[Devel] [PATCH] ve: add ability to set offset for monotonic time

[Cyrill Gorcunov]

On Mon, Nov 30, 2015 at 07:05:46PM +0300, Andrew Vagin wrote:
> > 
> > I've a few questions:
> > 
> >  - what about the rest of the clocks? Say CLOCK_BOOTTIME, CLOCK_MONOTONIC_RAW?
> 
> This offset affects all monotonic clocks:
> 
> #define clock_is_monotonic(which_clock) \
>         ((which_clock) == CLOCK_MONOTONIC || \
>          (which_clock) == CLOCK_MONOTONIC_RAW || \
>          (which_clock) == CLOCK_MONOTONIC_COARSE)
> 

OK

> Probably, we need to think about CLOCK_BOOTTIME, because it's monotonic
> too, but it isn't about this patch.

OK

> 
> >  - who is responsible to save and restore of the offsets, criu or libvzctl,
> >    or maybe p.haul?
> 
> Any of these tool can handle this offset.

That's the key moment: we need somehow exclude criu from vz specifics
but make it as general as possible. So I'm CC'ing Igor, Pavel and
Nikita.

As far as I understand we need to save current time somewhere,
then somehow pass it to destination machine and setup an offset.
In pcs6 all this were saved in checkpoint image file and restored
back by the kernel itself (so we only need to move the image to
destination machine). Now we have a bundle of tools involded
so making convenient api is very important at this early stage.