Re: [Qemu-devel] [PATCH v2 0/3] migration capability to discard the migrated ram pages

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

* Pavel Butsykin (pbutsykin@virtuozzo.com) wrote:
> On 14.02.2017 17:02, Dr. David Alan Gilbert wrote:
> > Hi Pavel,
> >    I was curious, having merged this, how you're using postcopy; do you switch
> > into postcopy mode immediately or wait until the first sync or what?
> > Do you find yourself in postcopy mode long enough that it's worth
> > doing the release?  If so on what size VMs are you working with?
> > 
> > Dave
> 
> Hi Dave,
> I'm sorry it took so long, I was on vacation. And thanks for the quick
> review and merge!
> 
> We want to use this function to update Qemu without rebooting VMs. It
> looks like a local migration on the same host. Now, switching into
> postcopy mode is done immediately, the size of VMs can be very
> different.

Thanks! Do you have libvirt magic to do that update?

Dave

> > * Pavel Butsykin (pbutsykin@virtuozzo.com) wrote:
> > > This feature frees the migrated memory on the source during postcopy-ram
> > > migration. In the second step of postcopy-ram migration when the source vm
> > > is put on pause we can free unnecessary memory. It will allow, in particular,
> > > to start relaxing the memory stress on the source host in a load-balancing
> > > scenario.
> > > 
> > > Changes from v1:
> > > - changed name of the interfaces (discard to release)
> > > - fix make check error
> > > - add more comments to qemu_iovec_release_ram()
> > > - rebase on "Postcopy: Hugepage support" (David's patch series)
> > > - removed ram_discard_page for xbzrle
> > > - fix erroneous release memory in complete precopy (tie release-ram to postcopy)
> > > 
> > > Pavel Butsykin (3):
> > >    migration: add MigrationState arg for ram_save_/compressed_/page()
> > >    add 'release-ram' migrate capability
> > >    migration: discard non-dirty ram pages after the start of postcopy
> > > 
> > >   include/migration/migration.h |  2 ++
> > >   include/migration/qemu-file.h |  3 ++-
> > >   migration/migration.c         | 13 ++++++++++
> > >   migration/qemu-file.c         | 59 ++++++++++++++++++++++++++++++++++++++-----
> > >   migration/ram.c               | 56 ++++++++++++++++++++++++++++++++++------
> > >   qapi-schema.json              |  5 +++-
> > >   6 files changed, 121 insertions(+), 17 deletions(-)
> > > 
> > > --
> > > 2.11.0
> > > 
> > > 
> > --
> > Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
> > 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK