[PATCH] more io scheduler updates

Small problem, we must of course also remember to take into account
where the last service point was (or will be).

deadline_get_last_sector() either returns the last offset serviced, or
the last one that will be (back of dispatch queue).

Otherwise the insert-at-head can be very unfair.

diff --git a/drivers/block/deadline-iosched.c b/drivers/block/deadline-iosched.c
index 53890b484ea35f75c746e911a96279cdc2c256e4..6ec9b3bdafb15603f0f400f71ab1cce4cdad74ca 100644 (file)
--- a/drivers/block/deadline-iosched.c
+++ b/drivers/block/deadline-iosched.c
@@ -137,6 +137,22 @@ deadline_find_hash(struct deadline_data *dd, sector_t offset)
        return rq;
 }
 
+static sector_t deadline_get_last_sector(struct deadline_data *dd)
+{
+       sector_t last_sec = dd->last_sector;
+
+       /*
+        * if dispatch is non-empty, disregard last_sector and check last one
+        */
+       if (!list_empty(dd->dispatch)) {
+               struct request *__rq = list_entry_rq(dd->dispatch->prev);
+
+               last_sec = __rq->sector + __rq->nr_sectors;
+       }
+
+       return last_sec;
+}
+
 static int
 deadline_merge(request_queue_t *q, struct list_head **insert, struct bio *bio)
 {
@@ -205,7 +221,9 @@ deadline_merge(request_queue_t *q, struct list_head **insert, struct bio *bio)
         */
        if (!*insert && !list_empty(sort_list)) {
                __rq = list_entry_rq(sort_list->next);
-               if (bio->bi_sector + bio_sectors(bio) < __rq->sector)
+
+               if (bio->bi_sector + bio_sectors(bio) < __rq->sector &&
+                   bio->bi_sector > deadline_get_last_sector(dd))
                        *insert = sort_list;
        }
 
@@ -268,18 +286,9 @@ deadline_move_to_dispatch(struct deadline_data *dd, struct request *rq)
 static void deadline_move_requests(struct deadline_data *dd, struct request *rq)
 {
        struct list_head *sort_head = &dd->sort_list[rq_data_dir(rq)];
-       sector_t last_sec = dd->last_sector;
+       sector_t last_sec = deadline_get_last_sector(dd);
        int batch_count = dd->fifo_batch;
 
-       /*
-        * if dispatch is non-empty, disregard last_sector and check last one
-        */
-       if (!list_empty(dd->dispatch)) {
-               struct request *__rq = list_entry_rq(dd->dispatch->prev);
-
-               last_sec = __rq->sector + __rq->nr_sectors;
-       }
-
        do {
                struct list_head *nxt = rq->queuelist.next;
                int this_rq_cost;