[CRIU] The progress of Time namespace

[Eric W. Biederman]

Adrian Reber <adrian at lisas.de> writes:

> On Fri, Jun 01, 2018 at 11:04:26AM +0800, yukon wrote:
>> I found that the criu community intent to resolve the timer issue[1], I
>> wonder if there is an issue to
>> track the progress?
>
> I have heard of other people experimenting with it and I also had a few
> patches to try it out. The point where I stopped is when I found out
> that most time calls are actually coming from the VDSO and not from the
> kernel and it is still unclear to me how to handle namespaces and VDSO
> correctly.
>
> I have also talked with Christian (on CC) about it and I also contacted
> Eric at some point (also on CC). Maybe they have more information about
> the current status.

Andrian.  My apologies for not getting back to you earlier (I was
swamped) but that is not a good excuse.  I was very impressed by what
you did.

For me personally I have been looking for a real world case where the
timers matter.  Having that would increase the priority of this work
from where I stand.

To date all I have done is recognize that a time namespace is almost
certainly something that we need, and read the code enough to have a
general sense of how the time infrastructure in the kernel works.

I think the VDSO has per cpu if not per process constants so we should
be able to affect this in a namespace.  If the VDSO does not we
certainly can make that happen.

I would be very happy to merge a time namespace.   I would probably even
start looking at implementation details if I had a compelling test case
in my hand.

Yukon.  I don't have the beginning of this thread.  So if you know of a
practical case that does not work because of timers I would love to hear
about it.

Eric