These are the possible reasons why a
job might experience poor performance.
Insufficient memory |
|
How to diagnose: |
View the properties of the job to determine which memory pool
the job is running in. Then view the properties of the memory pool
in IBM® Navigator
for i,
see Checking memory pool usage.
A high rate of faulting in a pool indicates that there is not enough
memory in the pool, or that too many jobs are in the pool competing
for the memory. |
Recovery: |
- Turn on the system tuner if you are not already using it. See Performance system
values: Automatically adjust memory pools and activity levels for
the information about automatically adjusting memory pools and activity
levels.
- If possible, manually tune the pool you are working with by increasing
the amount of memory in the pool or reducing the activity level for
the memory pool. You might also want to check the machine pool to
verify that the amount of memory being used is not affecting all jobs
on the system.
|
Activity level too low |
|
How to diagnose: |
View the properties of the job to determine its status and
which memory pool the job is running in. If the job shows a status
of Waiting for activity level, then view the properties
of the memory pool in IBM Navigator
for i,
see Checking memory pool usage.
A high rate of transitions to the ineligible state in a pool indicates
that too many jobs in the pool are competing for the memory. |
Recovery: |
- Turn on the system tuner if you are not already using it. See Performance system
values: Automatically adjust memory pools and activity levels for
the information about automatically adjusting memory pools and activity
levels.
- Manually tune the pool by increasing the activity level for the
memory pool.
|
Insufficient CPU resource |
|
How to diagnose: |
View the CPU % column for the job and other jobs in the Active
Jobs list of IBM Navigator
for i.
If the system is very busy, your job might not be getting enough CPU
resource to complete its work. |
Recovery: |
- If possible, end or hold unnecessary work on the system.
- If a few jobs are CPU intensive, change the run priority of these
jobs (a higher run priority value equals a lower run priority for
the job).
|
Memory pool paging option |
|
How to diagnose: |
If an application is disk intensive, if the CPU is under utilized
and if there is sufficient memory, the use of expert cache might be
beneficial. |
Recovery: |
The expert cache can be turned on in IBM Navigator
for i by changing
the Paging option for a shared memory pool to Calculated. The Paging
option is located on the Configuration tab
of the memory pool's Properties page and is
only available on shared pools(not private pools). |
For more information about performance, see Performance. If you
want more information about how to tune performance on your system,
see Tuning performance.