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Line 3: − + − Please contact the respective mentor for the idea you are interested in. For general questions feel free to send an email to the [mailto:criu@openvz.org mailing list] or write in [https://gitter.im/save-restore/criu gitter].+ − === 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> − − − − '''Summary:''' Support C/R of corked UDP socket − − There's UDP_CORK option for sockets. As man page says: − <pre> − If this option is enabled, then all data output on this socket − is accumulated into a single datagram that is transmitted when − the option is disabled. This option should not be used in − code intended to be portable. − </pre> − − Currently criu refuses to dump this case, so it's effectively a bug. Supporting − this will need extending the kernel API to allow criu read back the write queue − of the socket (see [[TCP connection|how it's done]] for TCP sockets, for example). Then − the queue is written into the image and is restored into the socket (with the CORK − bit set too). − + − * https://github.com/checkpoint-restore/criu/issues/409 − * https://github.com/criupatchwork/criu/commit/a532312 − * [[Sockets]], [[TCP connection]] − * [[https://groups.google.com/forum/#!topic/comp.os.linux.networking/Uz8PYiTCZSg UDP cork explained]] − + − * Skill level: intermediate (+linux kernel)+ − * Language: C+ − * Expected size: 350 hours − * Mentors: Alexander Mikhalitsyn <alexander@mihalicyn.com>, Andrei Vagin <avagin@gmail.com> − === Add support for pidfd file descriptors ===+ − + − '''Summary:''' Support C/R of pidfd descriptors+ − + − There is pidfd_open syscall which allows opening − a special PID file descriptor. A user can send a signal to − the process (pidfd_send_signal syscall), wait for the process − (poll() on pidfd). − − − − '''Links:''' − * https://lwn.net/Articles/801319/ − * https://lwn.net/Articles/794707/ − * https://github.com/torvalds/linux/blob/v5.16/kernel/fork.c#L1877 Line 79:
Line 26: − + − + − − === 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> − * Suggested by: Alexander Mikhalitsyn <alexander@mihalicyn.com> Line 176:
Line 103: − + − === Kubernetes operator for managing 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 − − develop a Kubernetes operator that automates the management of checkpoints and provides − a garbage collection mechanism to discard obsolete checkpoints. − + − + − + − * https://kubernetes.io/blog/2023/03/10/forensic-container-analysis/+ − * https://github.com/kubernetes/kubernetes/pull/115888+ − − − + − + − + − * Suggested by: Adrian Reber+ + + + + + + + + + + + + + + + + + + + + Line 268:
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no edit summary
This page contains project ideas for upcoming Google Summer of Code.
This page contains project ideas for upcoming Google Summer of Code.
== Contacts ==
== Contact ==
First, make sure to go through the [[GSoC Students Recommendations]]. Once you build CRIU locally and C/R a simple process successfully, please contact the respective mentor for the idea you are interested in. For general questions feel free to send an email to the [mailto:criu@lists.linux.dev mailing list] or write in [https://gitter.im/save-restore/criu gitter].
== Project ideas ==
== Project ideas ==
=== Add support for memory compression ===
=== Add support for checkpoint/restore of CORK-ed UDP socket ===
'''Links:'''
'''Summary:''' Support compression for page images
'''Details:'''
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!).
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.
At the moment CRIU can't dump processes that have pidfd's opened.
'''Details:'''
'''Details:'''
* Language: C
* Language: C
* Expected size: 350 hours
* Expected size: 350 hours
* Mentors: Alexander Mikhalitsyn <alexander@mihalicyn.com>, Christian Brauner <christian@brauner.io>
* Suggested by: Andrei Vagin <avagin@gmail.com>
* Suggested by: Alexander Mikhalitsyn <alexander@mihalicyn.com>
* Mentors: Radostin Stoyanov <rstoyanov@fedoraproject.org>, Alexander Mikhalitsyn <alexander@mihalicyn.com>, Andrei Vagin <avagin@gmail.com>
=== Use eBPF to lock and unlock the network ===
=== Use eBPF to lock and unlock the network ===
* Language: C
* Language: C
* Expected size: 350 hours
* Expected size: 350 hours
* Mentors: Radostin Stoyanov <rstoyanov@fedoraproject.org>, Pavel Tikhomirov <ptikhomirov@virtuozzo.com>, Prajwal S N <prajwalnadig21@gmail.com>
* Mentors: Radostin Stoyanov <rstoyanov@fedoraproject.org>, Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
* Suggested by: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
* Suggested by: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
'''Summary:''' Develop a Kubernetes operator that automates the management of container checkpoints
=== Add support for arm64 Guarded Control Stack (GCS) ===
'''Summary:''' Support arm64 Guarded Control Stack (GCS)
The arm64 Guarded Control Stack (GCS) feature provides support for
hardware protected stacks of return addresses, intended to provide
hardening against return oriented programming (ROP) attacks and to make
it easier to gather call stacks for applications such as profiling (taken from [1]).
