HP-UX System Administrator's Guide: Routine Management Tasks

6 Managing System Performance
This chapter provides some guidelines and suggestions for improving the performance
of a system or workgroup.
• “Performance Bottlenecks” (page 191)
• “Guidelines” (page 192)
• “Measuring Performance” (page 194)
• “Making Changes” (page 197)
Performance Bottlenecks
A system may perform slowly or sluggishly for a variety of reasons, and you may need
to do considerable investigation to determine the source of bottlenecks on a given
system. You need to consider the interrelationships between the different components
of the system, not just its individual components. Start with the tools described under
“Measuring Performance” (page 194).
Once you have isolated a performance problem and you decide how to address it,
change only one thing at a time. If you change more than one thing, you will not know
which change helped performance. It’s also possible that one change will improve
performance while another makes it worse, but you won’t know that unless you
implement them separately and measure performance in between.
The following shows some possible system bottlenecks:
CPU Bottlenecks:
• Many background processes running at a high priority consuming a lot of CPU
time, or a “runaway” process. If response time is unacceptable, lower the priority
of some processes, and kill any unwanted processes.
Memory Bottlenecks:
• high deactivations
• high paging activity
• little or no free memory available
• high CPU usage in System mode
Disk Bottlenecks:
• high disk activity
• high idle CPU time waiting for I/O requests to finish
• long disk queues
Performance Bottlenecks 191