Resolving a Memory Bottleneck

Although more memory is the easy solution to a memory bottleneck, it isn't always the right solution.

• Monitor your applications and replace or correct those that leak memory or use it inefficiently.

• Localize your application's data references. Page Fault Monitor (Pfmon.exe), a tool on the Windows NT Resource Kit 4.0 CD, produces a running list of hard and soft page faults generated by each function call in a process.

• Localize your application's code references. The Working Set Tuner, included in the Win32 Software Development Kit, recommends an optimal organization of code functions to localize code page access.

• Increase the size of the paging file. In general, the bigger you can make it, the better it is. You can also have multiple paging files, though you can have only one on each logical drive. To change the size of the paging file, use the Control Panel System applet Performance tab. (Right-click My Computer, select Properties, then select the Performance tab.) The Virtual Memory box shows the current size of your paging files and lets you add new files or change the size of existing ones.

• Check the available space on your hard drives. If you have added memory, increase the size of your paging files. The paging file might need to expand to map the additional memory. If the space is not available, it might produce the symptoms of a memory bottleneck.

• Increase the size of your secondary memory cache, especially if you've just added memory. When you add memory, the secondary cache must map the larger memory space.

The amount of secondary cache a system supports depends upon the design of the motherboard. Many motherboards support several secondary cache configurations (from 64K–512K or 256K–1 MB). Increasing cache size usually requires removing the existing static ram (SRAM) chips, replacing them with new SRAM chips, and changing some jumpers. Doing so would be helpful anytime you have a working set larger than your current secondary cache.

• Remove unnecessary protocols and drivers. Even idle protocols use space in the paged and nonpaged memory pools.

If all else fails, add memory. After struggling with a memory bottleneck and its grueling effects, you will find the improved response of the entire system well worth the investment.