We would like to support arm64 Guarded Control Stack (GCS) in CRIU, which means
that CRIU should be able to Checkpoint/Restore applications using GCS.
This task should not require any Linux kernel modifications
but will require a lot of effort to understand Linux kernel and
glibc support patches. We have a good example of support for
x86 shadow stack [4].
of checkpoints, which may lead to filling up all existing disk space. This project aims to
'''Links:'''
'''Links:'''
* https://github.com/checkpoint-restore/checkpoint-restore-operator
* [1] kernel support https://lore.kernel.org/all/20241001-arm64-gcs-v13-0-222b78d87eee@kernel.org
* https://kubernetes.io/docs/reference/node/kubelet-checkpoint-api/
* [2] libc support https://inbox.sourceware.org/libc-alpha/20250117174119.3254972-1-yury.khrustalev@arm.com
* https://kubernetes.io/blog/2022/12/05/forensic-container-checkpointing-alpha/
* [3] libc tests https://inbox.sourceware.org/libc-alpha/20250210114538.1723249-1-yury.khrustalev@arm.com
* [4] x86 support https://github.com/checkpoint-restore/criu/pull/2306
* https://github.com/kubernetes/enhancements/issues/2008
'''Details:'''
'''Details:'''
* Skill level: intermediate
* Skill level: expert (a lot of moving parts: Linux kernel / libc / CRIU)
* Language: Go
* Language: C
* Expected size: 350 hours
* Expected size: 350 hours
* Mentors: Adrian Reber <areber@redhat.com>, Radostin Stoyanov <rstoyanov@fedoraproject.org>, Prajwal S N <prajwalnadig21@gmail.com>
* Suggested by: Mike Rapoport <rppt@kernel.org>
* Mentors: Mike Rapoport <rppt@kernel.org>, Andrei Vagin <avagin@gmail.com>, Alexander Mikhalitsyn <alexander@mihalicyn.com>
== 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 ===
* Skill level: beginner
* Skill level: beginner
* Language: Python
* Language: Python
=== Add support for checkpoint/restore of CORK-ed UDP socket ===
'''Summary:''' Support C/R of corked UDP socket
There's UDP_CORK option for sockets. As man page says:
<pre>
If this option is enabled, then all data output on this socket
is accumulated into a single datagram that is transmitted when
the option is disabled. This option should not be used in
code intended to be portable.
</pre>
Currently criu refuses to dump this case, so it's effectively a bug. Supporting
this will need extending the kernel API to allow criu read back the write queue
of the socket (see [[TCP connection|how it's done]] for TCP sockets, for example). Then
the queue is written into the image and is restored into the socket (with the CORK
bit set too).
'''Notes:'''
We already had a couple (3) of tries for this problem:
* UDP_REPAIR approach didn't succeed: https://lore.kernel.org/netdev/721a2e32-c930-ad6b-5055-631b502ed11b@gmail.com/, https://lore.kernel.org/netdev/?q=udp_repair
* eBPF (CRIB) approach, socket queue iterator was not merged: https://lore.kernel.org/netdev/AM6PR03MB5848EDA002E3D7EACA7C6BDA99A52@AM6PR03MB5848.eurprd03.prod.outlook.com/, and we have general objections to CRIB approach https://lore.kernel.org/bpf/CAHk-=wjLWFa3i6+Tab67gnNumTYipj_HuheXr2RCq4zn0tCTzA@mail.gmail.com/
We still have one idea we didn't try, as UDP allows packets to be lost on the way on restore we can somehow mark the socket to drop all data before UNCORK. This way we don't really need to restore contents of UDP CORK-ed sockets send queue.
'''Links:'''
* https://github.com/checkpoint-restore/criu/issues/409
* https://github.com/criupatchwork/criu/commit/a532312
* [[Sockets]], [[TCP connection]]
* [[https://groups.google.com/forum/#!topic/comp.os.linux.networking/Uz8PYiTCZSg UDP cork explained]]
'''Details:'''
* Skill level: intermediate (+linux kernel)
* Language: C
* Expected size: 350 hours
* Mentors: Alexander Mikhalitsyn <alexander@mihalicyn.com>, Pavel Tikhomirov <ptikhomirov@virtuozzo.com>, Andrei Vagin <avagin@gmail.com>