Checkpoint/Restore In Userspace (CRIU) (pronounced kree-oo, /kriu/), is a software tool for the Linux operating system. Using this tool, it is possible to freeze a running application (or part of it) and checkpoint it to persistent storage as a collection of files. One 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, rather than in the kernel.
The initial version of CRIU software was presented to the Linux developers community by Pavel Emelyanov, the OpenVZ kernel team leader, on 15 July 2011.[3]
In September 2011, the project was presented at the Linux Plumbers Conference.[4] In general, most of the attendees took a positive view of the project, which is proven by the fact that a number of kernel patches required for implementing the project were included in the mainline kernel. Andrew Morton, however, was a bit skeptical:
A note on this: this is a project by various mad Russians to perform c/r mainly from userspace, with various oddball helper code added into the kernel where the need is demonstrated... However I'm less confident than the developers that it will all eventually work! So what I'm asking them to do is to wrap each piece of new code inside CONFIG_CHECKPOINT_RESTORE. So if it all eventually comes to tears and the project as a whole fails, it should be a simple matter to go through and delete all trace of it.
The CRIU tool is being developed as part of the OpenVZ project, with the aim of replacing the in-kernel checkpoint/restore. Though its main focus is to support the migration of containers, allowing users to check-point and restore the current state of running processes and process groups. The tool can currently be used on x86-64 and ARM systems and supports the following features:
Linux kernel-specific system calls: inotify, signalfd, eventfd and epoll
As of September 2013[update], no kernel patching is required because all of the required functionality has already been merged into the Linux kernel mainline since kernel version 3.11, which was released on September 2, 2013.[6][7]
TCP connection migration
One of the initial project goals was to support the migration of TCP connections, the biggest challenge being to suspend and then restore only one side of a connection. This was necessary for performing the live migration of containers (along with all their active network connections) between physical servers, the main scenario of using the checkpoint/restore feature in OpenVZ. To cope with this problem, a new feature, "TCP repair mode", was implemented. The feature was included in version 3.5 of the Linux kernel mainline[8] and provides users with additional means to disassemble and reconstruct TCP sockets without the necessity of exchanging network packets with the opposite side of the connection.
^Pavel Emelyanov (2011-07-15). "Checkpoint/restore mostly in the userspace".
^"Checkpoint/restart in the userspace". Linux Plumbers Conf 2011.
^"Merge branch 'akpm' (aka "Andrew's patch-bomb, take two")". Linux kernel source tree. 2012-01-13.
^"Installation: Linux Kernel". Linux kernel v3.11 or newer is required, with some specific options set
^"Linux kernel 3.11, Section 1.5. Detailed tracking of which pages a task writes". kernelnewbies.org. 2013-09-02. Retrieved 2016-05-03.
^Pavel Emelyanov (2012-02-29). "TCP connection repair". Linux Netdev Mailing List.
Further reading
Sanidhya Kashyap. "Rebootless Kernel Update and Validation".
Rami Rosen. "Linux Containers and the Future Cloud" (PDF).
CRIU Team. "Comparison to other CR projects".
March 13, 2023
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This article relies excessively on references to primary sources Please improve this article by adding secondary or tertiary sources Find sources CRIU news newspapers books scholar JSTOR August 2014 Learn how and when to remove this template message Checkpoint Restore In Userspace CRIU pronounced kree oo kriu is a software tool for the Linux operating system Using this tool it is possible to freeze a running application or part of it and checkpoint it to persistent storage as a collection of files One 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 rather than in the kernel CRIUDeveloper s OpenVZ Team at VirtuozzoInitial release23 July 2012 10 years ago 2012 07 23 1 Stable release3 17 May 5 2022 10 months ago 2022 05 05 2 Repositorygithub wbr com wbr checkpoint restore wbr criuWritten inC and AssemblerOperating systemLinuxPlatformx86 64 ARM Power ISA IBM System 390TypeApplication checkpointingLicenseGNU GPL v 2Websitecriu wbr org Contents 1 History 2 Use 3 TCP connection migration 4 References 5 Further readingHistory EditThe initial version of CRIU software was presented to the Linux developers community by Pavel Emelyanov the OpenVZ kernel team leader on 15 July 2011 3 In September 2011 the project was presented at the Linux Plumbers Conference 4 In general most of the attendees took a positive view of the project which is proven by the fact that a number of kernel patches required for implementing the project were included in the mainline kernel Andrew Morton however was a bit skeptical A note on this this is a project by various mad Russians to perform c r mainly from userspace with various oddball helper code added into the kernel where the need is demonstrated However I m less confident than the developers that it will all eventually work So what I m asking them to do is to wrap each piece of new code inside CONFIG CHECKPOINT RESTORE So if it all eventually comes to tears and the project as a whole fails it should be a simple matter to go through and delete all trace of it Andrew Morton 5 Use EditThe CRIU tool is being developed as part of the OpenVZ project with the aim of replacing the in kernel checkpoint restore Though its main focus is to support the migration of containers allowing users to check point and restore the current state of running processes and process groups The tool can currently be used on x86 64 and ARM systems and supports the following features Processes their hierarchy PIDs user and group authenticators UID GID SID etc system capabilities threads and running and stopped states Application memory memory mapped files and shared memory Open files Pipes and FIFOs Unix domain sockets Network sockets including TCP sockets in ESTABLISHED state see below System V IPC Timers Signals Terminals Linux kernel specific system calls a href Inotify html title Inotify inotify a signalfd eventfd and a href Epoll html title Epoll epoll a As of September 2013 update no kernel patching is required because all of the required functionality has already been merged into the Linux kernel mainline since kernel version 3 11 which was released on September 2 2013 6 7 TCP connection migration EditOne of the initial project goals was to support the migration of TCP connections the biggest challenge being to suspend and then restore only one side of a connection This was necessary for performing the live migration of containers along with all their active network connections between physical servers the main scenario of using the checkpoint restore feature in OpenVZ To cope with this problem a new feature TCP repair mode was implemented The feature was included in version 3 5 of the Linux kernel mainline 8 and provides users with additional means to disassemble and reconstruct TCP sockets without the necessity of exchanging network packets with the opposite side of the connection References Edit Pavel Emelyanov 2012 07 23 Checkpoint restore tool v0 1 Release schedule Pavel Emelyanov 2011 07 15 Checkpoint restore mostly in the userspace Checkpoint restart in the userspace Linux Plumbers Conf 2011 Merge branch akpm aka Andrew s patch bomb take two Linux kernel source tree 2012 01 13 Installation Linux Kernel Linux kernel v3 11 or newer is required with some specific options set Linux kernel 3 11 Section 1 5 Detailed tracking of which pages a task writes kernelnewbies org 2013 09 02 Retrieved 2016 05 03 Pavel Emelyanov 2012 02 29 TCP connection repair Linux Netdev Mailing List Further reading EditSanidhya Kashyap Rebootless Kernel Update and Validation Rami Rosen Linux Containers and the Future Cloud PDF CRIU Team Comparison to other CR projects Retrieved from https en wikipedia org w index php title CRIU amp oldid 1141245781, wikipedia, wiki, book, books, library,
