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The number of hard pagefaults per second on your system is displayed in the status panel. The status panel displays values for the current, minimum, maximum and average number of hard pagefaults per second.

About Hard Pagefaults

Windows uses a concept of virtual memory which relies on the page translation system provided by the CPU. Whenever a memory address is requested which is not available in physical memory (not resident), the page fault handler provided by the operating system will take over and temporarily suspend the task the CPU was performing. If the page in which the address resides is known to Windows but not resident, Windows will read in the required page from the page file. That is known as a hard pagefault and can take a lot of time to complete. If the page can be read in from the hard disk cache, or if the pagefile resides on a SSD (solid state drive), the price will be limited. However if it needs to physically read in the data from disk sectors on a spinning harddisk this takes a lot of time. This has an adverse effect on performance, responsiveness and real-time processing capabilities of your system.

The more programs you have loaded, the higher will be your memory load. Because Windows uses a concept of virtual memory with the use of a pagefile, your system is more likely to hit hard pagefaults as memory load increases. This will have an adverse effect on both performance and latency of your system. If you see that both memory load and the number of hard pagefaults per second is high, your system is likely to appear sluggish.

Reducing Hard Pagefaults

You can reduce the number of hard pagefaults by closing down programs that consume and make use of a lot of memory. Also, you could consider decreasing the size of the pagefile on your system. If it's an option to upgrade RAM on your system, you could consider adding more.

Measuring Hard Pagefaults

WhySoSlow currently only reports the number of hard pagefaults per second but not the time required to resolve them. If you wish to further investigate hard pagefaults on your system, you can use our LatencyMon tool for that.

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