On 12/12/23 09:18, Christoph Hellwig wrote:
On Tue, Dec 12, 2023 at 09:15:48AM -0800, Bart Van Assche wrote:
As mentioned before, UFS devices implement the SCSI command set and hence do not
support write append operations. If anyone else standardizes a write append
command for SCSI we can ask UFS vendors to implement that command. However, as
far as I know nobody in T10 is working on standardizing a write append command.
The actual hardware support does not matter, it's the programming model.
Even with the zone append emulation in sd you don't need to care about
reordering due to I/O priorities.
The actual hardware support does matter. Using the zone append emulation from
drivers/scsi/sd_zbc.c (or any other zone append emulation) is not an option for
high performance devices. This is because emulating zone append can only be done
by serializing write operations. Any such serialization negatively affects
performance.
Thanks,
Bart.
