1 files changed, 14 insertions, 40 deletions

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 10eb286f1f49..3fd8afc2174e 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -46,8 +46,8 @@ static const int cfq_hist_divisor = 4;
 #define CFQ_HW_QUEUE_MIN        (5)
 #define CFQ_SERVICE_SHIFT       12
 
-#define CFQQ_SEEK_THR           8 * 1024
-#define CFQQ_SEEKY(cfqq)        ((cfqq)->seek_mean > CFQQ_SEEK_THR)
+#define CFQQ_SEEK_THR           (sector_t)(8 * 100)
+#define CFQQ_SEEKY(cfqq)        (hweight32(cfqq->seek_history) > 32/8)
 
 #define RQ_CIC(rq)              \
         ((struct cfq_io_context *) (rq)->elevator_private)
@@ -132,9 +132,7 @@ struct cfq_queue {
 
         pid_t pid;
 
-        unsigned int seek_samples;
-        u64 seek_total;
-        sector_t seek_mean;
+        u32 seek_history;
         sector_t last_request_pos;
 
         struct cfq_rb_root *service_tree;
@@ -1668,16 +1666,7 @@ static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd,
 static inline int cfq_rq_close(struct cfq_data *cfqd, struct cfq_queue *cfqq,
                                struct request *rq, bool for_preempt)
 {
-        sector_t sdist = cfqq->seek_mean;
-
-        if (!sample_valid(cfqq->seek_samples))
-                sdist = CFQQ_SEEK_THR;
-
-        /* if seek_mean is big, using it as close criteria is meaningless */
-        if (sdist > CFQQ_SEEK_THR && !for_preempt)
-                sdist = CFQQ_SEEK_THR;
-
-        return cfq_dist_from_last(cfqd, rq) <= sdist;
+        return cfq_dist_from_last(cfqd, rq) <= CFQQ_SEEK_THR;
 }
 
 static struct cfq_queue *cfqq_close(struct cfq_data *cfqd,
@@ -2975,30 +2964,16 @@ static void
 cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_queue *cfqq,
                        struct request *rq)
 {
-        sector_t sdist;
-        u64 total;
-
-        if (!cfqq->last_request_pos)
-                sdist = 0;
-        else if (cfqq->last_request_pos < blk_rq_pos(rq))
-                sdist = blk_rq_pos(rq) - cfqq->last_request_pos;
-        else
-                sdist = cfqq->last_request_pos - blk_rq_pos(rq);
-
-        /*
-         * Don't allow the seek distance to get too large from the
-         * odd fragment, pagein, etc
-         */
-        if (cfqq->seek_samples <= 60) /* second&third seek */
-                sdist = min(sdist, (cfqq->seek_mean * 4) + 2*1024*1024);
-        else
-                sdist = min(sdist, (cfqq->seek_mean * 4) + 2*1024*64);
+        sector_t sdist = 0;
+        if (cfqq->last_request_pos) {
+                if (cfqq->last_request_pos < blk_rq_pos(rq))
+                        sdist = blk_rq_pos(rq) - cfqq->last_request_pos;
+                else
+                        sdist = cfqq->last_request_pos - blk_rq_pos(rq);
+        }
 
-        cfqq->seek_samples = (7*cfqq->seek_samples + 256) / 8;
-        cfqq->seek_total = (7*cfqq->seek_total + (u64)256*sdist) / 8;
-        total = cfqq->seek_total + (cfqq->seek_samples/2);
-        do_div(total, cfqq->seek_samples);
-        cfqq->seek_mean = (sector_t)total;
+        cfqq->seek_history <<= 1;
+        cfqq->seek_history |= (sdist > CFQQ_SEEK_THR);
 }
 
 /*
@@ -3023,8 +2998,7 @@ cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq,
                 cfq_mark_cfqq_deep(cfqq);
 
         if (!atomic_read(&cic->ioc->nr_tasks) || !cfqd->cfq_slice_idle ||
-            (!cfq_cfqq_deep(cfqq) && sample_valid(cfqq->seek_samples)
-             && CFQQ_SEEKY(cfqq)))
+            (!cfq_cfqq_deep(cfqq) && CFQQ_SEEKY(cfqq)))
                 enable_idle = 0;
         else if (sample_valid(cic->ttime_samples)) {
                 if (cic->ttime_mean > cfqd->cfq_slice_idle)