From be8fae6f6fbf2ac2bfdf21b571333b3e98f7c5a9 Mon Sep 17 00:00:00 2001 From: Tatyana Brokhman Date: Tue, 4 Dec 2012 16:04:15 +0200 Subject: block: Add API for urgent request handling This patch add support in block & elevator layers for handling urgent requests. The decision if a request is urgent or not is taken by the scheduler. Urgent request notification is passed to the underlying block device driver (eMMC for example). Block device driver may decide to interrupt the currently running low priority request to serve the new urgent request. By doing so READ latency is greatly reduced in read&write collision scenarios. Note that if the current scheduler doesn't implement the urgent request mechanism, this code path is never activated. Change-Id: I8aa74b9b45c0d3a2221bd4e82ea76eb4103e7cfa Signed-off-by: Tatyana Brokhman Signed-off-by: Stefan Guendhoer --- include/linux/blkdev.h | 4 ++++ include/linux/elevator.h | 2 ++ 2 files changed, 6 insertions(+) (limited to 'include/linux') diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index b3694b9d6..2e9fc2b42 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -387,6 +387,7 @@ struct request_queue { struct request_list root_rl; request_fn_proc *request_fn; + request_fn_proc *urgent_request_fn; make_request_fn *make_request_fn; prep_rq_fn *prep_rq_fn; unprep_rq_fn *unprep_rq_fn; @@ -487,6 +488,8 @@ struct request_queue { #endif struct queue_limits limits; + bool notified_urgent; + bool dispatched_urgent; /* * sg stuff @@ -993,6 +996,7 @@ extern struct request_queue *blk_init_queue_node(request_fn_proc *rfn, extern struct request_queue *blk_init_queue(request_fn_proc *, spinlock_t *); extern struct request_queue *blk_init_allocated_queue(struct request_queue *, request_fn_proc *, spinlock_t *); +extern void blk_urgent_request(struct request_queue *q, request_fn_proc *fn); extern void blk_cleanup_queue(struct request_queue *); extern void blk_queue_make_request(struct request_queue *, make_request_fn *); extern void blk_queue_bounce_limit(struct request_queue *, u64); diff --git a/include/linux/elevator.h b/include/linux/elevator.h index d458ea48d..b3afa35d5 100644 --- a/include/linux/elevator.h +++ b/include/linux/elevator.h @@ -26,6 +26,7 @@ typedef int (elevator_dispatch_fn) (struct request_queue *, int); typedef void (elevator_add_req_fn) (struct request_queue *, struct request *); typedef int (elevator_reinsert_req_fn) (struct request_queue *, struct request *); +typedef bool (elevator_is_urgent_fn) (struct request_queue *); typedef struct request *(elevator_request_list_fn) (struct request_queue *, struct request *); typedef void (elevator_completed_req_fn) (struct request_queue *, struct request *); typedef int (elevator_may_queue_fn) (struct request_queue *, int); @@ -53,6 +54,7 @@ struct elevator_ops elevator_dispatch_fn *elevator_dispatch_fn; elevator_add_req_fn *elevator_add_req_fn; elevator_reinsert_req_fn *elevator_reinsert_req_fn; + elevator_is_urgent_fn *elevator_is_urgent_fn; elevator_activate_req_fn *elevator_activate_req_fn; elevator_deactivate_req_fn *elevator_deactivate_req_fn; -- cgit v1.2.3