This looks good in general: Reviewed-by: Christoph Hellwig <hch@xxxxxx> Minor nitpicks below: > const bool has_sched_dispatch = e && e->type->ops.mq.dispatch_request; This is now only tested once, so you can remove the local variable for it. > + /* > + * We may clear DISPATCH_BUSY just after it > + * is set from another context, the only cost > + * is that one request is dequeued a bit early, > + * we can survive that. Given the window is > + * small enough, no need to worry about performance > + * effect. > + */ Use your 80 line real estate for comments please. > if (!has_sched_dispatch) > + if (!q->queue_depth) { > + blk_mq_flush_busy_ctxs(hctx, &rq_list); > + blk_mq_dispatch_rq_list(q, &rq_list); > + } else { > + blk_mq_do_dispatch_ctx(q, hctx); > + } > + } else { > blk_mq_do_dispatch_sched(q, e, hctx); > + } Maybe flatten this out to: if (e && e->type->ops.mq.dispatch_request) { blk_mq_do_dispatch_sched(q, e, hctx); } else if (q->queue_depth) { blk_mq_do_dispatch_ctx(q, hctx); } else { blk_mq_flush_busy_ctxs(hctx, &rq_list); blk_mq_dispatch_rq_list(q, &rq_list); } -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel