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android / kernel / bcm / refs/tags/android-wear-5.0.2_r0.5 / . / block / cfq-iosched.c
blob: c410752c5c654592761248bc193d49fb38efda45 [file] [log] [blame]
/*
* 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@kernel.dk>
*/
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/blkdev.h>
#include <linux/elevator.h>
#include <linux/jiffies.h>
#include <linux/rbtree.h>
#include <linux/ioprio.h>
#include <linux/blktrace_api.h>
#include "blk.h"
#include "blk-cgroup.h"
/*
* tunables
*/
/* max queue in one round of service */
static const int cfq_quantum = 8;
static const int cfq_fifo_expire[2] = { HZ / 4, HZ / 8 };
/* maximum backwards seek, in KiB */
static const int cfq_back_max = 16 * 1024;
/* penalty of a backwards seek */
static const int cfq_back_penalty = 2;
static const int cfq_slice_sync = HZ / 10;
static int cfq_slice_async = HZ / 25;
static const int cfq_slice_async_rq = 2;
static int cfq_slice_idle = HZ / 125;
static int cfq_group_idle = HZ / 125;
static const int cfq_target_latency = HZ * 3/10; /* 300 ms */
static const int cfq_hist_divisor = 4;
/*
* offset from end of service tree
*/
#define CFQ_IDLE_DELAY (HZ / 5)
/*
* below this threshold, we consider thinktime immediate
*/
#define CFQ_MIN_TT (2)
#define CFQ_SLICE_SCALE (5)
#define CFQ_HW_QUEUE_MIN (5)
#define CFQ_SERVICE_SHIFT 12
#define CFQQ_SEEK_THR (sector_t)(8 * 100)
#define CFQQ_CLOSE_THR (sector_t)(8 * 1024)
#define CFQQ_SECT_THR_NONROT (sector_t)(2 * 32)
#define CFQQ_SEEKY(cfqq) (hweight32(cfqq->seek_history) > 32/8)
#define RQ_CIC(rq) icq_to_cic((rq)->elv.icq)
#define RQ_CFQQ(rq) (struct cfq_queue *) ((rq)->elv.priv[0])
#define RQ_CFQG(rq) (struct cfq_group *) ((rq)->elv.priv[1])
static struct kmem_cache *cfq_pool;
#define CFQ_PRIO_LISTS IOPRIO_BE_NR
#define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
#define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT)
#define sample_valid(samples) ((samples) > 80)
#define rb_entry_cfqg(node) rb_entry((node), struct cfq_group, rb_node)
struct cfq_ttime {
unsigned long last_end_request;
unsigned long ttime_total;
unsigned long ttime_samples;
unsigned long ttime_mean;
};
/*
* Most of our rbtree usage is for sorting with min extraction, so
* if we cache the leftmost node we don't have to walk down the tree
* to find it. Idea borrowed from Ingo Molnars CFS scheduler. We should
* move this into the elevator for the rq sorting as well.
*/
struct cfq_rb_root {
struct rb_root rb;
struct rb_node *left;
unsigned count;
u64 min_vdisktime;
struct cfq_ttime ttime;
};
#define CFQ_RB_ROOT (struct cfq_rb_root) { .rb = RB_ROOT, \
.ttime = {.last_end_request = jiffies,},}
/*
* Per process-grouping structure
*/
struct cfq_queue {
/* reference count */
int ref;
/* various state flags, see below */
unsigned int flags;
/* parent cfq_data */
struct cfq_data *cfqd;
/* service_tree member */
struct rb_node rb_node;
/* service_tree key */
unsigned long rb_key;
/* prio tree member */
struct rb_node p_node;
/* prio tree root we belong to, if any */
struct rb_root *p_root;
/* sorted list of pending requests */
struct rb_root sort_list;
/* if fifo isn't expired, next request to serve */
struct request *next_rq;
/* 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;
/* time when queue got scheduled in to dispatch first request. */
unsigned long dispatch_start;
unsigned int allocated_slice;
unsigned int slice_dispatch;
/* time when first request from queue completed and slice started. */
unsigned long slice_start;
unsigned long slice_end;
long slice_resid;
/* pending priority requests */
int prio_pending;
/* number of requests that are on the dispatch list or inside driver */
int dispatched;
/* io prio of this group */
unsigned short ioprio, org_ioprio;
unsigned short ioprio_class;
pid_t pid;
u32 seek_history;
sector_t last_request_pos;
struct cfq_rb_root *service_tree;
struct cfq_queue *new_cfqq;
struct cfq_group *cfqg;
/* Number of sectors dispatched from queue in single dispatch round */
unsigned long nr_sectors;
};
/*
* First index in the service_trees.
* IDLE is handled separately, so it has negative index
*/
enum wl_class_t {
BE_WORKLOAD = 0,
RT_WORKLOAD = 1,
IDLE_WORKLOAD = 2,
CFQ_PRIO_NR,
};
/*
* Second index in the service_trees.
*/
enum wl_type_t {
ASYNC_WORKLOAD = 0,
SYNC_NOIDLE_WORKLOAD = 1,
SYNC_WORKLOAD = 2
};
struct cfqg_stats {
#ifdef CONFIG_CFQ_GROUP_IOSCHED
/* total bytes transferred */
struct blkg_rwstat service_bytes;
/* total IOs serviced, post merge */
struct blkg_rwstat serviced;
/* number of ios merged */
struct blkg_rwstat merged;
/* total time spent on device in ns, may not be accurate w/ queueing */
struct blkg_rwstat service_time;
/* total time spent waiting in scheduler queue in ns */
struct blkg_rwstat wait_time;
/* number of IOs queued up */
struct blkg_rwstat queued;
/* total sectors transferred */
struct blkg_stat sectors;
/* total disk time and nr sectors dispatched by this group */
struct blkg_stat time;
#ifdef CONFIG_DEBUG_BLK_CGROUP
/* time not charged to this cgroup */
struct blkg_stat unaccounted_time;
/* sum of number of ios queued across all samples */
struct blkg_stat avg_queue_size_sum;
/* count of samples taken for average */
struct blkg_stat avg_queue_size_samples;
/* how many times this group has been removed from service tree */
struct blkg_stat dequeue;
/* total time spent waiting for it to be assigned a timeslice. */
struct blkg_stat group_wait_time;
/* time spent idling for this blkcg_gq */
struct blkg_stat idle_time;
/* total time with empty current active q with other requests queued */
struct blkg_stat empty_time;
/* fields after this shouldn't be cleared on stat reset */
uint64_t start_group_wait_time;
uint64_t start_idle_time;
uint64_t start_empty_time;
uint16_t flags;
#endif /* CONFIG_DEBUG_BLK_CGROUP */
#endif /* CONFIG_CFQ_GROUP_IOSCHED */
};
/* This is per cgroup per device grouping structure */
struct cfq_group {
/* must be the first member */
struct blkg_policy_data pd;
/* group service_tree member */
struct rb_node rb_node;
/* group service_tree key */
u64 vdisktime;
/*
* The number of active cfqgs and sum of their weights under this
* cfqg. This covers this cfqg's leaf_weight and all children's
* weights, but does not cover weights of further descendants.
*
* If a cfqg is on the service tree, it's active. An active cfqg
* also activates its parent and contributes to the children_weight
* of the parent.
*/
int nr_active;
unsigned int children_weight;
/*
* vfraction is the fraction of vdisktime that the tasks in this
* cfqg are entitled to. This is determined by compounding the
* ratios walking up from this cfqg to the root.
*
* It is in fixed point w/ CFQ_SERVICE_SHIFT and the sum of all
* vfractions on a service tree is approximately 1. The sum may
* deviate a bit due to rounding errors and fluctuations caused by
* cfqgs entering and leaving the service tree.
*/
unsigned int vfraction;
/*
* There are two weights - (internal) weight is the weight of this
* cfqg against the sibling cfqgs. leaf_weight is the wight of
* this cfqg against the child cfqgs. For the root cfqg, both
* weights are kept in sync for backward compatibility.
*/
unsigned int weight;
unsigned int new_weight;
unsigned int dev_weight;
unsigned int leaf_weight;
unsigned int new_leaf_weight;
unsigned int dev_leaf_weight;
/* number of cfqq currently on this group */
int nr_cfqq;
/*
* Per group busy queues average. Useful for workload slice calc. We
* create the array for each prio class but at run time it is used
* only for RT and BE class and slot for IDLE class remains unused.
* This is primarily done to avoid confusion and a gcc warning.
*/
unsigned int busy_queues_avg[CFQ_PRIO_NR];
/*
* rr lists of queues with requests. We maintain service trees for
* RT and BE classes. These trees are subdivided in subclasses
* of SYNC, SYNC_NOIDLE and ASYNC based on workload type. For IDLE
* class there is no subclassification and all the cfq queues go on
* a single tree service_tree_idle.
* Counts are embedded in the cfq_rb_root
*/
struct cfq_rb_root service_trees[2][3];
struct cfq_rb_root service_tree_idle;
unsigned long saved_wl_slice;
enum wl_type_t saved_wl_type;
enum wl_class_t saved_wl_class;
/* number of requests that are on the dispatch list or inside driver */
int dispatched;
struct cfq_ttime ttime;
struct cfqg_stats stats; /* stats for this cfqg */
struct cfqg_stats dead_stats; /* stats pushed from dead children */
};
struct cfq_io_cq {
struct io_cq icq; /* must be the first member */
struct cfq_queue *cfqq[2];
struct cfq_ttime ttime;
int ioprio; /* the current ioprio */
#ifdef CONFIG_CFQ_GROUP_IOSCHED
uint64_t blkcg_id; /* the current blkcg ID */
#endif
};
/*
* Per block device queue structure
*/
struct cfq_data {
struct request_queue *queue;
/* Root service tree for cfq_groups */
struct cfq_rb_root grp_service_tree;
struct cfq_group *root_group;
/*
* The priority currently being served
*/
enum wl_class_t serving_wl_class;
enum wl_type_t serving_wl_type;
unsigned long workload_expires;
struct cfq_group *serving_group;
/*
* Each priority tree is sorted by next_request position. These
* trees are used when determining if two or more queues are
* interleaving requests (see cfq_close_cooperator).
