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Questions tagged [page-fault]

An interrupt that occurs when a program requests data that is not currently in main memory. The interrupt triggers the operating system to fetch the data from a virtual memory and load it into RAM.

A page fault (sometimes #pf or pf) is a trap to the software raised by the hardware when a program accesses a page that is mapped in the virtual address space, but not loaded in physical memory. In the typical case the operating system tries to handle the page fault by making the required page accessible at a location in physical memory or terminates the program in the case of an illegal access. The hardware that detects a page fault is the memory management unit in a processor. The exception handling software that handles the page fault is generally part of the operating system. -- source wikipedia.

Types of page-faults:

MINOR: If the page is loaded in memory at the time the fault is generated, but is not marked in the memory management unit as being loaded in memory, then it is called a minor or soft page fault.

MAJOR: This is the mechanism used by an operating system to increase the amount of program memory available on demand. The operating system delays loading parts of the program from disk until the program attempts to use it and the page fault is generated. If the page is not loaded in memory at the time of the fault, then it is called a major or hard page fault.

INVALID: If a page fault occurs for a reference to an address that is not part of the virtual address space, meaning there cannot be a page in memory corresponding to it, then it is called an invalid page fault. --source wikipedia

Handling illegal accesses and invalid page faults:

  • If the program receiving the error does not handle it, the operating system performs a default action, typically involving the termination of the running process that caused the error condition, and notifying the user that the program has malfunctioned.

  • Page faults, by their very nature, degrade the performance of a program or operating system and in the degenerate case can cause thrashing. Optimization of programs and the operating system that reduce the number of page faults improve the performance of the program or even the entire system.
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Minimize the number of page faults by loop interchange

Assume page size is 1024 words and each row is stored in one page. If the OS allocates 512 frames for a program and uses LRU page replacement algorithm, What will be the number of page faults in the following programs? int A[][] = new…
HARUN SASMAZ
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Why I get segfault in linux kernel module

I reserved a block of memory for my driver in dts: 

    reserved-memory {
        #size-cells = <2>;
        #address-cells = <2>;
        ranges;

        adc_reserved: ADC {
            compatible = "shared-dma-pool";
            reg = <0x5…
snip777
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Why page faults are usually handled by the OS, not hardware?

I find that during TLB missing process, some architecture use hardware to handle it while some use the OS. But when it comes to page fault, most of them use the OS instead of hardware. I tried to find the answer but didn't find any article explains…
akayuki
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OS development - page fault handling and disk driver

I am currently developing a tiny operating system for learning purposes (see here for the code) and I am currently tinkering with paging and memory management. For handling page faults, I understand I'd need some kind of disk driver in order to…
Davide Della Giustina
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Are anonymous memory mapping prefaulted on linux?

If one allocates memory using anonymous memory mapping using mmap system call on linux: mmap(NULL, 512*4096, MAP_READ|MAP_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, 0, 0); I was wondering if the mapped memory was prefaulted or if physical page is actualy…
Oliv
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How can two virtual memory pointing to same physical memory in linux

i was reading a page that told: "My microbenchmark begins by allocating one memory page, then creates two virtual address aliases pointing to it" First Question. i want to know how can i create two virtual address that pointing to same memory page…
alireza sadeghpour
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page faulting maskmovdqu / _mm_maskmoveu_si128 - how to avoid?

I have a function that streams out structured data. The data are Vec4/Vec3/Vec2/float-structures, so the maximum size is 16 bytes per structure. Now it may happen, that the stream is being read starting inside a structure. Simple solution: load…
St0fF
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How does the OS find the reasons of the page fault?

The page fault in memory may have been raised due to a lot of reasons. In what way is the OS figuring out the type of page fault occurred? This is necessary because different types of page faults needs to be treated differently.
Revan kumar
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What is the correlation between Page Fault and I/O?

I'm taking a course on OS in the Linux Kernel and it's written in my course and here's what's written in it: Big Page Cache is causing more Page Faults and thus less I/O. Small Page Cache is causing less Page Faults and thus more I/O. Why is that…
Yaklefak
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Java JVM Keep Memory Allocation Against Operating System

I am running 1.6.0_25 64bit on windows 7 64bit. I am trying to have the JVM run with maximum memory because my application is very memory intensive... but sadly... the memory allocation does not build up and there is a lot of Page Faults from…
Enas Yunis
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How to fix PAGE_FAULT_IN_NONPAGED_AREA in wdf driver

I meet a BSOD issue in a WDF filter driver when call WdfObjectDelete in Wdf01000!FxObject::CallCleanupCallbacks? Mosttime it works well but the issue happens sometime when reboot. Does anyone can give me some suggestions? Thanks. the stack as…
TQ.Liu
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Triggering page fault exception on Windows

I'm trying to do some tests on page fault exception on Windows. The requirement is to put some data into the page boundary so that reading the data will trigger a page fault exception. Concretely, the test consists of 7 bytes (for example) which are…
Ta Thanh Dinh
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Can a machine with 1GB memory run a 2GB binary without swap space?

When all pages are used up, will the operating system remove a page to make space for the new page, or will it be OOM? What if we delete the binary while the process is running. When there is a page fault and the operating system tries to load the…
Kevin
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Can a page fault be generated due to the absence of the page of inner page table?

Consider, 2 level paging , with Process P, Inner page table PTi, and outer page table PTo. Now we know that P and PTi are divided in various pages but PTo is in 1 page only. So in order to run process P, we need few pages of P , few pages of PTi…
Surbhi Jain
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When a page fault is returned from disk to physical memory, where is the page placed?

I'm confused about this. Don't all physical memory address directly correspond to their physical memory locations? For example, physical address 0x1000 is in the 0x1000's spot of physical memory, etc. In that case, when you have a page fault by…
JobHunter69
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