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Line 9: − + + + − '''Summary:''' CRIU puts a lots of logs when doing its job. Logging is done with simple fprintf function. They are typically useless, but ''if'' some operation fails -- the logs are the only way to find what was the reason for failure.+ + + − + − + − One of the solutions to the problem might be binary logging. The problem with binary logs is the amount of efforts to convert existing logs to binary form. Preferably, the switch to binary logging either keeps existing log() calls intact, either has some automatics to convert them.+ − + − The option to keep log() calls intact might be in pre-compilation pass of the sources. In this pass each <code>log(fmt, ...)</code> call gets translated into a call to a binary log function that saves <code>fmt</code> identifier copies all the args ''as is'' into the log file. The binary log decode utility, required in this case, should then find the fmt string by its ID in the log file and print the resulting message. − − '''Links:''' − * [[Better logging]] − + − + − + Line 57:
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Line 80: − * Suggested by: Alexander Mikhalitsyn <alexander@mihalicyn.com> − − === Add support for memfd_secret file descriptors === − − '''Summary:''' Support C/R of memfd_secret descriptors − − There is memfd_secret syscall which allows user to open − special memfd which is backed by special memory range which − is inaccessible by another processes (and the kernel too!). − − At the moment CRIU can't dump processes that have memfd_secret's opened. − − '''Links:''' − * https://lwn.net/Articles/865256/ − − '''Details:''' − * Skill level: intermediate − * Language: C − * Expected size: 350 hours − * Mentors: Alexander Mikhalitsyn <alexander@mihalicyn.com>, Mike Rapoport <mike.rapoport@gmail.com> Line 117:
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→Add support for checkpoint/restore of CORK-ed UDP socket
== Project ideas ==
== Project ideas ==
=== Optimize logging engine ===
=== Add support for memory compression ===
'''Summary:''' Support compression for page images
We would like to support memory page files compression
in CRIU using one of the fastest algorithms (it's matter
of discussion which one to choose!).
At the same time the printf family of functions is known to take some time to work -- they need to scan the format string for %-s and then convert the arguments into strings. If comparing criu dump with and without logs the time difference is notable (15%-20%), so speeding the logs up will help improve criu performance.
This task does not require any Linux kernel modifications
and scope is limited to CRIU itself. At the same time it's
complex enough as we need to touch memory dump/restore codepath
in CRIU and also handle many corner cases like page-server and stuff.
'''Details:'''
'''Details:'''
* Skill level: intermediate
* Skill level: intermediate
* Language: C, though decoder/preprocessor can be in any language
* Language: C
* Expected size: 350 hours
* Expected size: 350 hours
* Suggested by: Andrei Vagin
* Suggested by: Andrei Vagin <avagin@gmail.com>
* Mentors: Alexander Mikhalitsyn <alexander@mihalicyn.com>
* Mentors: Alexander Mikhalitsyn <alexander@mihalicyn.com>, Andrei Vagin <avagin@gmail.com>
=== Add support for checkpoint/restore of CORK-ed UDP socket ===
=== Add support for checkpoint/restore of CORK-ed UDP socket ===
* Language: C
* Language: C
* Expected size: 350 hours
* Expected size: 350 hours
* Mentors: Andrei Vagin <avagin@gmail.com>
* Mentors: Alexander Mikhalitsyn <alexander@mihalicyn.com>, Pavel Tikhomirov <ptikhomirov@virtuozzo.com>, Andrei Vagin <avagin@gmail.com>
=== Add support for pidfd file descriptors ===
=== Add support for pidfd file descriptors ===
* Expected size: 350 hours
* Expected size: 350 hours
* Mentors: Alexander Mikhalitsyn <alexander@mihalicyn.com>, Christian Brauner <christian@brauner.io>
* Mentors: Alexander Mikhalitsyn <alexander@mihalicyn.com>, Christian Brauner <christian@brauner.io>
* Suggested by: Alexander Mikhalitsyn <alexander@mihalicyn.com>
* Suggested by: Alexander Mikhalitsyn <alexander@mihalicyn.com>
* Language: C
* Language: C
* Expected size: 350 hours
* Expected size: 350 hours
* Mentor: Radostin Stoyanov <rstoyanov@fedoraproject.org>
* Mentors: Radostin Stoyanov <rstoyanov@fedoraproject.org>, Prajwal S N <prajwalnadig21@gmail.com>
* Suggested by: Adrian Reber <areber@redhat.com>
* Suggested by: Adrian Reber <areber@redhat.com>
* Mentor: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
* Mentor: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
* Suggested by: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
* Suggested by: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
=== Checkpointing of POSIX message queues ===
'''Summary:''' Add support for checkpoint/restore of POSIX message queues
POSIX message queues are a widely used inter-process communication mechanism. Message queues are implemented as files on a virtual filesystem (mqueue), where a file descriptor (message queue descriptor) is used to perform operations such as sending or receiving messages. To support checkpoint/restore of POSIX message queues, we need a kernel interface (similar to [https://github.com/checkpoint-restore/criu/commit/8ce9e947051e43430eb2ff06b96dddeba467b4fd MSG_PEEK]) that would enable the retrieval of messages from a queue without removing them. This project aims to implement such an interface that allows retrieving all messages and their priorities from a POSIX message queue.
