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[Qemu-block] ping Re: [PATCH 00/18] Dirty bitmaps postcopy migration

From: Vladimir Sementsov-Ogievskiy
Subject: [Qemu-block] ping Re: [PATCH 00/18] Dirty bitmaps postcopy migration
Date: Tue, 25 Oct 2016 16:04:35 +0300
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0


For now there are some notes mostly about accessory patches. What about migration itself? Is it ok? Has it a chance of being merged one day?

16.08.2016 13:25, Vladimir Sementsov-Ogievskiy wrote:
some bugs fixed, iotests a bit changed and merged into one test.
based on block-next (https://github.com/XanClic/qemu/commits/block-next)
clone: tag postcopy-v2 from https://src.openvz.org/scm/~vsementsov/qemu.git


These series are derived from my 'Dirty bitmaps migration' series. The
core idea is switch to postcopy migration and drop usage of meta

These patches provide dirty bitmap postcopy migration feature. Only
named dirty bitmaps are to be migrated. Migration may be enabled using
migration capabilities.

The overall method (thanks to John Snow):

1. migrate bitmaps meta data in .save_live_setup
    - create/find related bitmaps on target
    - disable them
    - create successors (anonimous children) only for enabled migrated
2. do nothing in precopy stage
3. just before target vm start: enable successors, created in (1)
4. migrate bitmap data
5. reclaime bitmaps (merge successors to their parents)
6. enable bitmaps (only bitmaps, which was enabled in source)

Some patches are unchnaged from (v7) of 'Dirty bitmaps migration'
(DBMv7). I've left Reviewed-by's for them, if you don't like it, say me
and I'll drop them in the following version.

So, relatively to last DBMv7:

01-04: new patches, splitting common postcopy migration out of ram
        postcopy migration
    05: equal to DBMv7.05
    06: new
    07: equal to DBMv7.06
    08: new
    09: equal to DBMv7.07
    10: new
    11: derived from DBMv7.08, see below
12-15: equal to DBMv7.09-12
    16: derived from DBMv7.13
        - switch from fifo to socket, as postcopy don't work with fifo
          for now
        - change parameters: size, granularity, regions
        - add time.sleep, to wait for postcopy migration phase (bad
          temporary solution.
        - drop Reviewed-by
    17: new

    11: the core patch of the series, it is derived from
        [DBMv7.08: migration: add migration_block-dirty-bitmap.c]
        There are a lot of changes related to switching from precopy to
        postcopy, but functions related to migration stream itself
        (structs, send/load sequences) are mostly unchnaged.

        So, changes, to switch from precopy to postcopy:
        - removed all staff related to meta bitmaps and dirty phase!!!
        - add dirty_bitmap_mig_enable_successors, and call it before
          target vm start in loadvm_postcopy_handle_run
        - add enabled_bitmaps list of bitmaps for

        - enabled flag is send with start bitmap chunk instead of
          completion chunk
        - sectors_per_chunk is calculated directly from CHUNK_SIZE, not
          using meta bitmap granularity

        - dirty_bitmap_save_iterate: remove dirty_phase, move bulk_phase
          to postcopy stage
        - dirty_bitmap_save_pending: remove dirty phase related pending,
          switch pending to non-postcopyable
        - dirty_bitmap_load_start: get enabled flag and prepare
          successors for enabled bitmaps, also add them to
          enabled_bitmaps list
        - dirty_bitmap_load_complete: for enabled bitmaps: merge them
          with successors and enable

        - savevm handlers:
          * remove separate savevm_dirty_bitmap_live_iterate_handlers state
            (it was bad idea, any way), and move its save_live_iterate to
          * add is_active_iterate savevm handler, which allows iterations
            only in postcopy stage (after stopping source vm)
          * add has_postcopy savevm handler. (ofcourse, just returning true)
          * use save_live_complete_postcopy instead of

        Other changes:
        - some debug output changed
        - remove MIN_LIVE_SIZE, is_live_iterative and related staff (it
          was needed to omit iterations if bitmap data is small, possibly
          this should be reimplemented)

Vladimir Sementsov-Ogievskiy (18):
   migration: add has_postcopy savevm handler
   migration: fix ram_save_pending
   migration: split common postcopy out of ram postcopy
   migration: introduce postcopy-only pending
   block: add bdrv_next_dirty_bitmap()
   block: add bdrv_dirty_bitmap_enable_successor()
   qapi: add dirty-bitmaps migration capability
   block/dirty-bitmap: add bdrv_dirty_bitmap_release_successor
   migration: include migrate_dirty_bitmaps in migrate_postcopy
   migration/qemu-file: add qemu_put_counted_string()
   migration: add is_active_iterate handler
   migration: add postcopy migration of dirty bitmaps
   iotests: maintain several vms in test
   iotests: add add_incoming_migration to VM class
   qapi: add md5 checksum of last dirty bitmap level to query-block
   iotests: add default node-name
   iotests: add dirty bitmap migration test 117
   iotests: add dirty bitmap postcopy test

  block/dirty-bitmap.c           |  26 ++
  include/block/dirty-bitmap.h   |   6 +
  include/migration/block.h      |   1 +
  include/migration/migration.h  |   6 +
  include/migration/qemu-file.h  |   2 +
  include/migration/vmstate.h    |   7 +-
  include/qemu/hbitmap.h         |   8 +
  include/sysemu/sysemu.h        |   5 +-
  migration/Makefile.objs        |   2 +-
  migration/block-dirty-bitmap.c | 699 +++++++++++++++++++++++++++++++++++++++++
  migration/block.c              |   7 +-
  migration/migration.c          |  66 ++--
  migration/postcopy-ram.c       |   4 +-
  migration/qemu-file.c          |  13 +
  migration/ram.c                |  19 +-
  migration/savevm.c             |  56 +++-
  migration/trace-events         |   2 +-
  qapi-schema.json               |   4 +-
  qapi/block-core.json           |   5 +-
  tests/qemu-iotests/169         | 134 ++++++++
  tests/qemu-iotests/169.out     |   5 +
  tests/qemu-iotests/group       |   2 +
  tests/qemu-iotests/iotests.py  |  21 +-
  util/hbitmap.c                 |   8 +
  vl.c                           |   1 +
  25 files changed, 1055 insertions(+), 54 deletions(-)
  create mode 100644 migration/block-dirty-bitmap.c
  create mode 100755 tests/qemu-iotests/169
  create mode 100644 tests/qemu-iotests/169.out

Best regards,

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