On Thu, Dec 22, 2016 at 04:57:36PM +0000, Bart Van Assche wrote:

On Thu, 2016-12-22 at 08:52 -0800, Omar Sandoval wrote:

quoted

This approach occurred to us, but we couldn't figure out a way to make
blk_mq_tag_to_rq() work with it. From skimming over the patches, I
didn't see a solution to that problem.

Hello Omar,

Can you clarify your comment? Since my patches initialize both tags->rqs[]
and sched_tags->rqs[] the function blk_mq_tag_to_rq() should still work.

Bart.

Sorry, you're right, it does work, but tags->rqs[] ends up being the
extra lookup table. I suspect that the runtime overhead of keeping that
up to date could be worse than copying the rq fields if you have lots of
CPUs but only one hardware queue.