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 also
wonder if we should add a code that will error out if it's not the case,
currently it would be silently ignored.
> + *
> + * Since: 10.9.0
> + */
> +# define VIR_MIGRATE_PARAM_MIGRATE_DISKS_DETECT_ZEROES "migrate_disks_detect_zeroes"
> +
> /**
> * VIR_MIGRATE_PARAM_DISKS_PORT:
> *
[...]
> diff --git a/src/qemu/qemu_migration.c b/src/qemu/qemu_migration.c
> index 94636e778d..7ae19dd0ce 100644
> --- a/src/qemu/qemu_migration.c
> +++ b/src/qemu/qemu_migration.c
> @@ -5316,9 +5348,11 @@ qemuMigrationSrcPerformTunnel(virQEMUDriver *driver,
> goto cleanup;
> }
>
> + /* Migration with NBD is not supported with _TUNNELED, thus
s/_TUNNELED/_TUNNELLED/
To match the incorrect spelling of the actual flag.
> + * 'migrate_disks_detect_zeroes' is NULL here */
> ret = qemuMigrationSrcRun(driver, vm, xmlin, persist_xml, cookiein, cookieinlen,
> cookieout, cookieoutlen, flags, resource, &spec,
> - dconn, graphicsuri, migrate_disks,
> + dconn, graphicsuri, migrate_disks, NULL,
> migParams, NULL);
>
> cleanup:
Pavel
Attachment:
signature.asc
Description: PGP signature
