>Ordinarily I'd prefer a host template attribute as Sumanesh proposed, >but I dislike wrapping the examination of that and the queue flag in >a macro that makes it not obvious how the behavior is affected. I think we can have a host template attribute and discard this check altogether, that is not check device_busy for both SDD and HDDs. As both you and Hannes mentioned, this change affects high end controllers most, and most of them have some storage IO size limit. Also, for HDD sequential IO is almost always large and touch the controller max IO size limit. Thus, I am not sure merge matters for these kind of controllers. Database use REDO log and small sequential IO, but those are targeted to SSDs, where latency and IOPs are far more important than IO merging. If this patch is opt-in for drivers, so any LLD that cannot take advantage of the flag need not set it, and would work as-is Thanks, Sumanesh
