Date: Fri, 5 May 2006 06:43:38 -0500
From: "Serge E. Hallyn" <serue@us.ibm.com>
To: Andi Kleen <ak@suse.de>
Cc: "Serge E. Hallyn" <serue@us.ibm.com>,
       "Eric W. Biederman" <ebiederm@xmission.com>, herbert@13thfloor.at,
       dev@sw.ru, linux-kernel@vger.kernel.org, sam@vilain.net, xemul@sw.ru,
       haveblue@us.ibm.com, clg@fr.ibm.com, frankeh@us.ibm.com
Subject: Re: [PATCH 7/7] uts namespaces: Implement CLONE_NEWUTS flag
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Quoting Andi Kleen (ak@suse.de):
> 
> > But, either the nsproxy is shared between tasks and you need to copy
> > youself a new one as soon as any ns changes
> 
> That would be the case. But it is only shared between tasks where 
> all the name spaces are the same.

Ok, that is how I was thinking.

> > , or it is not shared, and 
> > you don't need  that info at all (just make the change in the nsproxy
> > immediately)
> 
> Don't follow you here.
> 
> Basically the goal is to have a minimum number of nsproxies in the system without
> having to maintain a global hash table. So instead you assume that name space
> changes are infrequent. In the common case of clone without a name space change
> you just share the nsproxy of the parent. If there is a name space change of
> any kind you get a new one.
> 
> This won't get the absolute minimum number of nsproxies, but should be reasonably
> good without too much effort.

Ok.  Then I maintain that the bitmap of changed namespaces seems
unnecessary.  Since you're likely sharing an nsproxy with your parent
process, when you clone a new namespace you just want to immediately get
a new nsproxy pointing to the new namespaces.

Anyway this seems simple enough to just code up.  Simpler than
continuing to talk about it  :)

-serge
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