[Qemu-devel] [RFC PATCH v2 00/23] COarse-grain LOck-stepping(COLO) Virtual Machines for Non-stop Service

[Yang Hongyang]

Virtual machine (VM) replication is a well known technique for
providing application-agnostic software-implemented hardware fault
tolerance "non-stop service". COLO is a high availability solution.
Both primary VM (PVM) and secondary VM (SVM) run in parallel. They
receive the same request from client, and generate response in parallel
too. If the response packets from PVM and SVM are identical, they are
released immediately. Otherwise, a VM checkpoint (on demand) is
conducted. The idea is presented in Xen summit 2012, and 2013,
and academia paper in SOCC 2013. It's also presented in KVM forum
2013:
http://www.linux-kvm.org/wiki/images/1/1d/Kvm-forum-2013-COLO.pdf
Please refer to above document for detailed information. 
Please also refer to previous posted RFC proposal:
http://lists.nongnu.org/archive/html/qemu-devel/2014-06/msg05567.html

The patchset is also hosted on github:
https://github.com/macrosheep/qemu/tree/colo_v0.5

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

This patchset is RFC, But it is ready for demo the COLO idea
with QEMU-KVM.
Steps using this patchset to get an overview of COLO:
1. configure
2. compile
3. just like QEMU's normal migration, run 2 QEMU VM:
   - Primary VM 
   - Secondary VM with -incoming tcp:[IP]:[PORT] option
4. on Primary VM's QEMU monitor, run following command:
   migrate_set_capability colo on
   migrate tcp:[IP]:[PORT]
5. done
you will see two runing VMs, whenever you make changes to PVM, SVM
will be synced to PVM's state.

TODO list:
1. failover (will require heartbeat module: 
http://www.linux-ha.org/wiki/Downloads)
2. disk replication[COLO Disk manager]

Any comments/feedbacks are warmly welcomed.

Thanks,
Yang


Dr. David Alan Gilbert (1):
  QEMUSizedBuffer/QEMUFile

Yang Hongyang (22):
  configure: add CONFIG_COLO to switch COLO support
  COLO: introduce an api colo_supported() to indicate COLO support
  COLO migration: add a migration capability 'colo'
  COLO info: use colo info to tell migration target colo is enabled
  COLO save: integrate COLO checkpointed save into qemu migration
  COLO restore: integrate COLO checkpointed restore into qemu restore
  COLO: disable qdev hotplug
  COLO ctl: implement API's that communicate with colo agent
  COLO ctl: introduce is_slave() and is_master()
  COLO ctl: implement colo checkpoint protocol
  COLO ctl: add a RunState RUN_STATE_COLO
  COLO ctl: implement colo save
  COLO ctl: implement colo restore
  COLO save: reuse migration bitmap under colo checkpoint
  COLO ram cache: implement colo ram cache on slave
  HACK: trigger checkpoint every 500ms
  COLO nic: add command line switch
  COLO nic: init/remove colo nic devices when add/cleanup tap devices
  COLO nic: implement colo nic device interface support_colo()
  COLO nic: implement colo nic device interface configure()
  COLO nic: export colo nic APIs
  COLO nic: setup/teardown colo nic devices

 Makefile.objs                      |   2 +
 arch_init.c                        | 174 +++++++++++-
 configure                          |  14 +
 include/exec/cpu-all.h             |   1 +
 include/migration/migration-colo.h |  36 +++
 include/migration/migration.h      |  13 +
 include/migration/qemu-file.h      |  28 ++
 include/net/colo-nic.h             |  20 ++
 include/net/net.h                  |   4 +
 include/qemu/typedefs.h            |   1 +
 migration-colo-comm.c              |  78 ++++++
 migration-colo.c                   | 540 +++++++++++++++++++++++++++++++++++++
 migration.c                        |  47 ++--
 net/Makefile.objs                  |   1 +
 net/colo-nic.c                     | 227 ++++++++++++++++
 net/tap.c                          |  45 +++-
 network-colo                       | 194 +++++++++++++
 qapi-schema.json                   |  18 +-
 qemu-file.c                        | 410 ++++++++++++++++++++++++++++
 qemu-options.hx                    |  10 +-
 stubs/Makefile.objs                |   1 +
 stubs/migration-colo.c             |  34 +++
 vl.c                               |  12 +
 23 files changed, 1879 insertions(+), 31 deletions(-)
 create mode 100644 include/migration/migration-colo.h
 create mode 100644 include/net/colo-nic.h
 create mode 100644 migration-colo-comm.c
 create mode 100644 migration-colo.c
 create mode 100644 net/colo-nic.c
 create mode 100755 network-colo
 create mode 100644 stubs/migration-colo.c

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1.9.1