Re: [Qemu-devel] [RFC PATCH v4 00/28] COarse-grain LOck-stepping(COLO) Virtual Machines for Non-stop Service

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* zhanghailiang (zhang.zhanghailiang@huawei.com) wrote:
> On 2015/4/22 19:18, Dr. David Alan Gilbert wrote:
> >* zhanghailiang (zhang.zhanghailiang@huawei.com) wrote:
> >>Hi,
> >>
> >>ping ...
> >
> >I will get to look at this again; but not until after next week.
> >
> 
> OK, thanks for your reply. :)
> 
> >>The main blocked bugs for COLO have been solved,
> >
> >I've got the v3 set running, but the biggest problem I hit are problems
> >with the packet comparison module; I've seen a panic which I think is
> 
> What's the panic log?

See my reply to Wen I just sent.

> >in colo_send_checkpoint_req that I think is due to the use of
> >GFP_KERNEL to allocate the netlink message and I think it can schedule
> >there.  I tried making that a GFP_ATOMIC  but I'm hitting other
> >problems with :
> >
> >kcolo_thread, no conn, schedule out
> >
> 
> Er, it is OK to get this messages if you enable the debug,
> if there is no net connect to VM, or there is a checkpoint request happening,
> it is no need to compare any network packets. So we just schedule out the kcolo_thread.
> Is it just this messages been printed ? Or maybe some other problems ?

The problem is that the primary stops at that point; I've not looked why
yet.

> >that I've not had time to look into yet.
> >
> >So I only get about a 50% success rate of starting COLO.
> 
> This is really strange, yes, sometimes we can come across problems like kernel panic in our tests,
> but not so often. Can you describe the problems in detail ?
> 
> >I see there are stuff in the TODO of the colo-proxy that
> >seem to say the netlink stuff should change, maybe you're already fixing
> >that?
> >
> 
> Yes, we are trying to replace the  current netlink in COLO with nfnetlink interface.
> Hope to merge the code in next version.

Good.

> >>we also have finished some new features and optimization on COLO. (If you are interested in this,
> >>we can send them to you in private ;))
> >
> >>For easy of review, it is better to keep it simple now, so we will not add too much new codes into this frame
> >>patch set before it been totally reviewed.
> >
> >I'd like to see those; but I don't want to take code privately.
> >It's OK to post extra stuff as a separate set.
> >
> 
> Hmm, there is really a good idea, maybe we should also add a branch
> with all the optimization and new features in github.

Yes, that would be good.

