Re: [Qemu-devel] [PATCH COLO-Frame v8 00/34] COarse-grain LOck-stepping(COLO) Virtual Machines for Non-stop Service (FT)

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

* zhanghailiang (zhang.zhanghailiang@huawei.com) wrote:
> This is the 8th 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 is treated as a separate series.
> 
> As usual, we provide 'basic' and 'developing' branches in github:
> https://github.com/coloft/qemu/commits/colo-v1.5-basic
> https://github.com/coloft/qemu/commits/colo-v1.5-developing (more features)
> 
> The 'basic' branch is exactly the same with this patch series,
> We will keep this series simple as possible, just for easy review.
> 
> The extra features in colo-v1.5-developing branch:
> 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.
> 3) You get the statistic info about checkpoint by command 'info migrate'

I'm hitting a problem that I think is due to the new global_state section
that Juan recently added; if I cause a failover I hit:

ERROR: invalid runstate transition: 'colo' -> 'prelaunch'

(on the secondary).
I think the problem is that, the global_state is only sent for any 'unusual' states,
so in the first migration that gets done at startup, 'prelaunch' is included in the stream
in the global state, but then for later checkpoints the global_state probably isn't
sent.

I hacked around it by making global_state_needed return false; I guess
we need to find a better fix!

Dave


> Please reference to the follow link to test COLO.
> http://wiki.qemu.org/Features/COLO.
> 
> COLO is a totally new feature which is still in early stage,
> your comments and feedback are warmly welcomed.
> 
> NOTE:
> We have decided to re-implement the colo proxy in userspace (In qemu exactly).
> you can find the discussion about why & how to realize the colo proxy in qemu from the follow link:
> http://lists.nongnu.org/archive/html/qemu-devel/2015-07/msg04069.html
> 
> TODO:
> 1. COLO function switch on/off
> 2. The capability of continuous FT
> 3. Optimize the performance.
> 
> v8:
> - Move some global variables into MigrationIncomingState and MigrationState
> - Move some cleanup work form colo thread and colo incoming thread into failover
>   BH function and also fix the code logic for the cleanup work.
> - fix the bug that colo thread and colo incoming thread possibly block in the
>   socket 'recv' call when do failover work.
> - Optimize colo_flush_ram_cache()
> - Add migration state for incoming side, we use the state to verify if migration
>   incoming side is in COLO state or not (Patch 5).
> - Drop the patch 'COLO: Disable qdev hotplug when VM is in COLO mode', since it is not correct. 
> 
> zhanghailiang (34):
>   configure: Add parameter for configure to enable/disable COLO support
>   migration: Introduce capability 'colo' to migration
>   COLO: migrate colo related info to slave
>   colo-comm/migration: skip colo info section for special cases
>   migration: Add state records for migration incoming
>   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: Introduce state to record failover process
>   COLO failover: Implement COLO primary/secondary vm failover work
>   qmp event: Add event notification for COLO error
>   COLO failover: Don't do failover during loading VM's state
>   COLO: Add new command parameter 'forward_nic' 'colo_script' for net
>   COLO NIC: Init/remove colo nic devices when add/cleanup tap devices
>   tap: Make launch_script() public
>   COLO NIC: Implement colo nic device interface configure()
>   colo-nic: Handle secondary VM's original net device configure
>   COLO NIC: Implement colo nic init/destroy function
>   COLO NIC: Some init work related with proxy module
>   COLO: Handle nfnetlink message from proxy module
>   COLO: Do checkpoint according to the result of packets comparation
>   COLO: Improve checkpoint efficiency by do additional periodic
>     checkpoint
>   COLO: Add colo-set-checkpoint-period command
>   COLO NIC: Implement NIC checkpoint and failover
>   COLO: Implement shutdown checkpoint
>   COLO: Add block replication into colo process
> 
>  configure                     |  33 +-
>  docs/qmp/qmp-events.txt       |  16 +
>  hmp-commands.hx               |  30 ++
>  hmp.c                         |  15 +
>  hmp.h                         |   2 +
>  include/exec/cpu-all.h        |   1 +
>  include/migration/colo.h      |  45 +++
>  include/migration/failover.h  |  33 ++
>  include/migration/migration.h |  19 +
>  include/migration/qemu-file.h |   3 +-
>  include/net/colo-nic.h        |  37 ++
>  include/net/net.h             |   2 +
>  include/net/tap.h             |  19 +
>  include/sysemu/sysemu.h       |   3 +
>  migration/Makefile.objs       |   2 +
>  migration/colo-comm.c         |  75 ++++
>  migration/colo-failover.c     |  83 +++++
>  migration/colo.c              | 805 ++++++++++++++++++++++++++++++++++++++++++
>  migration/migration.c         | 116 ++++--
>  migration/qemu-file-buf.c     |  58 +++
>  migration/ram.c               | 242 ++++++++++++-
>  migration/savevm.c            |   2 +-
>  net/Makefile.objs             |   1 +
>  net/colo-nic.c                | 457 ++++++++++++++++++++++++
>  net/net.c                     |   2 +
>  net/tap.c                     |  90 +++--
>  qapi-schema.json              |  58 ++-
>  qapi/event.json               |  15 +
>  qemu-options.hx               |   7 +
>  qmp-commands.hx               |  42 +++
>  scripts/colo-proxy-script.sh  | 145 ++++++++
>  stubs/Makefile.objs           |   1 +
>  stubs/migration-colo.c        |  58 +++
>  trace-events                  |  10 +
>  vl.c                          |  37 +-
>  35 files changed, 2474 insertions(+), 90 deletions(-)
>  create mode 100644 include/migration/colo.h
>  create mode 100644 include/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 net/colo-nic.c
>  create mode 100755 scripts/colo-proxy-script.sh
>  create mode 100644 stubs/migration-colo.c
> 
> -- 
> 1.8.3.1
> 
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK