On 6/15/22 00:21, Damien Le Moal wrote:
On 6/15/22 14:49, 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.
For scsi, we already have the zone append emulation in the sd driver which
issues regular writes together with taking the zone lock. So UFS has zone
append, not as a native command though. But if for UFS device there are no
issue of command reordering underneath sd, then the zone append emulation
can be done without taking the zone write lock, which would result in the
same performance as what a native zone append command would give.
At least for the short term, that could be a good solution until native
zone append is added to zbc specs. That last part may face a lot of
pushback because of the difficulty of having that same command on ATA side.
Is there more information available about the difficulties of defining a
ZONE APPEND command for ATA? It seems to me that there is enough space
available in the ATA Status Return Descriptor to report the LBA back to
the host?
Thanks,
Bart.
