K 10
svn:author
V 3
imp
K 8
svn:date
V 27
2015-03-06T00:23:23.716708Z
K 7
svn:log
V 908
Implement "NCQ TRIM" by using Send First Party DMA commands with a
Dataset Management subcommand and setting the TRIM bit. For drives
that support this method of TRIM, better latency is expected because
TRIMs no longer act as a gating event forcing the queue to drain
before they are executed and holding off new commands while the TRIM
finishes. We still impose a one-at-a-time limit of the TRIMs, though
that could be relaxed (though you start running into fairness issues
if you have a lot of TRIMs competing with other I/Os), so that
optimization is left for the future.

Add a flag for supporting the NCQ DSM TRIM extention to the ata_cmd
structure.

Add a flag to adversize that the SIM knows how to do said kludge.

When NCQ DSM Trim fails, fall back to normal DSM Trim. However, treat
the original trim as advisory and don't reissue it. The stack is too
fragile at this point in the code to risk it.

END