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Re: [Xen-devel] [PATCH 00/27] Libxl migration v2





On 06/15/2015 09:44 PM, Andrew Cooper wrote:
This series adds support for the libxl migration v2 stream, and untangles the
existing layering violations of the toolstack and qemu records.

At the end of the series, legacy migration is no longer used.

Note: Remus support is broken and (RFC) fixed in separate patches in this
series.  It was too tangled to fix in a bisectable fashon.  Plain
suspend/migrate/resume however is (should be) bisectable along the entire
series.

By a quick test on both pv/hvm, Remus support is still broken. The Remus
save/restore part is working, but failover is broken. To solve this:
On libxl side:
1. buffer toolstack and qemu records at checkpoint.
2. If stream read failed on xl side, drop the buffered records, return with
   error code that indicate a failover.
3. If all stream buffered(xl side), process/apply the toolstack and qemu
   records, return with success.
4. If apply toolstack and qemu records failed, return error.

On libxc side:
check the return value of checkpoint callback, if it indicate a failover,
then do failover.


There are a couple of outstanding questions:

1) What to do about the toolstack/xenstore record.  It is currently by being
    passed around as a blob, but it might be better to split it out.

2) What (if any) ABI/API qualifications are needed? (Particularly in reference
    to patch 21)

The Remus code is untested by me, but is hopefully in the correct ballpark.
All other combinations of suspend/migrate/resume have been tested with PV and
HVM guests (qemu-trad and qemu-upstream), including 32 -> 64 bit migration
(which was the underlying bug causing us to write migration v2 in the first
place).

There are some further improvements which could be made.  In particular, it
appears that sending the toolstack record on each checkpoint is redundant, and
there is certainly room for some more pruning of the legacy migration code.

Anyway, thoughts/comments welcome.  Please test!

~Andrew


Andrew Cooper (22):
   tools/libxl: Fix libxl__ev_child_inuse() check for not-yet-initialised 
children
   tools/libxc: Always compile the compat qemu variables into xc_sr_context
   tools/libxl: Stash all restore parameters in domain_create_state
   tools/xl: Mandatory flag indicating the format of the migration stream
   tools/libxl: Introduce ROUNDUP()
   tools/libxl: Extra APIs for the save helper
   tools/libxl: Pass restore_fd as a parameter to libxl__xc_domain_restore()
   docs: Libxl migration v2 stream specification
   tools/python: Libxc migration v2 infrastructure
   tools/python: Libxl migration v2 infrastructure
   tools/python: Verification utility for v2 stream spec compliance
   tools/python: Conversion utility for legacy migration streams
   tools/libxl: Support converting a legacy stream to a v2 stream
   tools/libxl: Convert a legacy stream if needed
   tools/libxc+libxl+xl: Restore v2 streams
   tools/libxc+libxl+xl: Save v2 streams
   docs/libxl: [RFC] Introduce CHECKPOINT_END to support migration v2 remus 
streams
   tools/libxl: [RFC] Write checkpoint records into the stream
   tools/libx{c,l}: [RFC] Introduce restore_callbacks.checkpoint()
   tools/libxl: [RFC] Handle checkpoint records in a libxl migration v2 stream
   tools/libxc: Drop all XG_LIBXL_HVM_COMPAT code from libxc
   tools/libxl: Drop all knowledge of toolstack callbacks

Ian Jackson (2):
   libxl: cancellation: Preparations for save/restore cancellation
   libxl: cancellation: Handle SIGTERM in save/restore helper

Ross Lagerwall (3):
   tools/libxl: Migration v2 stream format
   tools/libxl: Infrastructure for reading a libxl migration v2 stream
   tools/libxl: Infrastructure for writing a v2 stream

  docs/specs/libxl-migration-stream.pandoc      |  218 ++++++++
  tools/libxc/Makefile                          |    2 -
  tools/libxc/include/xenguest.h                |    3 +
  tools/libxc/xc_sr_common.h                    |    5 -
  tools/libxc/xc_sr_restore.c                   |   33 +-
  tools/libxc/xc_sr_restore_x86_hvm.c           |  124 -----
  tools/libxc/xc_sr_save_x86_hvm.c              |   36 --
  tools/libxl/Makefile                          |    2 +
  tools/libxl/libxl_aoutils.c                   |    7 +
  tools/libxl/libxl_convert_callout.c           |  146 ++++++
  tools/libxl/libxl_create.c                    |   80 +--
  tools/libxl/libxl_dom.c                       |   61 +--
  tools/libxl/libxl_internal.h                  |  140 ++++-
  tools/libxl/libxl_save_callout.c              |   63 +--
  tools/libxl/libxl_save_helper.c               |   95 ++--
  tools/libxl/libxl_save_msgs_gen.pl            |    9 +-
  tools/libxl/libxl_sr_stream_format.h          |   58 +++
  tools/libxl/libxl_stream_read.c               |  663 ++++++++++++++++++++++++
  tools/libxl/libxl_stream_write.c              |  640 +++++++++++++++++++++++
  tools/libxl/libxl_types.idl                   |    2 +
  tools/libxl/xl_cmdimpl.c                      |    9 +-
  tools/python/Makefile                         |    4 +
  tools/python/scripts/convert-legacy-stream.py |  683 +++++++++++++++++++++++++
  tools/python/scripts/verify-stream-v2.py      |  174 +++++++
  tools/python/setup.py                         |    1 +
  tools/python/xen/migration/libxc.py           |  446 ++++++++++++++++
  tools/python/xen/migration/libxl.py           |  199 +++++++
  tools/python/xen/migration/tests.py           |   54 ++
  tools/python/xen/migration/verify.py          |   37 ++
  29 files changed, 3638 insertions(+), 356 deletions(-)
  create mode 100644 docs/specs/libxl-migration-stream.pandoc
  create mode 100644 tools/libxl/libxl_convert_callout.c
  create mode 100644 tools/libxl/libxl_sr_stream_format.h
  create mode 100644 tools/libxl/libxl_stream_read.c
  create mode 100644 tools/libxl/libxl_stream_write.c
  create mode 100755 tools/python/scripts/convert-legacy-stream.py
  create mode 100755 tools/python/scripts/verify-stream-v2.py
  create mode 100644 tools/python/xen/migration/__init__.py
  create mode 100644 tools/python/xen/migration/libxc.py
  create mode 100644 tools/python/xen/migration/libxl.py
  create mode 100644 tools/python/xen/migration/tests.py
  create mode 100644 tools/python/xen/migration/verify.py


--
Thanks,
Yang.

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