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

[Stefan Hajnoczi]

On Tue, Oct 25, 2016 at 04:04:35PM +0300, Vladimir Sementsov-Ogievskiy wrote:
> ping
> 
> 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?

This series mostly touches migration/ code.  Juan or DaveG?

> 16.08.2016 13:25, Vladimir Sementsov-Ogievskiy wrote:
> > v2:
> > 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
> > online: 
> > https://src.openvz.org/users/vsementsov/repos/qemu/browse?at=refs%2Ftags%2Fpostcopy-v2
> > 
> > v1:
> > 
> > These series are derived from my 'Dirty bitmaps migration' series. The
> > core idea is switch to postcopy migration and drop usage of meta
> > bitmaps.
> > 
> > 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
> >       bitmaps
> > 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
> >           dirty_bitmap_mig_enable_successors
> > 
> >         - 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
> >             savevm_dirty_bitmap_handlers
> >           * 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
> >             save_live_complete_precopy
> > 
> >         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,
> Vladimir
>

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