diff options
Diffstat (limited to 'block/cfq-iosched.c')
| -rw-r--r-- | block/cfq-iosched.c | 2464 |
1 files changed, 2464 insertions, 0 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c new file mode 100644 index 000000000000..2b64f5852bfd --- /dev/null +++ b/block/cfq-iosched.c @@ -0,0 +1,2464 @@ +/* + * linux/drivers/block/cfq-iosched.c + * + * CFQ, or complete fairness queueing, disk scheduler. + * + * Based on ideas from a previously unfinished io + * scheduler (round robin per-process disk scheduling) and Andrea Arcangeli. + * + * Copyright (C) 2003 Jens Axboe <axboe@suse.de> + */ +#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/mempool.h> +#include <linux/ioprio.h> +#include <linux/writeback.h> + +/* + * 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 int cfq_slice_sync = HZ / 10; +static int cfq_slice_async = HZ / 25; +static int cfq_slice_async_rq = 2; +static int cfq_slice_idle = HZ / 100; + +#define CFQ_IDLE_GRACE (HZ / 10) +#define CFQ_SLICE_SCALE (5) + +#define CFQ_KEY_ASYNC (0) +#define CFQ_KEY_ANY (0xffff) + +/* + * disable queueing at the driver/hardware level + */ +static int cfq_max_depth = 2; + +/* + * for the hash of cfqq inside the cfqd + */ +#define CFQ_QHASH_SHIFT 6 +#define CFQ_QHASH_ENTRIES (1 << CFQ_QHASH_SHIFT) +#define list_entry_qhash(entry) hlist_entry((entry), struct cfq_queue, cfq_hash) + +/* + * for the hash of crq inside the cfqq + */ +#define CFQ_MHASH_SHIFT 6 +#define CFQ_MHASH_BLOCK(sec) ((sec) >> 3) +#define CFQ_MHASH_ENTRIES (1 << CFQ_MHASH_SHIFT) +#define CFQ_MHASH_FN(sec) hash_long(CFQ_MHASH_BLOCK(sec), CFQ_MHASH_SHIFT) +#define rq_hash_key(rq) ((rq)->sector + (rq)->nr_sectors) +#define list_entry_hash(ptr) hlist_entry((ptr), struct cfq_rq, hash) + +#define list_entry_cfqq(ptr) list_entry((ptr), struct cfq_queue, cfq_list) +#define list_entry_fifo(ptr) list_entry((ptr), struct request, queuelist) + +#define RQ_DATA(rq) (rq)->elevator_private + +/* + * rb-tree defines + */ +#define RB_NONE (2) +#define RB_EMPTY(node) ((node)->rb_node == NULL) +#define RB_CLEAR_COLOR(node) (node)->rb_color = RB_NONE +#define RB_CLEAR(node) do { \ + (node)->rb_parent = NULL; \ + RB_CLEAR_COLOR((node)); \ + (node)->rb_right = NULL; \ + (node)->rb_left = NULL; \ +} while (0) +#define RB_CLEAR_ROOT(root) ((root)->rb_node = NULL) +#define rb_entry_crq(node) rb_entry((node), struct cfq_rq, rb_node) +#define rq_rb_key(rq) (rq)->sector + +static kmem_cache_t *crq_pool; +static kmem_cache_t *cfq_pool; +static kmem_cache_t *cfq_ioc_pool; + +#define CFQ_PRIO_LISTS IOPRIO_BE_NR +#define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE) +#define cfq_class_be(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_BE) +#define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT) + +#define ASYNC (0) +#define SYNC (1) + +#define cfq_cfqq_dispatched(cfqq) \ + ((cfqq)->on_dispatch[ASYNC] + (cfqq)->on_dispatch[SYNC]) + +#define cfq_cfqq_class_sync(cfqq) ((cfqq)->key != CFQ_KEY_ASYNC) + +#define cfq_cfqq_sync(cfqq) \ + (cfq_cfqq_class_sync(cfqq) || (cfqq)->on_dispatch[SYNC]) + +/* + * Per block device queue structure + */ +struct cfq_data { + atomic_t ref; + request_queue_t *queue; + + /* + * rr list of queues with requests and the count of them + */ + struct list_head rr_list[CFQ_PRIO_LISTS]; + struct list_head busy_rr; + struct list_head cur_rr; + struct list_head idle_rr; + unsigned int busy_queues; + + /* + * non-ordered list of empty cfqq's + */ + struct list_head empty_list; + + /* + * cfqq lookup hash + */ + struct hlist_head *cfq_hash; + + /* + * global crq hash for all queues + */ + struct hlist_head *crq_hash; + + unsigned int max_queued; + + mempool_t *crq_pool; + + int rq_in_driver; + + /* + * schedule slice state info + */ + /* + * idle window management + */ + struct timer_list idle_slice_timer; + struct work_struct unplug_work; + + struct cfq_queue *active_queue; + struct cfq_io_context *active_cic; + int cur_prio, cur_end_prio; + unsigned int dispatch_slice; + + struct timer_list idle_class_timer; + + sector_t last_sector; + unsigned long last_end_request; + + unsigned int rq_starved; + + /* + * tunables, see top of file + */ + unsigned int cfq_quantum; + unsigned int cfq_queued; + unsigned int cfq_fifo_expire[2]; + unsigned int cfq_back_penalty; + unsigned int cfq_back_max; + unsigned int cfq_slice[2]; + unsigned int cfq_slice_async_rq; + unsigned int cfq_slice_idle; + unsigned int cfq_max_depth; +}; + +/* + * Per process-grouping structure + */ +struct cfq_queue { + /* reference count */ + atomic_t ref; + /* parent cfq_data */ + struct cfq_data *cfqd; + /* cfqq lookup hash */ + struct hlist_node cfq_hash; + /* hash key */ + unsigned int key; + /* on either rr or empty list of cfqd */ + struct list_head cfq_list; + /* sorted list of pending requests */ + struct rb_root sort_list; + /* if fifo isn't expired, next request to serve */ + struct cfq_rq *next_crq; + /* requests queued in sort_list */ + int queued[2]; + /* currently allocated requests */ + int allocated[2]; + /* fifo list of requests in sort_list */ + struct list_head fifo; + + unsigned long slice_start; + unsigned long slice_end; + unsigned long slice_left; + unsigned long service_last; + + /* number of requests that are on the dispatch list */ + int on_dispatch[2]; + + /* io prio of this group */ + unsigned short ioprio, org_ioprio; + unsigned short ioprio_class, org_ioprio_class; + + /* various state flags, see below */ + unsigned int flags; +}; + +struct cfq_rq { + struct rb_node rb_node; + sector_t rb_key; + struct request *request; + struct hlist_node hash; + + struct cfq_queue *cfq_queue; + struct cfq_io_context *io_context; + + unsigned int crq_flags; +}; + +enum cfqq_state_flags { + CFQ_CFQQ_FLAG_on_rr = 0, + CFQ_CFQQ_FLAG_wait_request, + CFQ_CFQQ_FLAG_must_alloc, + CFQ_CFQQ_FLAG_must_alloc_slice, + CFQ_CFQQ_FLAG_must_dispatch, + CFQ_CFQQ_FLAG_fifo_expire, + CFQ_CFQQ_FLAG_idle_window, + CFQ_CFQQ_FLAG_prio_changed, + CFQ_CFQQ_FLAG_expired, +}; + +#define CFQ_CFQQ_FNS(name) \ +static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \ +{ \ + cfqq->flags |= (1 << CFQ_CFQQ_FLAG_##name); \ +} \ +static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \ +{ \ + cfqq->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \ +} \ +static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \ +{ \ + return (cfqq->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \ +} + +CFQ_CFQQ_FNS(on_rr); +CFQ_CFQQ_FNS(wait_request); +CFQ_CFQQ_FNS(must_alloc); +CFQ_CFQQ_FNS(must_alloc_slice); +CFQ_CFQQ_FNS(must_dispatch); +CFQ_CFQQ_FNS(fifo_expire); +CFQ_CFQQ_FNS(idle_window); +CFQ_CFQQ_FNS(prio_changed); +CFQ_CFQQ_FNS(expired); +#undef CFQ_CFQQ_FNS + +enum cfq_rq_state_flags { + CFQ_CRQ_FLAG_is_sync = 0, +}; + +#define CFQ_CRQ_FNS(name) \ +static inline void cfq_mark_crq_##name(struct cfq_rq *crq) \ +{ \ + crq->crq_flags |= (1 << CFQ_CRQ_FLAG_##name); \ +} \ +static inline void cfq_clear_crq_##name(struct cfq_rq *crq) \ +{ \ + crq->crq_flags &= ~(1 << CFQ_CRQ_FLAG_##name); \ +} \ +static inline int cfq_crq_##name(const struct cfq_rq *crq) \ +{ \ + return (crq->crq_flags & (1 << CFQ_CRQ_FLAG_##name)) != 0; \ +} + +CFQ_CRQ_FNS(is_sync); +#undef CFQ_CRQ_FNS + +static struct cfq_queue *cfq_find_cfq_hash(struct cfq_data *, unsigned int, unsigned short); +static void cfq_dispatch_insert(request_queue_t *, struct cfq_rq *); +static void cfq_put_cfqd(struct cfq_data *cfqd); + +#define process_sync(tsk) ((tsk)->flags & PF_SYNCWRITE) + +/* + * lots of deadline iosched dupes, can be abstracted later... + */ +static inline void cfq_del_crq_hash(struct cfq_rq *crq) +{ + hlist_del_init(&crq->hash); +} + +static inline void cfq_add_crq_hash(struct cfq_data *cfqd, struct cfq_rq *crq) +{ + const int hash_idx = CFQ_MHASH_FN(rq_hash_key(crq->request)); + + hlist_add_head(&crq->hash, &cfqd->crq_hash[hash_idx]); +} + +static struct request *cfq_find_rq_hash(struct cfq_data *cfqd, sector_t offset) +{ + struct hlist_head *hash_list = &cfqd->crq_hash[CFQ_MHASH_FN(offset)]; + struct hlist_node *entry, *next; + + hlist_for_each_safe(entry, next, hash_list) { + struct cfq_rq *crq = list_entry_hash(entry); + struct request *__rq = crq->request; + + if (!rq_mergeable(__rq)) { + cfq_del_crq_hash(crq); + continue; + } + + if (rq_hash_key(__rq) == offset) + return __rq; + } + + return NULL; +} + +/* + * scheduler run of queue, if there are requests pending and no one in the + * driver that will restart queueing + */ +static inline void cfq_schedule_dispatch(struct cfq_data *cfqd) +{ + if (!cfqd->rq_in_driver && cfqd->busy_queues) + kblockd_schedule_work(&cfqd->unplug_work); +} + +static int cfq_queue_empty(request_queue_t *q) +{ + struct cfq_data *cfqd = q->elevator->elevator_data; + + return !cfqd->busy_queues; +} + +/* + * Lifted from AS - choose which of crq1 and crq2 that is best served now. + * We choose the request that is closest to the head right now. Distance + * behind the head are penalized and only allowed to a certain extent. + */ +static struct cfq_rq * +cfq_choose_req(struct cfq_data *cfqd, struct cfq_rq *crq1, struct cfq_rq *crq2) +{ + sector_t last, s1, s2, d1 = 0, d2 = 0; + int r1_wrap = 0, r2_wrap = 0; /* requests are behind the disk head */ + unsigned long back_max; + + if (crq1 == NULL || crq1 == crq2) + return crq2; + if (crq2 == NULL) + return crq1; + + if (cfq_crq_is_sync(crq1) && !cfq_crq_is_sync(crq2)) + return crq1; + else if (cfq_crq_is_sync(crq2) && !cfq_crq_is_sync(crq1)) + return crq2; + + s1 = crq1->request->sector; + s2 = crq2->request->sector; + + last = cfqd->last_sector; + + /* + * by definition, 1KiB is 2 sectors + */ + back_max = cfqd->cfq_back_max * 2; + + /* + * 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 + back_max >= last) + d1 = (last - s1) * cfqd->cfq_back_penalty; + else + r1_wrap = 1; + + if (s2 >= last) + d2 = s2 - last; + else if (s2 + back_max >= last) + d2 = (last - s2) * cfqd->cfq_back_penalty; + else + r2_wrap = 1; + + /* Found required data */ + if (!r1_wrap && r2_wrap) + return crq1; + else if (!r2_wrap && r1_wrap) + return crq2; + else if (r1_wrap && r2_wrap) { + /* both behind the head */ + if (s1 <= s2) + return crq1; + else + return crq2; + } + + /* Both requests in front of the head */ + if (d1 < d2) + return crq1; + else if (d2 < d1) + return crq2; + else { + if (s1 >= s2) + return crq1; + else + return crq2; + } +} + +/* + * would be nice to take fifo expire time into account as well + */ +static struct cfq_rq * +cfq_find_next_crq(struct cfq_data *cfqd, struct cfq_queue *cfqq, + struct cfq_rq *last) +{ + struct cfq_rq *crq_next = NULL, *crq_prev = NULL; + struct rb_node *rbnext, *rbprev; + + if (!(rbnext = rb_next(&last->rb_node))) { + rbnext = rb_first(&cfqq->sort_list); + if (rbnext == &last->rb_node) + rbnext = NULL; + } + + rbprev = rb_prev(&last->rb_node); + + if (rbprev) + crq_prev = rb_entry_crq(rbprev); + if (rbnext) + crq_next = rb_entry_crq(rbnext); + + return cfq_choose_req(cfqd, crq_next, crq_prev); +} + +static void cfq_update_next_crq(struct cfq_rq *crq) +{ + struct cfq_queue *cfqq = crq->cfq_queue; + + if (cfqq->next_crq == crq) + cfqq->next_crq = cfq_find_next_crq(cfqq->cfqd, cfqq, crq); +} + +static void cfq_resort_rr_list(struct cfq_queue *cfqq, int preempted) +{ + struct cfq_data *cfqd = cfqq->cfqd; + struct list_head *list, *entry; + + BUG_ON(!cfq_cfqq_on_rr(cfqq)); + + list_del(&cfqq->cfq_list); + + if (cfq_class_rt(cfqq)) + list = &cfqd->cur_rr; + else if (cfq_class_idle(cfqq)) + list = &cfqd->idle_rr; + else { + /* + * if cfqq has requests in flight, don't allow it to be + * found in cfq_set_active_queue before it has finished them. + * this is done to increase fairness between a process that + * has lots of io pending vs one that only generates one + * sporadically or synchronously + */ + if (cfq_cfqq_dispatched(cfqq)) + list = &cfqd->busy_rr; + else + list = &cfqd->rr_list[cfqq->ioprio]; + } + + /* + * if queue was preempted, just add to front to be fair. busy_rr + * isn't sorted. + */ + if (preempted || list == &cfqd->busy_rr) { + list_add(&cfqq->cfq_list, list); + return; + } + + /* + * sort by when queue was last serviced + */ + entry = list; + while ((entry = entry->prev) != list) { + struct cfq_queue *__cfqq = list_entry_cfqq(entry); + + if (!__cfqq->service_last) + break; + if (time_before(__cfqq->service_last, cfqq->service_last)) + break; + } + + list_add(&cfqq->cfq_list, entry); +} + +/* + * add to busy list of queues for service, trying to be fair in ordering + * the pending list according to last request service + */ +static inline void +cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) +{ + BUG_ON(cfq_cfqq_on_rr(cfqq)); + cfq_mark_cfqq_on_rr(cfqq); + cfqd->busy_queues++; + + cfq_resort_rr_list(cfqq, 0); +} + +static inline void +cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) +{ + BUG_ON(!cfq_cfqq_on_rr(cfqq)); + cfq_clear_cfqq_on_rr(cfqq); + list_move(&cfqq->cfq_list, &cfqd->empty_list); + + BUG_ON(!cfqd->busy_queues); + cfqd->busy_queues--; +} + +/* + * rb tree support functions + */ +static inline void cfq_del_crq_rb(struct cfq_rq *crq) +{ + struct cfq_queue *cfqq = crq->cfq_queue; + struct cfq_data *cfqd = cfqq->cfqd; + const int sync = cfq_crq_is_sync(crq); + + BUG_ON(!cfqq->queued[sync]); + cfqq->queued[sync]--; + + cfq_update_next_crq(crq); + + rb_erase(&crq->rb_node, &cfqq->sort_list); + RB_CLEAR_COLOR(&crq->rb_node); + + if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY(&cfqq->sort_list)) + cfq_del_cfqq_rr(cfqd, cfqq); +} + +static struct cfq_rq * +__cfq_add_crq_rb(struct cfq_rq *crq) +{ + struct rb_node **p = &crq->cfq_queue->sort_list.rb_node; + struct rb_node *parent = NULL; + struct cfq_rq *__crq; + + while (*p) { + parent = *p; + __crq = rb_entry_crq(parent); + + if (crq->rb_key < __crq->rb_key) + p = &(*p)->rb_left; + else if (crq->rb_key > __crq->rb_key) + p = &(*p)->rb_right; + else + return __crq; + } + + rb_link_node(&crq->rb_node, parent, p); + return NULL; +} + +static void cfq_add_crq_rb(struct cfq_rq *crq) +{ + struct cfq_queue *cfqq = crq->cfq_queue; + struct cfq_data *cfqd = cfqq->cfqd; + struct request *rq = crq->request; + struct cfq_rq *__alias; + + crq->rb_key = rq_rb_key(rq); + cfqq->queued[cfq_crq_is_sync(crq)]++; + + /* + * looks a little odd, but the first insert might return an alias. + * if that happens, put the alias on the dispatch list + */ + while ((__alias = __cfq_add_crq_rb(crq)) != NULL) + cfq_dispatch_insert(cfqd->queue, __alias); + + rb_insert_color(&crq->rb_node, &cfqq->sort_list); + + if (!cfq_cfqq_on_rr(cfqq)) + cfq_add_cfqq_rr(cfqd, cfqq); + + /* + * check if this request is a better next-serve candidate + */ + cfqq->next_crq = cfq_choose_req(cfqd, cfqq->next_crq, crq); +} + +static inline void +cfq_reposition_crq_rb(struct cfq_queue *cfqq, struct cfq_rq *crq) +{ + rb_erase(&crq->rb_node, &cfqq->sort_list); + cfqq->queued[cfq_crq_is_sync(crq)]--; + + cfq_add_crq_rb(crq); +} + +static