x86 External Cache Issues

Many x86 systems include an L2 external (or physical) cache. The external cache is a physical cache that represents a portion of physical memory. The L2 external cache improves CPU performance by reducing the time needed for data to be stored and retrieved by the CPU.

For some types of external caches, however, the cache does not accurately reflect the contents of the physical memory, due to a hardware problem.

The Solaris software provides a default mechanism that solves this problem by flushing the external cache in x86 systems. However, this mechanism actually reduces CPU performance on systems with functioning external cache designs (for example, systems using the Intel^(R) Cache Controller chip set).

To improve CPU performance in x86 systems where the cache accurately reflects physical memory, you should turn off the Solaris cache flushing operation.

x86How to Turn Off Cache Flushing

1. Edit the /etc/system file.

2. Add the following line or uncomment if it already exists:

set cacheflsh = 0

3. Reboot the system.