Re: Linux Checkpoint-Restart - v19

Oren Laadan
2010-03-15T22:55:42Z

Hi,

Thanks for taking the time to evaluate c/r. You may want to also
try the latest, which is (as of now) ckpt-v20-rc2.

In the future, please CC the containers mailing list for issues
related to c/r, at "containers@lists.linux-foundation.org".

Jiro SEKIBA wrote:
> Hi,
>
> I'm trying to evaluate external checkpoint/restart with cr-v19 kernel.
> However, when I restart, I got "Killed" message in stdout.
> Do you have any tips or clue that are not in
> Documentation/checkpoint/usage.txt ?
>
> I'm using kernel pulled from
> git://git.ncl.cs.columbia.edu/pub/git/linux-cr.git .
> checkout tag named "ckpt-v19". Base distro is ubuntu 9.10.
>
> I ran self checkpioint/restart sample program in Documentation/checkpint.
> It works as written in usage.txt.
> However, I can not make external checkpint/restart work properly.
>
> I made a simple test program bellow and create checkpoint externally using
> the program in Documentation/checkpoint/, it looks checkpoint file is
> created properly.
> However, when I ran self_restart < ckpt.image, I got "Killed" message.

If you take an external checkpoint, then you need to match it
with an external restart, as opposed to self_restart.

Otherwise, restarting with self_restart from a checkpoint that is
not a self-checkpoint can yield unexpected results.

Since you don't mention in your post, I don't know if you are using
the tools from user-cr. If not, then you should use 'checkpoint' and
'restart' tools from there. It is available from:
git://git.ncl.cs.columbia.edu/pub/git/user-cr.git
(use the same branch as the one you used to linux-cr).

Once you have the tools compiled, and you checkpoint with the
'checkpoint' utility from there, you can restart with:
restart -v < ckpt.image

Oren.

>
> Is there any extra configurations other than cgroup freezer and
> checkpint/restart ?
> Or any limitation other than closing stdout,err,in ?
>
> what I did is following:
>
> # mount -t cgroup -o freezer cgroup /cgroup
> # mkdir /cgroup/0
> ..
> # ./test &
> # PID=$(ps | grep test | cut -f 2 -d' ')
> # echo $PID > /cgroup/0/tasks
> # sleep 3
> # echo FROZEN > /cgroup/0/freezer.state
> # ./checkpoint $PID > ckpt.image
> # mv /tmp/test.out /tmp/test.out.orig
> # cp /tmp/test.out.orig /tmp/test.out
> # echo THAWED > /cgroup/0/freezer.state
> # ./self_restart < ckpt.image
> Killed
>
> ----- test.c -----
> int main(void)
> {
> FILE *fp;
> int i;
>
> close(0);
> // close(1); // I got SEGV when I uncomment this line, when restarting
> close(2);
>
> fp = fopen("/tmp/test.out","w+");
>
> for(i=0;i<10;i++) {
> fprintf(fp,"%d\n",i);
> fflush(fp);
> sleep(1);
> }
>
> fclose(fp);
> return 0;
> }
> ----- test.c -----
>
> Thank you very much in advance
>
> 2010/2/23 Oren Laadan <orenl@cs.columbia.edu>:
>> Hi Andrew,
>>
>> We've put a stake in the ground for our next set of checkpoint/restart
>> patches, v19. It has some great new stuff, and we put extra effort to
>> address your concerns. We would like to have the code included in -mm
>> for wider feedback and testing.
>>
>> This one is able to checkpoint/restart screen and vnc sessions, and
>> live-migrate network servers between hosts. It also adds support for
>> x86-64 (in addition to x86-32, s390x and powerpc). It is rebased to
>> kernel 2.6.33-rc8.
>>
>> Since one of your main concerns was about what is not yet implemented
>> and how complicated or ugly it will be to support that, we've put up
>> a wiki page to address that. In it there is a simple table that lists
>> what is not implemented and the anticipated solution impact, and for
>> some entries a link to more details.
>>
>> The page is here: http://ckpt.wiki.kernel.org/index.php/Checklist
>>
>> We want to stress that the patchset is already very useful as-is. We
>> will keep working to implement more features cleanly. Some features we
>> are working on include network namespaces and device configurations,
>> mounts and mounts namespaces, and file locks. Should a complicated
>> feature prove hard to implement, users have alternatives systems like
>> kvm, until we manage to come up with a clean solution.
>>
>> We believe that maintenance is best addressed through testing. We now
>> have a comprehensive test-suite to automatically find regressions.
>> In addition, we ran LTP and the results are the same with CHECKPOINT=n
>> and =y.
>>
>> If desired we'll send the whole patchset to lkml, but the git trees
>> can be seen at:
>>
>> kernel: http://www.linux-cr.org/git/?p=linux-cr.git;a=summary
>> user tools: http://www.linux-cr.org/git/?p=user-cr.git;a=summary
>> tests suite: http://www.linux-cr.org/git/?p=tests-cr.git;a=summary
>>
>> Thanks,
>>
>> Application checkpoint/restart team
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>