Re: [RFC PATCH 6/9] livepatch: create per-task consistency model

Peter Zijlstra
2015-02-12T12:39:09Z

On Thu, Feb 12, 2015 at 01:25:14PM +0100, Jiri Kosina wrote:
> On Thu, 12 Feb 2015, Peter Zijlstra wrote:
>
> > Its not at all clear how all this would work to me. And I'm not
> > motivated enough to go try and reverse engineer your patch; IMO
> > livepatching is utter fail.
> >
> > If your infrastructure relies on the uptime of a single machine you've
> > lost already.
>
> Well, the fact indisputable fact is that there is a demand for this. It's
> not about one machine, it's about scheduling dowtimes of datacentres.

The changelog says:

> ... A patch can remain in the
> transition state indefinitely, if any of the tasks are stuck in the
> previous universe.

Therefore there is no scheduling anything. Without timeliness guarantees
you can't make a schedule.

Might as well just reboot, at least that's fairly well guaranteed to
happen.