*/
struct rb_root prio_trees[CFQ_PRIO_LISTS];
unsigned int busy_queues;
unsigned int busy_sync_queues;
int rq_in_driver;
int rq_in_flight[2];
/*
* queue-depth detection
*/
int rq_queued;
int hw_tag;
/*
* hw_tag can be
* -1 => indeterminate, (cfq will behave as if NCQ is present, to allow better detection)
* 1 => NCQ is present (hw_tag_est_depth is the estimated max depth)
* 0 => no NCQ
*/
int hw_tag_est_depth;
unsigned int hw_tag_samples;
/*
* idle window management
*/
struct timer_list idle_slice_timer;
struct work_struct unplug_work;
struct cfq_queue *active_queue;
struct cfq_io_cq *active_cic;
/*
* async queue for each priority case
*/
struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR];
struct cfq_queue *async_idle_cfqq;
sector_t last_position;
/*
* tunables, see top of file
*/
unsigned int cfq_quantum;
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_group_idle;
unsigned int cfq_latency;
unsigned int cfq_target_latency;
/*
* Fallback dummy cfqq for extreme OOM conditions
*/
struct cfq_queue oom_cfqq;
unsigned long last_delayed_sync;
};
static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd);
static struct cfq_rb_root *st_for(struct cfq_group *cfqg,
enum wl_class_t class,
enum wl_type_t type)
{
if (!cfqg)
return NULL;
if (class == IDLE_WORKLOAD)
return &cfqg->service_tree_idle;
return &cfqg->service_trees[class][type];
}
enum cfqq_state_flags {
CFQ_CFQQ_FLAG_on_rr = 0, /* on round-robin busy list */
CFQ_CFQQ_FLAG_wait_request, /* waiting for a request */
CFQ_CFQQ_FLAG_must_dispatch, /* must be allowed a dispatch */
CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */
CFQ_CFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */
CFQ_CFQQ_FLAG_idle_window, /* slice idling enabled */
CFQ_CFQQ_FLAG_prio_changed, /* task priority has changed */
CFQ_CFQQ_FLAG_slice_new, /* no requests dispatched in slice */
CFQ_CFQQ_FLAG_sync, /* synchronous queue */
CFQ_CFQQ_FLAG_coop, /* cfqq is shared */
CFQ_CFQQ_FLAG_split_coop, /* shared cfqq will be splitted */
CFQ_CFQQ_FLAG_deep, /* sync cfqq experienced large depth */
CFQ_CFQQ_FLAG_wait_busy, /* Waiting for next request */
};
#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_dispatch);
CFQ_CFQQ_FNS(must_alloc_slice);
CFQ_CFQQ_FNS(fifo_expire);
CFQ_CFQQ_FNS(idle_window);
CFQ_CFQQ_FNS(prio_changed);
CFQ_CFQQ_FNS(slice_new);
CFQ_CFQQ_FNS(sync);
CFQ_CFQQ_FNS(coop);
CFQ_CFQQ_FNS(split_coop);
CFQ_CFQQ_FNS(deep);
CFQ_CFQQ_FNS(wait_busy);
#undef CFQ_CFQQ_FNS
static inline struct cfq_group *pd_to_cfqg(struct blkg_policy_data *pd)
{
return pd ? container_of(pd, struct cfq_group, pd) : NULL;
}
static inline struct blkcg_gq *cfqg_to_blkg(struct cfq_group *cfqg)
{
return pd_to_blkg(&cfqg->pd);
}
#if defined(CONFIG_CFQ_GROUP_IOSCHED) && defined(CONFIG_DEBUG_BLK_CGROUP)
/* cfqg stats flags */
enum cfqg_stats_flags {
CFQG_stats_waiting = 0,
CFQG_stats_idling,
CFQG_stats_empty,
};
#define CFQG_FLAG_FNS(name) \
static inline void cfqg_stats_mark_##name(struct cfqg_stats *stats) \
{ \
stats->flags |= (1 << CFQG_stats_##name); \
} \
static inline void cfqg_stats_clear_##name(struct cfqg_stats *stats) \
{ \
stats->flags &= ~(1 << CFQG_stats_##name); \
} \
static inline int cfqg_stats_##name(struct cfqg_stats *stats) \
{ \
return (stats->flags & (1 << CFQG_stats_##name)) != 0; \
} \
CFQG_FLAG_FNS(waiting)
CFQG_FLAG_FNS(idling)
CFQG_FLAG_FNS(empty)
#undef CFQG_FLAG_FNS
/* This should be called with the queue_lock held. */
static void cfqg_stats_update_group_wait_time(struct cfqg_stats *stats)
{
unsigned long long now;
if (!cfqg_stats_waiting(stats))
return;
now = sched_clock();
if (time_after64(now, stats->start_group_wait_time))
blkg_stat_add(&stats->group_wait_time,
now - stats->start_group_wait_time);
cfqg_stats_clear_waiting(stats);
}
/* This should be called with the queue_lock held. */
static void cfqg_stats_set_start_group_wait_time(struct cfq_group *cfqg,
struct cfq_group *curr_cfqg)
{
struct cfqg_stats *stats = &cfqg->stats;
if (cfqg_stats_waiting(stats))
return;
if (cfqg == curr_cfqg)
return;
stats->start_group_wait_time = sched_clock();
cfqg_stats_mark_waiting(stats);
}
/* This should be called with the queue_lock held. */
static void cfqg_stats_end_empty_time(struct cfqg_stats *stats)
{
unsigned long long now;
if (!cfqg_stats_empty(stats))
return;
now = sched_clock();
if (time_after64(now, stats->start_empty_time))
blkg_stat_add(&stats->empty_time,
now - stats->start_empty_time);
cfqg_stats_clear_empty(stats);
}
static void cfqg_stats_update_dequeue(struct cfq_group *cfqg)
{
blkg_stat_add(&cfqg->stats.dequeue, 1);
}
static void cfqg_stats_set_start_empty_time(struct cfq_group *cfqg)
{
struct cfqg_stats *stats = &cfqg->stats;
if (blkg_rwstat_total(&stats->queued))
return;
/*
* group is already marked empty. This can happen if cfqq got new
* request in parent group and moved to this group while being added
* to service tree. Just ignore the event and move on.
*/
if (cfqg_stats_empty(stats))
return;
stats->start_empty_time = sched_clock();
cfqg_stats_mark_empty(stats);
}
static void cfqg_stats_update_idle_time(struct cfq_group *cfqg)
{
struct cfqg_stats *stats = &cfqg->stats;
if (cfqg_stats_idling(stats)) {
unsigned long long now = sched_clock();
if (time_after64(now, stats->start_idle_time))
blkg_stat_add(&stats->idle_time,
now - stats->start_idle_time);
cfqg_stats_clear_idling(stats);
}
}
static void cfqg_stats_set_start_idle_time(struct cfq_group *cfqg)
{
struct cfqg_stats *stats = &cfqg->stats;
BUG_ON(cfqg_stats_idling(stats));
stats->start_idle_time = sched_clock();
cfqg_stats_mark_idling(stats);
}
static void cfqg_stats_update_avg_queue_size(struct cfq_group *cfqg)
{
struct cfqg_stats *stats = &cfqg->stats;
blkg_stat_add(&stats->avg_queue_size_sum,
blkg_rwstat_total(&stats->queued));
blkg_stat_add(&stats->avg_queue_size_samples, 1);
cfqg_stats_update_group_wait_time(stats);
}
#else /* CONFIG_CFQ_GROUP_IOSCHED && CONFIG_DEBUG_BLK_CGROUP */
static inline void cfqg_stats_set_start_group_wait_time(struct cfq_group *cfqg, struct cfq_group *curr_cfqg) { }
static inline void cfqg_stats_end_empty_time(struct cfqg_stats *stats) { }
static inline void cfqg_stats_update_dequeue(struct cfq_group *cfqg) { }
static inline void cfqg_stats_set_start_empty_time(struct cfq_group *cfqg) { }
static inline void cfqg_stats_update_idle_time(struct cfq_group *cfqg) { }
static inline void cfqg_stats_set_start_idle_time(struct cfq_group *cfqg) { }
static inline void cfqg_stats_update_avg_queue_size(struct cfq_group *cfqg) { }
#endif /* CONFIG_CFQ_GROUP_IOSCHED && CONFIG_DEBUG_BLK_CGROUP */
#ifdef CONFIG_CFQ_GROUP_IOSCHED
static struct blkcg_policy blkcg_policy_cfq;
static inline struct cfq_group *blkg_to_cfqg(struct blkcg_gq *blkg)
{
return pd_to_cfqg(blkg_to_pd(blkg, &blkcg_policy_cfq));
}
static inline struct cfq_group *cfqg_parent(struct cfq_group *cfqg)
{
struct blkcg_gq *pblkg = cfqg_to_blkg(cfqg)->parent;
return pblkg ? blkg_to_cfqg(pblkg) : NULL;
}
static inline void cfqg_get(struct cfq_group *cfqg)
{
return blkg_get(cfqg_to_blkg(cfqg));
}
static inline void cfqg_put(struct cfq_group *cfqg)
{
return blkg_put(cfqg_to_blkg(cfqg));
}
#define cfq_log_cfqq(cfqd, cfqq, fmt, args...) do { \
char __pbuf[128]; \
\
blkg_path(cfqg_to_blkg((cfqq)->cfqg), __pbuf, sizeof(__pbuf)); \
blk_add_trace_msg((cfqd)->queue, "cfq%d%c%c %s " fmt, (cfqq)->pid, \
cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \
cfqq_type((cfqq)) == SYNC_NOIDLE_WORKLOAD ? 'N' : ' ',\
__pbuf, ##args); \
} while (0)
#define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do { \
char __pbuf[128]; \
\
blkg_path(cfqg_to_blkg(cfqg), __pbuf, sizeof(__pbuf)); \
blk_add_trace_msg((cfqd)->queue, "%s " fmt, __pbuf, ##args); \
} while (0)
static inline void cfqg_stats_update_io_add(struct cfq_group *cfqg,
struct cfq_group *curr_cfqg, int rw)
{
blkg_rwstat_add(&cfqg->stats.queued, rw, 1);
cfqg_stats_end_empty_time(&cfqg->stats);
