On Fri, Jul 08, 2022 at 09:58:25AM +0200, Sergei Shtepa wrote: > There was a goal to use the kernel innovations whenever possible. > Of course, it makes sense to return to bio based if it allows to > achieve better performance. This is not a matter of principle. In general blk-mq is designed for hardware drivers, while the bio based interface is for stacking drivers. There are some exceptions: dm-mpath is a stacking blk-mq driver, but one that just passes I/O through, and there is a bunch of hardware drivers implemented as bio based ones, although I suspect most of them would end up being improved by switching to blk-mq (or in most case by just deleting them).
