1 files changed, 165 insertions, 145 deletions

diff --git a/drivers/block/as-iosched.c b/drivers/block/as-iosched.c
index c6744ff38294..a78e160b59a3 100644
--- a/drivers/block/as-iosched.c
+++ b/drivers/block/as-iosched.c
@@ -4,7 +4,7 @@
  *  Anticipatory & deadline i/o scheduler.
  *
  *  Copyright (C) 2002 Jens Axboe <axboe@suse.de>
- *                     Nick Piggin <piggin@cyberone.com.au>
+ *                     Nick Piggin <nickpiggin@yahoo.com.au>
  *
  */
 #include <linux/kernel.h>
@@ -69,7 +69,7 @@
 
 /* Bits in as_io_context.state */
 enum as_io_states {
-        AS_TASK_RUNNING=0,      /* Process has not exitted */
+        AS_TASK_RUNNING=0,      /* Process has not exited */
         AS_TASK_IOSTARTED,      /* Process has started some IO */
         AS_TASK_IORUNNING,      /* Process has completed some IO */
 };
@@ -102,6 +102,9 @@ struct as_data {
 
         unsigned long exit_prob;        /* probability a task will exit while
                                            being waited on */
+        unsigned long exit_no_coop;     /* probablility an exited task will
+                                           not be part of a later cooperating
+                                           request */
         unsigned long new_ttime_total;  /* mean thinktime on new proc */
         unsigned long new_ttime_mean;
         u64 new_seek_total;             /* mean seek on new proc */
@@ -636,37 +639,152 @@ static void as_antic_timeout(unsigned long data)
                 kblockd_schedule_work(&ad->antic_work);
 
                 if (aic->ttime_samples == 0) {
-                        /* process anticipated on has exitted or timed out*/
+                        /* process anticipated on has exited or timed out*/
                         ad->exit_prob = (7*ad->exit_prob + 256)/8;
                 }
+                if (!test_bit(AS_TASK_RUNNING, &aic->state)) {
+                        /* process not "saved" by a cooperating request */
+                        ad->exit_no_coop = (7*ad->exit_no_coop + 256)/8;
+                }
         }
         spin_unlock_irqrestore(q->queue_lock, flags);
 }
 
