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:
> Hi,
> 
> ping ...

I will get to look at this again; but not until after next week.

> 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
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

that I've not had time to look into yet.

So I only get about a 50% success rate of starting COLO.
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?

> 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.

> 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.

Dave

> 
> 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