On Mon, Sep 30, 2024 at 06:34:05PM +0200, Peter Krempa wrote:
> On Mon, Sep 30, 2024 at 16:53:55 +0200, Pavel Hrdina wrote:
> > On Mon, Sep 30, 2024 at 03:29:34PM +0200, Peter Krempa wrote:
> > > The new 'VIR_MIGRATE_PARAM_MIGRATE_DISKS_DETECT_ZEROES' migration
> > > parameter allows users of migration to pass in a list of disks where
> > > zero-detection (which avoids transferring the zeroed-blocks) should be
> > > enabled for the migration connection. This comes at the cost of extra
> > > CPU cycles needed to check each block if it's all-zero.
> > >
> > > This is useful for storage backends where information about the
> > > allocation state of a block is not available and thus without this the
> > > image would become fully allocated on the destination.
> > >
> > > Signed-off-by: Peter Krempa <pkrempa@xxxxxxxxxx>
> > > ---
> > > include/libvirt/libvirt-domain.h | 13 ++++
> > > src/qemu/qemu_driver.c | 20 ++++--
> > > src/qemu/qemu_migration.c | 105 +++++++++++++++++++++++--------
> > > src/qemu/qemu_migration.h | 4 ++
> > > 4 files changed, 110 insertions(+), 32 deletions(-)
> > >
> > > diff --git a/include/libvirt/libvirt-domain.h b/include/libvirt/libvirt-domain.h
> > > index 4266237abe..6d4cc69c5d 100644
> > > --- a/include/libvirt/libvirt-domain.h
> > > +++ b/include/libvirt/libvirt-domain.h
> > > @@ -1240,6 +1240,19 @@ typedef enum {
> > > */
> > > # define VIR_MIGRATE_PARAM_MIGRATE_DISKS "migrate_disks"
> > >
> > > +/**
> > > + * VIR_MIGRATE_PARAM_MIGRATE_DISKS_DETECT_ZEROES:
> > > + *
> > > + * virDomainMigrate* params multiple field: The multiple values that list
> > > + * the block devices for which zero detection (to avoid transferring zero blocks)
> > > + * is to be enabled. This may increase CPU overhead of the migration. At the
> > > + * moment this is only supported by the QEMU driver but not for the tunnelled
> > > + * migration.
> >
> > We should note that it has to be subset of migrate_disks values.
>
> I'd argue that it's logical that this can apply only if the disk is
> being migrated.
My assumption was that it would apply only to disks listed in
VIR_MIGRATE_PARAM_MIGRATE_DISKS but due to incorrectly reading how
qemuMigrationAnyCopyDisk works it's not true so that comment would be
false as well.
With the _TUNNELLED fixed
Reviewed-by: Pavel Hrdina <phrdina@xxxxxxxxxx>
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