On 11/19/24 12:01 AM, Damien Le Moal wrote:
Impressive improvements but the changes are rather invasive. Have you tried simpler solution like forcing unplugging a zone write plug from the driver once a command is passed to the driver and the driver did not reject it ? It seems like this would make everything simpler on the block layer side. But I am not sure if the performance gains would be the same.
Hi Damien, I'm not sure that the approach of submitting a new zoned write if the driver did not reject the previous write would result in a simpler solution. SCSI devices are allowed to respond to any command with a unit attention instead of processing the command. If a unit attention is reported, the SCSI core requeues the command. In other words, even with this approach, proper support for requeued zoned writes in the block layer is required. Additionally, that approach is not compatible with using .queue_rqs(). While the SCSI core does not yet support a .queue_rqs() callback, I think it would be good to have this support in the SCSI core. If we need requeuing support anyway, why to select an approach that probably will result in lower performance than what has been implemented in this patch series? Thanks, Bart.
