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-rw-r--r--drivers/block/as-iosched.c1985
1 files changed, 0 insertions, 1985 deletions
diff --git a/drivers/block/as-iosched.c b/drivers/block/as-iosched.c
deleted file mode 100644
index c6744ff3829..00000000000
--- a/drivers/block/as-iosched.c
+++ /dev/null
@@ -1,1985 +0,0 @@
-/*
- * linux/drivers/block/as-iosched.c
- *
- * Anticipatory & deadline i/o scheduler.
- *
- * Copyright (C) 2002 Jens Axboe <axboe@suse.de>
- * Nick Piggin <piggin@cyberone.com.au>
- *
- */
-#include <linux/kernel.h>
-#include <linux/fs.h>
-#include <linux/blkdev.h>
-#include <linux/elevator.h>
-#include <linux/bio.h>
-#include <linux/config.h>
-#include <linux/module.h>
-#include <linux/slab.h>
-#include <linux/init.h>
-#include <linux/compiler.h>
-#include <linux/hash.h>
-#include <linux/rbtree.h>
-#include <linux/interrupt.h>
-
-#define REQ_SYNC 1
-#define REQ_ASYNC 0
-
-/*
- * See Documentation/block/as-iosched.txt
- */
-
-/*
- * max time before a read is submitted.
- */
-#define default_read_expire (HZ / 8)
-
-/*
- * ditto for writes, these limits are not hard, even
- * if the disk is capable of satisfying them.
- */
-#define default_write_expire (HZ / 4)
-
-/*
- * read_batch_expire describes how long we will allow a stream of reads to
- * persist before looking to see whether it is time to switch over to writes.
- */
-#define default_read_batch_expire (HZ / 2)
-
-/*
- * write_batch_expire describes how long we want a stream of writes to run for.
- * This is not a hard limit, but a target we set for the auto-tuning thingy.
- * See, the problem is: we can send a lot of writes to disk cache / TCQ in
- * a short amount of time...
- */
-#define default_write_batch_expire (HZ / 8)
-
-/*
- * max time we may wait to anticipate a read (default around 6ms)
- */
-#define default_antic_expire ((HZ / 150) ? HZ / 150 : 1)
-
-/*
- * Keep track of up to 20ms thinktimes. We can go as big as we like here,
- * however huge values tend to interfere and not decay fast enough. A program
- * might be in a non-io phase of operation. Waiting on user input for example,
- * or doing a lengthy computation. A small penalty can be justified there, and
- * will still catch out those processes that constantly have large thinktimes.
- */
-#define MAX_THINKTIME (HZ/50UL)
-
-/* Bits in as_io_context.state */
-enum as_io_states {
- AS_TASK_RUNNING=0, /* Process has not exitted */
- AS_TASK_IOSTARTED, /* Process has started some IO */
- AS_TASK_IORUNNING, /* Process has completed some IO */
-};
-
-enum anticipation_status {
- ANTIC_OFF=0, /* Not anticipating (normal operation) */
- ANTIC_WAIT_REQ, /* The last read has not yet completed */
- ANTIC_WAIT_NEXT, /* Currently anticipating a request vs
- last read (which has completed) */
- ANTIC_FINISHED, /* Anticipating but have found a candidate
- * or timed out */
-};
-
-struct as_data {
- /*
- * run time data
- */
-
- struct request_queue *q; /* the "owner" queue */
-
- /*
- * requests (as_rq s) are present on both sort_list and fifo_list
- */
- struct rb_root sort_list[2];
- struct list_head fifo_list[2];
-
- struct as_rq *next_arq[2]; /* next in sort order */
- sector_t last_sector[2]; /* last REQ_SYNC & REQ_ASYNC sectors */
- struct list_head *hash; /* request hash */
-
- unsigned long exit_prob; /* probability a task will exit while
- being waited on */
- unsigned long new_ttime_total; /* mean thinktime on new proc */
- unsigned long new_ttime_mean;
- u64 new_seek_total; /* mean seek on new proc */
- sector_t new_seek_mean;
-
- unsigned long current_batch_expires;
- unsigned long last_check_fifo[2];
- int changed_batch; /* 1: waiting for old batch to end */
- int new_batch; /* 1: waiting on first read complete */
- int batch_data_dir; /* current batch REQ_SYNC / REQ_ASYNC */
- int write_batch_count; /* max # of reqs in a write batch */
- int current_write_count; /* how many requests left this batch */
- int write_batch_idled; /* has the write batch gone idle? */
- mempool_t *arq_pool;
-
- enum anticipation_status antic_status;
- unsigned long antic_start; /* jiffies: when it started */
- struct timer_list antic_timer; /* anticipatory scheduling timer */
- struct work_struct antic_work; /* Deferred unplugging */
- struct io_context *io_context; /* Identify the expected process */
- int ioc_finished; /* IO associated with io_context is finished */
- int nr_dispatched;
-
- /*
- * settings that change how the i/o scheduler behaves
- */
- unsigned long fifo_expire[2];
- unsigned long batch_expire[2];
- unsigned long antic_expire;
-};
-
-#define list_entry_fifo(ptr) list_entry((ptr), struct as_rq, fifo)
-
-/*
- * per-request data.
- */
-enum arq_state {
- AS_RQ_NEW=0, /* New - not referenced and not on any lists */
- AS_RQ_QUEUED, /* In the request queue. It belongs to the
- scheduler */
- AS_RQ_DISPATCHED, /* On the dispatch list. It belongs to the
- driver now */
- AS_RQ_PRESCHED, /* Debug poisoning for requests being used */
- AS_RQ_REMOVED,
- AS_RQ_MERGED,
- AS_RQ_POSTSCHED, /* when they shouldn't be */
-};
-
-struct as_rq {
- /*
- * rbtree index, key is the starting offset
- */
- struct rb_node rb_node;
- sector_t rb_key;
-
- struct request *request;
-
- struct io_context *io_context; /* The submitting task */
-
- /*
- * request hash, key is the ending offset (for back merge lookup)
- */
- struct list_head hash;
- unsigned int on_hash;
-
- /*
- * expire fifo
- */
- struct list_head fifo;
- unsigned long expires;
-
- unsigned int is_sync;
- enum arq_state state;
-};
-
-#define RQ_DATA(rq) ((struct as_rq *) (rq)->elevator_private)
-
-static kmem_cache_t *arq_pool;
-
-/*
- * IO Context helper functions
- */
-
-/* Called to deallocate the as_io_context */
-static void free_as_io_context(struct as_io_context *aic)
-{
- kfree(aic);
-}
-
-/* Called when the task exits */
-static void exit_as_io_context(struct as_io_context *aic)
-{
- WARN_ON(!test_bit(AS_TASK_RUNNING, &aic->state));
- clear_bit(AS_TASK_RUNNING, &aic->state);
-}
-
-static struct as_io_context *alloc_as_io_context(void)
-{
- struct as_io_context *ret;
-
- ret = kmalloc(sizeof(*ret), GFP_ATOMIC);
- if (ret) {
- ret->dtor = free_as_io_context;
- ret->exit = exit_as_io_context;
- ret->state = 1 << AS_TASK_RUNNING;
- atomic_set(&ret->nr_queued, 0);
- atomic_set(&ret->nr_dispatched, 0);
- spin_lock_init(&ret->lock);
- ret->ttime_total = 0;
- ret->ttime_samples = 0;
- ret->ttime_mean = 0;
- ret->seek_total = 0;
- ret->seek_samples = 0;
- ret->seek_mean = 0;
- }
-
- return ret;
-}
-
-/*
- * If the current task has no AS IO context then create one and initialise it.
- * Then take a ref on the task's io context and return it.
- */
-static struct io_context *as_get_io_context(void)
-{
- struct io_context *ioc = get_io_context(GFP_ATOMIC);
- if (ioc && !ioc->aic) {
- ioc->aic = alloc_as_io_context();
- if (!ioc->aic) {
- put_io_context(ioc);
- ioc = NULL;
- }
- }
- return ioc;
-}
-
-static void as_put_io_context(struct as_rq *arq)
-{
- struct as_io_context *aic;
-
- if (unlikely(!arq->io_context))
- return;
-
- aic = arq->io_context->aic;
-
- if (arq->is_sync == REQ_SYNC && aic) {
- spin_lock(&aic->lock);
- set_bit(AS_TASK_IORUNNING, &aic->state);
- aic->last_end_request = jiffies;
- spin_unlock(&aic->lock);
- }
-
- put_io_context(arq->io_context);
-}
-
-/*
- * the back merge hash support functions
- */
-static const int as_hash_shift = 6;
-#define AS_HASH_BLOCK(sec) ((sec) >> 3)
-#define AS_HASH_FN(sec) (hash_long(AS_HASH_BLOCK((sec)), as_hash_shift))
-#define AS_HASH_ENTRIES (1 << as_hash_shift)
-#define rq_hash_key(rq) ((rq)->sector + (rq)->nr_sectors)
-#define list_entry_hash(ptr) list_entry((ptr), struct as_rq, hash)
-
-static inline void __as_del_arq_hash(struct as_rq *arq)
-{
- arq->on_hash = 0;
- list_del_init(&arq->hash);
-}
-
-static inline void as_del_arq_hash(struct as_rq *arq)
-{
- if (arq->on_hash)
- __as_del_arq_hash(arq);
-}
-
-static void as_add_arq_hash(struct as_data *ad, struct as_rq *arq)
-{
- struct request *rq = arq->request;
-
- BUG_ON(arq->on_hash);
-
- arq->on_hash = 1;
- list_add(&arq->hash, &ad->hash[AS_HASH_FN(rq_hash_key(rq))]);
-}
-
-/*
- * move hot entry to front of chain
- */
-static inline void as_hot_arq_hash(struct as_data *ad, struct as_rq *arq)
-{
- struct request *rq = arq->request;
- struct list_head *head = &ad->hash[AS_HASH_FN(rq_hash_key(rq))];
-
- if (!arq->on_hash) {
- WARN_ON(1);
- return;
- }
-
- if (arq->hash.prev != head) {
- list_del(&arq->hash);
- list_add(&arq->hash, head);
- }
-}
-
-static struct request *as_find_arq_hash(struct as_data *ad, sector_t offset)
-{
- struct list_head *hash_list = &ad->hash[AS_HASH_FN(offset)];
- struct list_head *entry, *next = hash_list->next;
-
- while ((entry = next) != hash_list) {
- struct as_rq *arq = list_entry_hash(entry);
- struct request *__rq = arq->request;
-
- next = entry->next;
-
- BUG_ON(!arq->on_hash);
-
- if (!rq_mergeable(__rq)) {
- as_del_arq_hash(arq);
- continue;
- }
-
- if (rq_hash_key(__rq) == offset)
- return __rq;
- }
-
- return NULL;
-}
-
-/*
- * rb tree support functions
- */
-#define RB_NONE (2)
-#define RB_EMPTY(root) ((root)->rb_node == NULL)
-#define ON_RB(node) ((node)->rb_color != RB_NONE)
-#define RB_CLEAR(node) ((node)->rb_color = RB_NONE)
-#define rb_entry_arq(node) rb_entry((node), struct as_rq, rb_node)
-#define ARQ_RB_ROOT(ad, arq) (&(ad)->sort_list[(arq)->is_sync])
-#define rq_rb_key(rq) (rq)->sector
-
-/*
- * as_find_first_arq finds the first (lowest sector numbered) request
- * for the specified data_dir. Used to sweep back to the start of the disk
- * (1-way elevator) after we process the last (highest sector) request.
- */
-static struct as_rq *as_find_first_arq(struct as_data *ad, int data_dir)
-{
- struct rb_node *n = ad->sort_list[data_dir].rb_node;
-
- if (n == NULL)
- return NULL;
-
- for (;;) {
- if (n->rb_left == NULL)
- return rb_entry_arq(n);
-
- n = n->rb_left;
- }
-}
-
-/*
- * Add the request to the rb tree if it is unique. If there is an alias (an
- * existing request against the same sector), which can happen when using
- * direct IO, then return the alias.
- */
-static struct as_rq *as_add_arq_rb(struct as_data *ad, struct as_rq *arq)
-{
- struct rb_node **p = &ARQ_RB_ROOT(ad, arq)->rb_node;
- struct rb_node *parent = NULL;
- struct as_rq *__arq;
- struct request *rq = arq->request;
-
- arq->rb_key = rq_rb_key(rq);
-
- while (*p) {
- parent = *p;
- __arq = rb_entry_arq(parent);
-
- if (arq->rb_key < __arq->rb_key)
- p = &(*p)->rb_left;
- else if (arq->rb_key > __arq->rb_key)
- p = &(*p)->rb_right;
- else
- return __arq;
- }
-
- rb_link_node(&arq->rb_node, parent, p);
- rb_insert_color(&arq->rb_node, ARQ_RB_ROOT(ad, arq));
-
- return NULL;
-}
-
-static inline void as_del_arq_rb(struct as_data *ad, struct as_rq *arq)
-{
- if (!ON_RB(&arq->rb_node)) {
- WARN_ON(1);
- return;
- }
-
- rb_erase(&arq->rb_node, ARQ_RB_ROOT(ad, arq));
- RB_CLEAR(&arq->rb_node);
-}
-
-static struct request *
-as_find_arq_rb(struct as_data *ad, sector_t sector, int data_dir)
-{
- struct rb_node *n = ad->sort_list[data_dir].rb_node;
- struct as_rq *arq;
-
- while (n) {
- arq = rb_entry_arq(n);
-
- if (sector < arq->rb_key)
- n = n->rb_left;
- else if (sector > arq->rb_key)
- n = n->rb_right;
- else
- return arq->request;
- }
-
- return NULL;
-}
-
-/*
- * IO Scheduler proper
- */
-
-#define MAXBACK (1024 * 1024) /*
- * Maximum distance the disk will go backward
- * for a request.
