Re: [Qemu-devel] [PATCH v3 0/5] Add ignore-external migration capability

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Yury Kotov (yury-kotov@yandex-team.ru) wrote:
> Hi,
> 
> The series adds a migration capability, which allows to skip shared RAM blocks
> during the migration. It's useful for fast local migration. E.g. to update QEMU
> for the running guests.

Queued

> 
> Usage example:
> 1. Start source VM:
>    qemu-system-x86 \
>      -m 4G \
>      -object memory-backend-file,id=mem0,size=4G,share=on,mem-path=/dev/shm/mem0 \
>      -numa node,memdev=mem0 \
>      -qmp unix:/tmp/qemu-qmp-1.sock,server,nowait \
> 
> 2. Start target VM:
>    qemu-system-x86 \
>      -m 4G \
>      -object memory-backend-file,id=mem0,size=4G,share=on,mem-path=/dev/shm/mem0 \
>      -numa node,memdev=mem0 \
>      -qmp unix:/tmp/qemu-qmp-2.sock,server,nowait \
>      -incoming defer
> 
> 3. Enable ignore-shared capability on both VMs:
>    { "execute": "migrate-set-capabilities" , "arguments":
>      { "capabilities": [ { "capability": "x-ignore-shared", "state": true } ] } }
> 
> 4. Start migration.
> 
> Another use case I keep in mind is to migrate to file. Usage is very similar.
> 
> V2 to V3:
> * Split "migration: Introduce ignore-shared capability"
> * Serialize the capabilities as strings rather than as indexes
> * Don't allow to enable postcopy and ignore-shared together
> * Skip the test for OSs which don't have /dev/shm
> * Add a check whether shared RAM has been really skipped
> 
> V1 to V2:
> * Keep migration stream compatibility
> * Reuse the existing code to ignore unwanted RAMBlocks
> * Add capability validation feature
> * ignore-external -> ignore-shared
> 
> Regards,
> Yury
> 
> Yury Kotov (5):
>   exec: Change RAMBlockIterFunc definition
>   migration: Introduce ignore-shared capability
>   migration: Add an ability to ignore shared RAM blocks
>   tests/migration-test: Add a test for ignore-shared capability
>   migration: Add capabilities validation
> 
>  exec.c                    |  38 +++++------
>  include/exec/cpu-common.h |   7 +-
>  migration/migration.c     |  14 ++++
>  migration/migration.h     |   5 +-
>  migration/postcopy-ram.c  |  48 +++++++------
>  migration/ram.c           | 110 ++++++++++++++++++++++--------
>  migration/rdma.c          |   9 ++-
>  migration/savevm.c        | 137 ++++++++++++++++++++++++++++++++++++++
>  qapi/migration.json       |   5 +-
>  stubs/ram-block.c         |  15 +++++
>  tests/migration-test.c    | 131 +++++++++++++++++++++++++++++-------
>  util/vfio-helpers.c       |   6 +-
>  12 files changed, 420 insertions(+), 105 deletions(-)
> 
> -- 
> 2.20.1
> 
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK