Chapter 3. Bandwidth and Processing Power

41

This report (which has been truncated horizontally to fit on the page) includes one column for each

interrupt level (the

i002/s

field illustrating the rate for interrupt level 2). If this were a multiprocessor

system, there would be one line per sample period for each CPU.

Another important point to note about this report is that

sar

adds or removes specific interrupt fields

if no data is collected for that field. This can be seen in the example report above; the end of the report

includes interrupt levels (3 and 10) that were not present at the start of the sampling period.

Note

There are two other interrupt related sar reports   sar  I ALL and sar  I XALL. However, the

default configuration for the sadc data collection utility does not collect the information necessary for

these reports. This can be changed by editing the file /etc/cron.d/sysstat, and changing this line:

*/10 * * * * root /usr/lib/sa/sa1 1 1

to look like this:

*/10 * * * * root /usr/lib/sa/sa1  I 1 1

Keep in mind that this change does cause additional information to be collected by sadc, and results

in larger data file sizes. Therefore, make sure your system configuration can support the additional

space consumption.

3.4. Additional Resources

This section includes various resources that can be used to learn more about the Red Hat Linux 

specific subject matter discussed in this chapter.

3.4.1. Installed Documentation

The following resources are installed in the course of a typical Red Hat Linux installation and can

help you learn more about the subject matter discussed in this chapter.

  vmstat(8)

man page   Displays a concise overview of process, memory, swap, I/O, system, and

CPU utilization.

  iostat(1)

man page   Displays CPU and I/O statistics.

  sar(1)

man page   Produces system resource utilization reports.

  sadc(8)

man page   Collects system utilization data.

  sa1(8)

man page   A script that runs

sadc

periodically.

  top(1)

man page   Displays CPU utilization and process level statistics.