- */
-
-#define BACK_PENALTY 2
-
-/*
- * as_choose_req selects the preferred one of two requests of the same data_dir
- * ignoring time - eg. timeouts, which is the job of as_dispatch_request
- */
-static struct as_rq *
-as_choose_req(struct as_data *ad, struct as_rq *arq1, struct as_rq *arq2)
-{
- int data_dir;
- sector_t last, s1, s2, d1, d2;
- int r1_wrap=0, r2_wrap=0; /* requests are behind the disk head */
- const sector_t maxback = MAXBACK;
-
- if (arq1 == NULL || arq1 == arq2)
- return arq2;
- if (arq2 == NULL)
- return arq1;
-
- data_dir = arq1->is_sync;
-
- last = ad->last_sector[data_dir];
- s1 = arq1->request->sector;
- s2 = arq2->request->sector;
-
- BUG_ON(data_dir != arq2->is_sync);
-
- /*
- * Strict one way elevator _except_ in the case where we allow
- * short backward seeks which are biased as twice the cost of a
- * similar forward seek.
- */
- if (s1 >= last)
- d1 = s1 - last;
- else if (s1+maxback >= last)
- d1 = (last - s1)*BACK_PENALTY;
- else {
- r1_wrap = 1;
- d1 = 0; /* shut up, gcc */
- }
-
- if (s2 >= last)
- d2 = s2 - last;
- else if (s2+maxback >= last)
- d2 = (last - s2)*BACK_PENALTY;
- else {
- r2_wrap = 1;
- d2 = 0;
- }
-
- /* Found required data */
- if (!r1_wrap && r2_wrap)
- return arq1;
- else if (!r2_wrap && r1_wrap)
- return arq2;
- else if (r1_wrap && r2_wrap) {
- /* both behind the head */
- if (s1 <= s2)
- return arq1;
- else
- return arq2;
- }
-
- /* Both requests in front of the head */
- if (d1 < d2)
- return arq1;
- else if (d2 < d1)
- return arq2;
- else {
- if (s1 >= s2)
- return arq1;
- else
- return arq2;
- }
-}
-
-/*
- * as_find_next_arq finds the next request after @prev in elevator order.
- * this with as_choose_req form the basis for how the scheduler chooses
- * what request to process next. Anticipation works on top of this.
- */
-static struct as_rq *as_find_next_arq(struct as_data *ad, struct as_rq *last)
-{
- const int data_dir = last->is_sync;
- struct as_rq *ret;
- struct rb_node *rbnext = rb_next(&last->rb_node);
- struct rb_node *rbprev = rb_prev(&last->rb_node);
- struct as_rq *arq_next, *arq_prev;
-
- BUG_ON(!ON_RB(&last->rb_node));
-
- if (rbprev)
- arq_prev = rb_entry_arq(rbprev);
- else
- arq_prev = NULL;
-
- if (rbnext)
- arq_next = rb_entry_arq(rbnext);
- else {
- arq_next = as_find_first_arq(ad, data_dir);
- if (arq_next == last)
- arq_next = NULL;
- }
-
- ret = as_choose_req(ad, arq_next, arq_prev);
-
- return ret;
-}
-
-/*
- * anticipatory scheduling functions follow
- */
-
-/*
- * as_antic_expired tells us when we have anticipated too long.
- * The funny "absolute difference" math on the elapsed time is to handle
- * jiffy wraps, and disks which have been idle for 0x80000000 jiffies.
- */
-static int as_antic_expired(struct as_data *ad)
-{
- long delta_jif;
-
- delta_jif = jiffies - ad->antic_start;
- if (unlikely(delta_jif < 0))
- delta_jif = -delta_jif;
- if (delta_jif < ad->antic_expire)
- return 0;
-
- return 1;
-}
-
-/*
- * as_antic_waitnext starts anticipating that a nice request will soon be
- * submitted. See also as_antic_waitreq
- */
-static void as_antic_waitnext(struct as_data *ad)
-{
- unsigned long timeout;
-
- BUG_ON(ad->antic_status != ANTIC_OFF
- && ad->antic_status != ANTIC_WAIT_REQ);
-
- timeout = ad->antic_start + ad->antic_expire;
-
- mod_timer(&ad->antic_timer, timeout);
-
- ad->antic_status = ANTIC_WAIT_NEXT;
-}
-
-/*
- * as_antic_waitreq starts anticipating. We don't start timing the anticipation
- * until the request that we're anticipating on has finished. This means we
- * are timing from when the candidate process wakes up hopefully.
- */
-static void as_antic_waitreq(struct as_data *ad)
-{
- BUG_ON(ad->antic_status == ANTIC_FINISHED);
- if (ad->antic_status == ANTIC_OFF) {
- if (!ad->io_context || ad->ioc_finished)
- as_antic_waitnext(ad);
- else
- ad->antic_status = ANTIC_WAIT_REQ;
- }
-}
-
-/*
- * This is called directly by the functions in this file to stop anticipation.
- * We kill the timer and schedule a call to the request_fn asap.
- */
-static void as_antic_stop(struct as_data *ad)
-{
- int status = ad->antic_status;
-
- if (status == ANTIC_WAIT_REQ || status == ANTIC_WAIT_NEXT) {
- if (status == ANTIC_WAIT_NEXT)
- del_timer(&ad->antic_timer);
- ad->antic_status = ANTIC_FINISHED;
- /* see as_work_handler */
- kblockd_schedule_work(&ad->antic_work);
- }
-}
-
-/*
- * as_antic_timeout is the timer function set by as_antic_waitnext.
- */
-static void as_antic_timeout(unsigned long data)
-{
- struct request_queue *q = (struct request_queue *)data;
- struct as_data *ad = q->elevator->elevator_data;
- unsigned long flags;
-
- spin_lock_irqsave(q->queue_lock, flags);
- if (ad->antic_status == ANTIC_WAIT_REQ
- || ad->antic_status == ANTIC_WAIT_NEXT) {
- struct as_io_context *aic = ad->io_context->aic;
-
- ad->antic_status = ANTIC_FINISHED;
- kblockd_schedule_work(&ad->antic_work);
-
- if (aic->ttime_samples == 0) {
- /* process anticipated on has exitted or timed out*/
- ad->exit_prob = (7*ad->exit_prob + 256)/8;
- }
- }
- spin_unlock_irqrestore(q->queue_lock, flags);
-}
-
-/*
- * 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)
-{
- 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) */
-
- if (ad->antic_status == ANTIC_OFF || !ad->ioc_finished)
- delay = 0;
- else
- delay = ((jiffies - ad->antic_start) * 1000) / HZ;
-
- if (delay <= 1)
- delta = 64;
- else if (delay <= 20 && delay <= ad->antic_expire)
- delta = 64 << (delay-1);
- else
- return 1;
-
- return (last - (delta>>1) <= next) && (next <= last + delta);
-}
-
-/*
- * as_can_break_anticipation returns true if we have been anticipating this
- * request.
- *
- * It also returns true if the process against which we are anticipating
- * submits a write - that's presumably an fsync, O_SYNC write, etc. We want to
- * 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 this task has queued some other IO, do not enter enticipation.
- */
-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);
-
- if (arq && ioc == arq->io_context) {
- /* request from same process */
- return 1;
- }
-
- if (ad->ioc_finished && as_antic_expired(ad)) {
- /*
- * In this situation status should really be FINISHED,
- * however the timer hasn't had the chance to run yet.
