[CRIU] [PATCH 0/9] Memory snapshot

[Pavel Emelyanov]

Hi,

Finally the most tempting (by me at least) feature of CRIU has
turned into active development stage and here's the first version.

It requires kernel support from here:
http://comments.gmane.org/gmane.linux.kernel.mm/98283

With this set crtools can create a chain of dumps where each next
one doesn't contain full memory dump, but takes parts of it from
the previous (parent) one. Next step would be mixing this ability
with pages transfer on page-server, which will give us an iterative
migration support.

So, the new --snapshot[=prev] option is introduced. When no =prev
argument is specified, it just creates a full dump and starts 
kernel memory tracker for task(s). When =prev directory is given
(it should be relative path to --images-dir option's path! not
to current dir) then the memory dump is created but pages, that 
hasn't changed since previous dump are not dumped. The -R option
is useful with --snapshot since by default crtools kills tasks
after dump.

Plz note, that after 2nd snapshot you cannot create yet another
one on the running tasks with the 1st one being parent, as all
the information about memory changes is reset in the kernel! 
There's no protection against this currently, will add one in
next version.

For restore nothing special is required, crtools will pick up
parent images itself.

And, as usual, better and automatic testing is required.

Thanks,
Pavel