From: ebiederm@xmission.com (Eric W. Biederman)
Subject: Setting monotonic time?
Date: Mon, 01 Oct 2018 11:15:32 +0200 [thread overview]
Message-ID: <877ej2xc23.fsf_-_@xmission.com> (raw)
Message-ID: <20181001091532.RN1YfcbsCOfIIKKf5KyWYmWpgirbozlmrDY87Tw8MS8@z> (raw)
In-Reply-To: <alpine.DEB.2.21.1809282023350.1432@nanos.tec.linutronix.de> (Thomas Gleixner's message of "Fri, 28 Sep 2018 21:32:15 +0200 (CEST)")
In the context of process migration there is a simpler subproblem that I
think it is worth exploring if we can do something about.
For a cluster of machines all running with synchronized
clocks. CLOCK_REALTIME matches. CLOCK_MONOTNIC does not match between
machines. Not having a matching CLOCK_MONOTONIC prevents successful
process migration between nodes in that cluster.
Would it be possible to allow setting CLOCK_MONOTONIC at the very
beginning of time? So that all of the nodes in a cluster can be in
sync?
No change in skew just in offset for CLOCK_MONOTONIC.
There are also dragons involved in coordinating things so that
CLOCK_MONOTONIC gets set before CLOCK_MONOTONIC gets used. So I don't
know if allowing CLOCK_MONOTONIC to be set would be practical but it
seems work exploring all on it's own.
Dmitry would setting CLOCK_MONOTONIC exactly once at boot time solve
your problem that is you are looking at a time namespace to solve?
Eric
next prev parent reply other threads:[~2018-10-01 9:15 UTC|newest]
Thread overview: 78+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-19 20:50 [RFC 00/20] ns: Introduce Time Namespace dima
2018-09-19 20:50 ` Dmitry Safonov
2018-09-19 20:50 ` [RFC 16/20] selftest: Add Time Namespace test for supported clocks dima
2018-09-19 20:50 ` Dmitry Safonov
2018-09-24 21:36 ` shuah
2018-09-24 21:36 ` Shuah Khan
2018-09-19 20:50 ` [RFC 17/20] selftest/timens: Add test for timerfd dima
2018-09-19 20:50 ` Dmitry Safonov
2018-09-19 20:50 ` [RFC 18/20] selftest/timens: Add test for clock_nanosleep dima
2018-09-19 20:50 ` Dmitry Safonov
2018-09-19 20:50 ` [RFC 19/20] timens/selftest: Add procfs selftest dima
2018-09-19 20:50 ` Dmitry Safonov
2018-09-19 20:50 ` [RFC 20/20] timens/selftest: Add timer offsets test dima
2018-09-19 20:50 ` Dmitry Safonov
2018-09-21 12:27 ` [RFC 00/20] ns: Introduce Time Namespace ebiederm
2018-09-21 12:27 ` Eric W. Biederman
2018-09-24 20:51 ` avagin
2018-09-24 20:51 ` Andrey Vagin
2018-09-24 22:02 ` ebiederm
2018-09-24 22:02 ` Eric W. Biederman
2018-09-25 1:42 ` avagin
2018-09-25 1:42 ` Andrey Vagin
2018-09-26 17:36 ` ebiederm
2018-09-26 17:36 ` Eric W. Biederman
2018-09-26 17:59 ` 0x7f454c46
2018-09-26 17:59 ` Dmitry Safonov
2018-09-27 21:30 ` tglx
2018-09-27 21:30 ` Thomas Gleixner
2018-09-27 21:41 ` tglx
2018-09-27 21:41 ` Thomas Gleixner
2018-10-01 23:20 ` avagin
2018-10-01 23:20 ` Andrey Vagin
2018-10-02 6:15 ` tglx
2018-10-02 6:15 ` Thomas Gleixner
2018-10-02 21:05 ` 0x7f454c46
2018-10-02 21:05 ` Dmitry Safonov
2018-10-02 21:26 ` tglx
2018-10-02 21:26 ` Thomas Gleixner
2018-09-28 17:03 ` ebiederm
2018-09-28 17:03 ` Eric W. Biederman
2018-09-28 19:32 ` tglx
2018-09-28 19:32 ` Thomas Gleixner
2018-10-01 9:05 ` ebiederm
2018-10-01 9:05 ` Eric W. Biederman
2018-10-01 9:15 ` ebiederm [this message]
2018-10-01 9:15 ` Setting monotonic time? Eric W. Biederman
2018-10-01 18:52 ` tglx
2018-10-01 18:52 ` Thomas Gleixner
2018-10-02 20:00 ` arnd
2018-10-02 20:00 ` Arnd Bergmann
2018-10-02 20:06 ` tglx
2018-10-02 20:06 ` Thomas Gleixner
2018-10-03 4:50 ` ebiederm
2018-10-03 4:50 ` Eric W. Biederman
2018-10-03 5:25 ` tglx
2018-10-03 5:25 ` Thomas Gleixner
2018-10-03 6:14 ` ebiederm
2018-10-03 6:14 ` Eric W. Biederman
2018-10-03 7:02 ` arnd
2018-10-03 7:02 ` Arnd Bergmann
2018-10-03 6:14 ` tglx
2018-10-03 6:14 ` Thomas Gleixner
2018-10-01 20:51 ` avagin
2018-10-01 20:51 ` Andrey Vagin
2018-10-02 6:16 ` tglx
2018-10-02 6:16 ` Thomas Gleixner
2018-10-21 1:41 ` [RFC 00/20] ns: Introduce Time Namespace avagin
2018-10-21 1:41 ` Andrei Vagin
2018-10-21 3:54 ` avagin
2018-10-21 3:54 ` Andrei Vagin
2018-10-29 20:33 ` tglx
2018-10-29 20:33 ` Thomas Gleixner
2018-10-29 21:21 ` ebiederm
2018-10-29 21:21 ` Eric W. Biederman
2018-10-29 21:36 ` tglx
2018-10-29 21:36 ` Thomas Gleixner
2018-10-31 16:26 ` avagin
2018-10-31 16:26 ` Andrei Vagin
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