[BLOCK] elevator: Make elevator=as work again for anticipatory

[pandora-kernel.git] / block / cfq-iosched.c

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index ecacca9..74fae2d 100644 (file)
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -1,6 +1,4 @@
 /*
- *  linux/drivers/block/cfq-iosched.c
- *
  *  CFQ, or complete fairness queueing, disk scheduler.
  *
  *  Based on ideas from a previously unfinished io
@@ -27,15 +25,15 @@
 /*
  * tunables
  */
-static int cfq_quantum = 4;            /* max queue in one round of service */
-static int cfq_queued = 8;             /* minimum rq allocate limit per-queue*/
-static int cfq_fifo_expire[2] = { HZ / 4, HZ / 8 };
-static int cfq_back_max = 16 * 1024;   /* maximum backwards seek, in KiB */
-static int cfq_back_penalty = 2;       /* penalty of a backwards seek */
+static const int cfq_quantum = 4;              /* max queue in one round of service */
+static const int cfq_queued = 8;               /* minimum rq allocate limit per-queue*/
+static const int cfq_fifo_expire[2] = { HZ / 4, HZ / 8 };
+static const int cfq_back_max = 16 * 1024;     /* maximum backwards seek, in KiB */
+static const int cfq_back_penalty = 2;         /* penalty of a backwards seek */
 
-static int cfq_slice_sync = HZ / 10;
+static const int cfq_slice_sync = HZ / 10;
 static int cfq_slice_async = HZ / 25;
-static int cfq_slice_async_rq = 2;
+static const int cfq_slice_async_rq = 2;
 static int cfq_slice_idle = HZ / 100;
 
 #define CFQ_IDLE_GRACE         (HZ / 10)
@@ -47,7 +45,7 @@ static int cfq_slice_idle = HZ / 100;
 /*
  * disable queueing at the driver/hardware level
  */
-static int cfq_max_depth = 2;
+static const int cfq_max_depth = 2;
 
 /*
  * for the hash of cfqq inside the cfqd
@@ -861,8 +859,8 @@ __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
         * store what was left of this slice, if the queue idled out
         * or was preempted
         */
-       if (time_after(now, cfqq->slice_end))
-               cfqq->slice_left = now - cfqq->slice_end;
+       if (time_after(cfqq->slice_end, now))
+               cfqq->slice_left = cfqq->slice_end - now;
        else
                cfqq->slice_left = 0;
 
@@ -999,7 +997,7 @@ cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
 /*
  * get next queue for service
  */
-static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd, int force)
+static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
 {
        unsigned long now = jiffies;
        struct cfq_queue *cfqq;
@@ -1023,7 +1021,7 @@ static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd, int force)
         */
        if (!RB_EMPTY(&cfqq->sort_list))
                goto keep_queue;
-       else if (!force && cfq_cfqq_class_sync(cfqq) &&
+       else if (cfq_cfqq_class_sync(cfqq) &&
                 time_before(now, cfqq->slice_end)) {
                if (cfq_arm_slice_timer(cfqd, cfqq))
                        return NULL;
@@ -1091,6 +1089,42 @@ __cfq_dispatch_requests(struct cfq_data *cfqd, struct cfq_queue *cfqq,
        return dispatched;
 }
 
+static int
+cfq_forced_dispatch_cfqqs(struct list_head *list)
+{
+       int dispatched = 0;
+       struct cfq_queue *cfqq, *next;
+       struct cfq_rq *crq;
+
+       list_for_each_entry_safe(cfqq, next, list, cfq_list) {
+               while ((crq = cfqq->next_crq)) {
+                       cfq_dispatch_insert(cfqq->cfqd->queue, crq);
+                       dispatched++;
+               }
+               BUG_ON(!list_empty(&cfqq->fifo));
+       }
+       return dispatched;
+}
+
+static int
+cfq_forced_dispatch(struct cfq_data *cfqd)
+{
+       int i, dispatched = 0;
+
+       for (i = 0; i < CFQ_PRIO_LISTS; i++)
+               dispatched += cfq_forced_dispatch_cfqqs(&cfqd->rr_list[i]);
+
+       dispatched += cfq_forced_dispatch_cfqqs(&cfqd->busy_rr);
+       dispatched += cfq_forced_dispatch_cfqqs(&cfqd->cur_rr);
+       dispatched += cfq_forced_dispatch_cfqqs(&cfqd->idle_rr);
+
+       cfq_slice_expired(cfqd, 0);
+
+       BUG_ON(cfqd->busy_queues);
+
+       return dispatched;
+}
+
 static int
 cfq_dispatch_requests(request_queue_t *q, int force)
 {
@@ -1100,7 +1134,10 @@ cfq_dispatch_requests(request_queue_t *q, int force)
        if (!cfqd->busy_queues)
                return 0;
 
-       cfqq = cfq_select_queue(cfqd, force);
+       if (unlikely(force))
+               return cfq_forced_dispatch(cfqd);
+
+       cfqq = cfq_select_queue(cfqd);
        if (cfqq) {
                int max_dispatch;
 
@@ -1115,12 +1152,9 @@ cfq_dispatch_requests(request_queue_t *q, int force)
                cfq_clear_cfqq_wait_request(cfqq);
                del_timer(&cfqd->idle_slice_timer);
 
-               if (!force) {
-                       max_dispatch = cfqd->cfq_quantum;
-                       if (cfq_class_idle(cfqq))
-                               max_dispatch = 1;
-               } else
-                       max_dispatch = INT_MAX;
+               max_dispatch = cfqd->cfq_quantum;
+               if (cfq_class_idle(cfqq))
+                       max_dispatch = 1;
 
                return __cfq_dispatch_requests(cfqd, cfqq, max_dispatch);
        }