On Mon, Nov 24, 2014 at 04:51:14PM +0100, Hannes Reinecke wrote: > It is useful as is, as we'll be getting prefixed logging output :-) Use the blk-mq code path if you care :) > Which I didn't do yet as the driver is using a larger tag map than > that one announced to the block layer. > This is to facilitate internal command submission, which should > always work independent on any tag starvation issues from the > upper layers. This is an "issue" for a lot of drivers. blk-mq provides a reserved_tags pool for that, which reserves a number of tags for internal use, those must be allocated using blk_mq_alloc_request with the reserved argument set to true. The lockless hpsa patches expose this to SCSI, which I'm generally fine with, but we need to find a way to transparently make this work for the old code path, too. This might be as simple as embedding a second blk_queue_tag structure into the Scsi_Host, adding a constant prefix to the tag and providing some wrappes in scsi that allow allocating a struct request (or rather scsi_cmnd) for internal use. -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
