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PFAULT Workload

The PFAULT workload is used with Linux guest virtual machines to randomly reference a specified amount of the guest's storage.

The PFAULT command syntax is:

     PFAULT [ megs [ samples [ seconds ] ]

The PFAULT program figures out how many 4096-byte pages there are in the number of megabytes specified (megs) and then calls a function to allocate each page separately. Pointers to the pages are put into an array. It then runs the number of sample repetitions specified (samples) of a page touching experiment. Each repetition of the experiment lasts the number of seconds specified (seconds).

Each experiment consists of over and over randomizing a page number and then touching the page by storing to it. As each repetition ends, the program prints out how many pages it touched along with the square of that touch count in the number of seconds specified. After the number of samples specified has been reached, the program prints out the mean number of touches, the mean of the "touches squared" values, and the standard deviation of the touch count mean. The mean and standard deviation of the touch count are useful in a t-test for comparing two runs of PFAULT.

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