Dave

> >>COLO is a totally new feature which is still in early stage, we hope to speed up the development,
> >>so your comments and feedback are warmly welcomed. :)
> >
> >Yes, it's getting there though; I don't think anyone else has
> >got this close to getting a full FT set working with disk and networking.
> >
> 
> Thanks,
> zhanghailiang
> 
> >>
> >>On 2015/3/26 13:29, zhanghailiang wrote:
> >>>This is the 4th version of COLO, here is only COLO frame part, include: VM checkpoint,
> >>>failover, proxy API, block replication API, not include block replication.
> >>>The block part has been sent by wencongyang:
> >>>[RFC PATCH COLO v2 00/13] Block replication for continuous checkpoints
> >>>
> >>>Compared with last version, there aren't too much optimize and new functions.
> >>>The main reason is that there is an known issue that still unsolved, we found
> >>>some dirty pages which have been missed setting bit in corresponding bitmap.
> >>>And it will trigger strange problem in VM.
> >>>We hope to resolve it before add more codes.
> >>>
> >>>You can get the newest integrated qemu colo patches from github:
> >>>https://github.com/coloft/qemu/commits/colo-v1.1
> >>>
> >>>About how to test COLO, Please reference to the follow link.
> >>>http://wiki.qemu.org/Features/COLO.
> >>>
> >>>Please review and test.
> >>>
> >>>Known issue still unsolved:
> >>>(1) Some pages dirtied without setting its corresponding dirty-bitmap.
> >>>
> >>>Previous posted RFC patch series:
> >>>http://lists.nongnu.org/archive/html/qemu-devel/2014-06/msg05567.html
> >>>http://lists.nongnu.org/archive/html/qemu-devel/2014-09/msg04459.html
> >>>https://lists.gnu.org/archive/html/qemu-devel/2015-02/msg04771.html
> >>>
> >>>TODO list:
> >>>1 Optimize the process of checkpoint, shorten the time-consuming:
> >>>   (Partly done, patch is not include into this series)
> >>>    1) separate ram and device save/load process to reduce size of extra memory
> >>>       used during checkpoint
> >>>    2) live migrate part of dirty pages to slave during sleep time.
> >>>2 Add more debug/stat info
> >>>   (Partly done, patch is not include into this series)
> >>>   include checkpoint count, proxy discompare count, downtime,
> >>>    number of live migrated pages, total sent pages, etc.
> >>>3 Strengthen failover
> >>>4 optimize proxy part, include proxy script.
> >>>5 The capability of continuous FT
> >>>
> >>>v4:
> >>>- New block replication scheme (use image-fleecing for sencondary side)
> >>>- Adress some comments from Eric Blake and Dave
> >>>- Add commmand colo-set-checkpoint-period to set the time of periodic checkpoint
> >>>- Add a delay (100ms) between continuous checkpoint requests to ensure VM
> >>>   run 100ms at least since last pause.
> >>>
> >>>v3:
> >>>- use proxy instead of colo agent to compare network packets
> >>>- add block replication
> >>>- Optimize failover disposal
> >>>- handle shutdown
> >>>
> >>>v2:
> >>>- use QEMUSizedBuffer/QEMUFile as COLO buffer
> >>>- colo support is enabled by default
> >>>- add nic replication support
> >>>- addressed comments from Eric Blake and Dr. David Alan Gilbert
> >>>
> >>>v1:
> >>>- implement the frame of colo
> >>>
> >>>Wen Congyang (1):
> >>>   COLO: Add block replication into colo process
> >>>
> >>>zhanghailiang (27):
> >>>   configure: Add parameter for configure to enable/disable COLO support
> >>>   migration: Introduce capability 'colo' to migration
> >>>   COLO: migrate colo related info to slave
> >>>   migration: Integrate COLO checkpoint process into migration
> >>>   migration: Integrate COLO checkpoint process into loadvm
> >>>   COLO: Implement colo checkpoint protocol
> >>>   COLO: Add a new RunState RUN_STATE_COLO
> >>>   QEMUSizedBuffer: Introduce two help functions for qsb
> >>>   COLO: Save VM state to slave when do checkpoint
> >>>   COLO RAM: Load PVM's dirty page into SVM's RAM cache temporarily
> >>>   COLO VMstate: Load VM state into qsb before restore it
> >>>   arch_init: Start to trace dirty pages of SVM
> >>>   COLO RAM: Flush cached RAM into SVM's memory
> >>>   COLO failover: Introduce a new command to trigger a failover
> >>>   COLO failover: Implement COLO master/slave failover work
> >>>   COLO failover: Don't do failover during loading VM's state
> >>>   COLO: Add new command parameter 'colo_nicname' 'colo_script' for net
> >>>   COLO NIC: Init/remove colo nic devices when add/cleanup tap devices
> >>>   COLO NIC: Implement colo nic device interface configure()
> >>>   COLO NIC : Implement colo nic init/destroy function
> >>>   COLO NIC: Some init work related with proxy module
> >>>   COLO: Do checkpoint according to the result of net packets comparing
> >>>   COLO: Improve checkpoint efficiency by do additional periodic
> >>>     checkpoint
> >>>   COLO: Add colo-set-checkpoint-period command
> >>>   COLO NIC: Implement NIC checkpoint and failover
> >>>   COLO: Disable qdev hotplug when VM is in COLO mode
> >>>   COLO: Implement shutdown checkpoint
> >>>
> >>>  arch_init.c                            | 199 +++++++-
> >>>  configure                              |  14 +
> >>>  hmp-commands.hx                        |  30 ++
> >>>  hmp.c                                  |  14 +
> >>>  hmp.h                                  |   2 +
> >>>  include/exec/cpu-all.h                 |   1 +
> >>>  include/migration/migration-colo.h     |  58 +++
> >>>  include/migration/migration-failover.h |  22 +
> >>>  include/migration/migration.h          |   3 +
> >>>  include/migration/qemu-file.h          |   3 +-
> >>>  include/net/colo-nic.h                 |  25 +
> >>>  include/net/net.h                      |   4 +
> >>>  include/sysemu/sysemu.h                |   3 +
> >>>  migration/Makefile.objs                |   2 +
> >>>  migration/colo-comm.c                  |  80 ++++
> >>>  migration/colo-failover.c              |  48 ++
> >>>  migration/colo.c                       | 809 +++++++++++++++++++++++++++++++++
> >>>  migration/migration.c                  |  60 ++-
> >>>  migration/qemu-file-buf.c              |  58 +++
> >>>  net/Makefile.objs                      |   1 +
> >>>  net/colo-nic.c                         | 438 ++++++++++++++++++
> >>>  net/tap.c                              |  45 +-
> >>>  qapi-schema.json                       |  42 +-
> >>>  qemu-options.hx                        |  10 +-
> >>>  qmp-commands.hx                        |  41 ++
> >>>  savevm.c                               |   2 +-
> >>>  scripts/colo-proxy-script.sh           |  97 ++++
> >>>  stubs/Makefile.objs                    |   1 +
> >>>  stubs/migration-colo.c                 |  58 +++
> >>>  vl.c                                   |  36 +-
> >>>  30 files changed, 2178 insertions(+), 28 deletions(-)
> >>>  create mode 100644 include/migration/migration-colo.h
> >>>  create mode 100644 include/migration/migration-failover.h
> >>>  create mode 100644 include/net/colo-nic.h
> >>>  create mode 100644 migration/colo-comm.c
> >>>  create mode 100644 migration/colo-failover.c
> >>>  create mode 100644 migration/colo.c
> >>>  create mode 100644 migration/colo.c.
> >>>  create mode 100644 net/colo-nic.c
> >>>  create mode 100755 scripts/colo-proxy-script.sh
> >>>  create mode 100644 stubs/migration-colo.c
> >>>
> >>
> >>
> >--
> >Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
> >
> >.
> >
> 
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK