On Thu, Jul 20 2006, Jeff Garzik wrote:Jens Axboe wrote:On Thu, Jul 20 2006, Jeff Garzik wrote:What tree are you looking at?James Bottomley wrote:That just means the map is shared, otherwise there should be little ifOn Thu, 2006-07-20 at 17:27 -0400, Jeff Garzik wrote:Not for the case being discussed in this thread, adapter-wide tags.Since _no individual SCSI driver_ uses the block layerThat's not quite true: 53c700 and tmscsim both use it ... I could with
tagging, it is likely that some instability and core kernel
will occur, in order to make that work.
the usage were wider, but at least 53c700 has pretty regular and
constant usage ... enough I think to validate the block tag code (it's
been using it for the last three years).
AFAICS, no file in include/scsi/* or drivers/scsi/* ever calls blk_queue_init_tags() with a non-NULL third arg.grpe again, it's in scsi_tcq.h.
There is only one user in the entire tree, and NULL is hardcoded as the third arg. This is 2.6.18-rc2:
Sorry, missed your non-NULL statement, I thought you meant in generel.
As long as you get the locking right for the map access, there's really
nothing that seperates shared vs non-shared tag mappings. So I don't
think it's a big deal.
If we don't encourage new drivers to use the block layer tagging, we
might as well not bother with it.