Cache Performance Counters
For performance monitoring, there is a Cache performance object and a full set of performance measurement counters that provide a great deal of information about the Cache Manager and related cache activity. To monitor cache effectiveness, there are counters that report on cache memory size, activity, and the various cache hit ratios. As we describe the various file caching mechanisms, we also discuss the relevant performance counters that are available to measure cache effectiveness.
Following Figure 7-1, it is important to monitor both the size of the file cache and the cache hit ratio. The real memory pages that the file cache occupies are counted as part of the system working set, subject to normal page trimming. The Memory object performance counter System Cache Resident Bytes reports the amount of real memory currently in use by the file cache. As the number of System Cache Resident Bytes increases, we normally expect that the various measures of hit ratio will also increase. Moreover, the cache size can grow simply as a function of the size of the files that are currently in use and their pattern of access. If there is little contention for real memory, the file cache grows in direct proportion to the rate of requests for new files (or new sections of currently open files). However, since the file cache must compete for real memory with other applications, what the other applications running in the system are doing at the same time ...