struct request *cfq_find_rq_rb(struct cfq_data *cfqd, sector_t sector) + +{ + struct cfq_queue *cfqq = cfq_find_cfq_hash(cfqd, current->pid, CFQ_KEY_ANY); + struct rb_node *n; + + if (!cfqq) + goto out; + + n = cfqq->sort_list.rb_node; + while (n) { + struct cfq_rq *crq = rb_entry_crq(n); + + if (sector < crq->rb_key) + n = n->rb_left; + else if (sector > crq->rb_key) + n = n->rb_right; + else + return crq->request; + } + +out: + return NULL; +} + +static void cfq_activate_request(request_queue_t *q, struct request *rq) +{ + struct cfq_data *cfqd = q->elevator->elevator_data; + + cfqd->rq_in_driver++; +} + +static void cfq_deactivate_request(request_queue_t *q, struct request *rq) +{ + struct cfq_data *cfqd = q->elevator->elevator_data; + + WARN_ON(!cfqd->rq_in_driver); + cfqd->rq_in_driver--; +} + +static void cfq_remove_request(struct request *rq) +{ + struct cfq_rq *crq = RQ_DATA(rq); + + list_del_init(&rq->queuelist); + cfq_del_crq_rb(crq); + cfq_del_crq_hash(crq); +} + +static int +cfq_merge(request_queue_t *q, struct request **req, struct bio *bio) +{ + struct cfq_data *cfqd = q->elevator->elevator_data; + struct request *__rq; + int ret; + + __rq = cfq_find_rq_hash(cfqd, bio->bi_sector); + if (__rq && elv_rq_merge_ok(__rq, bio)) { + ret = ELEVATOR_BACK_MERGE; + goto out; + } + + __rq = cfq_find_rq_rb(cfqd, bio->bi_sector + bio_sectors(bio)); + if (__rq && elv_rq_merge_ok(__rq, bio)) { + ret = ELEVATOR_FRONT_MERGE; + goto out; + } + + return ELEVATOR_NO_MERGE; +out: + *req = __rq; + return ret; +} + +static void cfq_merged_request(request_queue_t *q, struct request *req) +{ + struct cfq_data *cfqd = q->elevator->elevator_data; + struct cfq_rq *crq = RQ_DATA(req); + + cfq_del_crq_hash(crq); + cfq_add_crq_hash(cfqd, crq); + + if (rq_rb_key(req) != crq->rb_key) { + struct cfq_queue *cfqq = crq->cfq_queue; + + cfq_update_next_crq(crq); + cfq_reposition_crq_rb(cfqq, crq); + } +} + +static void +cfq_merged_requests(request_queue_t *q, struct request *rq, + struct request *next) +{ + cfq_merged_request(q, rq); + + /* + * reposition in fifo if next is older than rq + */ + if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) && + time_before(next->start_time, rq->start_time)) + list_move(&rq->queuelist, &next->queuelist); + + cfq_remove_request(next); +} + +static inline void +__cfq_set_active_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq) +{ + if (cfqq) { + /* + * stop potential idle class queues waiting service + */ + del_timer(&cfqd->idle_class_timer); + + cfqq->slice_start = jiffies; + cfqq->slice_end = 0; + cfqq->slice_left = 0; + cfq_clear_cfqq_must_alloc_slice(cfqq); + cfq_clear_cfqq_fifo_expire(cfqq); + cfq_clear_cfqq_expired(cfqq); + } + + cfqd->active_queue = cfqq; +} + +/* + * 0 + * 0,1 + * 0,1,2 + * 0,1,2,3 + * 0,1,2,3,4 + * 0,1,2,3,4,5 + * 0,1,2,3,4,5,6 + * 0,1,2,3,4,5,6,7 + */ +static int cfq_get_next_prio_level(struct cfq_data *cfqd) +{ + int prio, wrap; + + prio = -1; + wrap = 0; + do { + int p; + + for (p = cfqd->cur_prio; p <= cfqd->cur_end_prio; p++) { + if (!list_empty(&cfqd->rr_list[p])) { + prio = p; + break; + } + } + + if (prio != -1) + break; + cfqd->cur_prio = 0; + if (++cfqd->cur_end_prio == CFQ_PRIO_LISTS) { + cfqd->cur_end_prio = 0; + if (wrap) + break; + wrap = 1; + } + } while (1); + + if (unlikely(prio == -1)) + return -1; + + BUG_ON(prio >= CFQ_PRIO_LISTS); + + list_splice_init(&cfqd->rr_list[prio], &cfqd->cur_rr); + + cfqd->cur_prio = prio + 1; + if (cfqd->cur_prio > cfqd->cur_end_prio) { + cfqd->cur_end_prio = cfqd->cur_prio; + cfqd->cur_prio = 0; + } + if (cfqd->cur_end_prio == CFQ_PRIO_LISTS) { + cfqd->cur_prio = 0; + cfqd->cur_end_prio = 0; + } + + return prio; +} + +static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd) +{ + struct cfq_queue *cfqq; + + /* + * if current queue is expired but not done with its requests yet, + * wait for that to happen + */ + if ((cfqq = cfqd->active_queue) != NULL) { + if (cfq_cfqq_expired(cfqq) && cfq_cfqq_dispatched(cfqq)) + return NULL; + } + + /* + * if current list is non-empty, grab first entry. if it is empty, + * get next prio level and grab first entry then if any are spliced + */ + if (!list_empty(&cfqd->cur_rr) || cfq_get_next_prio_level(cfqd) != -1) + cfqq = list_entry_cfqq(cfqd->cur_rr.next); + + /* + * if we have idle queues and no rt or be queues had pending + * requests, either allow immediate service if the grace period + * has passed or arm the idle grace timer + */ + if (!cfqq && !list_empty(&cfqd->idle_rr)) { + unsigned long end = cfqd->last_end_request + CFQ_IDLE_GRACE; + + if (time_after_eq(jiffies, end)) + cfqq = list_entry_cfqq(cfqd->idle_rr.next); + else + mod_timer(&cfqd->idle_class_timer, end); + } + + __cfq_set_active_queue(cfqd, cfqq); + return cfqq; +} + +/* + * current cfqq expired its slice (or was too idle), select new one + */ +static void +__cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq, + int preempted) +{ + unsigned long now = jiffies; + + if (cfq_cfqq_wait_request(cfqq)) + del_timer(&cfqd->idle_slice_timer); + + if (!preempted && !cfq_cfqq_dispatched(cfqq)) + cfqq->service_last = now; + + cfq_clear_cfqq_must_dispatch(cfqq); + cfq_clear_cfqq_wait_request(cfqq); + + /* + * store what was left of this slice, if the queue idled out + * or was preempted + */ + if (time_after(cfqq->slice_end, now)) + cfqq->slice_left = cfqq->slice_end - now; + else + cfqq->slice_left = 0; + + if (cfq_cfqq_on_rr(cfqq)) + cfq_resort_rr_list(cfqq, preempted); + + if (cfqq == cfqd->active_queue) + cfqd->active_queue = NULL; + + if (cfqd->active_cic) { + put_io_context(cfqd->active_cic->ioc); + cfqd->active_cic = NULL; + } + + cfqd->dispatch_slice = 0; +} + +static inline void cfq_slice_expired(struct cfq_data *cfqd, int preempted) +{ + struct cfq_queue *cfqq = cfqd->active_queue; + + if (cfqq) { + /* + * use deferred expiry, if there are requests in progress as + * not to disturb the slice of the next queue + */ + if (cfq_cfqq_dispatched(cfqq)) + cfq_mark_cfqq_expired(cfqq); + else + __cfq_slice_expired(cfqd, cfqq, preempted); + } +} + +static int cfq_arm_slice_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq) + +{ + WARN_ON(!RB_EMPTY(&cfqq->sort_list)); + WARN_ON(cfqq != cfqd->active_queue); + + /* + * idle is disabled, either manually or by past process history + */ + if (!cfqd->cfq_slice_idle) + return 0; + if (!cfq_cfqq_idle_window(cfqq)) + return 0; + /* + * task has exited, don't wait + */ + if (cfqd->active_cic && !cfqd->active_cic->ioc->task) + return 0; + + cfq_mark_cfqq_must_dispatch(cfqq); + cfq_mark_cfqq_wait_request(cfqq); + + if (!timer_pending(&cfqd->idle_slice_timer)) { + unsigned long slice_left = min(cfqq->slice_end - 1, (unsigned long) cfqd->cfq_slice_idle); + + cfqd->idle_slice_timer.expires = jiffies + slice_left; + add_timer(&cfqd->idle_slice_timer); + } + + return 1; +} + +static void cfq_dispatch_insert(request_queue_t *q, struct cfq_rq *crq) +{ + struct cfq_data *cfqd = q->elevator->elevator_data; + struct cfq_queue *cfqq = crq->cfq_queue; + + cfqq->next_crq = cfq_find_next_crq(cfqd, cfqq, crq); + cfq_remove_request(crq->request); + cfqq->on_dispatch[cfq_crq_is_sync(crq)]++; + elv_dispatch_sort(q, crq->request); +} + +/* + * return expired entry, or NULL to just start from scratch in rbtree + */ +static inline struct cfq_rq *cfq_check_fifo(struct cfq_queue *cfqq) +{ + struct cfq_data *cfqd = cfqq->cfqd; + struct request *rq; + struct cfq_rq *crq; + + if (cfq_cfqq_fifo_expire(cfqq)) + return NULL; + + if (!list_empty(&cfqq->fifo)) { + int fifo = cfq_cfqq_class_sync(cfqq); + + crq = RQ_DATA(list_entry_fifo(cfqq->fifo.next)); + rq = crq->request; + if (time_after(jiffies, rq->start_time + cfqd->cfq_fifo_expire[fifo])) { + cfq_mark_cfqq_fifo_expire(cfqq); + return crq; + } + } + + return NULL; +} + +/* + * Scale schedule slice based on io priority. Use the sync time slice only + * if a queue is marked sync and has sync io queued. A sync queue with async + * io only, should not get full sync slice length. + */ +static inline int +cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) +{ + const int base_slice = cfqd->cfq_slice[cfq_cfqq_sync(cfqq)]; + + WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR); + + return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - cfqq->ioprio)); +} + +static inline void +cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) +{ + cfqq->slice_end = cfq_prio_to_slice(cfqd, cfqq) + jiffies; +} + +static inline int +cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq) +{ + const int base_rq = cfqd->cfq_slice_async_rq; + + WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR); + + return 2 * (base_rq + base_rq * (CFQ_PRIO_LISTS - 1 - cfqq->ioprio)); +} + +/* + * get next queue for service + */ +static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd) +{ + unsigned long now = jiffies; + struct cfq_queue *cfqq; + + cfqq = cfqd->active_queue; + if (!cfqq) + goto new_queue; + + if (cfq_cfqq_expired(cfqq)) + goto new_queue; + + /* + * slice has expired + */ + if (!cfq_cfqq_must_dispatch(cfqq) && time_after(now, cfqq->slice_end)) + goto expire; + + /* + * if queue has requests, dispatch one. if not, check if + * enough slice is left to wait for one + */ + if (!RB_EMPTY(&cfqq->sort_list)) + goto keep_queue; + else if (cfq_cfqq_class_sync(cfqq) && + time_before(now, cfqq->slice_end)) { + if (cfq_arm_slice_timer(cfqd, cfqq)) + return NULL; + } + +expire: + cfq_slice_expired(cfqd, 0); +new_queue: + cfqq = cfq_set_active_queue(cfqd); +keep_queue: + return cfqq; +} + +static int +__cfq_dispatch_requests(struct cfq_data *cfqd, struct cfq_queue *cfqq, + int max_dispatch) +{ + int dispatched = 0; + + BUG_ON(RB_EMPTY(&cfqq->sort_list)); + + do { + struct cfq_rq *crq; + + /* + * follow expired path, else get first next available + */ + if ((crq = cfq_check_fifo(cfqq)) == NULL) + crq = cfqq->next_crq; + + /* + * finally, insert request into driver dispatch list + */ + cfq_dispatch_insert(cfqd->queue, crq); + + cfqd->dispatch_slice++; + dispatched++; + + if (!cfqd->active_cic) { + atomic_inc(&crq->io_context->ioc->refcount); + cfqd->active_cic = crq->io_context; + } + + if (RB_EMPTY(&cfqq->sort_list)) + break; + + } while (dispatched < max_dispatch); + + /* + * if slice end isn't set yet, set it. if at least one request was + * sync, use the sync time slice value + */ + if (!cfqq->slice_end) + cfq_set_prio_slice(cfqd, cfqq); + + /* + * expire an async queue immediately if it has used up its slice. idle + * queue always expire after 1 dispatch round. + */ + if ((!cfq_cfqq_sync(cfqq) && + cfqd->dispatch_slice >= cfq_prio_to_maxrq(cfqd, cfqq)) || + cfq_class_idle(cfqq)) + cfq_slice_expired(cfqd, 0); + + 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) +{ + struct cfq_data *cfqd = q->elevator->elevator_data; + struct cfq_queue *cfqq; + + if (!cfqd->busy_queues) + return 0; + + if (unlikely(force)) + return cfq_forced_dispatch(cfqd); + + cfqq = cfq_select_queue(cfqd); + if (cfqq) { + int max_dispatch; + + /* + * if idle window is disabled, allow queue buildup + */ + if (!cfq_cfqq_idle_window(cfqq) && + cfqd->rq_in_driver >= cfqd->cfq_max_depth) + return 0; + + cfq_clear_cfqq_must_dispatch(cfqq); + cfq_clear_cfqq_wait_request(cfqq); + del_timer(&cfqd->idle_slice_timer); + + max_dispatch = cfqd->cfq_quantum; + if (cfq_class_idle(cfqq)) + max_dispatch = 1; + + return __cfq_dispatch_requests(cfqd, cfqq, max_dispatch); + } + + return 0; +} + +/* + * task holds one reference to the queue, dropped when task exits. each crq + * in-flight on this queue also holds a reference, dropped when crq is freed. + * + * queue lock must be held here. + */ +static void cfq_put_queue(struct cfq_queue *cfqq) +{ + struct cfq_data *cfqd = cfqq->cfqd; + + BUG_ON(atomic_read(&cfqq->ref) <= 0); + + if (!atomic_dec_and_test(&cfqq->ref)) + return; + + BUG_ON(rb_first(&cfqq->sort_list)); + BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]); + BUG_ON(cfq_cfqq_on_rr(cfqq)); + + if (unlikely(cfqd->active_queue == cfqq)) { + __cfq_slice_expired(cfqd, cfqq, 0); + cfq_schedule_dispatch(cfqd); + } + + cfq_put_cfqd(cfqq->cfqd); + + /* + * it's on the empty list and still hashed + */ + list_del(&cfqq->cfq_list); + hlist_del(&cfqq->cfq_hash); + kmem_cache_free(cfq_pool, cfqq); +} + +static inline struct cfq_queue * +__cfq_find_cfq_hash(struct cfq_data *cfqd, unsigned int key, unsigned int prio, + const int hashval) +{ + struct hlist_head *hash_list = &cfqd->cfq_hash[hashval]; + struct hlist_node *entry, *next; + + hlist_for_each_safe(entry, next, hash_list) { + struct cfq_queue *__cfqq = list_entry_qhash(entry); + const unsigned short __p = IOPRIO_PRIO_VALUE(__cfqq->ioprio_class, __cfqq->ioprio); + + if (__cfqq->key == key && (__p == prio || prio == CFQ_KEY_ANY)) + return __cfqq; + } + + return NULL; +} + +static struct cfq_queue * +cfq_find_cfq_hash(struct cfq_data *cfqd, unsigned int key, unsigned short prio) +{ + return __cfq_find_cfq_hash(cfqd, key, prio, hash_long(key, CFQ_QHASH_SHIFT)); +} + +static void cfq_free_io_context(struct cfq_io_context *cic) +{ + struct cfq_io_context *__cic; + struct list_head *entry, *next; + + list_for_each_safe(entry, next, &cic->list) { + __cic = list_entry(entry, struct cfq_io_context, list); + kmem_cache_free(cfq_ioc_pool, __cic); + } + + kmem_cache_free(cfq_ioc_pool, cic); +} + +/* + * Called with interrupts disabled + */ +static void cfq_exit_single_io_context(struct cfq_io_context *cic) +{ + struct cfq_data *cfqd = cic->cfqq->cfqd; + request_queue_t *q = cfqd->queue; + + WARN_ON(!irqs_disabled()); + + spin_lock(q->queue_lock); + + if (unlikely(cic->cfqq == cfqd->active_queue)) { + __cfq_slice_expired(cfqd, cic->cfqq, 0); + cfq_schedule_dispatch(cfqd); + } + + cfq_put_queue(cic->cfqq); + cic->cfqq = NULL; + spin_unlock(q->queue_lock); +} + +/* + * Another task may update the task cic list, if it is doing a queue lookup + * on its behalf. cfq_cic_lock excludes such concurrent updates + */ +static void cfq_exit_io_context(struct cfq_io_context *cic) +{ + struct cfq_io_context *__cic; + struct list_head *entry; + unsigned long flags; + + local_irq_save(flags); + + /* + * put the reference this task is holding to the various queues + */ + list_for_each(entry, &cic->list) { + __cic = list_entry(entry, struct cfq_io_context, list); + cfq_exit_single_io_context(__cic); + } + + cfq_exit_single_io_context(cic); + local_irq_restore(flags); +} + +static struct cfq_io_context * +cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask) +{ + struct cfq_io_context *cic = kmem_cache_alloc(cfq_ioc_pool, gfp_mask); + + if (cic) { + INIT_LIST_HEAD(&cic->list); + cic->cfqq = NULL; + cic->key = NULL; + cic->last_end_request = jiffies; + cic->ttime_total = 0; + cic->ttime_samples = 0; + cic->ttime_mean = 0; + cic->dtor = cfq_free_io_context; + cic->exit = cfq_exit_io_context; + } + + return