I did not understand what is the relationship between aborts and CDL.
Sounds to me that this would tie in to something like Time Limited Error
Recovery (TLER) and LR bit set based on ioprio?
I am unclear where do aborts come into play here.
CDL: Command Duration Limits
One use case is reading from storage for audio visual output.
An application only wants to wait so long (e.g. one or two frames
on the video output) before it wants to forget about the current
read (i.e. "abort" it) and move onto the next read. An alert viewer
might notice a momentary freeze frame.
The SCSI CDL mechanism uses the DL0, DL1 and DL2 bits in the READ(16,32)
commands. CDL also depends on the CDLP and RWCDLP fields in the
REPORT SUPPORTED OPERATION CODES command and one of the CDL
mode pages. So there may be some additional "wiring" needed in the
SCSI subsystem.
I still don't understand where issuing aborts from userspace come into
play here...
The only connection is that aborts are obsolete and unnecessary if
you have a working CDL implementation.
OK, that makes sense. Indeed I *think* that nvme can support CDL and if
this is useful for userspace then this is an interesting path to take.
