cfq-iosched: fix ncq detection code

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

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index c2ef5d1..47abd24 100644 (file)
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -191,8 +191,14 @@ struct cfq_data {
         */
        int rq_queued;
        int hw_tag;
-       int hw_tag_samples;
-       int rq_in_driver_peak;
+       /*
+        * hw_tag can be
+        * -1 => indeterminate, (cfq will behave as if NCQ is present, to allow better detection)
+        *  1 => NCQ is present (hw_tag_est_depth is the estimated max depth)
+        *  0 => no NCQ
+        */
+       int hw_tag_est_depth;
+       unsigned int hw_tag_samples;
 
        /*
         * idle window management
@@ -2518,8 +2524,11 @@ static void cfq_update_hw_tag(struct cfq_data *cfqd)
 {
        struct cfq_queue *cfqq = cfqd->active_queue;
 
-       if (rq_in_driver(cfqd) > cfqd->rq_in_driver_peak)
-               cfqd->rq_in_driver_peak = rq_in_driver(cfqd);
+       if (rq_in_driver(cfqd) > cfqd->hw_tag_est_depth)
+               cfqd->hw_tag_est_depth = rq_in_driver(cfqd);
+
+       if (cfqd->hw_tag == 1)
+               return;
 
        if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN &&
            rq_in_driver(cfqd) <= CFQ_HW_QUEUE_MIN)
@@ -2538,13 +2547,10 @@ static void cfq_update_hw_tag(struct cfq_data *cfqd)
        if (cfqd->hw_tag_samples++ < 50)
                return;
 
-       if (cfqd->rq_in_driver_peak >= CFQ_HW_QUEUE_MIN)
+       if (cfqd->hw_tag_est_depth >= CFQ_HW_QUEUE_MIN)
                cfqd->hw_tag = 1;
        else
                cfqd->hw_tag = 0;
-
-       cfqd->hw_tag_samples = 0;
-       cfqd->rq_in_driver_peak = 0;
 }
 
 static void cfq_completed_request(struct request_queue *q, struct request *rq)
@@ -2951,7 +2957,7 @@ static void *cfq_init_queue(struct request_queue *q)
        cfqd->cfq_slice_async_rq = cfq_slice_async_rq;
        cfqd->cfq_slice_idle = cfq_slice_idle;
        cfqd->cfq_latency = 1;
-       cfqd->hw_tag = 1;
+       cfqd->hw_tag = -1;
        cfqd->last_end_sync_rq = jiffies;
        return cfqd;
 }