cic; +} + +static void cfq_init_prio_data(struct cfq_queue *cfqq) +{ + struct task_struct *tsk = current; + int ioprio_class; + + if (!cfq_cfqq_prio_changed(cfqq)) + return; + + ioprio_class = IOPRIO_PRIO_CLASS(tsk->ioprio); + switch (ioprio_class) { + default: + printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class); + case IOPRIO_CLASS_NONE: + /* + * no prio set, place us in the middle of the BE classes + */ + cfqq->ioprio = task_nice_ioprio(tsk); + cfqq->ioprio_class = IOPRIO_CLASS_BE; + break; + case IOPRIO_CLASS_RT: + cfqq->ioprio = task_ioprio(tsk); + cfqq->ioprio_class = IOPRIO_CLASS_RT; + break; + case IOPRIO_CLASS_BE: + cfqq->ioprio = task_ioprio(tsk); + cfqq->ioprio_class = IOPRIO_CLASS_BE; + break; + case IOPRIO_CLASS_IDLE: + cfqq->ioprio_class = IOPRIO_CLASS_IDLE; + cfqq->ioprio = 7; + cfq_clear_cfqq_idle_window(cfqq); + break; + } + + /* + * keep track of original prio settings in case we have to temporarily + * elevate the priority of this queue + */ + cfqq->org_ioprio = cfqq->ioprio; + cfqq->org_ioprio_class = cfqq->ioprio_class; + + if (cfq_cfqq_on_rr(cfqq)) + cfq_resort_rr_list(cfqq, 0); + + cfq_clear_cfqq_prio_changed(cfqq); +} + +static inline void changed_ioprio(struct cfq_queue *cfqq) +{ + if (cfqq) { + struct cfq_data *cfqd = cfqq->cfqd; + + spin_lock(cfqd->queue->queue_lock); + cfq_mark_cfqq_prio_changed(cfqq); + cfq_init_prio_data(cfqq); + spin_unlock(cfqd->queue->queue_lock); + } +} + +/* + * callback from sys_ioprio_set, irqs are disabled + */ +static int cfq_ioc_set_ioprio(struct io_context *ioc, unsigned int ioprio) +{ + struct cfq_io_context *cic = ioc->cic; + + changed_ioprio(cic->cfqq); + + list_for_each_entry(cic, &cic->list, list) + changed_ioprio(cic->cfqq); + + return 0; +} + +static struct cfq_queue * +cfq_get_queue(struct cfq_data *cfqd, unsigned int key, unsigned short ioprio, + gfp_t gfp_mask) +{ + const int hashval = hash_long(key, CFQ_QHASH_SHIFT); + struct cfq_queue *cfqq, *new_cfqq = NULL; + +retry: + cfqq = __cfq_find_cfq_hash(cfqd, key, ioprio, hashval); + + if (!cfqq) { + if (new_cfqq) { + cfqq = new_cfqq; + new_cfqq = NULL; + } else if (gfp_mask & __GFP_WAIT) { + spin_unlock_irq(cfqd->queue->queue_lock); + new_cfqq = kmem_cache_alloc(cfq_pool, gfp_mask); + spin_lock_irq(cfqd->queue->queue_lock); + goto retry; + } else { + cfqq = kmem_cache_alloc(cfq_pool, gfp_mask); + if (!cfqq) + goto out; + } + + memset(cfqq, 0, sizeof(*cfqq)); + + INIT_HLIST_NODE(&cfqq->cfq_hash); + INIT_LIST_HEAD(&cfqq->cfq_list); + RB_CLEAR_ROOT(&cfqq->sort_list); + INIT_LIST_HEAD(&cfqq->fifo); + + cfqq->key = key; + hlist_add_head(&cfqq->cfq_hash, &cfqd->cfq_hash[hashval]); + atomic_set(&cfqq->ref, 0); + cfqq->cfqd = cfqd; + atomic_inc(&cfqd->ref); + cfqq->service_last = 0; + /* + * set ->slice_left to allow preemption for a new process + */ + cfqq->slice_left = 2 * cfqd->cfq_slice_idle; + cfq_mark_cfqq_idle_window(cfqq); + cfq_mark_cfqq_prio_changed(cfqq); + cfq_init_prio_data(cfqq); + } + + if (new_cfqq) + kmem_cache_free(cfq_pool, new_cfqq); + + atomic_inc(&cfqq->ref); +out: + WARN_ON((gfp_mask & __GFP_WAIT) && !cfqq); + return cfqq; +} + +/* + * Setup general io context and cfq io context. There can be several cfq + * io contexts per general io context, if this process is doing io to more + * than one device managed by cfq. Note that caller is holding a reference to + * cfqq, so we don't need to worry about it disappearing + */ +static struct cfq_io_context * +cfq_get_io_context(struct cfq_data *cfqd, pid_t pid, gfp_t gfp_mask) +{ + struct io_context *ioc = NULL; + struct cfq_io_context *cic; + + might_sleep_if(gfp_mask & __GFP_WAIT); + + ioc = get_io_context(gfp_mask); + if (!ioc) + return NULL; + + if ((cic = ioc->cic) == NULL) { + cic = cfq_alloc_io_context(cfqd, gfp_mask); + + if (cic == NULL) + goto err; + + /* + * manually increment generic io_context usage count, it + * cannot go away since we are already holding one ref to it + */ + ioc->cic = cic; + ioc->set_ioprio = cfq_ioc_set_ioprio; + cic->ioc = ioc; + cic->key = cfqd; + atomic_inc(&cfqd->ref); + } else { + struct cfq_io_context *__cic; + + /* + * the first cic on the list is actually the head itself + */ + if (cic->key == cfqd) + goto out; + + /* + * cic exists, check if we already are there. linear search + * should be ok here, the list will usually not be more than + * 1 or a few entries long + */ + list_for_each_entry(__cic, &cic->list, list) { + /* + * this process is already holding a reference to + * this queue, so no need to get one more + */ + if (__cic->key == cfqd) { + cic = __cic; + goto out; + } + } + + /* + * nope, process doesn't have a cic assoicated with this + * cfqq yet. get a new one and add to list + */ + __cic = cfq_alloc_io_context(cfqd, gfp_mask); + if (__cic == NULL) + goto err; + + __cic->ioc = ioc; + __cic->key = cfqd; + atomic_inc(&cfqd->ref); + list_add(&__cic->list, &cic->list); + cic = __cic; + } + +out: + return cic; +err: + put_io_context(ioc); + return NULL; +} + +static void +cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_io_context *cic) +{ + unsigned long elapsed, ttime; + + /* + * if this context already has stuff queued, thinktime is from + * last queue not last end + */ +#if 0 + if (time_after(cic->last_end_request, cic->last_queue)) + elapsed = jiffies - cic->last_end_request; + else + elapsed = jiffies - cic->last_queue; +#else + elapsed = jiffies - cic->last_end_request; +#endif + + ttime = min(elapsed, 2UL * cfqd->cfq_slice_idle); + + cic->ttime_samples = (7*cic->ttime_samples + 256) / 8; + cic->ttime_total = (7*cic->ttime_total + 256*ttime) / 8; + cic->ttime_mean = (cic->ttime_total + 128) / cic->ttime_samples; +} + +#define sample_valid(samples) ((samples) > 80) + +/* + * Disable idle window if the process thinks too long or seeks so much that + * it doesn't matter + */ +static void +cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq, + struct cfq_io_context *cic) +{ + int enable_idle = cfq_cfqq_idle_window(cfqq); + + if (!cic->ioc->task || !cfqd->cfq_slice_idle) + enable_idle = 0; + else if (sample_valid(cic->ttime_samples)) { + if (cic->ttime_mean > cfqd->cfq_slice_idle) + enable_idle = 0; + else + enable_idle = 1; + } + + if (enable_idle) + cfq_mark_cfqq_idle_window(cfqq); + else + cfq_clear_cfqq_idle_window(cfqq); +} + + +/* + * Check if new_cfqq should preempt the currently active queue. Return 0 for + * no or if we aren't sure, a 1 will cause a preempt. + */ +static int +cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq, + struct cfq_rq *crq) +{ + struct cfq_queue *cfqq = cfqd->active_queue; + + if (cfq_class_idle(new_cfqq)) + return 0; + + if (!cfqq) + return 1; + + if (cfq_class_idle(cfqq)) + return 1; + if (!cfq_cfqq_wait_request(new_cfqq)) + return 0; + /* + * if it doesn't have slice left, forget it + */ + if (new_cfqq->slice_left < cfqd->cfq_slice_idle) + return 0; + if (cfq_crq_is_sync(crq) && !cfq_cfqq_sync(cfqq)) + return 1; + + return 0; +} + +/* + * cfqq preempts the active queue. if we allowed preempt with no slice left, + * let it have half of its nominal slice. + */ +static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq) +{ + struct cfq_queue *__cfqq, *next; + + list_for_each_entry_safe(__cfqq, next, &cfqd->cur_rr, cfq_list) + cfq_resort_rr_list(__cfqq, 1); + + if (!cfqq->slice_left) + cfqq->slice_left = cfq_prio_to_slice(cfqd, cfqq) / 2; + + cfqq->slice_end = cfqq->slice_left + jiffies; + __cfq_slice_expired(cfqd, cfqq, 