On Fri, Feb 03, 2023 at 04:00:06PM +0530, Pankaj Raghav wrote: > move to blk-mq based request processing as brd is one of the few drivers > that still uses submit_bio interface. The changes are pretty trivial > to start using blk-mq. The performance increases up to 125% for direct IO > read workloads. There is a slight dip in performance for direct IO write > workload but considering the general performance gain with blk-mq > support, it is not a lot. Can you find out why writes regress, and what improves for reads? In general blk-mq is doing a lot more work for better batching, but much of that batching should not matter for a simple ramdisk. So the results look a little odd to me, and extra numbers and explanations would really help.
