On 3/26/23 01:31, Bart Van Assche wrote: > On 3/24/23 19:00, Damien Le Moal wrote: >> The trick here could be to have the UFS LLD to unlock the target zone of a write >> when the command is sent to the device, instead of when the command completes. >> This way, the zone is still locked when there is a requeue and there is no >> reordering. That could allow for write qd > 1 in the case of UFS. And this >> method could actually work for regular writes too. > > Hi Damien, > > Although the above sounds interesting to me, I think the following two > scenarios are not handled by the above approach and can lead to reordering: > * The SCSI device reporting a unit attention. > * The SCSI device responding with the SCSI status "BUSY". The UFS > standard explicitly allows this. From the UFS standard: "If the unit is > not ready to accept a new command (e.g., still processing previous > command) a STATUS response of BUSY will be returned." Yes, that likely would be an issue for regular writes, but likely not for zone append emulation using regular writes though, since a "busy" return for a ZA emulated regular write can be resent later with a different aligned write location. -- Damien Le Moal Western Digital Research
