On 6/14/22 22:49, Christoph Hellwig wrote:
On Tue, Jun 14, 2022 at 04:56:52PM -0700, Bart Van Assche wrote:
The performance penalty of zone locking is not acceptable for our use case.
Does this mean that zone locking needs to be preserved for AHCI but not for
UFS?
It means you use case needs to use zone append, and we need to make sure
it is added to SCSI assuming your are on SCSI based on your other comments.
Using ZONE APPEND instead of SCSI WRITE commands would have the
following consequences:
* Data of a single file might be stored out-of-order on the storage medium.
* A translation table would have to be stored on the storage medium with
one entry per ZONE APPEND command with the LBAs of where the ZONE APPEND
commands wrote their data. I think that translation table can be
considered as another L2P table. One of our motivations to switch to
zoned storage is to get rid of nested L2P tables.
Both aspects above would have a negative impact on sequential read
performance. Hence our preference to use WRITE commands for zoned
storage instead of ZONE APPEND commands.
Thanks,
Bart.
