HP NonStop G-Series - Manual (Page 155)

Balancing and Tuning a System
Measure User’s Guide — 520560-003
7- 19
Checking and Tuning Problem Areas
Continue until the disk queues are balanced, but move only one file at a time. After
moving a file, check the effect of the change. If you have shifted the problem from one
disk to another, either move the file back and try a different file or try moving the file to
a different disk.
Balancing CPU Activity
You can consider CPU activity balanced when all CPUs have approximately the same
CPU-QTIME in the LIST CPU command display. Balanced CPU activity also denotes
an even distribution of work requests among CPUs. CPU queue lengths should be
examined and balanced as well.
Processes receive CPU time based on their priority. (Process priority assignments are
discussed later. For a complete discussion of priorities and scheduling, see the
Guardian Programmer’s Guide.) Processes with the same priority compete for
processing time. Processes at different priorities do not compete because higher
priority processes preempt lower priority processes. For this reason, you should
balance processing requirements for each priority level across all CPUs. That is,
processing requirements for processes at priority 220 should be balanced, processes
at priority 200 should be balanced, and so on for each priority level. In a mixed
environment, batch processes should run at a much lower priority than anything else
on the system.
To balance CPU activity, first examine the activity in each CPU. To do so, list the CPUs
in order of their CPU-BUSY-TIME counter values. (In Enform, you can define a new
CPU busy time field and use that field for CPU balancing.)
7+ LIST CPU *, BY CPU-BUSY-TIME
When you know which CPUs are overutilized and which have processing time to
spare, balance the CPU activity by moving processes from the overutilized CPUs to
the other CPUs.
To determine the processing requirements of all processes in a CPU, list the processes
by their CPU-BUSY-TIME counter values, and balance the processing requirements
for processes at a given priority level. (In MEASCOM, you must note the priority level
in the report header. In Enform, you can list processes over the PRIORITY field of the
process records.)
To list the processes in CPU 4 according to their CPU-BUSY-TIME counter values:
8+ LIST PROCESS 4,*, BY CPU-BUSY-TIME
In choosing a process to move, consider these factors as well as the CPU-BUSY-TIME
counter value:
•
The duration of the process. A short-term process does not require much
processing time, regardless of its CPU-BUSY-TIME value.
•
The ease with which the process can be moved. Moving a system I/O process
(IOP) can be done by a PRIMARY command. Moving an application process can
be simple or impossible depending on the application code.