Re: [Qemu-devel] [PATCH RFC 00/17] Dirty bitmaps postcopy migration

[John Snow]

Juan, have you had the chance to look at this yet?

--js

On 03/14/2016 07:37 AM, Vladimir Sementsov-Ogievskiy wrote:
> ping
> 
> On 12.02.2016 21:00, Vladimir Sementsov-Ogievskiy wrote:
>> Hi all!
>>
>> 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 (17):
>>    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
>>    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 migration test 170
>>
>>   block/dirty-bitmap.c           |  16 +
>>   include/block/dirty-bitmap.h   |   4 +
>>   include/migration/block.h      |   1 +
>>   include/migration/migration.h  |   5 +
>>   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 | 646
>> +++++++++++++++++++++++++++++++++++++++++
>>   migration/block.c              |   7 +-
>>   migration/migration.c          |  63 ++--
>>   migration/postcopy-ram.c       |   4 +-
>>   migration/qemu-file.c          |  13 +
>>   migration/ram.c                |  19 +-
>>   migration/savevm.c             |  56 +++-
>>   qapi-schema.json               |   4 +-
>>   qapi/block-core.json           |   5 +-
>>   tests/qemu-iotests/117         |  82 ++++++
>>   tests/qemu-iotests/117.out     |   5 +
>>   tests/qemu-iotests/170         | 101 +++++++
>>   tests/qemu-iotests/170.out     |   5 +
>>   tests/qemu-iotests/group       |   2 +
>>   tests/qemu-iotests/iotests.py  |  17 +-
>>   trace-events                   |   2 +-
>>   util/hbitmap.c                 |   8 +
>>   vl.c                           |   1 +
>>   27 files changed, 1035 insertions(+), 55 deletions(-)
>>   create mode 100644 migration/block-dirty-bitmap.c
>>   create mode 100755 tests/qemu-iotests/117
>>   create mode 100644 tests/qemu-iotests/117.out
>>   create mode 100755 tests/qemu-iotests/170
>>   create mode 100644 tests/qemu-iotests/170.out
>>
> 
>