Re: [RFC][PATCH 1/2] Track in-kernel when we expect checkpoint/restart to work

From: "Serge E. Hallyn" <serue@us.ibm.com>
To: Greg Kurz <gkurz@fr.ibm.com>
Cc: Chris Friesen <cfriesen@nortel.com>,
	arnd@arndb.de, containers@lists.linux-foundation.org,
	linux-kernel@vger.kernel.org,
	Dave Hansen <dave@linux.vnet.ibm.com>,
	Ingo Molnar <mingo@elte.hu>, Daniel Lezcano <dlezcano@fr.ibm.com>
Subject: Re: [RFC][PATCH 1/2] Track in-kernel when we expect checkpoint/restart to work
Date: Mon, 13 Oct 2008 11:46:00 -0500	[thread overview]
Message-ID: <20081013164559.GA31636@us.ibm.com> (raw)
In-Reply-To: <1223885897.4404.5.camel@localhost.localdomain>

Quoting Greg Kurz (gkurz@fr.ibm.com):
> On Fri, 2008-10-10 at 11:18 -0600, Chris Friesen wrote:
> > Greg Kurz wrote:
> > 
> > > This flag is weak... testing it gives absolutly no hint whether the
> > > checkpoint may succeed or not. As it is designed now, a user can only be
> > > aware that checkpoint is *forever* denied. I agree that it's only useful
> > > as a "flexible CR todo list".
> > 
> > I don't think it's true that it gives "absolutly no hint".
> > 
> > If the flag is not set, then checkpoint will succeed, right?  Whereas if 
> 
> Wrong. Unless you test_and_checkpoint atomically, the flag doesn't help.

Atomically wrt what?  Presumably you test and checkpoint while the
container is frozen...

> > the flag is set, then it's an indication that checkpoint could fail (but 
> > may still succeed if whatever condition caused the flag to be set is no 
> > longer true).
> > 
> > Chris
> > 
> -- 
> Gregory Kurz                                     gkurz@fr.ibm.com
> Software Engineer @ IBM/Meiosys                  http://www.ibm.com
> Tel +33 (0)534 638 479                           Fax +33 (0)561 400 420
> 
> "Anarchy is about taking complete responsibility for yourself."
>         Alan Moore.
> 
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