1); + __cfq_set_active_queue(cfqd, cfqq); +} + +/* + * should really be a ll_rw_blk.c helper + */ +static void cfq_start_queueing(struct cfq_data *cfqd, struct cfq_queue *cfqq) +{ + request_queue_t *q = cfqd->queue; + + if (!blk_queue_plugged(q)) + q->request_fn(q); + else + __generic_unplug_device(q); +} + +/* + * Called when a new fs request (crq) is added (to cfqq). Check if there's + * something we should do about it + */ +static void +cfq_crq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq, + struct cfq_rq *crq) +{ + struct cfq_io_context *cic; + + cfqq->next_crq = cfq_choose_req(cfqd, cfqq->next_crq, crq); + + /* + * we never wait for an async request and we don't allow preemption + * of an async request. so just return early + */ + if (!cfq_crq_is_sync(crq)) + return; + + cic = crq->io_context; + + cfq_update_io_thinktime(cfqd, cic); + cfq_update_idle_window(cfqd, cfqq, cic); + + cic->last_queue = jiffies; + + if (cfqq == cfqd->active_queue) { + /* + * if we are waiting for a request for this queue, let it rip + * immediately and flag that we must not expire this queue + * just now + */ + if (cfq_cfqq_wait_request(cfqq)) { + cfq_mark_cfqq_must_dispatch(cfqq); + del_timer(&cfqd->idle_slice_timer); + cfq_start_queueing(cfqd, cfqq); + } + } else if (cfq_should_preempt(cfqd, cfqq, crq)) { + /* + * not the active queue - expire current slice if it is + * idle and has expired it's mean thinktime or this new queue + * has some old slice time left and is of higher priority + */ + cfq_preempt_queue(cfqd, cfqq); + cfq_mark_cfqq_must_dispatch(cfqq); + cfq_start_queueing(cfqd, cfqq); + } +} + +static void cfq_insert_request(request_queue_t *q, struct request *rq) +{ + struct cfq_data *cfqd = q->elevator->elevator_data; + struct cfq_rq *crq = RQ_DATA(rq); + struct cfq_queue *cfqq = crq->cfq_queue; + + cfq_init_prio_data(cfqq); + + cfq_add_crq_rb(crq); + + list_add_tail(&rq->queuelist, &cfqq->fifo); + + if (rq_mergeable(rq)) + cfq_add_crq_hash(cfqd, crq); + + cfq_crq_enqueued(cfqd, cfqq, crq); +} + +static void cfq_completed_request(request_queue_t *q, struct request *rq) +{ + struct cfq_rq *crq = RQ_DATA(rq); + struct cfq_queue *cfqq = crq->cfq_queue; + struct cfq_data *cfqd = cfqq->cfqd; + const int sync = cfq_crq_is_sync(crq); + unsigned long now; + + now = jiffies; + + WARN_ON(!cfqd->rq_in_driver); + WARN_ON(!cfqq->on_dispatch[sync]); + cfqd->rq_in_driver--; + cfqq->on_dispatch[sync]--; + + if (!cfq_class_idle(cfqq)) + cfqd->last_end_request = now; + + if (!cfq_cfqq_dispatched(cfqq)) { + if (cfq_cfqq_on_rr(cfqq)) { + cfqq->service_last = now; + cfq_resort_rr_list(cfqq, 0); + } + if (cfq_cfqq_expired(cfqq)) { + __cfq_slice_expired(cfqd, cfqq, 0); + cfq_schedule_dispatch(cfqd); + } + } + + if (cfq_crq_is_sync(crq)) + crq->io_context->last_end_request = now; +} + +static struct request * +cfq_former_request(request_queue_t *q, struct request *rq) +{ + struct cfq_rq *crq = RQ_DATA(rq); + struct rb_node *rbprev = rb_prev(&crq->rb_node); + + if (rbprev) + return rb_entry_crq(rbprev)->request; + + return NULL; +} + +static struct request * +cfq_latter_request(request_queue_t *q, struct request *rq) +{ + struct cfq_rq *crq = RQ_DATA(rq); + struct rb_node *rbnext = rb_next(&crq->rb_node); + + if (rbnext) + return rb_entry_crq(rbnext)->request; + + return NULL; +} + +/* + * we temporarily boost lower priority queues if they are holding fs exclusive + * resources. they are boosted to normal prio (CLASS_BE/4) + */ +static void cfq_prio_boost(struct cfq_queue *cfqq) +{ + const int ioprio_class = cfqq->ioprio_class; + const int ioprio = cfqq->ioprio; + + if (has_fs_excl()) { + /* + * boost idle prio on transactions that would lock out other + * users of the filesystem + */ + if (cfq_class_idle(cfqq)) + cfqq->ioprio_class = IOPRIO_CLASS_BE; + if (cfqq->ioprio > IOPRIO_NORM) + cfqq->ioprio = IOPRIO_NORM; + } else { + /* + * check if we need to unboost the queue + */ + if (cfqq->ioprio_class != cfqq->org_ioprio_class) + cfqq->ioprio_class = cfqq->org_ioprio_class; + if (cfqq->ioprio != cfqq->org_ioprio) + cfqq->ioprio = cfqq->org_ioprio; + } + + /* + * refile between round-robin lists if we moved the priority class + */ + if ((ioprio_class != cfqq->ioprio_class || ioprio != cfqq->ioprio) && + cfq_cfqq_on_rr(cfqq)) + cfq_resort_rr_list(cfqq, 0); +} + +static inline pid_t cfq_queue_pid(struct task_struct *task, int rw) +{ + if (rw == READ || process_sync(task)) + return task->pid; + + return CFQ_KEY_ASYNC; +} + +static inline int +__cfq_may_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq, + struct task_struct *task, int rw) +{ +#if 1 + if ((cfq_cfqq_wait_request(cfqq) || cfq_cfqq_must_alloc(cfqq)) && + !cfq_cfqq_must_alloc_slice(cfqq)) { + cfq_mark_cfqq_must_alloc_slice(cfqq); + return ELV_MQUEUE_MUST; + } + + return ELV_MQUEUE_MAY; +#else + if (!cfqq || task->flags & PF_MEMALLOC) + return ELV_MQUEUE_MAY; + if (!cfqq->allocated[rw] || cfq_cfqq_must_alloc(cfqq)) { + if (cfq_cfqq_wait_request(cfqq)) + return ELV_MQUEUE_MUST; + + /* + * only allow 1 ELV_MQUEUE_MUST per slice, otherwise we + * can quickly flood the queue with writes from a single task + */ + if (rw == READ || !cfq_cfqq_must_alloc_slice(cfqq)) { + cfq_mark_cfqq_must_alloc_slice(cfqq); + return ELV_MQUEUE_MUST; + } + + return ELV_MQUEUE_MAY; + } + if (cfq_class_idle(cfqq)) + return ELV_MQUEUE_NO; + if (cfqq->allocated[rw] >= cfqd->max_queued) { + struct io_context *ioc = get_io_context(GFP_ATOMIC); + int ret = ELV_MQUEUE_NO; + + if (ioc && ioc->nr_batch_requests) + ret = ELV_MQUEUE_MAY; + + put_io_context(ioc); + return ret; + } + + return ELV_MQUEUE_MAY; +#endif +} + +static int cfq_may_queue(request_queue_t *q, int rw, struct bio *bio) +{ + struct cfq_data *cfqd = q->elevator->elevator_data; + struct task_struct *tsk = current; + struct cfq_queue *cfqq; + + /* + * don't force setup of a queue from here, as a call to may_queue + * does not necessarily imply that a request actually will be queued. + * so just lookup a possibly existing queue, or return 'may queue' + * if that fails + */ + cfqq = cfq_find_cfq_hash(cfqd, cfq_queue_pid(tsk, rw), tsk->ioprio); + if (cfqq) { + cfq_init_prio_data(cfqq); + cfq_prio_boost(cfqq); + + return __cfq_may_queue(cfqd, cfqq, tsk, rw); + } + + return ELV_MQUEUE_MAY; +} + +static void cfq_check_waiters(request_queue_t *q, struct cfq_queue *cfqq) +{ + struct cfq_data *cfqd = q->elevator->elevator_data; + struct request_list *rl = &q->rq; + + if (cfqq->allocated[READ] <= cfqd->max_queued || cfqd->rq_starved) { + smp_mb(); + if (waitqueue_active(&rl->wait[READ])) + wake_up(&rl->wait[READ]); + } + + if (cfqq->allocated[WRITE] <= cfqd->max_queued || cfqd->rq_starved) { + smp_mb(); + if (waitqueue_active(&rl->wait[WRITE])) + wake_up(&rl->wait[WRITE]); + } +} + +/* + * queue lock held here + */ +static void cfq_put_request(request_queue_t *q, struct request *rq) +{ + struct cfq_data *cfqd = q->elevator->elevator_data; + struct cfq_rq *crq = RQ_DATA(rq); + + if (crq) { + struct cfq_queue *cfqq = crq->cfq_queue; + const int rw = rq_data_dir(rq); + + BUG_ON(!cfqq->allocated[rw]); + cfqq->allocated[rw]--; + + put_io_context(crq->io_context->ioc); + + mempool_free(crq, cfqd->crq_pool); + rq->elevator_private = NULL; + + cfq_check_waiters(q, cfqq); + cfq_put_queue(cfqq); + } +} + +/* + * Allocate cfq data structures associated with this request. + */ +static int +cfq_set_request(request_queue_t *q, struct request *rq, struct