- */
- return 1;
- }
-
- aic = ioc->aic;
- 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;
- }
-
- if (atomic_read(&aic->nr_dispatched) > 0) {
- /* process has more requests dispatched */
- return 1;
- }
-
- if (arq && arq->is_sync == REQ_SYNC && as_close_req(ad, 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
- * two or more cooperating processes working in the same
- * area.
- */
- spin_lock(&aic->lock);
- aic->last_end_request = jiffies;
- spin_unlock(&aic->lock);
- return 1;
- }
-
-
- if (aic->ttime_samples == 0) {
- if (ad->new_ttime_mean > ad->antic_expire)
- return 1;
- if (ad->exit_prob > 128)
- 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;
-}
-
-/*
- * as_can_anticipate indicates weather we should either run arq
- * or keep anticipating a better request.
- */
-static int as_can_anticipate(struct as_data *ad, struct as_rq *arq)
-{
- if (!ad->io_context)
- /*
- * Last request submitted was a write
- */
- return 0;
-
- if (ad->antic_status == ANTIC_FINISHED)
- /*
- * Don't restart if we have just finished. Run the next request
- */
- return 0;
-
- if (as_can_break_anticipation(ad, arq))
- /*
- * This request is a good candidate. Don't keep anticipating,
- * run it.
- */
- return 0;
-
- /*
- * OK from here, we haven't finished, and don't have a decent request!
- * 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
- * request might be one we are "anticipating"
- */
-static void as_update_arq(struct as_data *ad, struct as_rq *arq)
-{
- const int data_dir = arq->is_sync;
-
- /* keep the next_arq cache up to date */
- ad->next_arq[data_dir] = as_choose_req(ad, arq, ad->next_arq[data_dir]);
-
- /*
- * have we been anticipating this request?
- * or does it come from the same process as the one we are anticipating
- * for?
- */
- if (ad->antic_status == ANTIC_WAIT_REQ
- || ad->antic_status == ANTIC_WAIT_NEXT) {
- if (as_can_break_anticipation(ad, arq))
- as_antic_stop(ad);
- }
-}
-
-/*
- * Gathers timings and resizes the write batch automatically
- */
-static void update_write_batch(struct as_data *ad)
-{
- unsigned long batch = ad->batch_expire[REQ_ASYNC];
- long write_time;
-
- write_time = (jiffies - ad->current_batch_expires) + batch;
- if (write_time < 0)
- write_time = 0;
-
- if (write_time > batch && !ad->write_batch_idled) {
- if (write_time > batch * 3)
- ad->write_batch_count /= 2;
- else
- ad->write_batch_count--;
- } else if (write_time < batch && ad->current_write_count == 0) {
- if (batch > write_time * 3)
- ad->write_batch_count *= 2;
- else
- ad->write_batch_count++;
- }
-
- if (ad->write_batch_count < 1)
- ad->write_batch_count = 1;
-}
-
-/*
- * as_completed_request is to be called when a request has completed and
- * returned something to the requesting process, be it an error or data.
- */
-static void as_completed_request(request_queue_t *q, struct request *rq)
-{
- struct as_data *ad = q->elevator->elevator_data;
- struct as_rq *arq = RQ_DATA(rq);
-
- WARN_ON(!list_empty(&rq->queuelist));
-
- if (arq->state != AS_RQ_REMOVED) {
- printk("arq->state %d\n", arq->state);
- WARN_ON(1);
- goto out;
- }
-
- if (ad->changed_batch && ad->nr_dispatched == 1) {
- kblockd_schedule_work(&ad->antic_work);
- ad->changed_batch = 0;
-
- if (ad->batch_data_dir == REQ_SYNC)
- ad->new_batch = 1;
- }
- WARN_ON(ad->nr_dispatched == 0);
- ad->nr_dispatched--;
-
- /*
- * Start counting the batch from when a request of that direction is
- * actually serviced. This should help devices with big TCQ windows
- * and writeback caches
- */
- if (ad->new_batch && ad->batch_data_dir == arq->is_sync) {
- update_write_batch(ad);
- ad->current_batch_expires = jiffies +
- ad->batch_expire[REQ_SYNC];
- ad->new_batch = 0;
- }
-
- if (ad->io_context == arq->io_context && ad->io_context) {
- ad->antic_start = jiffies;
- ad->ioc_finished = 1;
- if (ad->antic_status == ANTIC_WAIT_REQ) {
- /*
- * We were waiting on this request, now anticipate
- * the next one
- */
- as_antic_waitnext(ad);
- }
- }
-
- as_put_io_context(arq);
-out:
- arq->state = AS_RQ_POSTSCHED;
-}
-
-/*
- * as_remove_queued_request removes a request from the pre dispatch queue
- * without updating refcounts. It is expected the caller will drop the
- * reference unless it replaces the request at somepart of the elevator
- * (ie. the dispatch queue)
- */
-static void as_remove_queued_request(request_queue_t *q, struct request *rq)
-{
- struct as_rq *arq = RQ_DATA(rq);
- const int data_dir = arq->is_sync;
- struct as_data *ad = q->elevator->elevator_data;
-
- WARN_ON(arq->state != AS_RQ_QUEUED);
-
- if (arq->io_context && arq->io_context->aic) {
- BUG_ON(!atomic_read(&arq->io_context->aic->nr_queued));
- atomic_dec(&arq->io_context->aic->nr_queued);
- }
-
- /*
- * Update the "next_arq" cache if we are about to remove its
- * entry
- */
- if (ad->next_arq[data_dir] == arq)
- ad->next_arq[data_dir] = as_find_next_arq(ad, arq);
-
- list_del_init(&arq->fifo);
- as_del_arq_hash(arq);
- as_del_arq_rb(ad, arq);
-}
-
-/*
- * as_fifo_expired returns 0 if there are no expired reads on the fifo,
- * 1 otherwise. It is ratelimited so that we only perform the check once per
- * `fifo_expire' interval. Otherwise a large number of expired requests
- * would create a hopeless seekstorm.
- *
- * See as_antic_expired comment.
- */
-static int as_fifo_expired(struct as_data *ad, int adir)
-{
- struct as_rq *arq;
- long delta_jif;
-
- delta_jif = jiffies - ad->last_check_fifo[adir];
- if (unlikely(delta_jif < 0))
- delta_jif = -delta_jif;
- if (delta_jif < ad->fifo_expire[adir])
- return 0;
-
- ad->last_check_fifo[adir] = jiffies;
-
- if (list_empty(&ad->fifo_list[adir]))
- return 0;
-
- arq = list_entry_fifo(ad->fifo_list[adir].next);
-
- return time_after(jiffies, arq->expires);
-}
-
-/*
- * as_batch_expired returns true if the current batch has expired. A batch
- * is a set of reads or a set of writes.
