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Date: Thu, 24 May 2012 23:48:15 +0400
From: Pavel Emelyanov <xemul@parallels.com>
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To: Matt Helsley <matthltc@us.ibm.com>, Cyrill Gorcunov <gorcunov@openvz.org>
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Subject: Re: [rfc v2 0/7] procfs fdinfo extension v2
References: <20120523102541.382837149@openvz.org> <20120524180121.GK798@count0.beaverton.ibm.com>
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On 05/24/2012 10:01 PM, Matt Helsley wrote:
> On Wed, May 23, 2012 at 02:25:41PM +0400, Cyrill Gorcunov wrote:
> 
> <snip>
> 
>>  - finally it would be great to have ability to attach tasks to
>>    frozen tasks cgroup to thaw them at one moment (the preliminary
>>    patch I've proposed pretty long ago, but Tejun was modifying cgroups
>>    code and asked to wait until 3.4 is release, so I didn't check
>>    the current status of task cgroups at moment, I've it in my todo list)
> 
> This still strikes me as the wrong way to go about freezing for c/r.
> You never explained why you had to do it this way. Why can't you inject
> the parasite thread, move that thread out of the cgroup-to-be-frozen,
> then freeze?

Matt, I think that Cyrill copied this from some old wishlist and I didn't update him
in time :(

The thing is that we seem to have resolved all the issues with freezing/unfreezing
the processes we're checkpoiting/restoring, and currently we are OK with the existing
ptrace functionality. No more modifications of freeze cgroup are required.

Cyrill?

> As best I can tell your reply last time only fleshed out the details
> of *how* you would like it to work, not *why it needs to* work that way:
> 
> 	http://lkml.org/lkml/2011/11/30/27
> 
> Cheers,
> 	-Matt Helsley
> 
> .
> 

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