The Backend Engineering Show with Hussein Nasser

CPU and Kernel Page Faults

The Backend Engineering Show with Hussein Nasser

Show Notes

Page faults occurs when the process tries to access a memory that isn’t backed by a physical page kernel raises a fault which loads a page. It happens on first access, stack expansion, COW, swap and much more. However it comes with a cost.

In this episode of the backend engineering show I dissect the need and the cost page faults in the kernel.

0:00 Intro 4:00 Virtual memory Abstraction of physical memory Memory sharing Allow more processes to run , unused go to disk Numa, kernel can place memory near the cpu 12:00 VMA areas Text/code Data BSS Heap Stack 19:50 Kernel mode 25:30 What is a Page fault? 30:30 First access page fault 33:00 Stack Expansion page fault 34:30 CoW page fault 38:00 Swap page fault 39:39 File backed page fault 40:29 Permission page fault 45:30 Summary

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