On Fri, Aug 25, 2023 at 13:52:14 +0200, Kristina Hanicova wrote:
This introduces the ability to set the discard granularity option for a disk. It defines the smallest amount of data that can be discarded in a single operation (useful for managing and optimizing storage).
Signed-off-by: Kristina Hanicova <khanicov@redhat.com> --- docs/formatdomain.rst | 6 +++++- src/conf/domain_conf.c | 19 ++++++++++++++++++- src/conf/domain_conf.h | 1 + src/conf/domain_validate.c | 3 ++- src/conf/schemas/domaincommon.rng | 5 +++++ src/qemu/qemu_domain.c | 2 ++ 6 files changed, 33 insertions(+), 3 deletions(-)
diff --git a/docs/formatdomain.rst b/docs/formatdomain.rst index cd9cb02bf8..0d0812f08c 100644 --- a/docs/formatdomain.rst +++ b/docs/formatdomain.rst @@ -2588,7 +2588,7 @@ paravirtualized driver is specified via the ``disk`` element. <driver name='qemu' type='raw'/> <source dev='/dev/sda'/> <geometry cyls='16383' heads='16' secs='63' trans='lba'/> - <blockio logical_block_size='512' physical_block_size='4096'/> + <blockio logical_block_size='512' physical_block_size='4096' discard_granularity='4096'/> <target dev='hdj' bus='ide'/> </disk> <disk type='volume' device='disk'> @@ -3435,6 +3435,10 @@ paravirtualized driver is specified via the ``disk`` element. this would be the value returned by the BLKPBSZGET ioctl and describes the disk's hardware sector size which can be relevant for the alignment of disk data. + ``discard_granularity`` + The smallest amount of data that can be discarded in a single operation. + It impacts the unmap operations and it must be a multiple of a + ``logical_block_size``.
Add a note that most hypervisors select the proper setting and users don't really need to tweak this. Reviewed-by: Peter Krempa <pkrempa@redhat.com>