cfqg_stats_set_start_group_wait_time(cfqg, curr_cfqg);
}
static inline void cfqg_stats_update_timeslice_used(struct cfq_group *cfqg,
unsigned long time, unsigned long unaccounted_time)
{
blkg_stat_add(&cfqg->stats.time, time);
#ifdef CONFIG_DEBUG_BLK_CGROUP
blkg_stat_add(&cfqg->stats.unaccounted_time, unaccounted_time);
#endif
}
static inline void cfqg_stats_update_io_remove(struct cfq_group *cfqg, int rw)
{
blkg_rwstat_add(&cfqg->stats.queued, rw, -1);
}
static inline void cfqg_stats_update_io_merged(struct cfq_group *cfqg, int rw)
{
blkg_rwstat_add(&cfqg->stats.merged, rw, 1);
}
static inline void cfqg_stats_update_dispatch(struct cfq_group *cfqg,
uint64_t bytes, int rw)
{
blkg_stat_add(&cfqg->stats.sectors, bytes >> 9);
blkg_rwstat_add(&cfqg->stats.serviced, rw, 1);
blkg_rwstat_add(&cfqg->stats.service_bytes, rw, bytes);
}
static inline void cfqg_stats_update_completion(struct cfq_group *cfqg,
uint64_t start_time, uint64_t io_start_time, int rw)
{
struct cfqg_stats *stats = &cfqg->stats;
unsigned long long now = sched_clock();
if (time_after64(now, io_start_time))
blkg_rwstat_add(&stats->service_time, rw, now - io_start_time);
if (time_after64(io_start_time, start_time))
blkg_rwstat_add(&stats->wait_time, rw,
io_start_time - start_time);
}
/* @stats = 0 */
static void cfqg_stats_reset(struct cfqg_stats *stats)
{
/* queued stats shouldn't be cleared */
blkg_rwstat_reset(&stats->service_bytes);
blkg_rwstat_reset(&stats->serviced);
blkg_rwstat_reset(&stats->merged);
blkg_rwstat_reset(&stats->service_time);
blkg_rwstat_reset(&stats->wait_time);
blkg_stat_reset(&stats->time);
#ifdef CONFIG_DEBUG_BLK_CGROUP
blkg_stat_reset(&stats->unaccounted_time);
blkg_stat_reset(&stats->avg_queue_size_sum);
blkg_stat_reset(&stats->avg_queue_size_samples);
blkg_stat_reset(&stats->dequeue);
blkg_stat_reset(&stats->group_wait_time);
blkg_stat_reset(&stats->idle_time);
blkg_stat_reset(&stats->empty_time);
#endif
}
/* @to += @from */
static void cfqg_stats_merge(struct cfqg_stats *to, struct cfqg_stats *from)
{
/* queued stats shouldn't be cleared */
blkg_rwstat_merge(&to->service_bytes, &from->service_bytes);
blkg_rwstat_merge(&to->serviced, &from->serviced);
blkg_rwstat_merge(&to->merged, &from->merged);
blkg_rwstat_merge(&to->service_time, &from->service_time);
blkg_rwstat_merge(&to->wait_time, &from->wait_time);
blkg_stat_merge(&from->time, &from->time);
#ifdef CONFIG_DEBUG_BLK_CGROUP
blkg_stat_merge(&to->unaccounted_time, &from->unaccounted_time);
blkg_stat_merge(&to->avg_queue_size_sum, &from->avg_queue_size_sum);
blkg_stat_merge(&to->avg_queue_size_samples, &from->avg_queue_size_samples);
blkg_stat_merge(&to->dequeue, &from->dequeue);
blkg_stat_merge(&to->group_wait_time, &from->group_wait_time);
blkg_stat_merge(&to->idle_time, &from->idle_time);
blkg_stat_merge(&to->empty_time, &from->empty_time);
#endif
}
/*
* Transfer @cfqg's stats to its parent's dead_stats so that the ancestors'
* recursive stats can still account for the amount used by this cfqg after
* it's gone.
*/
static void cfqg_stats_xfer_dead(struct cfq_group *cfqg)
{
struct cfq_group *parent = cfqg_parent(cfqg);
lockdep_assert_held(cfqg_to_blkg(cfqg)->q->queue_lock);
if (unlikely(!parent))
return;
cfqg_stats_merge(&parent->dead_stats, &cfqg->stats);
cfqg_stats_merge(&parent->dead_stats, &cfqg->dead_stats);
cfqg_stats_reset(&cfqg->stats);
cfqg_stats_reset(&cfqg->dead_stats);
}
#else /* CONFIG_CFQ_GROUP_IOSCHED */
static inline struct cfq_group *cfqg_parent(struct cfq_group *cfqg) { return NULL; }
static inline void cfqg_get(struct cfq_group *cfqg) { }
static inline void cfqg_put(struct cfq_group *cfqg) { }
#define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
blk_add_trace_msg((cfqd)->queue, "cfq%d%c%c " fmt, (cfqq)->pid, \
cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \
cfqq_type((cfqq)) == SYNC_NOIDLE_WORKLOAD ? 'N' : ' ',\
##args)
#define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do {} while (0)
static inline void cfqg_stats_update_io_add(struct cfq_group *cfqg,
struct cfq_group *curr_cfqg, int rw) { }
static inline void cfqg_stats_update_timeslice_used(struct cfq_group *cfqg,
unsigned long time, unsigned long unaccounted_time) { }
static inline void cfqg_stats_update_io_remove(struct cfq_group *cfqg, int rw) { }
static inline void cfqg_stats_update_io_merged(struct cfq_group *cfqg, int rw) { }
static inline void cfqg_stats_update_dispatch(struct cfq_group *cfqg,
uint64_t bytes, int rw) { }
static inline void cfqg_stats_update_completion(struct cfq_group *cfqg,
uint64_t start_time, uint64_t io_start_time, int rw) { }
#endif /* CONFIG_CFQ_GROUP_IOSCHED */
#define cfq_log(cfqd, fmt, args...) \
blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args)
/* Traverses through cfq group service trees */
#define for_each_cfqg_st(cfqg, i, j, st) \
for (i = 0; i <= IDLE_WORKLOAD; i++) \
for (j = 0, st = i < IDLE_WORKLOAD ? &cfqg->service_trees[i][j]\
: &cfqg->service_tree_idle; \
(i < IDLE_WORKLOAD && j <= SYNC_WORKLOAD) || \
(i == IDLE_WORKLOAD && j == 0); \
j++, st = i < IDLE_WORKLOAD ? \
&cfqg->service_trees[i][j]: NULL) \
static inline bool cfq_io_thinktime_big(struct cfq_data *cfqd,
struct cfq_ttime *ttime, bool group_idle)
{
unsigned long slice;
if (!sample_valid(ttime->ttime_samples))
return false;
if (group_idle)
slice = cfqd->cfq_group_idle;
else
slice = cfqd->cfq_slice_idle;
return ttime->ttime_mean > slice;
}
static inline bool iops_mode(struct cfq_data *cfqd)
{
/*
* If we are not idling on queues and it is a NCQ drive, parallel
* execution of requests is on and measuring time is not possible
* in most of the cases until and unless we drive shallower queue
* depths and that becomes a performance bottleneck. In such cases
* switch to start providing fairness in terms of number of IOs.
*/
if (!cfqd->cfq_slice_idle && cfqd->hw_tag)
return true;
else
return false;
}
static inline enum wl_class_t cfqq_class(struct cfq_queue *cfqq)
{
if (cfq_class_idle(cfqq))
return IDLE_WORKLOAD;
if (cfq_class_rt(cfqq))
return RT_WORKLOAD;
return BE_WORKLOAD;
}
static enum wl_type_t cfqq_type(struct cfq_queue *cfqq)
{
if (!cfq_cfqq_sync(cfqq))
return ASYNC_WORKLOAD;
if (!cfq_cfqq_idle_window(cfqq))
return SYNC_NOIDLE_WORKLOAD;
return SYNC_WORKLOAD;
}
static inline int cfq_group_busy_queues_wl(enum wl_class_t wl_class,
struct cfq_data *cfqd,
struct cfq_group *cfqg)
{
if (wl_class == IDLE_WORKLOAD)
return cfqg->service_tree_idle.count;
return cfqg->service_trees[wl_class][ASYNC_WORKLOAD].count +
cfqg->service_trees[wl_class][SYNC_NOIDLE_WORKLOAD].count +
cfqg->service_trees[wl_class][SYNC_WORKLOAD].count;
}
static inline int cfqg_busy_async_queues(struct cfq_data *cfqd,
struct cfq_group *cfqg)
{
return cfqg->service_trees[RT_WORKLOAD][ASYNC_WORKLOAD].count +
cfqg->service_trees[BE_WORKLOAD][ASYNC_WORKLOAD].count;
}
static void cfq_dispatch_insert(struct request_queue *, struct request *);
static struct cfq_queue *cfq_get_queue(struct cfq_data *cfqd, bool is_sync,
struct cfq_io_cq *cic, struct bio *bio,
gfp_t gfp_mask);
static inline struct cfq_io_cq *icq_to_cic(struct io_cq *icq)
{
/* cic->icq is the first member, %NULL will convert to %NULL */
return container_of(icq, struct cfq_io_cq, icq);
}
static inline struct cfq_io_cq *cfq_cic_lookup(struct cfq_data *cfqd,
struct io_context *ioc)
{
if (ioc)
return icq_to_cic(ioc_lookup_icq(ioc, cfqd->queue));
return NULL;
}
static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_cq *cic, bool is_sync)
{
return cic->cfqq[is_sync];
}
static inline void cic_set_cfqq(struct cfq_io_cq *cic, struct cfq_queue *cfqq,
bool is_sync)
{
cic->cfqq[is_sync] = cfqq;
}
static inline struct cfq_data *cic_to_cfqd(struct cfq_io_cq *cic)
{
return cic->icq.q->elevator->elevator_data;
}
/*
* We regard a request as SYNC, if it's either a read or has the SYNC bit
* set (in which case it could also be direct WRITE).
