Lower Response Time of Fork by Extending Copy-on-Write to Page Tables

Explore techniques for improving fork system call performance in this conference talk from the Linux Foundation. Dive into the intricacies of process address space, virtual memory areas, and page table structures. Learn about the history and implementation of fork() in the Linux kernel, including Copy-On-Write concepts for physical pages. Discover a proposed extension of Copy-On-Write to page tables, examining its potential benefits for memory usage and response time. Analyze RFC patch feedback, related discussions, and future directions for optimizing fork operations in Linux systems.

Syllabus

Intro
Overview
Process Address Space
Virtual Memory Area
Data Structure of VMAs
Layout of Linked List Sorted VMA
Layout of Five-Level Page Table
Some Page Table Details
History of fork system call
fork() in Linux Kernel
VM part of fork()
Copy-On-Write Concept
Current COW of Physical Page
On-Demand Fork with Vitrual Address Space
Copy-On-Write of Page Table
COW PTE table with Vitrual Address Space
Copy-On-Write Page Table State
Copy-On-Write Page Table of Memory Usage
RFC Patch of COW Page Table
RFC Patch Feedbacks
userfaultfd of Write Protection (uffd-wp)
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