Ingo Molnar wrote:

* Dave Hansen [off-list ref] wrote:

quoted

On Tue, 2008-10-21 at 12:21 -0700, Andrew Morton wrote:

quoted

On Mon, 20 Oct 2008 01:40:28 -0400
Oren Laadan [off-list ref] wrote:

quoted

These patches implement basic checkpoint-restart [CR]. This version
(v7) supports basic tasks with simple private memory, and open files
(regular files and directories only).

- how useful is this code as it stands in real-world usage?

Right now, an application must be specifically written to use these 
mew system calls.  It must be a single process and not share any 
resources with other processes.  The only file descriptors that may be 
open are simple files and may not include sockets or pipes.

What this means in practice is that it is useful for a simple app 
doing computational work.

say a chemistry application doing calculations. Or a raytracer with a 
large job. Both can take many hours (days!) even on very fast machine 
and the restrictions on rebootability can hurt in such cases.

You should reach a minimal level of initial practical utility: say some 
helper tool that allows testers to checkpoint and restore a real PovRay 
session - without any modification to a stock distro PovRay.

There are the liblxc userspace tools doing that.

http://sourceforge.net/projects/lxc/

There are the lxc-checkpoint and lxc-restart commands to test the Oren's 
patches with the external checkpoint Cedric did. These commands are 
experimental and under development so a hack may be necessary for 
checkpoint/restart.

I didn't tried with Oren's external checkpoint yet, but I think the 
commands should work. Actually these commands relies on the freezer, so 
the checkpoint command does freeze, checkpoint, unfreeze. (and kill if 
specified).

	lxc-create -n foo

	lxc-start -n foo mypovray

	lxc-checkpoint -s -n foo > myckptfile

	lxc-restart -n foo < myckptfile

Thanks
   -- Daniel
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