bio *bio, + gfp_t gfp_mask) +{ + struct cfq_data *cfqd = q->elevator->elevator_data; + struct task_struct *tsk = current; + struct cfq_io_context *cic; + const int rw = rq_data_dir(rq); + pid_t key = cfq_queue_pid(tsk, rw); + struct cfq_queue *cfqq; + struct cfq_rq *crq; + unsigned long flags; + + might_sleep_if(gfp_mask & __GFP_WAIT); + + cic = cfq_get_io_context(cfqd, key, gfp_mask); + + spin_lock_irqsave(q->queue_lock, flags); + + if (!cic) + goto queue_fail; + + if (!cic->cfqq) { + cfqq = cfq_get_queue(cfqd, key, tsk->ioprio, gfp_mask); + if (!cfqq) + goto queue_fail; + + cic->cfqq = cfqq; + } else + cfqq = cic->cfqq; + + cfqq->allocated[rw]++; + cfq_clear_cfqq_must_alloc(cfqq); + cfqd->rq_starved = 0; + atomic_inc(&cfqq->ref); + spin_unlock_irqrestore(q->queue_lock, flags); + + crq = mempool_alloc(cfqd->crq_pool, gfp_mask); + if (crq) { + RB_CLEAR(&crq->rb_node); + crq->rb_key = 0; + crq->request = rq; + INIT_HLIST_NODE(&crq->hash); + crq->cfq_queue = cfqq; + crq->io_context = cic; + + if (rw == READ || process_sync(tsk)) + cfq_mark_crq_is_sync(crq); + else + cfq_clear_crq_is_sync(crq); + + rq->elevator_private = crq; + return 0; + } + + spin_lock_irqsave(q->queue_lock, flags); + cfqq->allocated[rw]--; + if (!(cfqq->allocated[0] + cfqq->allocated[1])) + cfq_mark_cfqq_must_alloc(cfqq); + cfq_put_queue(cfqq); +queue_fail: + if (cic) + put_io_context(cic->ioc); + /* + * mark us rq allocation starved. we need to kickstart the process + * ourselves if there are no pending requests that can do it for us. + * that would be an extremely rare OOM situation + */ + cfqd->rq_starved = 1; + cfq_schedule_dispatch(cfqd); + spin_unlock_irqrestore(q->queue_lock, flags); + return 1; +} + +static void cfq_kick_queue(void *data) +{ + request_queue_t *q = data; + struct cfq_data *cfqd = q->elevator->elevator_data; + unsigned long flags; + + spin_lock_irqsave(q->queue_lock, flags); + + if (cfqd->rq_starved) { + struct request_list *rl = &q->rq; + + /* + * we aren't guaranteed to get a request after this, but we + * have to be opportunistic + */ + smp_mb(); + if (waitqueue_active(&rl->wait[READ])) + wake_up(&rl->wait[READ]); + if (waitqueue_active(&rl->wait[WRITE])) + wake_up(&rl->wait[WRITE]); + } + + blk_remove_plug(q); + q->request_fn(q); + spin_unlock_irqrestore(q->queue_lock, flags); +} + +/* + * Timer running if the active_queue is currently idling inside its time slice + */ +static void cfq_idle_slice_timer(unsigned long data) +{ + struct cfq_data *cfqd = (struct cfq_data *) data; + struct cfq_queue *cfqq; + unsigned long flags; + + spin_lock_irqsave(cfqd->queue->queue_lock, flags); + + if ((cfqq = cfqd->active_queue) != NULL) { + unsigned long now = jiffies; + + /* + * expired + */ + if (time_after(now, cfqq->slice_end)) + goto expire; + + /* + * only expire and reinvoke request handler, if there are + * other queues with pending requests + */ + if (!cfqd->busy_queues) { + cfqd->idle_slice_timer.expires = min(now + cfqd->cfq_slice_idle, cfqq->slice_end); + add_timer(&cfqd->idle_slice_timer); + goto out_cont; + } + + /* + * not expired and it has a request pending, let it dispatch + */ + if (!RB_EMPTY(&cfqq->sort_list)) { + cfq_mark_cfqq_must_dispatch(cfqq); + goto out_kick; + } + } +expire: + cfq_slice_expired(cfqd, 0); +out_kick: + cfq_schedule_dispatch(cfqd); +out_cont: + spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); +} + +/* + * Timer running if an idle class queue is waiting for service + */ +static void cfq_idle_class_timer(unsigned long data) +{ + struct cfq_data *cfqd = (struct cfq_data *) data; + unsigned long flags, end; + + spin_lock_irqsave(cfqd->queue->queue_lock, flags); + + /* + * race with a non-idle queue, reset timer + */ + end = cfqd->last_end_request + CFQ_IDLE_GRACE; + if (!time_after_eq(jiffies, end)) { + cfqd->idle_class_timer.expires = end; + add_timer(&cfqd->idle_class_timer); + } else + cfq_schedule_dispatch(cfqd); + + spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); +} + +static void cfq_shutdown_timer_wq(struct cfq_data *cfqd) +{ + del_timer_sync(&cfqd->idle_slice_timer); + del_timer_sync(&cfqd->idle_class_timer); + blk_sync_queue(cfqd->queue); +} + +static void cfq_put_cfqd(struct cfq_data *cfqd) +{ + request_queue_t *q = cfqd->queue; + + if (!atomic_dec_and_test(&cfqd->ref)) + return; + + cfq_shutdown_timer_wq(cfqd); + blk_put_queue(q); + + mempool_destroy(cfqd->crq_pool); + kfree(cfqd->crq_hash); + kfree(cfqd->cfq_hash); + kfree(cfqd); +} + +static void cfq_exit_queue(elevator_t *e) +{ + struct cfq_data *cfqd = e->elevator_data; + + cfq_shutdown_timer_wq(cfqd); + cfq_put_cfqd(cfqd); +} + +static int cfq_init_queue(request_queue_t *q, elevator_t *e) +{ + struct cfq_data *cfqd; + int i; + + cfqd = kmalloc(sizeof(*cfqd), GFP_KERNEL); + if (!cfqd) + return -ENOMEM; + + memset(cfqd, 0, sizeof(*cfqd)); + + for (i = 0; i < CFQ_PRIO_LISTS; i++) + INIT_LIST_HEAD(&cfqd->rr_list[i]); + + INIT_LIST_HEAD(&cfqd->busy_rr); + INIT_LIST_HEAD(&cfqd->cur_rr); + INIT_LIST_HEAD(&cfqd->idle_rr); + INIT_LIST_HEAD(&cfqd->empty_list); + + cfqd->crq_hash = kmalloc(sizeof(struct hlist_head) * CFQ_MHASH_ENTRIES, GFP_KERNEL); + if (!cfqd->crq_hash) + goto out_crqhash; + + cfqd->cfq_hash = kmalloc(sizeof(struct hlist_head) * CFQ_QHASH_ENTRIES, GFP_KERNEL); + if (!cfqd->cfq_hash) + goto out_cfqhash; + + cfqd->crq_pool = mempool_create(BLKDEV_MIN_RQ, mempool_alloc_slab, mempool_free_slab, crq_pool); + if (!cfqd->crq_pool) + goto out_crqpool; + + for (i = 0; i < CFQ_MHASH_ENTRIES; i++) + INIT_HLIST_HEAD(&cfqd->crq_hash[i]); + for (i = 0; i < CFQ_QHASH_ENTRIES; i++) + INIT_HLIST_HEAD(&cfqd->cfq_hash[i]); + + e->elevator_data = cfqd; + + cfqd->queue = q; + atomic_inc(&q->refcnt); + + cfqd->max_queued = q->nr_requests / 4; + q->nr_batching = cfq_queued; + + init_timer(&cfqd->idle_slice_timer); + cfqd->idle_slice_timer.function = cfq_idle_slice_timer; + cfqd->idle_slice_timer.data = (unsigned long) cfqd; + + init_timer(&cfqd->idle_class_timer); + cfqd->idle_class_timer.function = cfq_idle_class_timer; + cfqd->idle_class_timer.data = (unsigned long) cfqd; + + INIT_WORK(&cfqd->unplug_work, cfq_kick_queue, q); + + atomic_set(&cfqd->ref, 1); + + cfqd->cfq_queued = cfq_queued; + cfqd->cfq_quantum = cfq_quantum; + cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0]; + cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1]; + cfqd->cfq_back_max = cfq_back_max; + cfqd->cfq_back_penalty = cfq_back_penalty; + cfqd->cfq_slice[0] = cfq_slice_async; + cfqd->cfq_slice[1] = cfq_slice_sync; + cfqd->cfq_slice_async_rq = cfq_slice_async_rq; + cfqd->cfq_slice_idle = cfq_slice_idle; + cfqd->cfq_max_depth = cfq_max_depth; + + return 0; +out_crqpool: + kfree(cfqd->cfq_hash); +out_cfqhash: + kfree(cfqd->crq_hash); +out_crqhash: + kfree(cfqd); + return -ENOMEM; +} + +static void cfq_slab_kill(void) +{ + if (crq_pool) + kmem_cache_destroy(crq_pool); + if (cfq_pool) + kmem_cache_destroy(cfq_pool); + if (cfq_ioc_pool) + kmem_cache_destroy(cfq_ioc_pool); +} + +static int __init cfq_slab_setup(void) +{ + crq_pool = kmem_cache_create("crq_pool", sizeof(struct cfq_rq), 0, 0, + NULL, NULL); + if (!crq_pool) + goto fail; + + cfq_pool = kmem_cache_create("cfq_pool", sizeof(struct cfq_queue), 0, 0, + NULL, NULL); + if (!cfq_pool) + goto fail; + + cfq_ioc_pool = kmem_cache_create("cfq_ioc_pool", + sizeof(struct cfq_io_context), 0, 0, NULL, NULL); + if (!cfq_ioc_pool) + goto fail; + + return 0; +fail: + cfq_slab_kill(); + return -ENOMEM; +} + +/* + * sysfs parts below --> + */ +struct cfq_fs_entry { + struct attribute attr; + ssize_t (*show)(struct cfq_data *, char *); + ssize_t (*store)(struct cfq_data *, const char *, size_t); +}; + +static ssize_t +cfq_var_show(unsigned int var, char *page) +{ + return sprintf(page, "%d\n", var); +} + +static ssize_t +cfq_var_store(unsigned int *var, const char *page, size_t count) +{ + char *p = (char *) page; + + *var = simple_strtoul(p, &p, 10); + return count; +} + +#define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \ +static ssize_t __FUNC(struct cfq_data *cfqd, char *page) \ +{ \ + unsigned int __data = __VAR; \ + if (__CONV) \ + __data = jiffies_to_msecs(__data); \ + return cfq_var_show(__data, (page)); \ +} +SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0); +SHOW_FUNCTION(cfq_queued_show, cfqd->cfq_queued, 0); +SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1); +SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1); +SHOW_FUNCTION(cfq_back_max_show, cfqd->cfq_back_max, 0); +SHOW_FUNCTION(cfq_back_penalty_show, cfqd->cfq_back_penalty, 0); +SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1); +SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1); +SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1); +SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0); +SHOW_FUNCTION(cfq_max_depth_show, cfqd->cfq_max_depth, 0); +#undef SHOW_FUNCTION + +#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \ +static ssize_t __FUNC(struct cfq_data *cfqd, const char *page, size_t count) \ +{ \ + unsigned int __data; \ + int ret = cfq_var_store(&__data, (page), count); \ + if (__data < (MIN)) \ + __data = (MIN); \ + else if (__data > (MAX)) \ + __data = (MAX); \ + if (__CONV) \ + *(__PTR) = msecs_to_jiffies(__data); \ + else \ + *(__PTR) = __data; \ + return ret; \ +} +STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0); +STORE_FUNCTION(cfq_queued_store, &cfqd->cfq_queued, 1, UINT_MAX, 0); +STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1, UINT_MAX, 1); +STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1, UINT_MAX, 1); +STORE_FUNCTION(cfq_back_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0); +STORE_FUNCTION(cfq_back_penalty_store, &cfqd->cfq_back_penalty, 1, UINT_MAX, 0); +STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1); +STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1); +STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1); +STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1, UINT_MAX, 0); +STORE_FUNCTION(cfq_max_depth_store, &cfqd->cfq_max_depth, 1, UINT_MAX, 0); +#undef STORE_FUNCTION + +static struct cfq_fs_entry cfq_quantum_entry = { + .attr = {.name = "quantum", .mode = S_IRUGO | S_IWUSR }, + .show = cfq_quantum_show, + .store = cfq_quantum_store, +}; +static struct cfq_fs_entry cfq_queued_entry = { + .attr = {.name = "queued", .mode = S_IRUGO | S_IWUSR }, + .show = cfq_queued_show, + .store = cfq_queued_store, +}; +static struct cfq_fs_entry cfq_fifo_expire_sync_entry = { + .attr = {.name = "fifo_expire_sync", .mode = S_IRUGO | S_IWUSR }, + .show = cfq_fifo_expire_sync_show, + .store = cfq_fifo_expire_sync_store, +}; +static struct cfq_fs_entry cfq_fifo_expire_async_entry = { + .attr = {.name = "fifo_expire_async", .mode = S_IRUGO | S_IWUSR }, + .show = cfq_fifo_expire_async_show, + .store = cfq_fifo_expire_async_store, +}; +static struct cfq_fs_entry cfq_back_max_entry = { + .attr = {.name = "back_seek_max", .mode = S_IRUGO | S_IWUSR }, + .show = cfq_back_max_show, + .store = cfq_back_max_store, +}; +static struct cfq_fs_entry cfq_back_penalty_entry = { + .attr = {.name = "back_seek_penalty", .mode = S_IRUGO | S_IWUSR }, + .show = cfq_back_penalty_show, + .store = cfq_back_penalty_store, +}; +static struct cfq_fs_entry cfq_slice_sync_entry = { + .attr = {.name = "slice_sync", .mode = S_IRUGO | S_IWUSR }, + .show = cfq_slice_sync_show, + .store = cfq_slice_sync_store, +}; +static struct cfq_fs_entry cfq_slice_async_entry = { + .attr = {.name = "slice_async", .mode = S_IRUGO | S_IWUSR }, + .show = cfq_slice_async_show, + .store = cfq_slice_async_store, +}; +static struct cfq_fs_entry cfq_slice_async_rq_entry = { + .attr = {.name = "slice_async_rq", .mode = S_IRUGO | S_IWUSR }, + .show = cfq_slice_async_rq_show, + .store = cfq_slice_async_rq_store, +}; +static struct cfq_fs_entry cfq_slice_idle_entry = { + .attr = {.name = "slice_idle", .mode = S_IRUGO | S_IWUSR }, + .show = cfq_slice_idle_show, + .store = cfq_slice_idle_store, +}; +static struct cfq_fs_entry cfq_max_depth_entry = { + .attr = {.name = "max_depth", .mode = S_IRUGO | S_IWUSR }, + .show = cfq_max_depth_show, + .store = cfq_max_depth_store, +}; + +static struct attribute *default_attrs[] = { + &cfq_quantum_entry.attr, + &cfq_queued_entry.attr, + &cfq_fifo_expire_sync_entry.attr, + &cfq_fifo_expire_async_entry.attr, + &cfq_back_max_entry.attr, + &cfq_back_penalty_entry.attr, + &cfq_slice_sync_entry.attr, + &cfq_slice_async_entry.attr, + &cfq_slice_async_rq_entry.attr, + &cfq_slice_idle_entry.attr, + &cfq_max_depth_entry.attr, + NULL, +}; + +#define to_cfq(atr) container_of((atr), struct cfq_fs_entry, attr) + +static ssize_t +cfq_attr_show(struct kobject *kobj, struct attribute *attr, char *page) +{ + elevator_t *e = container_of(kobj, elevator_t, kobj); + struct cfq_fs_entry *entry = to_cfq(attr); + + if (!entry->show) + return -EIO; + + return entry->show(e->elevator_data, page); +} + +static ssize_t +cfq_attr_store(struct kobject *kobj, struct attribute *attr, + const char *page, size_t length) +{ + elevator_t *e = container_of(kobj, elevator_t, kobj); + struct cfq_fs_entry *entry = to_cfq(attr); + + if (!entry->store) + return -EIO; + + return entry->store(e->elevator_data, page, length); +} + +static struct sysfs_ops cfq_sysfs_ops = { + .show = cfq_attr_show, + .store = cfq_attr_store, +}; + +static struct kobj_type cfq_ktype = { + .sysfs_ops = &cfq_sysfs_ops, + .default_attrs = default_attrs, +}; + +static struct elevator_type iosched_cfq = { + .ops = { + .elevator_merge_fn = cfq_merge, + .elevator_merged_fn = cfq_merged_request, + .elevator_merge_req_fn = cfq_merged_requests, + .elevator_dispatch_fn = cfq_dispatch_requests, + .elevator_add_req_fn = cfq_insert_request, + .elevator_activate_req_fn = cfq_activate_request, + .elevator_deactivate_req_fn = cfq_deactivate_request, + .elevator_queue_empty_fn = cfq_queue_empty, + .elevator_completed_req_fn = cfq_completed_request, + .elevator_former_req_fn = cfq_former_request, + .elevator_latter_req_fn = cfq_latter_request, + .elevator_set_req_fn = cfq_set_request, + .elevator_put_req_fn = cfq_put_request, + .elevator_may_queue_fn = cfq_may_queue, + .elevator_init_fn = cfq_init_queue, + .elevator_exit_fn = cfq_exit_queue, + }, + .elevator_ktype = &cfq_ktype, + .elevator_name = "cfq", + .elevator_owner = THIS_MODULE, +}; + +static int __init cfq_init(void) +{ + int ret; + + /* + * could be 0 on HZ < 1000 setups + */ + if (!cfq_slice_async) + cfq_slice_async = 1; + if (!cfq_slice_idle) + cfq_slice_idle = 1; + + if (cfq_slab_setup()) + return -ENOMEM; + + ret = elv_register(&iosched_cfq); + if (ret) + cfq_slab_kill(); + + return ret; +} + +static void __exit cfq_exit(void) +{ + elv_unregister(&iosched_cfq); + cfq_slab_kill(); +} + +module_init(cfq_init); +module_exit(cfq_exit); + +MODULE_AUTHOR("Jens Axboe"); +MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler"); |
