Re: [PATCH 0/9] namespaces: Introduction

[Stephen Hemminger <shemminger@osdl.org>]

On Fri, 19 May 2006 09:40:47 -0700
Andrew Morton <akpm@osdl.org> wrote:

> ebiederm@xmission.com (Eric W. Biederman) wrote:
> >
> >  > Herbert Poetzl <herbert@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?

Werner has demonstrated TCP connection passing
	http://tcpcp.sourceforge.net/