[CRIU] rewriting images via criu (or crit?)

[Tycho Andersen]

On Mon, Oct 27, 2014 at 09:41:48PM +0400, Pavel Emelyanov wrote:
> On 10/27/2014 08:32 PM, Tycho Andersen wrote:
> 
> >> I mean, yes, plugin isn't very flexible tool, but it should be faster than
> >> calling
> >> a separate tool to modify image. For flexibility one could use crit written
> >> in python.
> > 
> > Isn't it mostly just saving you an extra fork()? Assuming the
> > performance critical bits of crit were written in C, shouldn't it be
> > essentially equivalent to doing it in criu?
> 
> How about doing restore-time modification in streaming mode?
> Like -- criu forks crit with 2 pipes (1 unix seq-packet socket),
> then sends there images reading modified versions back. This
> should save a lot of time for fork() (we do fork() a lot in criu
> restore anyway, e.g. for netns setup), but will still make it
> possible to use Python powers for images manipulations.

So you'd do something like pass --crit-cli="..." to criu, which would
pass that to crit which would read from the pipe and do what it
wanted?

Tycho

> Thanks,
> Pavel
> 
>