Re: [Qemu-devel] [PATCH v1] migration: skip sending ram pages released by virtio-balloon driver.

[Eric Blake <eblake@redhat.com>]

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On 03/04/2016 02:02 AM, Jitendra Kolhe wrote:
> While measuring live migration performance for qemu/kvm guest, it
> was observed that the qemu doesn’t maintain any intelligence for the
> guest ram pages which are release by the guest balloon driver and
> treat such pages as any other normal guest ram pages. This has direct
> impact on overall migration time for the guest which has released
> (ballooned out) memory to the host.
> 

> Signed-off-by: Jitendra Kolhe <jitendra.kolhe@hpe.com>
> ---
>  balloon.c                          | 253 ++++++++++++++++++++++++++++++++++++-
>  exec.c                             |   3 +
>  hw/virtio/virtio-balloon.c         |  35 ++++-
>  include/hw/virtio/virtio-balloon.h |   1 +
>  include/migration/migration.h      |   1 +
>  include/sysemu/balloon.h           |  15 ++-
>  migration/migration.c              |   9 ++
>  migration/ram.c                    |  23 +++-
>  qapi-schema.json                   |   5 +-
>  9 files changed, 337 insertions(+), 8 deletions(-)
> 

> +++ b/qapi-schema.json
> @@ -544,11 +544,14 @@
>  #          been migrated, pulling the remaining pages along as needed. NOTE: If
>  #          the migration fails during postcopy the VM will fail.  (since 2.5)
>  #
> +# @skip-balloon: Skip scaning ram pages released by virtio-balloon driver.

s/scaning/scanning/

> +#          (since 2.5)

You've missed 2.5.  In fact, this is borderline between new feature and
bug fix, so you may have even missed 2.6 since soft freeze has already
passed, in which case this should read 2.7.

Does this need to be an option, or should it be unconditionally enabled?

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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