+static void as_update_thinktime(struct as_data *ad, struct as_io_context *aic,
+                                unsigned long ttime)
+{
+        /* fixed point: 1.0 == 1<<8 */
+        if (aic->ttime_samples == 0) {
+                ad->new_ttime_total = (7*ad->new_ttime_total + 256*ttime) / 8;
+                ad->new_ttime_mean = ad->new_ttime_total / 256;
+
+                ad->exit_prob = (7*ad->exit_prob)/8;
+        }
+        aic->ttime_samples = (7*aic->ttime_samples + 256) / 8;
+        aic->ttime_total = (7*aic->ttime_total + 256*ttime) / 8;
+        aic->ttime_mean = (aic->ttime_total + 128) / aic->ttime_samples;
+}
+
+static void as_update_seekdist(struct as_data *ad, struct as_io_context *aic,
+                                sector_t sdist)
+{
+        u64 total;
+
+        if (aic->seek_samples == 0) {
+                ad->new_seek_total = (7*ad->new_seek_total + 256*(u64)sdist)/8;
+                ad->new_seek_mean = ad->new_seek_total / 256;
+        }
+
+        /*
+         * Don't allow the seek distance to get too large from the
+         * odd fragment, pagein, etc
+         */
+        if (aic->seek_samples <= 60) /* second&third seek */
+                sdist = min(sdist, (aic->seek_mean * 4) + 2*1024*1024);
+        else
+                sdist = min(sdist, (aic->seek_mean * 4) + 2*1024*64);
+
+        aic->seek_samples = (7*aic->seek_samples + 256) / 8;
+        aic->seek_total = (7*aic->seek_total + (u64)256*sdist) / 8;
+        total = aic->seek_total + (aic->seek_samples/2);
+        do_div(total, aic->seek_samples);
+        aic->seek_mean = (sector_t)total;
+}
+
+/*
+ * as_update_iohist keeps a decaying histogram of IO thinktimes, and
+ * updates @aic->ttime_mean based on that. It is called when a new
+ * request is queued.
+ */
+static void as_update_iohist(struct as_data *ad, struct as_io_context *aic,
+                                struct request *rq)
+{
+        struct as_rq *arq = RQ_DATA(rq);
+        int data_dir = arq->is_sync;
+        unsigned long thinktime = 0;
+        sector_t seek_dist;
+
+        if (aic == NULL)
+                return;
+
+        if (data_dir == REQ_SYNC) {
+                unsigned long in_flight = atomic_read(&aic->nr_queued)
+                                        + atomic_read(&aic->nr_dispatched);
+                spin_lock(&aic->lock);
+                if (test_bit(AS_TASK_IORUNNING, &aic->state) ||
+                        test_bit(AS_TASK_IOSTARTED, &aic->state)) {
+                        /* Calculate read -> read thinktime */
+                        if (test_bit(AS_TASK_IORUNNING, &aic->state)
+                                                        && in_flight == 0) {
+                                thinktime = jiffies - aic->last_end_request;
+                                thinktime = min(thinktime, MAX_THINKTIME-1);
+                        }
+                        as_update_thinktime(ad, aic, thinktime);
+
+                        /* Calculate read -> read seek distance */
+                        if (aic->last_request_pos < rq->sector)
+                                seek_dist = rq->sector - aic->last_request_pos;
+                        else
+                                seek_dist = aic->last_request_pos - rq->sector;
+                        as_update_seekdist(ad, aic, seek_dist);
+                }
+                aic->last_request_pos = rq->sector + rq->nr_sectors;
+                set_bit(AS_TASK_IOSTARTED, &aic->state);
+                spin_unlock(&aic->lock);
+        }
+}
+
 /*
  * as_close_req decides if one request is considered "close" to the
  * previous one issued.
  */
-static int as_close_req(struct as_data *ad, struct as_rq *arq)
+static int as_close_req(struct as_data *ad, struct as_io_context *aic,
+                                struct as_rq *arq)
 {
         unsigned long delay;    /* milliseconds */
         sector_t last = ad->last_sector[ad->batch_data_dir];
         sector_t next = arq->request->sector;
         sector_t delta; /* acceptable close offset (in sectors) */
+        sector_t s;
 
         if (ad->antic_status == ANTIC_OFF || !ad->ioc_finished)
                 delay = 0;
         else
                 delay = ((jiffies - ad->antic_start) * 1000) / HZ;
 
-        if (delay <= 1)
-                delta = 64;
+        if (delay == 0)
+                delta = 8192;
         else if (delay <= 20 && delay <= ad->antic_expire)
-                delta = 64 << (delay-1);
+                delta = 8192 << delay;
         else
                 return 1;
 
-        return (last - (delta>>1) <= next) && (next <= last + delta);
+        if ((last <= next + (delta>>1)) && (next <= last + delta))
+                return 1;
+
+        if (last < next)
+                s = next - last;
+        else
+                s = last - next;
+
+        if (aic->seek_samples == 0) {
+                /*
+                 * Process has just started IO. Use past statistics to
+                 * gauge success possibility
+                 */
+                if (ad->new_seek_mean > s) {
+                        /* this request is better than what we're expecting */
+                        return 1;
+                }
+
+        } else {
+                if (aic->seek_mean > s) {
+                        /* this request is better than what we're expecting */
+                        return 1;
+                }
+        }
+
+        return 0;
 }
 
