eG Monitoring
 
Measures reported by WinMemoryTest

This test reports statistics pertaining to the memory utilization of Microsoft Windows systems. To understand the metrics reported by this test, it is essential to understand how memory is handled by the Operating System. On any system, memory is partitioned into a part that is available for user processes, and another that is available to the OS kernel. The kernel memory area is divided into several parts, with the two major parts (called “pools”) being a nonpaged pool and a paged pool. The nonpaged pool is a section of memory that cannot, under any circumstances, be paged to disk. The paged pool is a section of memory that can be paged to disk. (Just being stored in the paged pool doesn't necessarily mean that something has been paged to disk. It just means that it has either been paged to disk or it could be paged to disk.) Sandwiched directly in between the nonpaged and paged pools (although technically part of the nonpaged pool) is a section of memory called the “System Page Table Entries,” or “System PTEs”.

This test tracks critical metrics corresponding to the System PTEs and the pool areas of kernel memory.

The measures made by this test are as follows:

Measurement Description Measurement Unit Interpretation
Free_sys_page_table Indicates the number of page table entries not currently in use by the system Number The maximum number of System PTEs that a server can have is set when theserver boots. In heavily-used servers, you can run out of system PTEs. Youcan use the registry to increase the number of system PTEs, but that encroaches into the paged pool area, and you could run out of paged pool memory. Running out ofeither one is bad, and the goal should be to tune your server so that you run out of both at the exact same time. Typically, the value of this metric should be above 3000.
Page_read_rate The average number of times per second the disk was read to resolve hard fault paging Reads/Sec  
Page_write_rate The average number of times per second the pages are written to disk to free up the physical memory Writes/Sec  
Page_input_rate The number of times per second that a process needed toaccess apiece of memory that was not in its working set, meaning that the system hadto retrieve itfrom the page file Pages/Sec  
Page_output_rate The number of times per second the system decided to trim a process's working set by writing some memory to disk in order to free up physical memory for another process Pages/Sec This value is a critical measure of the memory utilization on a server. Ifthis value never increases, then there is sufficient memory in the system. Instantaneous spikes of this value are acceptable, but if the value itself starts to rise over time or with load, it implies that there is a memory shortage on the server.
Pool_nonpaged_data The total size of the kernel memory nonpaged pool MB The kernel memory nonpage pool is an area of system memory (that is, physical memory used by the operating system) for kernel objects that cannot be written to disk, but must remain in physical memory as long as the objects are allocated. Typically, there should be no more than 100 MB of non-paged pool memory being used.
Pool_paged_data The total size of the Paged Pool MB If the Paged Pool starts to run out of space (when it's 80% full by default), the system will automatically take some memory away from the System File Cache and give it to the PagedPool. This makes the System File Cache smaller. However, the system file cache is critical, and so it will never reach zero. Hence, a significant increase in the paged pool size is a problem.This metric is a useful indicator of memory leaks in a system. A memory leak occurs when the system allocates more memory to a process than the process gives back to thepool. Any time of process can cause a memory leak. If the amount of pagedpool data keeps increasing even though the workload on the server remains constant, it is an indicator of a memory leak.
Commited_bytes_in_use The committed bytes as a percentage of the Commit Limit. Percent Whenever this measure exceeds 80-90%, the application requests to allocate memory in the virtual memory (page file). This ratio can be reduced by increasing the Physical memory or the Page file.
Pool_nonpaged_failures The number of times allocations have failed from non paged pool. Number Generally, a non-zero value indicates a shortage of physical memory.
Pool_paged_failures The number of times allocations have failed from paged pool. Number A non-zero value for this measure indicates the shortage of physical memory.
Copy_read_hits The percentage of copy read calls satisfied by reads from the Cache Percent Any value over 80% for this measure is excellent.
Copy_reads_sec Indicates the rate at which read operations from pages of the file system cache involve a copy read. Reads/Sec A copy read is a file read operation that is satisfied by a memory copy from a page in the cache to the application's buffer. The LAN redirector uses this method for retrieving information from the cache, as does the LAN server for small transfers. This method is also used by the disk file systems.