Re: [rfc v2 0/7] procfs fdinfo extension v2

From: Pavel Emelyanov
Date: Thu May 24 2012 - 15:49:19 EST


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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