*/
static inline bool cfq_bio_sync(struct bio *bio)
{
return bio_data_dir(bio) == READ || (bio->bi_rw & REQ_SYNC);
}
/*
* 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->busy_queues) {
cfq_log(cfqd, "schedule dispatch");
kblockd_schedule_work(cfqd->queue, &cfqd->unplug_work);
}
}
/*
* 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_slice(struct cfq_data *cfqd, bool sync,
unsigned short prio)
{
const int base_slice = cfqd->cfq_slice[sync];
WARN_ON(prio >= IOPRIO_BE_NR);
return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - prio));
}
static inline int
cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
{
return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio);
}
/**
* cfqg_scale_charge - scale disk time charge according to cfqg weight
* @charge: disk time being charged
* @vfraction: vfraction of the cfqg, fixed point w/ CFQ_SERVICE_SHIFT
*
* Scale @charge according to @vfraction, which is in range (0, 1]. The
* scaling is inversely proportional.
*
* scaled = charge / vfraction
*
* The result is also in fixed point w/ CFQ_SERVICE_SHIFT.
*/
static inline u64 cfqg_scale_charge(unsigned long charge,
unsigned int vfraction)
{
u64 c = charge << CFQ_SERVICE_SHIFT; /* make it fixed point */
/* charge / vfraction */
c <<= CFQ_SERVICE_SHIFT;
do_div(c, vfraction);
return c;
}
static inline u64 max_vdisktime(u64 min_vdisktime, u64 vdisktime)
{
s64 delta = (s64)(vdisktime - min_vdisktime);
if (delta > 0)
min_vdisktime = vdisktime;
return min_vdisktime;
}
static inline u64 min_vdisktime(u64 min_vdisktime, u64 vdisktime)
{
s64 delta = (s64)(vdisktime - min_vdisktime);
if (delta < 0)
min_vdisktime = vdisktime;
return min_vdisktime;
}
static void update_min_vdisktime(struct cfq_rb_root *st)
{
struct cfq_group *cfqg;
if (st->left) {
cfqg = rb_entry_cfqg(st->left);
st->min_vdisktime = max_vdisktime(st->min_vdisktime,
cfqg->vdisktime);
}
}
/*
* get averaged number of queues of RT/BE priority.
* average is updated, with a formula that gives more weight to higher numbers,
* to quickly follows sudden increases and decrease slowly
*/
static inline unsigned cfq_group_get_avg_queues(struct cfq_data *cfqd,
struct cfq_group *cfqg, bool rt)
{
unsigned min_q, max_q;
unsigned mult = cfq_hist_divisor - 1;
unsigned round = cfq_hist_divisor / 2;
unsigned busy = cfq_group_busy_queues_wl(rt, cfqd, cfqg);
min_q = min(cfqg->busy_queues_avg[rt], busy);
max_q = max(cfqg->busy_queues_avg[rt], busy);
cfqg->busy_queues_avg[rt] = (mult * max_q + min_q + round) /
cfq_hist_divisor;
return cfqg->busy_queues_avg[rt];
}
static inline unsigned
cfq_group_slice(struct cfq_data *cfqd, struct cfq_group *cfqg)
{
return cfqd->cfq_target_latency * cfqg->vfraction >> CFQ_SERVICE_SHIFT;
}
static inline unsigned
cfq_scaled_cfqq_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
{
unsigned slice = cfq_prio_to_slice(cfqd, cfqq);
if (cfqd->cfq_latency) {
/*
* interested queues (we consider only the ones with the same
* priority class in the cfq group)
*/
unsigned iq = cfq_group_get_avg_queues(cfqd, cfqq->cfqg,
cfq_class_rt(cfqq));
unsigned sync_slice = cfqd->cfq_slice[1];
unsigned expect_latency = sync_slice * iq;
unsigned group_slice = cfq_group_slice(cfqd, cfqq->cfqg);
if (expect_latency > group_slice) {
unsigned base_low_slice = 2 * cfqd->cfq_slice_idle;
/* scale low_slice according to IO priority
* and sync vs async */
unsigned low_slice =
min(slice, base_low_slice * slice / sync_slice);
/* the adapted slice value is scaled to fit all iqs
* into the target latency */
slice = max(slice * group_slice / expect_latency,
low_slice);
}
}
return slice;
}
static inline void
cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
{
unsigned slice = cfq_scaled_cfqq_slice(cfqd, cfqq);
cfqq->slice_start = jiffies;
cfqq->slice_end = jiffies + slice;
cfqq->allocated_slice = slice;
cfq_log_cfqq(cfqd, cfqq, "set_slice=%lu", cfqq->slice_end - jiffies);
}
/*
* We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end
* isn't valid until the first request from the dispatch is activated
* and the slice time set.
*/
static inline bool cfq_slice_used(struct cfq_queue *cfqq)
{
if (cfq_cfqq_slice_new(cfqq))
return false;
if (time_before(jiffies, cfqq->slice_end))
return false;
return true;
}
/*
* Lifted from AS - choose which of rq1 and rq2 that is best served now.
* We choose the request that is closest to the head right now. Distance
* behind the head is penalized and only allowed to a certain extent.
*/
static struct request *
cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2, sector_t last)
{
sector_t s1, s2, d1 = 0, d2 = 0;
unsigned long back_max;
#define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */
#define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */
unsigned wrap = 0; /* bit mask: requests behind the disk head? */
if (rq1 == NULL || rq1 == rq2)
return rq2;
if (rq2 == NULL)
return rq1;
if (rq_is_sync(rq1) != rq_is_sync(rq2))
return rq_is_sync(rq1) ? rq1 : rq2;
if ((rq1->cmd_flags ^ rq2->cmd_flags) & REQ_PRIO)
return rq1->cmd_flags & REQ_PRIO ? rq1 : rq2;
s1 = blk_rq_pos(rq1);
s2 = blk_rq_pos(rq2);
/*
* 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
wrap |= CFQ_RQ1_WRAP;
if (s2 >= last)
d2 = s2 - last;
else if (s2 + back_max >= last)
d2 = (last - s2) * cfqd->cfq_back_penalty;
else
wrap |= CFQ_RQ2_WRAP;
/* Found required data */
/*
* By doing switch() on the bit mask "wrap" we avoid having to
* check two variables for all permutations: --> faster!
*/
switch (wrap) {
case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
if (d1 < d2)
return rq1;
else if (d2 < d1)
return rq2;
else {
if (s1 >= s2)
return rq1;
else
return rq2;
}
case CFQ_RQ2_WRAP:
return rq1;
case CFQ_RQ1_WRAP:
return rq2;
case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */
default:
/*
* Since both rqs are wrapped,
* start with the one that's further behind head
* (--> only *one* back seek required),
* since back seek takes more time than forward.
*/
if (s1 <= s2)
return rq1;
else
return rq2;
}
}
/*
* The below is leftmost cache rbtree addon
*/
static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root)
{
/* Service tree is empty */
if (!root->count)
return NULL;
if (!root->left)
root->left = rb_first(&root->rb);
if (root->left)
return rb_entry(root->left, struct cfq_queue, rb_node);
return NULL;
}
static struct cfq_group *cfq_rb_first_group(struct cfq_rb_root *root)
{
if (!root->left)
root->left = rb_first(&root->rb);
if (root->left)
return rb_entry_cfqg(root->left);
return NULL;
}
static void rb_erase_init(struct rb_node *n, struct rb_root *root)
{
rb_erase(n, root);
RB_CLEAR_NODE(n);
}
static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root)
{
if (root->left == n)
root->left = NULL;
rb_erase_init(n, &root->rb);
--root->count;
}
/*
* would be nice to take fifo expire time into account as well
*/
static struct request *
cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
struct request *last)
{
struct rb_node *rbnext = rb_next(&last->rb_node);
struct rb_node *rbprev = rb_prev(&last->rb_node);
struct request *next = NULL, *prev = NULL;
BUG_ON(RB_EMPTY_NODE(&last->rb_node));
if (rbprev)
prev = rb_entry_rq(rbprev);
if (rbnext)
next = rb_entry_rq(rbnext);
else {
rbnext = rb_first(&cfqq->sort_list);
if (rbnext && rbnext != &last->rb_node)
next = rb_entry_rq(rbnext);
}
return cfq_choose_req(cfqd, next, prev, blk_rq_pos(last));
}
static unsigned long cfq_slice_offset(struct cfq_data *cfqd,
struct cfq_queue *cfqq)
{
/*
* just an approximation, should be ok.
