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→Add support for checkpoint/restore of CORK-ed UDP socket
=== Add support for checkpoint/restore of CORK-ed UDP socket ===
=== Add support for checkpoint/restore of CORK-ed UDP socket ===
'''Summary:''' TODO: Short description of the project
'''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).
'''Links:'''
'''Links:'''
* https://github.com/checkpoint-restore/criu/issues/409
* https://github.com/checkpoint-restore/criu/issues/409
* Wiki links to relevant material
* [[Sockets]], [[TCP connection]]
* External links to mailing lists or web sites
* [[https://groups.google.com/forum/#!topic/comp.os.linux.networking/Uz8PYiTCZSg UDP cork explained]]
'''Details:'''
'''Details:'''
* Skill level: beginner or intermediate or advanced
* Skill level: intermediate (+linux kernel)
* Language: C
* Language: C
* Mentor: Pavel Emelianov <xemul@virtuozzo.com>
* Mentor: Pavel Emelianov <xemul@virtuozzo.com>
* Suggested by: Pavel Emelianov <xemul@virtuozzo.com>
* Suggested by: Pavel Emelianov <xemul@virtuozzo.com>
=== Optimize the pre-dump algorithm ===
=== Optimize the pre-dump algorithm ===