- */
-static inline int as_batch_expired(struct as_data *ad)
-{
- if (ad->changed_batch || ad->new_batch)
- return 0;
-
- if (ad->batch_data_dir == REQ_SYNC)
- /* TODO! add a check so a complete fifo gets written? */
- return time_after(jiffies, ad->current_batch_expires);
-
- return time_after(jiffies, ad->current_batch_expires)
- || ad->current_write_count == 0;
-}
-
-/*
- * move an entry to dispatch queue
- */
-static void as_move_to_dispatch(struct as_data *ad, struct as_rq *arq)
-{
- struct request *rq = arq->request;
- const int data_dir = arq->is_sync;
-
- BUG_ON(!ON_RB(&arq->rb_node));
-
- as_antic_stop(ad);
- ad->antic_status = ANTIC_OFF;
-
- /*
- * This has to be set in order to be correctly updated by
- * as_find_next_arq
- */
- ad->last_sector[data_dir] = rq->sector + rq->nr_sectors;
-
- if (data_dir == REQ_SYNC) {
- /* In case we have to anticipate after this */
- copy_io_context(&ad->io_context, &arq->io_context);
- } else {
- if (ad->io_context) {
- put_io_context(ad->io_context);
- ad->io_context = NULL;
- }
-
- if (ad->current_write_count != 0)
- ad->current_write_count--;
- }
- ad->ioc_finished = 0;
-
- ad->next_arq[data_dir] = as_find_next_arq(ad, arq);
-
- /*
- * take it off the sort and fifo list, add to dispatch queue
- */
- while (!list_empty(&rq->queuelist)) {
- struct request *__rq = list_entry_rq(rq->queuelist.next);
- struct as_rq *__arq = RQ_DATA(__rq);
-
- list_del(&__rq->queuelist);
-
- elv_dispatch_add_tail(ad->q, __rq);
-
- if (__arq->io_context && __arq->io_context->aic)
- atomic_inc(&__arq->io_context->aic->nr_dispatched);
-
- WARN_ON(__arq->state != AS_RQ_QUEUED);
- __arq->state = AS_RQ_DISPATCHED;
-
- ad->nr_dispatched++;
- }
-
- as_remove_queued_request(ad->q, rq);
- WARN_ON(arq->state != AS_RQ_QUEUED);
-
- elv_dispatch_sort(ad->q, rq);
-
- arq->state = AS_RQ_DISPATCHED;
- if (arq->io_context && arq->io_context->aic)
- atomic_inc(&arq->io_context->aic->nr_dispatched);
- ad->nr_dispatched++;
-}
-
-/*
- * as_dispatch_request selects the best request according to
- * read/write expire, batch expire, etc, and moves it to the dispatch
- * queue. Returns 1 if a request was found, 0 otherwise.
- */
-static int as_dispatch_request(request_queue_t *q, int force)
-{
- struct as_data *ad = q->elevator->elevator_data;
- struct as_rq *arq;
- const int reads = !list_empty(&ad->fifo_list[REQ_SYNC]);
- const int writes = !list_empty(&ad->fifo_list[REQ_ASYNC]);
-
- if (unlikely(force)) {
- /*
- * Forced dispatch, accounting is useless. Reset
- * accounting states and dump fifo_lists. Note that
- * batch_data_dir is reset to REQ_SYNC to avoid
- * screwing write batch accounting as write batch
- * accounting occurs on W->R transition.
- */
- int dispatched = 0;
-
- ad->batch_data_dir = REQ_SYNC;
- ad->changed_batch = 0;
- ad->new_batch = 0;
-
- while (ad->next_arq[REQ_SYNC]) {
- as_move_to_dispatch(ad, ad->next_arq[REQ_SYNC]);
- dispatched++;
- }
- ad->last_check_fifo[REQ_SYNC] = jiffies;
-
- while (ad->next_arq[REQ_ASYNC]) {
- as_move_to_dispatch(ad, ad->next_arq[REQ_ASYNC]);
- dispatched++;
- }
- ad->last_check_fifo[REQ_ASYNC] = jiffies;
-
- return dispatched;
- }
-
- /* Signal that the write batch was uncontended, so we can't time it */
- if (ad->batch_data_dir == REQ_ASYNC && !reads) {
- if (ad->current_write_count == 0 || !writes)
- ad->write_batch_idled = 1;
- }
-
- if (!(reads || writes)
- || ad->antic_status == ANTIC_WAIT_REQ
- || ad->antic_status == ANTIC_WAIT_NEXT
- || ad->changed_batch)
- return 0;
-
- if (!(reads && writes && as_batch_expired(ad)) ) {
- /*
- * batch is still running or no reads or no writes
- */
- arq = ad->next_arq[ad->batch_data_dir];
-
- if (ad->batch_data_dir == REQ_SYNC && ad->antic_expire) {
- if (as_fifo_expired(ad, REQ_SYNC))
- goto fifo_expired;
-
- if (as_can_anticipate(ad, arq)) {
- as_antic_waitreq(ad);
- return 0;
- }
- }
-
- if (arq) {
- /* we have a "next request" */
- if (reads && !writes)
- ad->current_batch_expires =
- jiffies + ad->batch_expire[REQ_SYNC];
- goto dispatch_request;
- }
- }
-
- /*
- * at this point we are not running a batch. select the appropriate
- * data direction (read / write)
- */
-
- if (reads) {
- BUG_ON(RB_EMPTY(&ad->sort_list[REQ_SYNC]));
-
- if (writes && ad->batch_data_dir == REQ_SYNC)
- /*
- * Last batch was a read, switch to writes
- */
- goto dispatch_writes;
-
- if (ad->batch_data_dir == REQ_ASYNC) {
- WARN_ON(ad->new_batch);
- ad->changed_batch = 1;
- }
- ad->batch_data_dir = REQ_SYNC;
- arq = list_entry_fifo(ad->fifo_list[ad->batch_data_dir].next);
- ad->last_check_fifo[ad->batch_data_dir] = jiffies;
- goto dispatch_request;
- }
-
- /*
- * the last batch was a read
- */
-
- if (writes) {
-dispatch_writes:
- BUG_ON(RB_EMPTY(&ad->sort_list[REQ_ASYNC]));
-
- if (ad->batch_data_dir == REQ_SYNC) {
- ad->changed_batch = 1;
-
- /*
- * new_batch might be 1 when the queue runs out of
- * reads. A subsequent submission of a write might
- * cause a change of batch before the read is finished.
- */
- ad->new_batch = 0;
- }
- ad->batch_data_dir = REQ_ASYNC;
- ad->current_write_count = ad->write_batch_count;
- ad->write_batch_idled = 0;
- arq = ad->next_arq[ad->batch_data_dir];
- goto dispatch_request;
- }
-
- BUG();
- return 0;
-
-dispatch_request:
- /*
- * If a request has expired, service it.
- */
-
- if (as_fifo_expired(ad, ad->batch_data_dir)) {
-fifo_expired:
- arq = list_entry_fifo(ad->fifo_list[ad->batch_data_dir].next);
- BUG_ON(arq == NULL);
- }
-
- if (ad->changed_batch) {
- WARN_ON(ad->new_batch);
-
- if (ad->nr_dispatched)
- return 0;
-
- if (ad->batch_data_dir == REQ_ASYNC)
- ad->current_batch_expires = jiffies +
- ad->batch_expire[REQ_ASYNC];
- else
- ad->new_batch = 1;
-
- ad->changed_batch = 0;
- }
-
- /*
- * arq is the selected appropriate request.