 /*
@@ -678,7 +796,7 @@ static int as_close_req(struct as_data *ad, struct as_rq *arq)
  * dispatch it ASAP, because we know that application will not be submitting
  * any new reads.
  *
- * If the task which has submitted the request has exitted, break anticipation.
+ * If the task which has submitted the request has exited, break anticipation.
  *
  * If this task has queued some other IO, do not enter enticipation.
  */
@@ -686,7 +804,6 @@ static int as_can_break_anticipation(struct as_data *ad, struct as_rq *arq)
 {
         struct io_context *ioc;
         struct as_io_context *aic;
-        sector_t s;
 
         ioc = ad->io_context;
         BUG_ON(!ioc);
@@ -708,13 +825,6 @@ static int as_can_break_anticipation(struct as_data *ad, struct as_rq *arq)
         if (!aic)
                 return 0;
 
-        if (!test_bit(AS_TASK_RUNNING, &aic->state)) {
-                /* process anticipated on has exitted */
-                if (aic->ttime_samples == 0)
-                        ad->exit_prob = (7*ad->exit_prob + 256)/8;
-                return 1;
-        }
-
         if (atomic_read(&aic->nr_queued) > 0) {
                 /* process has more requests queued */
                 return 1;
@@ -725,57 +835,45 @@ static int as_can_break_anticipation(struct as_data *ad, struct as_rq *arq)
                 return 1;
         }
 
-        if (arq && arq->is_sync == REQ_SYNC && as_close_req(ad, arq)) {
+        if (arq && arq->is_sync == REQ_SYNC && as_close_req(ad, aic, arq)) {
                 /*
                  * Found a close request that is not one of ours.
                  *
-                 * This makes close requests from another process reset
-                 * our thinktime delay. Is generally useful when there are
+                 * This makes close requests from another process update
+                 * our IO history. Is generally useful when there are
                  * two or more cooperating processes working in the same
                  * area.
                  */
-                spin_lock(&aic->lock);
-                aic->last_end_request = jiffies;
-                spin_unlock(&aic->lock);
+                if (!test_bit(AS_TASK_RUNNING, &aic->state)) {
+                        if (aic->ttime_samples == 0)
+                                ad->exit_prob = (7*ad->exit_prob + 256)/8;
+
+                        ad->exit_no_coop = (7*ad->exit_no_coop)/8;
+                }
+
+                as_update_iohist(ad, aic, arq->request);
                 return 1;
         }
 
+        if (!test_bit(AS_TASK_RUNNING, &aic->state)) {
+                /* process anticipated on has exited */
+                if (aic->ttime_samples == 0)
+                        ad->exit_prob = (7*ad->exit_prob + 256)/8;
+
+                if (ad->exit_no_coop > 128)
+                        return 1;
+        }
 
         if (aic->ttime_samples == 0) {
                 if (ad->new_ttime_mean > ad->antic_expire)
                         return 1;
-                if (ad->exit_prob > 128)
+                if (ad->exit_prob * ad->exit_no_coop > 128*256)
                         return 1;
         } else if (aic->ttime_mean > ad->antic_expire) {
                 /* the process thinks too much between requests */
                 return 1;
         }
 
-        if (!arq)
-                return 0;
-
-        if (ad->last_sector[REQ_SYNC] < arq->request->sector)
-                s = arq->request->sector - ad->last_sector[REQ_SYNC];
-        else
-                s = ad->last_sector[REQ_SYNC] - arq->request->sector;
-
-        if (aic->seek_samples == 0) {
-                /*
-                 * Process has just started IO. Use past statistics to
-                 * guage success possibility
-                 */
-                if (ad->new_seek_mean > s) {
-                        /* this request is better than what we're expecting */
-                        return 1;
-                }
-
-        } else {
-                if (aic->seek_mean > s) {
-                        /* this request is better than what we're expecting */
-                        return 1;
-                }
-        }
-
         return 0;
 }
 
