): Response time statistics for write calls

Detailed NFS Server Statistics (by Client):

Client: Client host name
Reads: Number of NFS read requests received from this client
Read Sizes (Bytes): Size statistics for read requests
Read Times (Msec): Response time statistics for read requests
Writes: Number of NFS write requests received from this client
Write Sizes (Bytes): Size statistics for write requests
Write Times (Msec): Response time statistics for write requests
Other Calls: Number of other NFS requests received from this client
Other Times (Msec): Response time statistics for other requests

Examples

To monitor network activity during the execution of certain application programs and generate all report types, enter:
```
netpmon
<run application programs and commands here>
trcstop
```
The netpmon command automatically starts the system trace and puts itself in the background. Application programs and system commands can be run at this time. After the trcstop command is issued, all reports are displayed on standard output.
To generate CPU and NFS report types and write the reports to the nmon.out file, enter:
```
netpmon -o nmon.out -O cpu,nfs
<run application programs and commands here>
trcstop
```
The netpmon command immediately starts the system trace. After the trcstop command is issued, the I/O activity report is written to the nmon.out file. Only the CPU and NFS reports will be generated.
To generate all report types and write verbose output to the nmon.out file, enter:
```
netpmon -v -o nmon.out
<run application programs and commands here>
trcstop
```
With the verbose output, the netpmon command indicates the steps it is taking to start up the trace. The summary and detailed reports include all files and processes, instead of just the 20 most active files and processes.

Related Information

The trcstop command.

The recv subroutine, recvfrom subroutine, send subroutine, and sendto subroutine.