*/
return (cfqq->cfqg->nr_cfqq - 1) * (cfq_prio_slice(cfqd, 1, 0) -
cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio));
}
static inline s64
cfqg_key(struct cfq_rb_root *st, struct cfq_group *cfqg)
{
return cfqg->vdisktime - st->min_vdisktime;
}
static void
__cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
{
struct rb_node **node = &st->rb.rb_node;
struct rb_node *parent = NULL;
struct cfq_group *__cfqg;
s64 key = cfqg_key(st, cfqg);
int left = 1;
while (*node != NULL) {
parent = *node;
__cfqg = rb_entry_cfqg(parent);
if (key < cfqg_key(st, __cfqg))
node = &parent->rb_left;
else {
node = &parent->rb_right;
left = 0;
}
}
if (left)
st->left = &cfqg->rb_node;
rb_link_node(&cfqg->rb_node, parent, node);
rb_insert_color(&cfqg->rb_node, &st->rb);
}
static void
cfq_update_group_weight(struct cfq_group *cfqg)
{
BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node));
if (cfqg->new_weight) {
cfqg->weight = cfqg->new_weight;
cfqg->new_weight = 0;
}
if (cfqg->new_leaf_weight) {
cfqg->leaf_weight = cfqg->new_leaf_weight;
cfqg->new_leaf_weight = 0;
}
}
static void
cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
{
unsigned int vfr = 1 << CFQ_SERVICE_SHIFT; /* start with 1 */
struct cfq_group *pos = cfqg;
struct cfq_group *parent;
bool propagate;
/* add to the service tree */
BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node));
cfq_update_group_weight(cfqg);
__cfq_group_service_tree_add(st, cfqg);
/*
* Activate @cfqg and calculate the portion of vfraction @cfqg is
* entitled to. vfraction is calculated by walking the tree
* towards the root calculating the fraction it has at each level.
* The compounded ratio is how much vfraction @cfqg owns.
*
* Start with the proportion tasks in this cfqg has against active
* children cfqgs - its leaf_weight against children_weight.
*/
propagate = !pos->nr_active++;
pos->children_weight += pos->leaf_weight;
vfr = vfr * pos->leaf_weight / pos->children_weight;
/*
* Compound ->weight walking up the tree. Both activation and
* vfraction calculation are done in the same loop. Propagation
* stops once an already activated node is met. vfraction
* calculation should always continue to the root.
*/
while ((parent = cfqg_parent(pos))) {
if (propagate) {
propagate = !parent->nr_active++;
parent->children_weight += pos->weight;
}
vfr = vfr * pos->weight / parent->children_weight;
pos = parent;
}
cfqg->vfraction = max_t(unsigned, vfr, 1);
}
static void
cfq_group_notify_queue_add(struct cfq_data *cfqd, struct cfq_group *cfqg)
{
struct cfq_rb_root *st = &cfqd->grp_service_tree;
struct cfq_group *__cfqg;
struct rb_node *n;
cfqg->nr_cfqq++;
if (!RB_EMPTY_NODE(&cfqg->rb_node))
return;
/*
* Currently put the group at the end. Later implement something
* so that groups get lesser vtime based on their weights, so that
* if group does not loose all if it was not continuously backlogged.
*/
n = rb_last(&st->rb);
if (n) {
__cfqg = rb_entry_cfqg(n);
cfqg->vdisktime = __cfqg->vdisktime + CFQ_IDLE_DELAY;
} else
cfqg->vdisktime = st->min_vdisktime;
cfq_group_service_tree_add(st, cfqg);
}
static void
cfq_group_service_tree_del(struct cfq_rb_root *st, struct cfq_group *cfqg)
{
struct cfq_group *pos = cfqg;
bool propagate;
/*
* Undo activation from cfq_group_service_tree_add(). Deactivate
* @cfqg and propagate deactivation upwards.
*/
propagate = !--pos->nr_active;
pos->children_weight -= pos->leaf_weight;
while (propagate) {
struct cfq_group *parent = cfqg_parent(pos);
/* @pos has 0 nr_active at this point */
WARN_ON_ONCE(pos->children_weight);
pos->vfraction = 0;
if (!parent)
break;
propagate = !--parent->nr_active;
parent->children_weight -= pos->weight;
pos = parent;
}
/* remove from the service tree */
if (!RB_EMPTY_NODE(&cfqg->rb_node))
cfq_rb_erase(&cfqg->rb_node, st);
}
static void
cfq_group_notify_queue_del(struct cfq_data *cfqd, struct cfq_group *cfqg)
{
struct cfq_rb_root *st = &cfqd->grp_service_tree;
BUG_ON(cfqg->nr_cfqq < 1);
cfqg->nr_cfqq--;
/* If there are other cfq queues under this group, don't delete it */
if (cfqg->nr_cfqq)
return;
cfq_log_cfqg(cfqd, cfqg, "del_from_rr group");
cfq_group_service_tree_del(st, cfqg);
cfqg->saved_wl_slice = 0;
cfqg_stats_update_dequeue(cfqg);
}
static inline unsigned int cfq_cfqq_slice_usage(struct cfq_queue *cfqq,
unsigned int *unaccounted_time)
{
unsigned int slice_used;
/*
* Queue got expired before even a single request completed or
* got expired immediately after first request completion.
*/
if (!cfqq->slice_start || cfqq->slice_start == jiffies) {
/*
* Also charge the seek time incurred to the group, otherwise
* if there are mutiple queues in the group, each can dispatch
* a single request on seeky media and cause lots of seek time
* and group will never know it.
*/
slice_used = max_t(unsigned, (jiffies - cfqq->dispatch_start),
1);
} else {
slice_used = jiffies - cfqq->slice_start;
if (slice_used > cfqq->allocated_slice) {
*unaccounted_time = slice_used - cfqq->allocated_slice;
slice_used = cfqq->allocated_slice;
}
if (time_after(cfqq->slice_start, cfqq->dispatch_start))
*unaccounted_time += cfqq->slice_start -
cfqq->dispatch_start;
}
return slice_used;
}
static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg,
struct cfq_queue *cfqq)
{
struct cfq_rb_root *st = &cfqd->grp_service_tree;
unsigned int used_sl, charge, unaccounted_sl = 0;
int nr_sync = cfqg->nr_cfqq - cfqg_busy_async_queues(cfqd, cfqg)
- cfqg->service_tree_idle.count;
unsigned int vfr;
BUG_ON(nr_sync < 0);
used_sl = charge = cfq_cfqq_slice_usage(cfqq, &unaccounted_sl);
if (iops_mode(cfqd))
charge = cfqq->slice_dispatch;
else if (!cfq_cfqq_sync(cfqq) && !nr_sync)
charge = cfqq->allocated_slice;
/*
* Can't update vdisktime while on service tree and cfqg->vfraction
* is valid only while on it. Cache vfr, leave the service tree,
* update vdisktime and go back on. The re-addition to the tree
* will also update the weights as necessary.
*/
vfr = cfqg->vfraction;
cfq_group_service_tree_del(st, cfqg);
cfqg->vdisktime += cfqg_scale_charge(charge, vfr);
cfq_group_service_tree_add(st, cfqg);
/* This group is being expired. Save the context */
if (time_after(cfqd->workload_expires, jiffies)) {
cfqg->saved_wl_slice = cfqd->workload_expires
- jiffies;
cfqg->saved_wl_type = cfqd->serving_wl_type;
cfqg->saved_wl_class = cfqd->serving_wl_class;
} else
cfqg->saved_wl_slice = 0;
cfq_log_cfqg(cfqd, cfqg, "served: vt=%llu min_vt=%llu", cfqg->vdisktime,
st->min_vdisktime);
cfq_log_cfqq(cfqq->cfqd, cfqq,
"sl_used=%u disp=%u charge=%u iops=%u sect=%lu",
used_sl, cfqq->slice_dispatch, charge,
iops_mode(cfqd), cfqq->nr_sectors);
cfqg_stats_update_timeslice_used(cfqg, used_sl, unaccounted_sl);
cfqg_stats_set_start_empty_time(cfqg);
}
/**
* cfq_init_cfqg_base - initialize base part of a cfq_group
* @cfqg: cfq_group to initialize
*
* Initialize the base part which is used whether %CONFIG_CFQ_GROUP_IOSCHED
* is enabled or not.
*/
static void cfq_init_cfqg_base(struct cfq_group *cfqg)
{
struct cfq_rb_root *st;
int i, j;
for_each_cfqg_st(cfqg, i, j, st)
*st = CFQ_RB_ROOT;
RB_CLEAR_NODE(&cfqg->rb_node);
cfqg->ttime.last_end_request = jiffies;
}
#ifdef CONFIG_CFQ_GROUP_IOSCHED
static void cfq_pd_init(struct blkcg_gq *blkg)
{
struct cfq_group *cfqg = blkg_to_cfqg(blkg);
cfq_init_cfqg_base(cfqg);
cfqg->weight = blkg->blkcg->cfq_weight;
cfqg->leaf_weight = blkg->blkcg->cfq_leaf_weight;
}
static void cfq_pd_offline(struct blkcg_gq *blkg)
{
/*
* @blkg is going offline and will be ignored by
* blkg_[rw]stat_recursive_sum(). Transfer stats to the parent so
* that they don't get lost. If IOs complete after this point, the
* stats for them will be lost. Oh well...
*/
cfqg_stats_xfer_dead(blkg_to_cfqg(blkg));
}
/* offset delta from cfqg->stats to cfqg->dead_stats */
static const int dead_stats_off_delta = offsetof(struct cfq_group, dead_stats) -
offsetof(struct cfq_group, stats);
/* to be used by recursive prfill, sums live and dead stats recursively */
static u64 cfqg_stat_pd_recursive_sum(struct blkg_policy_data *pd, int off)
{
u64 sum = 0;
sum += blkg_stat_recursive_sum(pd, off);
sum += blkg_stat_recursive_sum(pd, off + dead_stats_off_delta);
return sum;
}
/* to be used by recursive prfill, sums live and dead rwstats recursively */
static struct blkg_rwstat cfqg_rwstat_pd_recursive_sum(struct blkg_policy_data *pd,
int off)
{
struct blkg_rwstat a, b;
a = blkg_rwstat_recursive_sum(pd, off);
b = blkg_rwstat_recursive_sum(pd, off + dead_stats_off_delta);
blkg_rwstat_merge(&a, &b);
return a;
}
static void cfq_pd_reset_stats(struct blkcg_gq *blkg)
{
struct cfq_group *cfqg = blkg_to_cfqg(blkg);
cfqg_stats_reset(&cfqg->stats);
cfqg_stats_reset(&cfqg->dead_stats);
}
/*
* Search for the cfq group current task belongs to. request_queue lock must
* be held.