- */
- as_move_to_dispatch(ad, arq);
-
- return 1;
-}
-
-/*
- * 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)
-{
- struct request *req = arq->request;
- struct list_head *insert = alias->request->queuelist.prev;
-
- /*
- * Transfer list of aliases
- */
- while (!list_empty(&req->queuelist)) {
- struct request *__rq = list_entry_rq(req->queuelist.next);
- struct as_rq *__arq = RQ_DATA(__rq);
-
- list_move_tail(&__rq->queuelist, &alias->request->queuelist);
-
- WARN_ON(__arq->state != AS_RQ_QUEUED);
- }
-
- /*
- * Another request with the same start sector on the rbtree.
- * Link this request to that sector. They are untangled in
- * as_move_to_dispatch
- */
- list_add(&arq->request->queuelist, insert);
-
- /*
- * Don't want to have to handle merges.
- */
- as_del_arq_hash(arq);
- arq->request->flags |= REQ_NOMERGE;
-}
-
-/*
- * add arq to rbtree and fifo
- */
-static void as_add_request(request_queue_t *q, struct request *rq)
-{
- struct as_data *ad = q->elevator->elevator_data;
- struct as_rq *arq = RQ_DATA(rq);
- struct as_rq *alias;
- int data_dir;
-
- if (arq->state != AS_RQ_PRESCHED) {
- printk("arq->state: %d\n", arq->state);
- WARN_ON(1);
- }
- arq->state = AS_RQ_NEW;
-
- if (rq_data_dir(arq->request) == READ
- || current->flags&PF_SYNCWRITE)
- arq->is_sync = 1;
- else
- arq->is_sync = 0;
- data_dir = arq->is_sync;
-
- arq->io_context = as_get_io_context();
-
- if (arq->io_context) {
- as_update_iohist(ad, arq->io_context->aic, arq->request);
- atomic_inc(&arq->io_context->aic->nr_queued);
- }
-
- alias = as_add_arq_rb(ad, arq);
- if (!alias) {
- /*
- * set expire time (only used for reads) and add to fifo list
- */
- arq->expires = jiffies + ad->fifo_expire[data_dir];
- list_add_tail(&arq->fifo, &ad->fifo_list[data_dir]);
-
- if (rq_mergeable(arq->request))
- as_add_arq_hash(ad, arq);
- as_update_arq(ad, arq); /* keep state machine up to date */
-
- } else {
- as_add_aliased_request(ad, arq, alias);
-
- /*
- * have we been anticipating this request?
- * or does it come from the same process as the one we are
- * anticipating for?
- */
- if (ad->antic_status == ANTIC_WAIT_REQ
- || ad->antic_status == ANTIC_WAIT_NEXT) {
- if (as_can_break_anticipation(ad, arq))
- as_antic_stop(ad);
- }
- }
-
- arq->state = AS_RQ_QUEUED;
-}
-
-static void as_activate_request(request_queue_t *q, struct request *rq)
-{
- struct as_rq *arq = RQ_DATA(rq);
-
- WARN_ON(arq->state != AS_RQ_DISPATCHED);
- arq->state = AS_RQ_REMOVED;
- if (arq->io_context && arq->io_context->aic)
- atomic_dec(&arq->io_context->aic->nr_dispatched);
-}
-
-static void as_deactivate_request(request_queue_t *q, struct request *rq)
-{
- struct as_rq *arq = RQ_DATA(rq);
-
- WARN_ON(arq->state != AS_RQ_REMOVED);
- arq->state = AS_RQ_DISPATCHED;
- if (arq->io_context && arq->io_context->aic)
- atomic_inc(&arq->io_context->aic->nr_dispatched);
-}
-
-/*
- * as_queue_empty tells us if there are requests left in the device. It may
- * not be the case that a driver can get the next request even if the queue
- * is not empty - it is used in the block layer to check for plugging and
- * merging opportunities
- */
-static int as_queue_empty(request_queue_t *q)
-{
- struct as_data *ad = q->elevator->elevator_data;
-
- return list_empty(&ad->fifo_list[REQ_ASYNC])
- && list_empty(&ad->fifo_list[REQ_SYNC]);
-}
-
-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);
- struct request *ret = NULL;
-
- if (rbprev)
- ret = rb_entry_arq(rbprev)->request;
-
- return ret;
-}
-
-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);
- struct request *ret = NULL;
-
- if (rbnext)
- ret = rb_entry_arq(rbnext)->request;
-
- return ret;
-}
-
-static int
-as_merge(request_queue_t *q, struct request **req, struct bio *bio)
-{
- struct as_data *ad = q->elevator->elevator_data;
- sector_t rb_key = bio->bi_sector + bio_sectors(bio);
- struct request *__rq;
- int ret;
-
- /*
- * see if the merge hash can satisfy a back merge
- */
- __rq = as_find_arq_hash(ad, bio->bi_sector);
- if (__rq) {
- BUG_ON(__rq->sector + __rq->nr_sectors != bio->bi_sector);
-
- if (elv_rq_merge_ok(__rq, bio)) {
- ret = ELEVATOR_BACK_MERGE;
- goto out;
- }
- }
-
- /*
- * check for front merge
- */
- __rq = as_find_arq_rb(ad, rb_key, bio_data_dir(bio));
- if (__rq) {
- BUG_ON(rb_key != rq_rb_key(__rq));
-
- if (elv_rq_merge_ok(__rq, bio)) {
- ret = ELEVATOR_FRONT_MERGE;
- goto out;
- }
- }
-
- return ELEVATOR_NO_MERGE;
-out:
- if (ret) {
- if (rq_mergeable(__rq))
- as_hot_arq_hash(ad, RQ_DATA(__rq));
- }
- *req = __rq;
- return ret;
-}
-
-static void as_merged_request(request_queue_t *q, struct request *req)
-{
- struct as_data *ad = q->elevator->elevator_data;
- struct as_rq *arq = RQ_DATA(req);
-
- /*
- * hash always needs to be repositioned, key is end sector
- */
- as_del_arq_hash(arq);
- as_add_arq_hash(ad, arq);
-
- /*
- * if the merge was a front merge, we need to reposition request
- */
- if (rq_rb_key(req) != arq->rb_key) {
- struct as_rq *alias, *next_arq = NULL;
-
- if (ad->next_arq[arq->is_sync] == arq)
- next_arq = as_find_next_arq(ad, arq);
-
- /*
- * Note! We should really be moving any old aliased requests
- * off this request and try to insert them into the rbtree. We
- * currently don't bother. Ditto the next function.
- */
- as_del_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)
- ad->next_arq[arq->is_sync] = next_arq;
- }
- /*
- * Note! At this stage of this and the next function, our next
- * request may not be optimal - eg the request may have "grown"
- * behind the disk head. We currently don't bother adjusting.
