In the course of an IT career, many of us may have sat at our desks looking at a sluggish application and wondered, "If I increase the amount of memory here or there, will this improve performance?" And, hopefully, your next thoughts would have been about the impact on I/O operations and cost, CPU usage, and transaction response times.
Although the magnitude of these changes can vary widely based on a number of factors, including potential I/Os to be eliminated, resource contention, workload, configuration, and tuning, you should carefully consider whether your environment could benefit from the addition of more memory to your software functions.
Significant performance benefits can be experienced by increasing the amount of memory assigned to various functions in the IBM® z/OS® software stack, operating system, and middleware products. IBM DB2® and IBM MQ buffer pools, dump services, and large page exploitation are just a few of the functions whose ease of use and performance can be improved when more memory is made available to them.
Recently, an IBM Redbooks Redpaper was published that can help you to examine the performance implications of increasing memory in the following areas:
- DB2 buffer pools
- DB2 tuning
- IBM Cognos® Dynamic Cubes
- MDM with larger DB2 buffer pools
- Java heaps and Garbage Collection tuning and Java large page use
- MQ v8 64-bit buffer pool tuning
- Enabling more in-memory use by IBM CICS® without paging
- TCP/IP FTP
- DFSort I/O reduction
- Fixed pages and fixed large pages
Different environments, of course, may experience a wide range of performance benefits but there does seem to be enough evidence to suggest that configuring more memory could be a positive enhancement for many installations due to reduced I/O rates, improving transaction response times, and in some cases, reduced CPU time.
To read more about this and see some examples, read the IBM Redbooks Redpaper :