*/
static struct cfq_group *cfq_lookup_create_cfqg(struct cfq_data *cfqd,
struct blkcg *blkcg)
{
struct request_queue *q = cfqd->queue;
struct cfq_group *cfqg = NULL;
/* avoid lookup for the common case where there's no blkcg */
if (blkcg == &blkcg_root) {
cfqg = cfqd->root_group;
} else {
struct blkcg_gq *blkg;
blkg = blkg_lookup_create(blkcg, q);
if (!IS_ERR(blkg))
cfqg = blkg_to_cfqg(blkg);
}
return cfqg;
}
static void cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg)
{
/* Currently, all async queues are mapped to root group */
if (!cfq_cfqq_sync(cfqq))
cfqg = cfqq->cfqd->root_group;
cfqq->cfqg = cfqg;
/* cfqq reference on cfqg */
cfqg_get(cfqg);
}
static u64 cfqg_prfill_weight_device(struct seq_file *sf,
struct blkg_policy_data *pd, int off)
{
struct cfq_group *cfqg = pd_to_cfqg(pd);
if (!cfqg->dev_weight)
return 0;
return __blkg_prfill_u64(sf, pd, cfqg->dev_weight);
}
static int cfqg_print_weight_device(struct cgroup *cgrp, struct cftype *cft,
struct seq_file *sf)
{
blkcg_print_blkgs(sf, cgroup_to_blkcg(cgrp),
cfqg_prfill_weight_device, &blkcg_policy_cfq, 0,
false);
return 0;
}
static u64 cfqg_prfill_leaf_weight_device(struct seq_file *sf,
struct blkg_policy_data *pd, int off)
{
struct cfq_group *cfqg = pd_to_cfqg(pd);
if (!cfqg->dev_leaf_weight)
return 0;
return __blkg_prfill_u64(sf, pd, cfqg->dev_leaf_weight);
}
static int cfqg_print_leaf_weight_device(struct cgroup *cgrp,
struct cftype *cft,
struct seq_file *sf)
{
blkcg_print_blkgs(sf, cgroup_to_blkcg(cgrp),
cfqg_prfill_leaf_weight_device, &blkcg_policy_cfq, 0,
false);
return 0;
}
static int cfq_print_weight(struct cgroup *cgrp, struct cftype *cft,
struct seq_file *sf)
{
seq_printf(sf, "%u\n", cgroup_to_blkcg(cgrp)->cfq_weight);
return 0;
}
static int cfq_print_leaf_weight(struct cgroup *cgrp, struct cftype *cft,
struct seq_file *sf)
{
seq_printf(sf, "%u\n",
cgroup_to_blkcg(cgrp)->cfq_leaf_weight);
return 0;
}
static int __cfqg_set_weight_device(struct cgroup *cgrp, struct cftype *cft,
const char *buf, bool is_leaf_weight)
{
struct blkcg *blkcg = cgroup_to_blkcg(cgrp);
struct blkg_conf_ctx ctx;
struct cfq_group *cfqg;
int ret;
ret = blkg_conf_prep(blkcg, &blkcg_policy_cfq, buf, &ctx);
if (ret)
return ret;
ret = -EINVAL;
cfqg = blkg_to_cfqg(ctx.blkg);
if (!ctx.v || (ctx.v >= CFQ_WEIGHT_MIN && ctx.v <= CFQ_WEIGHT_MAX)) {
if (!is_leaf_weight) {
cfqg->dev_weight = ctx.v;
cfqg->new_weight = ctx.v ?: blkcg->cfq_weight;
} else {
cfqg->dev_leaf_weight = ctx.v;
cfqg->new_leaf_weight = ctx.v ?: blkcg->cfq_leaf_weight;
}
ret = 0;
}
blkg_conf_finish(&ctx);
return ret;
}
static int cfqg_set_weight_device(struct cgroup *cgrp, struct cftype *cft,
const char *buf)
{
return __cfqg_set_weight_device(cgrp, cft, buf, false);
}
static int cfqg_set_leaf_weight_device(struct cgroup *cgrp, struct cftype *cft,
const char *buf)
{
return __cfqg_set_weight_device(cgrp, cft, buf, true);
}
static int __cfq_set_weight(struct cgroup *cgrp, struct cftype *cft, u64 val,
bool is_leaf_weight)
{
struct blkcg *blkcg = cgroup_to_blkcg(cgrp);
struct blkcg_gq *blkg;
if (val < CFQ_WEIGHT_MIN || val > CFQ_WEIGHT_MAX)
return -EINVAL;
spin_lock_irq(&blkcg->lock);
if (!is_leaf_weight)
blkcg->cfq_weight = val;
else
blkcg->cfq_leaf_weight = val;
hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) {
struct cfq_group *cfqg = blkg_to_cfqg(blkg);
if (!cfqg)
continue;
if (!is_leaf_weight) {
if (!cfqg->dev_weight)
cfqg->new_weight = blkcg->cfq_weight;
} else {
if (!cfqg->dev_leaf_weight)
cfqg->new_leaf_weight = blkcg->cfq_leaf_weight;
}
}
spin_unlock_irq(&blkcg->lock);
return 0;
}
static int cfq_set_weight(struct cgroup *cgrp, struct cftype *cft, u64 val)
{
return __cfq_set_weight(cgrp, cft, val, false);
}
static int cfq_set_leaf_weight(struct cgroup *cgrp, struct cftype *cft, u64 val)
{
return __cfq_set_weight(cgrp, cft, val, true);
}
static int cfqg_print_stat(struct cgroup *cgrp, struct cftype *cft,
struct seq_file *sf)
{
struct blkcg *blkcg = cgroup_to_blkcg(cgrp);
blkcg_print_blkgs(sf, blkcg, blkg_prfill_stat, &blkcg_policy_cfq,
cft->private, false);
return 0;
}
static int cfqg_print_rwstat(struct cgroup *cgrp, struct cftype *cft,
struct seq_file *sf)
{
struct blkcg *blkcg = cgroup_to_blkcg(cgrp);
blkcg_print_blkgs(sf, blkcg, blkg_prfill_rwstat, &blkcg_policy_cfq,
cft->private, true);
return 0;
}
static u64 cfqg_prfill_stat_recursive(struct seq_file *sf,
struct blkg_policy_data *pd, int off)
{
u64 sum = cfqg_stat_pd_recursive_sum(pd, off);
return __blkg_prfill_u64(sf, pd, sum);
}
static u64 cfqg_prfill_rwstat_recursive(struct seq_file *sf,
struct blkg_policy_data *pd, int off)
{
struct blkg_rwstat sum = cfqg_rwstat_pd_recursive_sum(pd, off);
return __blkg_prfill_rwstat(sf, pd, &sum);
}
static int cfqg_print_stat_recursive(struct cgroup *cgrp, struct cftype *cft,
struct seq_file *sf)
{
struct blkcg *blkcg = cgroup_to_blkcg(cgrp);
blkcg_print_blkgs(sf, blkcg, cfqg_prfill_stat_recursive,
&blkcg_policy_cfq, cft->private, false);
return 0;
}
static int cfqg_print_rwstat_recursive(struct cgroup *cgrp, struct cftype *cft,
struct seq_file *sf)
{
struct blkcg *blkcg = cgroup_to_blkcg(cgrp);
blkcg_print_blkgs(sf, blkcg, cfqg_prfill_rwstat_recursive,
&blkcg_policy_cfq, cft->private, true);
return 0;
}
#ifdef CONFIG_DEBUG_BLK_CGROUP
static u64 cfqg_prfill_avg_queue_size(struct seq_file *sf,
struct blkg_policy_data *pd, int off)
{
struct cfq_group *cfqg = pd_to_cfqg(pd);
u64 samples = blkg_stat_read(&cfqg->stats.avg_queue_size_samples);
u64 v = 0;
if (samples) {
v = blkg_stat_read(&cfqg->stats.avg_queue_size_sum);
v = div64_u64(v, samples);
}
__blkg_prfill_u64(sf, pd, v);
return 0;
}
/* print avg_queue_size */
static int cfqg_print_avg_queue_size(struct cgroup *cgrp, struct cftype *cft,
struct seq_file *sf)
{
struct blkcg *blkcg = cgroup_to_blkcg(cgrp);
blkcg_print_blkgs(sf, blkcg, cfqg_prfill_avg_queue_size,
&blkcg_policy_cfq, 0, false);
return 0;
}
#endif /* CONFIG_DEBUG_BLK_CGROUP */
static struct cftype cfq_blkcg_files[] = {
/* on root, weight is mapped to leaf_weight */
{
.name = "weight_device",
.flags = CFTYPE_ONLY_ON_ROOT,
.read_seq_string = cfqg_print_leaf_weight_device,
.write_string = cfqg_set_leaf_weight_device,
.max_write_len = 256,
},
{
.name = "weight",
.flags = CFTYPE_ONLY_ON_ROOT,
.read_seq_string = cfq_print_leaf_weight,
.write_u64 = cfq_set_leaf_weight,
},
/* no such mapping necessary for !roots */
{
.name = "weight_device",
.flags = CFTYPE_NOT_ON_ROOT,
.read_seq_string = cfqg_print_weight_device,
.write_string = cfqg_set_weight_device,
.max_write_len = 256,
},
{
.name = "weight",
.flags = CFTYPE_NOT_ON_ROOT,
.read_seq_string = cfq_print_weight,
.write_u64 = cfq_set_weight,
},
{
.name = "leaf_weight_device",
.read_seq_string = cfqg_print_leaf_weight_device,
.write_string = cfqg_set_leaf_weight_device,
.max_write_len = 256,
},
{
.name = "leaf_weight",
.read_seq_string = cfq_print_leaf_weight,
.write_u64 = cfq_set_leaf_weight,
},
/* statistics, covers only the tasks in the cfqg */
{
.name = "time",
.private = offsetof(struct cfq_group, stats.time),
.read_seq_string = cfqg_print_stat,
},
{
.name = "sectors",
.private = offsetof(struct cfq_group, stats.sectors),
.read_seq_string = cfqg_print_stat,
},
{
.name = "io_service_bytes",
.private = offsetof(struct cfq_group, stats.service_bytes),
.read_seq_string = cfqg_print_rwstat,
},
{
.name = "io_serviced",
.private = offsetof(struct cfq_group, stats.serviced),
.read_seq_string = cfqg_print_rwstat,
},
{
.name = "io_service_time",
.private = offsetof(struct cfq_group, stats.service_time),
