Microsoft KB Archive/139609

= PerfMon: High Number of Pages/Sec Not Necessarily Low Memory =

Article ID: 139609

Article Last Modified on 2/22/2007

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APPLIES TO


 * Microsoft Windows 2000 Server
 * Microsoft Windows 2000 Advanced Server
 * Microsoft Windows 2000 Professional Edition
 * Microsoft Windows NT Workstation 3.51
 * Microsoft Windows NT Workstation 4.0 Developer Edition
 * Microsoft Windows NT Server 3.51
 * Microsoft Windows NT Server 4.0 Standard Edition

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This article was previously published under Q139609





SUMMARY
When using Performance Monitor, you might encounter high Memory: Pages/sec counter values that are not related to either paging file activity or cache activity. These high values may instead be caused by the an application sequentially reading a memory mapped file.



MORE INFORMATION
The following information is from the Performance Monitor counter definition information for the Memory Pages/sec counter:

Pages/sec is the number of pages read from the disk or written to the disk to resolve memory references to pages that were not in memory at the time of the reference. This is the sum of Pages Input/sec and Pages Output/sec. This counter includes paging traffic on behalf of the system Cache to access file data for applications. This is the primary counter to observe if you are concerned about excessive memory pressure (that is, thrashing), and the excessive paging that may result. This counter, however, also accounts for such activity as the sequential reading of memory mapped files, whether cached or not. The typical indication of this is when you see high number of Memory: Pages/sec, a "normal" (average, relative to the system being monitored) or high number of Memory: Available Bytes, and a normal or small amount of Paging File: % Usage. In the case of a non-cached memory mapped file, you also see normal or low cache (cache fault) activity.

As seen from the above information, a high number of Memory: Pages/sec is not necessarily indicative of memory pressure or a Performance Monitor reporting error. It is necessary to monitor other counters, such as those mentioned above, to get the complete picture of what is happening in your particular case.

Additional query words: prodnt pages per second percent

Keywords: KB139609

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