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Download Tarball: criu-4.2.tar.gz Version: 4.2 "CRIUTIBILITY" Released: 13 Nov 2025 GIT tag: v4.2 Installation • Usage Releases

Welcome to CRIU, a project to implement checkpoint/restore functionality for Linux in userspace.

Checkpoint/Restore In Userspace, or CRIU (pronounced kree-oo, IPA: /krɪʊ/, Russian: криу), is a software tool for Linux operating system. Using this tool, you can freeze a running application (or part of it) and checkpoint it to a hard drive as a collection of files. You can then use the files to restore and run the application from the point it was frozen at. The distinctive feature of the CRIU project is that it is mainly implemented in user space.

http://static.openvz.org/criu_88x31.gif is a project of http://static.openvz.org/openvz_88x31.gif and is sponsored and supported by http://static.openvz.org/parallels_88x31.gif

Using

Installation

What to do to have CRIU on your system

Usage

How to run the tool

Usage scenarios

Ideas how crtools can be used (some are crazy indeed)

What software is supported

Describes TODO list in higher level terms

Category:HOWTO

Collection of real world examples of how to use CRIU. Some are complex, some are not.

What can change after C/R

CRIU cannot (yet) save and restore every single bit of tasks' state. This page describes what bits visible through standard kernel API are such.

Developing

If you're interested in CRIU development, please subscribe to the criu mailing list: http://lists.openvz.org/mailman/listinfo/criu

Images

Description of image files format

Commits

Mainline kernel commits tracker

Manpages

Kernel's manpages commits tracker

ZDTM Test Suite

Zero downtime test suite

TODO

Current TODO list

Postulates

What to keep in mind when writing new code

Code coverage results

Shows how zdtm run covers the crtools code paths

How to submit patches

Events Linux Plumbers Conference 2025 December 12, 2025, Tokyo, Japan, Containers and Checkpoint/Restore Microconference Files on Unmounted Mounts Guarded Control Stack on arm64: Challenges in Enabling Shadow Stack Support for CRIU Optimizing Checkpoints with Built-in Memory Page Compression CANOPIE-HPC @ Supercomputing 2025 November 17, 2025, St. Louis, MO Engine-Agnostic Model Hot-Swapping for Cost-Effective LLM Inference Container Plumbing Days 2025 August 28, 2025, Amsterdam, Netherlands Enabling Secure Container Checkpointing for Distributed Model Training High Performance Container Workshop @ ISC 2025 June 13, 2025, Hamburg, Germany Transparent Hot-Swapping of Containerized AI/ML Workloads

Under the hood

• Sockets
• Memory dumping and restoring
• Checkpoint/Restore
• TCP connection
• Porting crtools to new kernel releases
• Files
• Pending signals
• Stages of restoring
• COW
• Code blobs
• Comparison to other CR projects

External links

• 2025-11-17, Engine-Agnostic Model Hot-Swapping for Cost-Effective LLM Inference
• 2025-08-13, Software Availability Protection in Cyber-Physical Systems
• 2025-07-14, PhoenixOS: Concurrent OS-level GPU Checkpoint and Restore with Validated Speculation
• 2025-06-18, Improving Checkpoint/Restore Functionality in Kubernetes
• 2025-06-17, LWN.net: A parallel path for GPU restore in CRIU
• 2025-06-13, Kubernetes Scheduling with Checkpoint/Restore: Challenges and Open Problems

More external articles...

Other

• Project history
• Logo description
• Events
• Join the CRIU acronym fun