On 30/11/2018 5:47 PM, Anton Nefedov wrote: > qmp query-blockstats provides stats info for write/read/flush ops. > > Patches 1-7 implement the similar for discard (unmap) command for scsi > and ide disks. > Discard stat "unmap_ops / unmap_bytes" is supposed to account the ops that > have completed without an error. > > However, discard operation is advisory. Specifically, > - common block layer ignores ENOTSUP error code. > That might be returned if the block driver does not support discard, > or discard has been configured to be ignored. > - format drivers such as qcow2 may ignore discard if they were configured > to ignore that, or if the corresponding area is already marked unused > (unallocated / zero clusters). > > And what is actually useful is the number of bytes actually discarded > down on the host filesystem. > To achieve that, driver-specific statistics has been added to blockstats > (patch 9). > With patch 8, file-posix driver accounts discard operations on its level too. >
ping