@@ -809,94 +907,11 @@ static int as_can_anticipate(struct as_data *ad, struct as_rq *arq)
          * Status is either ANTIC_OFF so start waiting,
          * ANTIC_WAIT_REQ so continue waiting for request to finish
          * or ANTIC_WAIT_NEXT so continue waiting for an acceptable request.
-         *
          */
 
         return 1;
 }
 
-static void as_update_thinktime(struct as_data *ad, struct as_io_context *aic, unsigned long ttime)
-{
-        /* fixed point: 1.0 == 1<<8 */
-        if (aic->ttime_samples == 0) {
-                ad->new_ttime_total = (7*ad->new_ttime_total + 256*ttime) / 8;
-                ad->new_ttime_mean = ad->new_ttime_total / 256;
-
-                ad->exit_prob = (7*ad->exit_prob)/8;
-        }
-        aic->ttime_samples = (7*aic->ttime_samples + 256) / 8;
-        aic->ttime_total = (7*aic->ttime_total + 256*ttime) / 8;
-        aic->ttime_mean = (aic->ttime_total + 128) / aic->ttime_samples;
-}
-
-static void as_update_seekdist(struct as_data *ad, struct as_io_context *aic, sector_t sdist)
-{
-        u64 total;
-
-        if (aic->seek_samples == 0) {
-                ad->new_seek_total = (7*ad->new_seek_total + 256*(u64)sdist)/8;
-                ad->new_seek_mean = ad->new_seek_total / 256;
-        }
-
-        /*
-         * Don't allow the seek distance to get too large from the
-         * odd fragment, pagein, etc
-         */
-        if (aic->seek_samples <= 60) /* second&third seek */
-                sdist = min(sdist, (aic->seek_mean * 4) + 2*1024*1024);
-        else
-                sdist = min(sdist, (aic->seek_mean * 4) + 2*1024*64);
-
-        aic->seek_samples = (7*aic->seek_samples + 256) / 8;
-        aic->seek_total = (7*aic->seek_total + (u64)256*sdist) / 8;
-        total = aic->seek_total + (aic->seek_samples/2);
-        do_div(total, aic->seek_samples);
-        aic->seek_mean = (sector_t)total;
-}
-
-/*
- * as_update_iohist keeps a decaying histogram of IO thinktimes, and
- * updates @aic->ttime_mean based on that. It is called when a new
- * request is queued.
- */
-static void as_update_iohist(struct as_data *ad, struct as_io_context *aic, struct request *rq)
-{
-        struct as_rq *arq = RQ_DATA(rq);
-        int data_dir = arq->is_sync;
-        unsigned long thinktime;
-        sector_t seek_dist;
-
-        if (aic == NULL)
-                return;
-
-        if (data_dir == REQ_SYNC) {
-                unsigned long in_flight = atomic_read(&aic->nr_queued)
-                                        + atomic_read(&aic->nr_dispatched);
-                spin_lock(&aic->lock);
-                if (test_bit(AS_TASK_IORUNNING, &aic->state) ||
-                        test_bit(AS_TASK_IOSTARTED, &aic->state)) {
-                        /* Calculate read -> read thinktime */
-                        if (test_bit(AS_TASK_IORUNNING, &aic->state)
-                                                        && in_flight == 0) {
-                                thinktime = jiffies - aic->last_end_request;
-                                thinktime = min(thinktime, MAX_THINKTIME-1);
-                        } else
-                                thinktime = 0;
-                        as_update_thinktime(ad, aic, thinktime);
-
-                        /* Calculate read -> read seek distance */
-                        if (aic->last_request_pos < rq->sector)
-                                seek_dist = rq->sector - aic->last_request_pos;
-                        else
-                                seek_dist = aic->last_request_pos - rq->sector;
-                        as_update_seekdist(ad, aic, seek_dist);
-                }
-                aic->last_request_pos = rq->sector + rq->nr_sectors;
-                set_bit(AS_TASK_IOSTARTED, &aic->state);
-                spin_unlock(&aic->lock);
-        }
-}
-
 /*
  * as_update_arq must be called whenever a request (arq) is added to
  * the sort_list. This function keeps caches up to date, and checks if the
@@ -1201,7 +1216,7 @@ static int as_dispatch_request(request_queue_t *q, int force)
                 || ad->changed_batch)
                 return 0;
 
