Performance Testing : Potential Problems

Excessive Paging

Paging is where the system writes or reads a page of memory to the disk subsystem. This is done because more physical memory (RAM) is needed than was available. The disk subsystem takes the place of memory in this case.

Writing and reading from disk is exponentially slower than writing or reading from memory and therefore too much paging will have a performance impact.

Paging File Size

The paging file is the file used when the system pages information in and out of memory (process mentioned above). The file is configured through control panel…system…performance. Processor Queues 100% processor usage is not always bad, although it is true that a faster processor will improve things, it may be that a single application easily uses 100% of the faster processor as well. This becomes a problem is other processes are queued waiting for processor time

Processor Congestion

The server work queue is the queue of requests waiting for processor time. This is the list of work the system must do to answer server network requests.

Network Throughput

If the number of pages/sec increases and the number of bytes Total/sec decreases then the server is doing more work but handling less network traffic, which may be a sign that physical memory is the bottleneck. Note, network cards use nonpaged memory, so the physical memory may be taken up with network tasks, leaving less for the paged memory processes use, hence the excessive paging.