'''Links:'''
* https://github.com/checkpoint-restore/criu/issues/2285
* https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/ipc/mqueue.c
* https://www.man7.org/tlpi/download/TLPI-52-POSIX_Message_Queues.pdf
'''Details:'''
* Skill level: intermediate
* Language: C
* Expected size: 350 hours
* Mentors: Radostin Stoyanov <rstoyanov@fedoraproject.org>, Pavel Tikhomirov <ptikhomirov@virtuozzo.com>, Prajwal S N <prajwalnadig21@gmail.com>
* Suggested by: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
=== Kubernetes operator for managing container checkpoints ===
'''Summary:''' Develop a Kubernetes operator that automates the management of container checkpoints
Container checkpointing has recently been introduced as an alpha feature in Kubernetes.
To enable this feature, the kubelet API was extended with an endpoint that enables the
creation of checkpoints for individual containers. By default, all container checkpoints
are stored as tar archives in <code>/var/lib/kubelet/checkpoints</code> using the following
file name format: <code>checkpoint-<pod-name>_<namespace-name>-<container-name>-<timestamp>.tar</code>.
However, the current implementation does not provide a mechanism for limiting the number
of checkpoints, which may lead to filling up all existing disk space. This project aims to
develop a Kubernetes operator that automates the management of checkpoints and provides
a garbage collection mechanism to discard obsolete checkpoints.
'''Links:'''
* https://github.com/checkpoint-restore/checkpoint-restore-operator
* https://kubernetes.io/docs/reference/node/kubelet-checkpoint-api/
* https://kubernetes.io/blog/2022/12/05/forensic-container-checkpointing-alpha/
* https://kubernetes.io/blog/2023/03/10/forensic-container-analysis/
* https://github.com/kubernetes/kubernetes/pull/115888
* https://github.com/kubernetes/enhancements/issues/2008
'''Details:'''
* Skill level: intermediate
* Language: Go
* Expected size: 350 hours
* Mentors: Adrian Reber <areber@redhat.com>, Radostin Stoyanov <rstoyanov@fedoraproject.org>, Prajwal S N <prajwalnadig21@gmail.com>
* Suggested by: Adrian Reber
== Suspended project ideas ==
== Suspended project ideas ==
Listed here are tasks that seem suitable for GSoC, but currently do not have anybody to mentor it.
Listed here are tasks that seem suitable for GSoC, but currently do not have anybody to mentor it.
=== Optimize logging engine ===
'''Summary:''' CRIU puts a lots of logs when doing its job. Logging is done with simple fprintf function. They are typically useless, but ''if'' some operation fails -- the logs are the only way to find what was the reason for failure.
At the same time the printf family of functions is known to take some time to work -- they need to scan the format string for %-s and then convert the arguments into strings. If comparing criu dump with and without logs the time difference is notable (15%-20%), so speeding the logs up will help improve criu performance.
One of the solutions to the problem might be binary logging. The problem with binary logs is the amount of efforts to convert existing logs to binary form. Preferably, the switch to binary logging either keeps existing log() calls intact, either has some automatics to convert them.
The option to keep log() calls intact might be in pre-compilation pass of the sources. In this pass each <code>log(fmt, ...)</code> call gets translated into a call to a binary log function that saves <code>fmt</code> identifier copies all the args ''as is'' into the log file. The binary log decode utility, required in this case, should then find the fmt string by its ID in the log file and print the resulting message.
'''Links:'''
* [[Better logging]]
'''Details:'''
* Skill level: intermediate
* Language: C, though decoder/preprocessor can be in any language
* Expected size: 350 hours
* Suggested by: Andrei Vagin
* Mentors: Alexander Mikhalitsyn <alexander@mihalicyn.com>
=== IOUring support ===
=== IOUring support ===