-        if (!(reads && writes && as_batch_expired(ad)) ) {
+        if (!(reads && writes && as_batch_expired(ad))) {
                 /*
                  * batch is still running or no reads or no writes
                  */
@@ -1316,7 +1331,8 @@ fifo_expired:
  * Add arq to a list behind alias
  */
 static inline void
-as_add_aliased_request(struct as_data *ad, struct as_rq *arq, struct as_rq *alias)
+as_add_aliased_request(struct as_data *ad, struct as_rq *arq,
+                                struct as_rq *alias)
 {
         struct request  *req = arq->request;
         struct list_head *insert = alias->request->queuelist.prev;
@@ -1441,8 +1457,8 @@ static int as_queue_empty(request_queue_t *q)
                 && list_empty(&ad->fifo_list[REQ_SYNC]);
 }
 
-static struct request *
-as_former_request(request_queue_t *q, struct request *rq)
+static struct request *as_former_request(request_queue_t *q,
+                                        struct request *rq)
 {
         struct as_rq *arq = RQ_DATA(rq);
         struct rb_node *rbprev = rb_prev(&arq->rb_node);
@@ -1454,8 +1470,8 @@ as_former_request(request_queue_t *q, struct request *rq)
         return ret;
 }
 
-static struct request *
-as_latter_request(request_queue_t *q, struct request *rq)
+static struct request *as_latter_request(request_queue_t *q,
+                                        struct request *rq)
 {
         struct as_rq *arq = RQ_DATA(rq);
         struct rb_node *rbnext = rb_next(&arq->rb_node);
@@ -1537,7 +1553,7 @@ static void as_merged_request(request_queue_t *q, struct request *req)
                  * currently don't bother. Ditto the next function.
                  */
                 as_del_arq_rb(ad, arq);
-                if ((alias = as_add_arq_rb(ad, arq)) ) {
+                if ((alias = as_add_arq_rb(ad, arq))) {
                         list_del_init(&arq->fifo);
                         as_add_aliased_request(ad, arq, alias);
                         if (next_arq)
@@ -1551,9 +1567,8 @@ static void as_merged_request(request_queue_t *q, struct request *req)
         }
 }
 
-static void
-as_merged_requests(request_queue_t *q, struct request *req,
-                         struct request *next)
+static void as_merged_requests(request_queue_t *q, struct request *req,
+                                struct request *next)
 {
         struct as_data *ad = q->elevator->elevator_data;
         struct as_rq *arq = RQ_DATA(req);
@@ -1576,7 +1591,7 @@ as_merged_requests(request_queue_t *q, struct request *req,
                         next_arq = as_find_next_arq(ad, arq);
 
                 as_del_arq_rb(ad, arq);
-                if ((alias = as_add_arq_rb(ad, arq)) ) {
+                if ((alias = as_add_arq_rb(ad, arq))) {
                         list_del_init(&arq->fifo);
                         as_add_aliased_request(ad, arq, alias);
                         if (next_arq)
@@ -1806,9 +1821,14 @@ static ssize_t as_est_show(struct as_data *ad, char *page)
 {
         int pos = 0;
 
-        pos += sprintf(page+pos, "%lu %% exit probability\n", 100*ad->exit_prob/256);
+        pos += sprintf(page+pos, "%lu %% exit probability\n",
+                                100*ad->exit_prob/256);
+        pos += sprintf(page+pos, "%lu %% probability of exiting without a "
+                                "cooperating process submitting IO\n",
+                                100*ad->exit_no_coop/256);
         pos += sprintf(page+pos, "%lu ms new thinktime\n", ad->new_ttime_mean);
-        pos += sprintf(page+pos, "%llu sectors new seek distance\n", (unsigned long long)ad->new_seek_mean);
+        pos += sprintf(page+pos, "%llu sectors new seek distance\n",
+                                (unsigned long long)ad->new_seek_mean);
 
         return pos;
 }