[CRIU] Image cache/proxy TODO

[Mike Rapoport]

Hi Radostin,

On Fri, Sep 14, 2018 at 07:55:32AM +0100, Radostin Stoyanov wrote:
> On 14/09/18 05:19, Mike Rapoport wrote:
> > On Sat, Sep 08, 2018 at 10:18:27AM +0100, Radostin Stoyanov wrote:
> >> Hi all,
> >>
> >> I would like to work towards merging the remote option and image
> >> cache/proxy into
> >> the master branch of CRIU and I was wondering what needs to be done?
> >>

[ ... ]

> >>
> >> 6. Check how proxy/cache works with incremental dumps.
> > I'd also check what happens with lazy-pages. I suspect --remote
> > --lazy-pages won't play well together, so probably they should be at least
> > made mutually exclusive.
  
> Hi Mike,
> 
> Yes, the page-server, which is used with --lazy-pages, is not needed
> because we already have the cache/proxy connection.

It's a bit more tricky. With lazy-pages we wouldn't want the cache/proxy in
the middle to keep the remote page fault latency as small as possible.
Besides, the communication between dump and lazy-pages is request -
response, while the cache/proxy presume that dump is always the writer and
restore is always the reader.

> However, I am thinking about implementing a hybrid-copy algorithm (as
> described in [1]) rather than just making them mutually exclusive.
> Something similar to Adrian's article [2] for combining pre-copy and
> post-copy migration.

Well, the hybrid-copy is pretty much what Adrian described with a lot of
math added to select which pages to send in the pre-copy round :)

Yet, that would be really cool to have it in CRIU!

> What do you think?
> 
> [1] http://www.mdpi.com/1999-5903/9/3/37/pdf
> [2] https://lisas.de/~adrian/?p=1253
> 
> Radostin
> >> 7. Add support for cache/proxy into go-phaul code.
> >>
> >> Is there anything else?
> >>
> >> [1] https://criu.org/Image_cache/proxy_TODO
> >> [2]
> >> https://github.com/checkpoint-restore/criu/commit/a14f0d0effc92985a79a9a9da86e338b968c26d6
> >>
> >> Thanks,
> >> Radostin
> >> _______________________________________________
> >> CRIU mailing list
> >> CRIU at openvz.org
> >> https://lists.openvz.org/mailman/listinfo/criu
> >>
> 

-- 
Sincerely yours,
Mike.