Re: Linux Checkpoint-Restart - v19

From: Oren Laadan
Date: Mon Mar 01 2010 - 17:56:26 EST

Andrew Morton wrote:
On Mon, 22 Feb 2010 18:17:00 -0500
Oren Laadan <orenl@xxxxxxxxxxxxxxx> wrote:

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:

Does "Refuses to Checkpoint" mean that an attempt to checkpoint will
fail, return the failure to userspace and the system continues as


Also, there is a mechanism in place to report the reason for the
failure (e.g. the offending resource) to the user.

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:

user tools:;a=summary
tests suite:;a=summary

I'd suggest waiting until very shortly after 2.6.34-rc1 then please
send all the patches onto the list and let's get to work.

Sounds good -- will do.


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