- */
- }
-}
-
-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);
- struct as_rq *anext = RQ_DATA(next);
-
- BUG_ON(!arq);
- BUG_ON(!anext);
-
- /*
- * reposition arq (this is the merged request) in hash, and in rbtree
- * in case of a front merge
- */
- as_del_arq_hash(arq);
- as_add_arq_hash(ad, arq);
-
- if (rq_rb_key(req) != arq->rb_key) {
- struct as_rq *alias, *next_arq = NULL;
-
- if (ad->next_arq[arq->is_sync] == arq)
- next_arq = as_find_next_arq(ad, arq);
-
- as_del_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)
- ad->next_arq[arq->is_sync] = next_arq;
- }
- }
-
- /*
- * if anext expires before arq, assign its expire time to arq
- * and move into anext position (anext will be deleted) in fifo
- */
- if (!list_empty(&arq->fifo) && !list_empty(&anext->fifo)) {
- if (time_before(anext->expires, arq->expires)) {
- list_move(&arq->fifo, &anext->fifo);
- arq->expires = anext->expires;
- /*
- * Don't copy here but swap, because when anext is
- * removed below, it must contain the unused context
- */
- swap_io_context(&arq->io_context, &anext->io_context);
- }
- }
-
- /*
- * Transfer list of aliases
- */
- while (!list_empty(&next->queuelist)) {
- struct request *__rq = list_entry_rq(next->queuelist.next);
- struct as_rq *__arq = RQ_DATA(__rq);
-
- list_move_tail(&__rq->queuelist, &req->queuelist);
-
- WARN_ON(__arq->state != AS_RQ_QUEUED);
- }
-
- /*
- * kill knowledge of next, this one is a goner
- */
- as_remove_queued_request(q, next);
- as_put_io_context(anext);
-
- anext->state = AS_RQ_MERGED;
-}
-
-/*
- * This is executed in a "deferred" process context, by kblockd. It calls the
- * driver's request_fn so the driver can submit that request.
- *
- * IMPORTANT! This guy will reenter the elevator, so set up all queue global
- * state before calling, and don't rely on any state over calls.
- *
- * FIXME! dispatch queue is not a queue at all!
- */
-static void as_work_handler(void *data)
-{
- struct request_queue *q = data;
- unsigned long flags;
-
- spin_lock_irqsave(q->queue_lock, flags);
- if (!as_queue_empty(q))
- q->request_fn(q);
- spin_unlock_irqrestore(q->queue_lock, flags);
-}
-
-static void as_put_request(request_queue_t *q, struct request *rq)
-{
- struct as_data *ad = q->elevator->elevator_data;
- struct as_rq *arq = RQ_DATA(rq);
-
- if (!arq) {
- WARN_ON(1);
- return;
- }
-
- if (unlikely(arq->state != AS_RQ_POSTSCHED &&
- arq->state != AS_RQ_PRESCHED &&
- arq->state != AS_RQ_MERGED)) {
- printk("arq->state %d\n", arq->state);
- WARN_ON(1);
- }
-
- mempool_free(arq, ad->arq_pool);
- rq->elevator_private = NULL;
-}
-
-static int as_set_request(request_queue_t *q, struct request *rq,
- struct bio *bio, gfp_t gfp_mask)
-{
- struct as_data *ad = q->elevator->elevator_data;
- struct as_rq *arq = mempool_alloc(ad->arq_pool, gfp_mask);
-
- if (arq) {
- memset(arq, 0, sizeof(*arq));
- RB_CLEAR(&arq->rb_node);
- arq->request = rq;
- arq->state = AS_RQ_PRESCHED;
- arq->io_context = NULL;
- INIT_LIST_HEAD(&arq->hash);
- arq->on_hash = 0;
- INIT_LIST_HEAD(&arq->fifo);
- rq->elevator_private = arq;
- return 0;
- }
-
- return 1;
-}
-
-static int as_may_queue(request_queue_t *q, int rw, struct bio *bio)
-{
- int ret = ELV_MQUEUE_MAY;
- struct as_data *ad = q->elevator->elevator_data;
- struct io_context *ioc;
- if (ad->antic_status == ANTIC_WAIT_REQ ||
- ad->antic_status == ANTIC_WAIT_NEXT) {
- ioc = as_get_io_context();
- if (ad->io_context == ioc)
- ret = ELV_MQUEUE_MUST;
- put_io_context(ioc);
- }
-
- return ret;
-}
-
-static void as_exit_queue(elevator_t *e)
-{
- struct as_data *ad = e->elevator_data;
-
- del_timer_sync(&ad->antic_timer);
- kblockd_flush();
-
- BUG_ON(!list_empty(&ad->fifo_list[REQ_SYNC]));
- BUG_ON(!list_empty(&ad->fifo_list[REQ_ASYNC]));
-
- mempool_destroy(ad->arq_pool);
- put_io_context(ad->io_context);
- kfree(ad->hash);
- kfree(ad);
-}
-
-/*
- * initialize elevator private data (as_data), and alloc a arq for
- * each request on the free lists
- */
-static int as_init_queue(request_queue_t *q, elevator_t *e)
-{
- struct as_data *ad;
- int i;
-
- if (!arq_pool)
- return -ENOMEM;
-
- ad = kmalloc_node(sizeof(*ad), GFP_KERNEL, q->node);
- if (!ad)
- return -ENOMEM;
- memset(ad, 0, sizeof(*ad));
-
- ad->q = q; /* Identify what queue the data belongs to */
-
- ad->hash = kmalloc_node(sizeof(struct list_head)*AS_HASH_ENTRIES,
- GFP_KERNEL, q->node);
- if (!ad->hash) {
- kfree(ad);
- return -ENOMEM;
- }
-
- ad->arq_pool = mempool_create_node(BLKDEV_MIN_RQ, mempool_alloc_slab,
- mempool_free_slab, arq_pool, q->node);
- if (!ad->arq_pool) {
- kfree(ad->hash);
- kfree(ad);
- return -ENOMEM;
- }
-
- /* anticipatory scheduling helpers */
- ad->antic_timer.function = as_antic_timeout;
- ad->antic_timer.data = (unsigned long)q;
- init_timer(&ad->antic_timer);
- INIT_WORK(&ad->antic_work, as_work_handler, q);
-
- for (i = 0; i < AS_HASH_ENTRIES; i++)
- INIT_LIST_HEAD(&ad->hash[i]);
-
- INIT_LIST_HEAD(&ad->fifo_list[REQ_SYNC]);
- INIT_LIST_HEAD(&ad->fifo_list[REQ_ASYNC]);
- ad->sort_list[REQ_SYNC] = RB_ROOT;
- ad->sort_list[REQ_ASYNC] = RB_ROOT;
- ad->fifo_expire[REQ_SYNC] = default_read_expire;
- ad->fifo_expire[REQ_ASYNC] = default_write_expire;
- ad->antic_expire = default_antic_expire;
- ad->batch_expire[REQ_SYNC] = default_read_batch_expire;
- ad->batch_expire[REQ_ASYNC] = default_write_batch_expire;
- e->elevator_data = ad;
-
- ad->current_batch_expires = jiffies + ad->batch_expire[REQ_SYNC];
- ad->write_batch_count = ad->batch_expire[REQ_ASYNC] / 10;
- if (ad->write_batch_count < 2)
- ad->write_batch_count = 2;
-
- return 0;
-}
-
-/*
- * sysfs parts below
- */
-struct as_fs_entry {
