View source for Comparison to other CR projects

This pages tries to explain differences between CRIU and other C/R solutions.

== [http://dmtcp.sourceforge.net DMTCP] ==

{{:DMTCP}}

== [https://ftg.lbl.gov/projects/CheckpointRestart BLCR] ==

Berkeley Lab Checkpoint/Restart (BLCR) is a part of the Scalable Systems Software Suite , 
developed by the Future Technologies Group at Lawrence Berkeley National Lab under SciDAC 
funding from the United States Department of Energy. It is an Open Source, system-level 
checkpointer designed with High Performance Computing (HPC) applications in mind: in particular 
CPU and memory intensive batch-scheduled MPI jobs. BLCR is implemented as a GPL-licensed 
loadable kernel module for Linux 2.4.x and 2.6.x kernels on the x86, x86_64, PPC/PPC64, ARM architectures, and a 
small LGPL-licensed library.

== [http://criu.org CRIU], [http://dmtcp.sourceforge.net DMTCP], [https://ftg.lbl.gov/projects/CheckpointRestart BLCR], [https://openvz.org OpenVZ] ==
 
“looks\seems like yes/no” - i found only unproved message(s) saying “yes”/“no”

“not yet” - it is officially planned or i found no reasons, why it can’t be done.


{| class="wikitable sortable"
|-
!
! CRIU
! DMTCP
! BLCR
! OpenVZ

|-
| Arch
| x86_64, ARM
| x86, x86_64, ARM
| x86, x86_64, PPC/PPC64, ARM
| x86, x86_64

|-
| OS
| Linux
| Linux
| Linux
| Linux

|-
| Need in modified kernel
| No, provided it's 3.11 and above
| No
| No, just need to load module. May be problems with installation on new kernels
| Yes

|-
| App need to pre-load special libraries
| No
| Yes
| Yes
| No

|-
| Requires root privileges
| No, but user can only manipulate tasks belonging to him
| No
| No
| Yes

|-
| Need to modify programs to C/R
| No
| No
| Yes. There are some difficulties with statically linked applications, and with LinuxThreads (it does not support them at all)
| No


|-
| Need to prepare tasks
| No
| Yes. It preloadsthe DMTCP library. That library runs before the routinemain(). It creates a second thread. Thecheckpoint thread then creates a socket to the DMTCP coordinator andregisters itself. The checkpoint thread also creates a signal handler.
| Yes. CR shall notify processes when a checkpoint is to occur (before the kernel takes a checkpoint) to allow the processes to prepare itself accordingly.
| No


|-
| Does it change behavior of the c/r-ed programs?
| No
| Yes, because of wrappers on system calls
| Yes, because of wrappers on system calls
| No

|-
| Live migration
| Yes, even if kernel, libs, etc are newer. Can use Memory Changes Tracking to decrease freeze time
| Yes, if both kernels are recent
| Yes, but if all components are the same. Even if prelinked addresses are different,it will not restore, but it can save the whole used libs and localization files to restore program on the different machine
| Yes

|-
| Containers
| Yes, LXC and OpenVZ containers
| No. It doesn't support namespaces, so it probably can’t dump containers 
| Looks like no
| Yes

|-
| Parallel/distributed computations libraries
| No (in plans)
| Yes. OpenMPI, MPICH2, OpenMP, Cilk are alredy supported and Infiniband is in progress
| Yes. Cray MPI, Intel MPI, LAM/MPI, MPICH-V, MPICH2, MVAPICH, Open MPI, SGI MPT
| Yes

|-
| C/R gdb with debugging app
| No, because they are using the same interface
| Yes
| No
| Yes

|-
| X-Windows apps (KDE, GNOME, etc)
| Yes, by using vnc
| Yes, by using vnc
| Looks like no
| Yes, by using vnc


|-
| Solutions for invocation in the custom software
| Yes. [[RPC]] and [[C API]]
| Yes. Plugins and API
| Not yet
| Yes. via ioctl calls

|-
| colspan="4" |

|-
| Unix sockets
| Yes
| Yes
| No
| Yes

|-
| UDP sockets
| Yes, both ipv4 and ipv6
| Not yet. Developers of dmtcp had no request for this
| Not yet
| Yes

|-
| TCP sockets
| Yes
| Yes
| Not yet
| Yes

|-
| Established tcp connection
| Yes
| No, but you can write a simple DMTCP plugin that tells DMTCP how you want to reconnect on restart
| No
| Yes

|-
| Infiniband
| No
| Not yet, developing is on the half-way
| No
| No

|-
| Multithread support
| Yes
| Yes
| Yes
| Yes

|-
| Multiprocess
| Yes
| Yes
| Yes
| Yes

|-
| Process groups and sessions
| Yes
| Yes
| Not yet
| Yes

|-
| Zombies
| Yes
| No
| No
| Yes

|-
| Namespaces
| Yes
| No
| No
| Yes

|-
| Ptraced programs
| No
| Yes
| No
| Yes

|-
| System V IPC
| Yes
| Yes
| No
| Yes

|-
| Memory mappings
| Yes, all kinds
| Yes
| Yes, partially 
| Yes

|-
| Pipes
| Yes
| Yes
| Not yet
| Yes

|-
| Terminals
| Yes, but only Unix98 PTYs
| Yes
| Yes
| Yes

|-
| Non-posix files (inotify, signalfd, eventfd, etc)
| Yes, inotify, fanotify, epoll, signalfd, eventfd
| Yes, epoll, eventfd, signalfd are already supported and inotify will be supported in future
| Looks like no
| Yes

|-
| Timers
| Yes
| No. Any counter or timer active since the beginning of a process will consider the restarted process to be a new process.
| Yes
| Yes

|-
| Shared resources (files, mm, etc.)
| Yes. SysVIPC, files, fd table and memory
| Yes. System V shared memory(shmget, etc.), mmap-based shared memory, shared sockets, pipes, file descriptors
| No, but it is planned to suppord shared mmap regions
| Yes

|-
| Block devices
| No
| Looks like yes
| No
| No


|-
| Character devices
| Yes, only /dev/null, /dev/zero, etc. are supported
| Yes, looks like null and zero are supported
| Yes, /dev/null and /dev/zero
| Yes

|-
| Capture the contents of open files
| Yes, if file is unlinked
| Looks like no
| Not yet
| Yes

|}

== Sources ==
DMTCP:
*http://dmtcp.sourceforge.net/
*http://dmtcp.sourceforge.net/papers/dmtcp.pdf
*http://www.ccs.neu.edu/home/gene/papers/ccgrid06.pdf
*http://research.cs.wisc.edu/htcondor/CondorWeek2010/condor-presentations/cooperman-dmtcp.pdf
*http://dmtcp.sourceforge.net/papers/mtcp.pdf

BLCR:
*https://upc-bugs.lbl.gov/blcr/doc/html/
*https://ftg.lbl.gov/assets/projects/CheckpointRestart/Pubs/LBNL-49659.pdf
*https://ftg.lbl.gov/assets/projects/CheckpointRestart/Pubs/blcr.pdf
*https://ftg.lbl.gov/assets/projects/CheckpointRestart/Pubs/checkpointSurvey-020724b.pdf
*https://ftg.lbl.gov/assets/projects/CheckpointRestart/Pubs/lacsi-2003.pdf
*https://ftg.lbl.gov/assets/projects/CheckpointRestart/Pubs/LBNL-60520.pdf

== External links ==

* [http://dmtcp.sourceforge.net/FAQ.html#Internals How does DMTCP work?]

[[Category:Under the hood]]