.read_seq_string = cfqg_print_rwstat,
},
{
.name = "io_wait_time",
.private = offsetof(struct cfq_group, stats.wait_time),
.read_seq_string = cfqg_print_rwstat,
},
{
.name = "io_merged",
.private = offsetof(struct cfq_group, stats.merged),
.read_seq_string = cfqg_print_rwstat,
},
{
.name = "io_queued",
.private = offsetof(struct cfq_group, stats.queued),
.read_seq_string = cfqg_print_rwstat,
},
/* the same statictics which cover the cfqg and its descendants */
{
.name = "time_recursive",
.private = offsetof(struct cfq_group, stats.time),
.read_seq_string = cfqg_print_stat_recursive,
},
{
.name = "sectors_recursive",
.private = offsetof(struct cfq_group, stats.sectors),
.read_seq_string = cfqg_print_stat_recursive,
},
{
.name = "io_service_bytes_recursive",
.private = offsetof(struct cfq_group, stats.service_bytes),
.read_seq_string = cfqg_print_rwstat_recursive,
},
{
.name = "io_serviced_recursive",
.private = offsetof(struct cfq_group, stats.serviced),
.read_seq_string = cfqg_print_rwstat_recursive,
},
{
.name = "io_service_time_recursive",
.private = offsetof(struct cfq_group, stats.service_time),
.read_seq_string = cfqg_print_rwstat_recursive,
},
{
.name = "io_wait_time_recursive",
.private = offsetof(struct cfq_group, stats.wait_time),
.read_seq_string = cfqg_print_rwstat_recursive,
},
{
.name = "io_merged_recursive",
.private = offsetof(struct cfq_group, stats.merged),
.read_seq_string = cfqg_print_rwstat_recursive,
},
{
.name = "io_queued_recursive",
.private = offsetof(struct cfq_group, stats.queued),
.read_seq_string = cfqg_print_rwstat_recursive,
},
#ifdef CONFIG_DEBUG_BLK_CGROUP
{
.name = "avg_queue_size",
.read_seq_string = cfqg_print_avg_queue_size,
},
{
.name = "group_wait_time",
.private = offsetof(struct cfq_group, stats.group_wait_time),
.read_seq_string = cfqg_print_stat,
},
{
.name = "idle_time",
.private = offsetof(struct cfq_group, stats.idle_time),
.read_seq_string = cfqg_print_stat,
},
{
.name = "empty_time",
.private = offsetof(struct cfq_group, stats.empty_time),
.read_seq_string = cfqg_print_stat,
},
{
.name = "dequeue",
.private = offsetof(struct cfq_group, stats.dequeue),
.read_seq_string = cfqg_print_stat,
},
{
.name = "unaccounted_time",
.private = offsetof(struct cfq_group, stats.unaccounted_time),
.read_seq_string = cfqg_print_stat,
},
#endif /* CONFIG_DEBUG_BLK_CGROUP */
{ } /* terminate */
};
#else /* GROUP_IOSCHED */
static struct cfq_group *cfq_lookup_create_cfqg(struct cfq_data *cfqd,
struct blkcg *blkcg)
{
return cfqd->root_group;
}
static inline void
cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) {
cfqq->cfqg = cfqg;
}
#endif /* GROUP_IOSCHED */
/*
* The cfqd->service_trees holds all pending cfq_queue's that have
* requests waiting to be processed. It is sorted in the order that
* we will service the queues.
*/
static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
bool add_front)
{
struct rb_node **p, *parent;
struct cfq_queue *__cfqq;
unsigned long rb_key;
struct cfq_rb_root *st;
int left;
int new_cfqq = 1;
st = st_for(cfqq->cfqg, cfqq_class(cfqq), cfqq_type(cfqq));
if (cfq_class_idle(cfqq)) {
rb_key = CFQ_IDLE_DELAY;
parent = rb_last(&st->rb);
if (parent && parent != &cfqq->rb_node) {
__cfqq = rb_entry(parent, struct cfq_queue, rb_node);
rb_key += __cfqq->rb_key;
} else
rb_key += jiffies;
} else if (!add_front) {
/*
* Get our rb key offset. Subtract any residual slice
* value carried from last service. A negative resid
* count indicates slice overrun, and this should position
* the next service time further away in the tree.
*/
rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies;
rb_key -= cfqq->slice_resid;
cfqq->slice_resid = 0;
} else {
rb_key = -HZ;
__cfqq = cfq_rb_first(st);
rb_key += __cfqq ? __cfqq->rb_key : jiffies;
}
if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
new_cfqq = 0;
/*
* same position, nothing more to do
*/
if (rb_key == cfqq->rb_key && cfqq->service_tree == st)
return;
cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
cfqq->service_tree = NULL;
}
left = 1;
parent = NULL;
cfqq->service_tree = st;
p = &st->rb.rb_node;
while (*p) {
parent = *p;
__cfqq = rb_entry(parent, struct cfq_queue, rb_node);
/*
* sort by key, that represents service time.
*/
if (time_before(rb_key, __cfqq->rb_key))
p = &parent->rb_left;
else {
p = &parent->rb_right;
left = 0;
}
}
if (left)
st->left = &cfqq->rb_node;
cfqq->rb_key = rb_key;
rb_link_node(&cfqq->rb_node, parent, p);
rb_insert_color(&cfqq->rb_node, &st->rb);
st->count++;
if (add_front || !new_cfqq)
return;
cfq_group_notify_queue_add(cfqd, cfqq->cfqg);
}
static struct cfq_queue *
cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root,
sector_t sector, struct rb_node **ret_parent,
struct rb_node ***rb_link)
{
struct rb_node **p, *parent;
struct cfq_queue *cfqq = NULL;
parent = NULL;
p = &root->rb_node;
while (*p) {
struct rb_node **n;
parent = *p;
cfqq = rb_entry(parent, struct cfq_queue, p_node);
/*
* Sort strictly based on sector. Smallest to the left,
* largest to the right.
*/
if (sector > blk_rq_pos(cfqq->next_rq))
n = &(*p)->rb_right;
else if (sector < blk_rq_pos(cfqq->next_rq))
n = &(*p)->rb_left;
else
break;
p = n;
cfqq = NULL;
}
*ret_parent = parent;
if (rb_link)
*rb_link = p;
return cfqq;
}
static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq)
{
struct rb_node **p, *parent;
struct cfq_queue *__cfqq;
if (cfqq->p_root) {
rb_erase(&cfqq->p_node, cfqq->p_root);
cfqq->p_root = NULL;
}
if (cfq_class_idle(cfqq))
return;
if (!cfqq->next_rq)
return;
cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio];
__cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root,
blk_rq_pos(cfqq->next_rq), &parent, &p);
if (!__cfqq) {
rb_link_node(&cfqq->p_node, parent, p);
rb_insert_color(&cfqq->p_node, cfqq->p_root);
} else
cfqq->p_root = NULL;
}
/*
* Update cfqq's position in the service tree.
*/
static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq)
{
/*
* Resorting requires the cfqq to be on the RR list already.
*/
if (cfq_cfqq_on_rr(cfqq)) {
cfq_service_tree_add(cfqd, cfqq, 0);
cfq_prio_tree_add(cfqd, cfqq);
}
}
/*
* add to busy list of queues for service, trying to be fair in ordering
* the pending list according to last request service
*/
static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
{
cfq_log_cfqq(cfqd, cfqq, "add_to_rr");
BUG_ON(cfq_cfqq_on_rr(cfqq));
cfq_mark_cfqq_on_rr(cfqq);
cfqd->busy_queues++;
if (cfq_cfqq_sync(cfqq))
cfqd->busy_sync_queues++;
cfq_resort_rr_list(cfqd, cfqq);
}
/*
* Called when the cfqq no longer has requests pending, remove it from
* the service tree.
*/
static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
{
cfq_log_cfqq(cfqd, cfqq, "del_from_rr");
BUG_ON(!cfq_cfqq_on_rr(cfqq));
cfq_clear_cfqq_on_rr(cfqq);
if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
cfqq->service_tree = NULL;
}
if (cfqq->p_root) {
rb_erase(&cfqq->p_node, cfqq->p_root);
cfqq->p_root = NULL;
}
cfq_group_notify_queue_del(cfqd, cfqq->cfqg);
BUG_ON(!cfqd->busy_queues);
cfqd->busy_queues--;
if (cfq_cfqq_sync(cfqq))
cfqd->busy_sync_queues--;
}
/*
* rb tree support functions
*/
static void cfq_del_rq_rb(struct request *rq)
{
struct cfq_queue *cfqq = RQ_CFQQ(rq);
const int sync = rq_is_sync(rq);
BUG_ON(!cfqq->queued[sync]);
cfqq->queued[sync]--;
elv_rb_del(&cfqq->sort_list, rq);
if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) {
/*
* Queue will be deleted from service tree when we actually
* expire it later. Right now just remove it from prio tree
* as it is empty.
