Difference between revisions of "Time namespace"

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(remove TODO, add LWN link)
 
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Two things (for now) we want to solve with this:
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The time namespace support has been merged in the 5.6 kernel. The current implementation allows setting per-namespace offsets to the system monotonic and boot-time clocks.
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# Shift timer's offsets
 
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# Make start-time remain "unchanged" after C/R
 
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# Continuous flow of monotonic time (CLOCK_MONOTONIC).
 
  
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What about other kinds of counters like perf events and trace events?
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[https://github.com/checkpoint-restore/criu/pull/1002 The time namespace support] in CRIU has been merged in the [[Download/criu/3.14 | 3.14 release]].
  
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=TODO=
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[https://lwn.net/Articles/766089/ LWN article about time namespaces]
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==Required in RFC==
 
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* btime in /proc/stat (used by pstools)
 
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* starttime in /proc/pid/stat
 
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* selftests to test all we've added
 
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* TIME_NS iffdefery everywhere
 
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==Maybe later==
 
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* CLONE_NEWTIME reuses the last free flag from sys_clone() - any way to still keep extensibility for the syscall?
 
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* arm64/arm32/s390/power64 - add archs vvar support (nit: big/little-endianess for timespec::nsec)
 
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* REALTIME-related:
 
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** REALTIME offsets
 
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** vvar offsets will need synchronization (like gtod_read_begin()/gtod_read_retry())
 
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** vfs modification/creation time should work
 
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** utime()/utimes()/futimesat() (with times == NULL)
 
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** utimensat()/futimens() - with UTIME_NOW
 
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** mq_timedsend()/mq_timedreceive()
 
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** semtimedop()
 
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** timerfd
 
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** timer_create()
 
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** COARSE times
 
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** clock_nanosleep()
 
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* Adjtime (too complicated for PoC)
 
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* Cpu time for thread/pid/pgid (times())
 
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* /proc/stat ticks? (top uses them e.g.)
 
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* pid creation time (probably different unrelated API)
 
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* clock_tai - if we care about isolation from host's time
 
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=Git=
 
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* [https://github.com/0x7f454c46/linux/tree/wip/time-ns https://github.com/0x7f454c46/linux/tree/wip/time-ns]
 
  
 
=Links=
 
=Links=
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* [https://lwn.net/Articles/817650/ 04/2020 <nowiki>[PATCH v3 0/6] arm64: add the time namespace support</nowiki>]
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* [https://lore.kernel.org/lkml/158016896588.31887.14143226032971732742.tglx@nanos.tec.linutronix.de/ 01/2020<nowiki> [GIT pull] timers/core for 5.6-rc1</nowiki>]
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* [https://lkml.kernel.org/r/20191112012724.250792-1-dima@arista.com 11/2019 PATCHv8 00/34 kernel: Introduce Time Namespace]
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* [https://lkml.kernel.org/r/20190206001107.16488-1-dima@arista.com 02/2019 PATCH 00/32 kernel: Introduce Time Namespace]
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* [https://lists.linuxfoundation.org/pipermail/ksummit-discuss/2018-November/006210.html 11/2018 <nowiki>[Ksummit-discuss] [TECH-TOPIC] Multiple time domains</nowiki>]
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* [https://lwn.net/Articles/766089/ 09/2018 LWN: Time namespaces]
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* [https://lkml.org/lkml/2018/9/19/950 09/2018 RFC 00/20 ns: Introduce Time Namespace]
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* [https://lists.openvz.org/pipermail/criu/2018-June/041486.html 06/2018 The progress of Time namespace]
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* [https://blog.jessfraz.com/post/two-objects-not-namespaced-linux-kernel/ 04/2017 Two Objects not Namespaced by the Linux Kernel]
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* [https://github.com/littlepretty/VirtualTimeKernel 00/2017 VirtualTimeKernel]
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* [http://publish.illinois.edu/science-of-security-lablet/files/2014/05/DSSnet-A-Smart-Grid-Modeling-Platform-Combining-Electrical-Power-Distributtion-System-Simulation-and-Software-Defined-Networking-Emulation.pdf 00/2016 Article about usage of time namespace in VirtualTimeKernel]
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* [https://pt.slideshare.net/kolyshkin/whats-missing-from-upstream-kernel-containers 08/2015 What's missing from upstream kernel containers?]
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* [https://ckpt.wiki.kernel.org/index.php/LPC2009 09/2009 LPC2009]
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* [https://www.landley.net/kdocs/ols/2006/ols2006v1-pages-101-112.pdf 00/2006 Multiple Instances of the Global Linux Namespaces]
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* [https://lwn.net/Articles/180375/ 04/2006 LWN: Virtual time]
  
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* [https://lists.openvz.org/pipermail/criu/2018-June/041486.html The progress of Time namespace]
 
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* [https://blog.jessfraz.com/post/two-objects-not-namespaced-linux-kernel/ Two Objects not Namespaced by the Linux Kernel]
 
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* [https://lwn.net/Articles/180375/ Virtual time]
 
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* [https://pt.slideshare.net/kolyshkin/whats-missing-from-upstream-kernel-containers What's missing from upstream kernel containers?]
 
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* [https://ckpt.wiki.kernel.org/index.php/LPC2009 LPC2009]
 
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* [https://www.landley.net/kdocs/ols/2006/ols2006v1-pages-101-112.pdf Multiple Instances of the Global Linux Namespaces]
 
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* [https://github.com/littlepretty/VirtualTimeKernel VirtualTimeKernel]
 
  
 
[[Category: Empty articles]]
 
[[Category: Empty articles]]
 
[[Category: Plans]]
 
[[Category: Plans]]

Latest revision as of 14:53, 29 April 2020

The time namespace support has been merged in the 5.6 kernel. The current implementation allows setting per-namespace offsets to the system monotonic and boot-time clocks.

The time namespace support in CRIU has been merged in the 3.14 release.

LWN article about time namespaces

Links[edit]

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