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Using IBM Rational Performance Tester: Resource monitoring Part 3, Monitoring with UNIX/Linux rstatd

 

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Monitor using rstatd for Linux/UNIX systems

The rstat daemon (rpc.rstatd) returns performance statistics for UNIX-based operating systems. The performance statistics are retrieved from the kernel itself.

The rstat daemon may already be installed and running on most Solaris and Linux installations, however, this configuration will depend on the vendor and distribution. The rstat daemon is normally started by the inetd daemon.

 

Performance counters

The statistics monitored are restricted to fifteen performance counters, which include processor, disk, memory, and network utilization.

Performance counter Description
Percentage User CPU Time Percentage user time is the percentage of non-idle processor time spent in user mode.
Percentage IOWAIT CPU Time Percentage IOWAIT time is the percentage of non-idle processor time spent waiting for I/O to complete.
Percentage of System CPU Time Percentage system time is the percentage of non-idle processor time spent in system mode.
Percentage of Idle CPU Time Percentage of time that the processor is idle.
Total Disk Transfers per second Total number of disk transfers on each of the disk interfaces (per second).
Total VM Pages Paged IN per second Total number of pages paged in per second. (Paging vs. swapping: see Note 1, below)
Total VM Pages Paged OUT per second Total number of pages paged out per second. (Paging vs. swapping)
Total VM Pages Swapped IN per second Total number of pages swapped in per second. (Paging vs. swapping)
Total VM Pages Swapped OUT per second Total number of pages swapped out per second. (Paging vs. swapping)
Total Interrupts per second Total number of interrupts per second.
Total Inbound packets on all interfaces per second Total number of inbound packets on all interfaces per second
Total Inbound errors on all interfaces per second Total number of inbound errors on all interfaces per second
Total Outbound packets on all interfaces per second Total number of outbound packets on all interfaces per second
Total Outbound errors on all interfaces per second Total number of outbound errors on all interfaces per second
Total collisions seen on all interfaces per second Total number of collisions seen on all interfaces per second
Total context switches per second Total number of context switches per second
Average number of jobs in run queue (1 minute average) Number of jobs in the run queue averaged over the last 1 minute. See Note 2, below
Average number of jobs in run queue (5 minute average) Number of jobs in the run queue averaged over the last 5 minutes.
Average number of jobs in run queue (15 minute average) Number of jobs in the run queue averaged over the last 15 minutes.

  1. Paging is a light-weight mechanism whereby the operating system reads/writes pages of memory from/to the disk; swapping is similar to paging, but is more heavy-weight in that entire processes can have all their pages read/written from/to disk.

  2. The jobs on the run queue are the processes that are ready to run on the processor.

 

Data collection

The rstat daemon is a native application that specifically operates on UNIX-based systems, such as Solaris, HP-UX, AIX, and Linux. Performance Tester integrates with the daemon through a Java-based RPC client, which is responsible for marshalling transactions to and processing the results from a rstat daemon. The RPC client is bundled within an Eclipse plug-in that extends the Resource Monitoring platform within Performance Tester.

When performance counters are selected to be monitored, a Remote Service Monitor (RSM) program polls the counters at an interval and sends alerts to the client upon detection. The RSM program sends resource data to the client at reporting intervals set by the client or system administrator.

Depending on the setup of your account and the UNIX-based operating system, the system administrator might control the location and maintenance of the RSM programs that monitor your account. The RSM program obtains the performance data from the rstatd server, which returns performance statistics obtained from the kernel.

The version of rstatd that is supported in Performance Tester is the RSTATVERS_TIME version, or version 3. The rstatd is backwards compatible, therefore, versions greater than 3 will support the RSTATVERS_TIME edition. Historically, this version has been in existence well before 1995.

 

System configuration

In this section we describe how to configure the system for the rstat daemon.

 

Installing rstatd on Linux

The rstat daemon is freely available on the Internet for the Linux platform, and is already bundled in most UNIX-based platforms. The following are installation instructions for rstatd on Linux using the open source version of rstatd available on SourceForge:


Creating the rstatd file

service rstatd {
  type = RPC
  socket_type = dgram
  protocol = udp
  server = /usr/local/sbin/rpc.rstatd
  wait = yes
  user = root
  rpc_version = 2-4
  disable = no
}

Ensure that the value specified by the server parameter is actually where the rpc.rstatd daemon is installed. If it is not installed in /usr/local/sbin change the parameters above to reflect this configuration.


Restarting the inetd daemon

/etc/rc.d/init.d/xinetd restart

rpcinfo -p localhost

The daemon should be listed several times, which is due to the different RPC versions available for clients to use.

 

Portmapper service

The rstatd uses the Remote Procedure Call (RPC) system to facilitate connecting to the system portmapper daemon running on a well-known port. The rstatd will use RPC to create a listener that asks the portmapper for a port to use for communication with a remote client. The portmapper selects an unused port and assigns it to the listener.

Performance Tester requires the portmapper daemon to be running on the remote Linux/UNIX system. Run the following command to verify that the daemon is started:
Verifying that the rstatd has started

rpcinfo -p localhost

This command will generate output similar to the following output:
Typical output of rpcinfo command

program vers proto   port
100000    2   tcp    111  portmapper
100000    2   udp    111  portmapper
100024    1   udp  32768  status
100024    1   tcp  32769  status
100001    2   udp  32770  rstatd
100001    3   udp  32770  rstatd
100001    4   udp  32770  rstatd

The output indicates that the portmapper is operating using the TCP and UDP protocols using port 111, the default port.

If the portmapper daemon is not listed in the output of the rpcinfo command, as shown above, the daemon may not be installed or not configured to run. It is recommended to contact your system administrator and request that the portmapper RPC program be started.

To view the most commonly used RPC program numbers is held in a file called /etc/rpc on each system. The file consists of a series of entries, one per service, such as:
Typical RPC program numbers

  portmapper      100000  portmap sunrpc
  rstatd          100001  rstat rstat_svc rup perfmeter
  rusersd         100002  rusers
  nfs             100003  nfsprog
  ypserv          100004  ypprog
  mountd          100005  mount showmount
  ypbind          100007
  walld           100008  rwall shutdown
  yppasswdd       100009  yppasswd
  etherstatd      100010  etherstat
  rquotad         100011  rquotaprog quota rquota
  sprayd          100012  spray
  3270_mapper     100013
  rje_mapper      100014
  selection_svc   100015  selnsvc
  database_svc    100016

 

Configuring a performance schedule

To configure resource monitoring using UNIX rstatd monitor, create a new or add an existing location to a given performance schedule, as described in Resource monitoring using IBM Rational Performance Tester: Part 1, Scheduling and reporting.

Enter a target Linux/UNIX host name from which to collect data from and select the UNIX rstatd monitor item from the list of available data sources.

On the Resource page, select the type of data you want to capture. The tree view shows all available performance counters, with a default set of counters pre-selected.

Clearing Show only selected counters allows you to see all available counters. Be selective; monitoring all possible resource data requires substantial amounts of memory. Hover over a counter with your mouse to see details about what that counter measures.

On the Options tab, the time interval properties can be configured:


Once configuration is complete and saved, the resource monitoring location is added to the performance schedule.