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What is a "Page Fault"? How do the number of page faults impact performance?


1 comment

  • Sam Kirchoff

    There are two types of page faults; hard and soft.

    Soft is when the data being sought is actually in memory, but can't be found by address. These can quickly be corrected and the data retrieved without paging to disk.

    Hard faults are when the data being sought is not in memory at all and forces a retrieval from physical storage before going into memory.

    DPACK only tracks hard faults. Windows will fault much more than a Linux/Unix and it's part of the design. It is not always a problem.

    Huge amounts of faulting and a correlation to poor performance or other symptoms can mean an improper allocation of memory. Faults that get gradually higher and higher without stopping could indicate other poor application design like a memory leak.


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