- struct attribute attr;
- ssize_t (*show)(struct as_data *, char *);
- ssize_t (*store)(struct as_data *, const char *, size_t);
-};
-
-static ssize_t
-as_var_show(unsigned int var, char *page)
-{
- return sprintf(page, "%d\n", var);
-}
-
-static ssize_t
-as_var_store(unsigned long *var, const char *page, size_t count)
-{
- char *p = (char *) page;
-
- *var = simple_strtoul(p, &p, 10);
- return count;
-}
-
-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 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);
-
- return pos;
-}
-
-#define SHOW_FUNCTION(__FUNC, __VAR) \
-static ssize_t __FUNC(struct as_data *ad, char *page) \
-{ \
- return as_var_show(jiffies_to_msecs((__VAR)), (page)); \
-}
-SHOW_FUNCTION(as_readexpire_show, ad->fifo_expire[REQ_SYNC]);
-SHOW_FUNCTION(as_writeexpire_show, ad->fifo_expire[REQ_ASYNC]);
-SHOW_FUNCTION(as_anticexpire_show, ad->antic_expire);
-SHOW_FUNCTION(as_read_batchexpire_show, ad->batch_expire[REQ_SYNC]);
-SHOW_FUNCTION(as_write_batchexpire_show, ad->batch_expire[REQ_ASYNC]);
-#undef SHOW_FUNCTION
-
-#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX) \
-static ssize_t __FUNC(struct as_data *ad, const char *page, size_t count) \
-{ \
- int ret = as_var_store(__PTR, (page), count); \
- if (*(__PTR) < (MIN)) \
- *(__PTR) = (MIN); \
- else if (*(__PTR) > (MAX)) \
- *(__PTR) = (MAX); \
- *(__PTR) = msecs_to_jiffies(*(__PTR)); \
- return ret; \
-}
-STORE_FUNCTION(as_readexpire_store, &ad->fifo_expire[REQ_SYNC], 0, INT_MAX);
-STORE_FUNCTION(as_writeexpire_store, &ad->fifo_expire[REQ_ASYNC], 0, INT_MAX);
-STORE_FUNCTION(as_anticexpire_store, &ad->antic_expire, 0, INT_MAX);
-STORE_FUNCTION(as_read_batchexpire_store,
- &ad->batch_expire[REQ_SYNC], 0, INT_MAX);
-STORE_FUNCTION(as_write_batchexpire_store,
- &ad->batch_expire[REQ_ASYNC], 0, INT_MAX);
-#undef STORE_FUNCTION
-
-static struct as_fs_entry as_est_entry = {
- .attr = {.name = "est_time", .mode = S_IRUGO },
- .show = as_est_show,
-};
-static struct as_fs_entry as_readexpire_entry = {
- .attr = {.name = "read_expire", .mode = S_IRUGO | S_IWUSR },
- .show = as_readexpire_show,
- .store = as_readexpire_store,
-};
-static struct as_fs_entry as_writeexpire_entry = {
- .attr = {.name = "write_expire", .mode = S_IRUGO | S_IWUSR },
- .show = as_writeexpire_show,
- .store = as_writeexpire_store,
-};
-static struct as_fs_entry as_anticexpire_entry = {
- .attr = {.name = "antic_expire", .mode = S_IRUGO | S_IWUSR },
- .show = as_anticexpire_show,
- .store = as_anticexpire_store,
-};
-static struct as_fs_entry as_read_batchexpire_entry = {
- .attr = {.name = "read_batch_expire", .mode = S_IRUGO | S_IWUSR },
- .show = as_read_batchexpire_show,
- .store = as_read_batchexpire_store,
-};
-static struct as_fs_entry as_write_batchexpire_entry = {
- .attr = {.name = "write_batch_expire", .mode = S_IRUGO | S_IWUSR },
- .show = as_write_batchexpire_show,
- .store = as_write_batchexpire_store,
-};
-
-static struct attribute *default_attrs[] = {
- &as_est_entry.attr,
- &as_readexpire_entry.attr,
- &as_writeexpire_entry.attr,
- &as_anticexpire_entry.attr,
- &as_read_batchexpire_entry.attr,
- &as_write_batchexpire_entry.attr,
- NULL,
-};
-
-#define to_as(atr) container_of((atr), struct as_fs_entry, attr)
-
-static ssize_t
-as_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
-{
- elevator_t *e = container_of(kobj, elevator_t, kobj);
- struct as_fs_entry *entry = to_as(attr);
-
- if (!entry->show)
- return -EIO;
-
- return entry->show(e->elevator_data, page);
-}
-
-static ssize_t
-as_attr_store(struct kobject *kobj, struct attribute *attr,
- const char *page, size_t length)
-{
- elevator_t *e = container_of(kobj, elevator_t, kobj);
- struct as_fs_entry *entry = to_as(attr);
-
- if (!entry->store)
- return -EIO;
-
- return entry->store(e->elevator_data, page, length);
-}
-
-static struct sysfs_ops as_sysfs_ops = {
- .show = as_attr_show,
- .store = as_attr_store,
-};
-
-static struct kobj_type as_ktype = {
- .sysfs_ops = &as_sysfs_ops,
- .default_attrs = default_attrs,
-};
-
-static struct elevator_type iosched_as = {
- .ops = {
- .elevator_merge_fn = as_merge,
- .elevator_merged_fn = as_merged_request,
- .elevator_merge_req_fn = as_merged_requests,
- .elevator_dispatch_fn = as_dispatch_request,
- .elevator_add_req_fn = as_add_request,
- .elevator_activate_req_fn = as_activate_request,
- .elevator_deactivate_req_fn = as_deactivate_request,
- .elevator_queue_empty_fn = as_queue_empty,
- .elevator_completed_req_fn = as_completed_request,
- .elevator_former_req_fn = as_former_request,
- .elevator_latter_req_fn = as_latter_request,
- .elevator_set_req_fn = as_set_request,
- .elevator_put_req_fn = as_put_request,
- .elevator_may_queue_fn = as_may_queue,
- .elevator_init_fn = as_init_queue,
- .elevator_exit_fn = as_exit_queue,
- },
-
- .elevator_ktype = &as_ktype,
- .elevator_name = "anticipatory",
- .elevator_owner = THIS_MODULE,
-};
-
-static int __init as_init(void)
-{
- int ret;
-
- arq_pool = kmem_cache_create("as_arq", sizeof(struct as_rq),
- 0, 0, NULL, NULL);
- if (!arq_pool)
- return -ENOMEM;
-
- ret = elv_register(&iosched_as);
- if (!ret) {
- /*
- * don't allow AS to get unregistered, since we would have
- * to browse all tasks in the system and release their
- * as_io_context first
- */
- __module_get(THIS_MODULE);
- return 0;
- }
-
- kmem_cache_destroy(arq_pool);
- return ret;
-}
-
-static void __exit as_exit(void)
-{
- elv_unregister(&iosched_as);
- kmem_cache_destroy(arq_pool);
-}
-
-module_init(as_init);
-module_exit(as_exit);
-
-MODULE_AUTHOR("Nick Piggin");
-MODULE_LICENSE("GPL");
-MODULE_DESCRIPTION("anticipatory IO scheduler");