[Devel] Re: [PATCH 0/9] namespaces: Introduction

[Andrew Morton]

ebiederm at xmission.com (Eric W. Biederman) wrote:
>
>  > Herbert Poetzl <herbert at 13thfloor.at> wrote:
>  >>
>  >> let me
>  >>  give a simple example here:
>  >
>  > Examples are useful.
>  >
>  >>   "pid virtualization"
>  >> 
>  >>   - Linux-VServer doesn't really need that right now.
>  >>     we are perfectly fine with "pid isolation" here, we
>  >>     only "virtualize" the init pid to make pstree happy
>  >> 
>  >>   - Snapshot/Restart and Migration will require "full"
>  >>     pid virtualization (that's where Eric and OpenVZ
>  >>     are heading towards)
>  >
>  > snapshot/restart/migration worry me.  If they require complete
>  > serialisation of complex kernel data structures then we have a problem,
>  > because it means that any time anyone changes such a structure they need to
>  > update (and test) the serialisation.
> 
>  There is a strict limit to what is user visible, and if it isn't user visible
>  we will never need it in a checkpoint.  So internal implementation details
>  should not matter.

Migration of currently-open sockets (for example) would require storing of
a lot of state, wouldn't it?