*/
if (cfqq->p_root) {
rb_erase(&cfqq->p_node, cfqq->p_root);
cfqq->p_root = NULL;
}
}
}
static void cfq_add_rq_rb(struct request *rq)
{
struct cfq_queue *cfqq = RQ_CFQQ(rq);
struct cfq_data *cfqd = cfqq->cfqd;
struct request *prev;
cfqq->queued[rq_is_sync(rq)]++;
elv_rb_add(&cfqq->sort_list, rq);
if (!cfq_cfqq_on_rr(cfqq))
cfq_add_cfqq_rr(cfqd, cfqq);
/*
* check if this request is a better next-serve candidate
*/
prev = cfqq->next_rq;
cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq, cfqd->last_position);
/*
* adjust priority tree position, if ->next_rq changes
*/
if (prev != cfqq->next_rq)
cfq_prio_tree_add(cfqd, cfqq);
BUG_ON(!cfqq->next_rq);
}
static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq)
{
elv_rb_del(&cfqq->sort_list, rq);
cfqq->queued[rq_is_sync(rq)]--;
cfqg_stats_update_io_remove(RQ_CFQG(rq), rq->cmd_flags);
cfq_add_rq_rb(rq);
cfqg_stats_update_io_add(RQ_CFQG(rq), cfqq->cfqd->serving_group,
rq->cmd_flags);
}
static struct request *
cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio)
{
struct task_struct *tsk = current;
struct cfq_io_cq *cic;
struct cfq_queue *cfqq;
cic = cfq_cic_lookup(cfqd, tsk->io_context);
if (!cic)
return NULL;
cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
if (cfqq)
return elv_rb_find(&cfqq->sort_list, bio_end_sector(bio));
return NULL;
}
static void cfq_activate_request(struct request_queue *q, struct request *rq)
{
struct cfq_data *cfqd = q->elevator->elevator_data;
cfqd->rq_in_driver++;
cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d",
cfqd->rq_in_driver);
cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq);
}
static void cfq_deactivate_request(struct request_queue *q, struct request *rq)
{
struct cfq_data *cfqd = q->elevator->elevator_data;
WARN_ON(!cfqd->rq_in_driver);
cfqd->rq_in_driver--;
cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d",
cfqd->rq_in_driver);
}
static void cfq_remove_request(struct request *rq)
{
struct cfq_queue *cfqq = RQ_CFQQ(rq);
if (cfqq->next_rq == rq)
cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq);
list_del_init(&rq->queuelist);
cfq_del_rq_rb(rq);
cfqq->cfqd->rq_queued--;
cfqg_stats_update_io_remove(RQ_CFQG(rq), rq->cmd_flags);
if (rq->cmd_flags & REQ_PRIO) {
WARN_ON(!cfqq->prio_pending);
cfqq->prio_pending--;
}
}
static int cfq_merge(struct request_queue *q, struct request **req,
struct bio *bio)
{
struct cfq_data *cfqd = q->elevator->elevator_data;
struct request *__rq;
__rq = cfq_find_rq_fmerge(cfqd, bio);
if (__rq && elv_rq_merge_ok(__rq, bio)) {
*req = __rq;
return ELEVATOR_FRONT_MERGE;
}
return ELEVATOR_NO_MERGE;
}
static void cfq_merged_request(struct request_queue *q, struct request *req,
int type)
{
if (type == ELEVATOR_FRONT_MERGE) {
struct cfq_queue *cfqq = RQ_CFQQ(req);
cfq_reposition_rq_rb(cfqq, req);
}
}
static void cfq_bio_merged(struct request_queue *q, struct request *req,
struct bio *bio)
{
cfqg_stats_update_io_merged(RQ_CFQG(req), bio->bi_rw);
}
static void
cfq_merged_requests(struct request_queue *q, struct request *rq,
struct request *next)
{
struct cfq_queue *cfqq = RQ_CFQQ(rq);
struct cfq_data *cfqd = q->elevator->elevator_data;
/*
* reposition in fifo if next is older than rq
*/
if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) &&
time_before(rq_fifo_time(next), rq_fifo_time(rq)) &&
cfqq == RQ_CFQQ(next)) {
list_move(&rq->queuelist, &next->queuelist);
rq_set_fifo_time(rq, rq_fifo_time(next));
}
if (cfqq->next_rq == next)
cfqq->next_rq = rq;
cfq_remove_request(next);
cfqg_stats_update_io_merged(RQ_CFQG(rq), next->cmd_flags);
cfqq = RQ_CFQQ(next);
/*
* all requests of this queue are merged to other queues, delete it
* from the service tree. If it's the active_queue,
* cfq_dispatch_requests() will choose to expire it or do idle
*/
if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list) &&
cfqq != cfqd->active_queue)
cfq_del_cfqq_rr(cfqd, cfqq);
}
static int cfq_allow_merge(struct request_queue *q, struct request *rq,
struct bio *bio)
{
struct cfq_data *cfqd = q->elevator->elevator_data;
struct cfq_io_cq *cic;
struct cfq_queue *cfqq;
/*
* Disallow merge of a sync bio into an async request.
*/
if (cfq_bio_sync(bio) && !rq_is_sync(rq))
return false;
/*
* Lookup the cfqq that this bio will be queued with and allow
* merge only if rq is queued there.
*/
cic = cfq_cic_lookup(cfqd, current->io_context);
if (!cic)
return false;
cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
return cfqq == RQ_CFQQ(rq);
}
static inline void cfq_del_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq)
{
del_timer(&cfqd->idle_slice_timer);
cfqg_stats_update_idle_time(cfqq->cfqg);
}
static void __cfq_set_active_queue(struct cfq_data *cfqd,
struct cfq_queue *cfqq)
{
if (cfqq) {
cfq_log_cfqq(cfqd, cfqq, "set_active wl_class:%d wl_type:%d",
cfqd->serving_wl_class, cfqd->serving_wl_type);
cfqg_stats_update_avg_queue_size(cfqq->cfqg);
cfqq->slice_start = 0;
cfqq->dispatch_start = jiffies;
cfqq->allocated_slice = 0;
cfqq->slice_end = 0;
cfqq->slice_dispatch = 0;
cfqq->nr_sectors = 0;
cfq_clear_cfqq_wait_request(cfqq);
cfq_clear_cfqq_must_dispatch(cfqq);
cfq_clear_cfqq_must_alloc_slice(cfqq);
cfq_clear_cfqq_fifo_expire(cfqq);
cfq_mark_cfqq_slice_new(cfqq);
cfq_del_timer(cfqd, cfqq);
}
cfqd->active_queue = 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,
bool timed_out)
{
cfq_log_cfqq(cfqd, cfqq, "slice expired t=%d", timed_out);
if (cfq_cfqq_wait_request(cfqq))
cfq_del_timer(cfqd, cfqq);
cfq_clear_cfqq_wait_request(cfqq);
cfq_clear_cfqq_wait_busy(cfqq);
/*
* If this cfqq is shared between multiple processes, check to
* make sure that those processes are still issuing I/Os within
* the mean seek distance. If not, it may be time to break the
* queues apart again.
*/
if (cfq_cfqq_coop(cfqq) && CFQQ_SEEKY(cfqq))
cfq_mark_cfqq_split_coop(cfqq);
/*
* store what was left of this slice, if the queue idled/timed out
*/
if (timed_out) {
if (cfq_cfqq_slice_new(cfqq))
cfqq->slice_resid = cfq_scaled_cfqq_slice(cfqd, cfqq);
else
cfqq->slice_resid = cfqq->slice_end - jiffies;
cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid);
}
cfq_group_served(cfqd, cfqq->cfqg, cfqq);
if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list))
cfq_del_cfqq_rr(cfqd, cfqq);
cfq_resort_rr_list(cfqd, cfqq);
if (cfqq == cfqd->active_queue)
cfqd->active_queue = NULL;
if (cfqd->active_cic) {
put_io_context(cfqd->active_cic->icq.ioc);
cfqd->active_cic = NULL;
}
}
static inline void cfq_slice_expired(struct cfq_data *cfqd, bool timed_out)
{
struct cfq_queue *cfqq = cfqd->active_queue;
if (cfqq)
__cfq_slice_expired(cfqd, cfqq, timed_out);
}
/*
* Get next queue for service. Unless we have a queue preemption,
* we'll simply select the first cfqq in the service tree.
*/
static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd)
{
struct cfq_rb_root *st = st_for(cfqd->serving_group,
cfqd->serving_wl_class, cfqd->serving_wl_type);
if (!cfqd->rq_queued)
return NULL;
/* There is nothing to dispatch */
if (!st)
return NULL;
if (RB_EMPTY_ROOT(&st->rb))
return NULL;
return cfq_rb_first(st);
}
static struct cfq_queue *cfq_get_next_queue_forced(struct cfq_data *cfqd)
{
struct cfq_group *cfqg;
struct cfq_queue *cfqq;
int i, j;
struct cfq_rb_root *st;
if (!cfqd->rq_queued)
return NULL;
cfqg = cfq_get_next_cfqg(cfqd);
if (!cfqg)
return NULL;
for_each_cfqg_st(cfqg, i, j, st)
if ((cfqq = cfq_rb_first(st)) != NULL)
return cfqq;
return NULL;
}
/*
* Get and set a new active queue for service.
*/
static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd,
struct cfq_queue *cfqq)
{
if (!cfqq)
cfqq = cfq_get_next_queue(cfqd);
__cfq_set_active_queue(cfqd, cfqq);
return cfqq;
}
static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd,
struct request *rq)
{
if (blk_rq_pos(rq) >= cfqd->last_position)
return blk_rq_pos(rq) - cfqd->last_position;
else
return cfqd->last_position - blk_rq_pos(rq);
}
static inline int cfq_rq_close(struct cfq_data *cfqd, struct cfq_queue *cfqq,
struct request *rq)
{
return cfq_dist_from_last(cfqd, rq) <= CFQQ_CLOSE_THR;
}
static struct cfq_queue *cfqq_close(struct cfq_data *cfqd,
struct cfq_queue *cur_cfqq)
{
struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio];
struct rb_node *parent, *node;
struct cfq_queue *__cfqq;
sector_t sector = cfqd->last_position;
if (RB_EMPTY_ROOT(root))
return NULL;
/*
* First, if we find a request starting at the end of the last
* request, choose it.
*/
__cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL);
if (__cfqq)
return __cfqq;
/*
* If the exact sector wasn't found, the parent of the NULL leaf
* will contain the closest sector.
*/
__cfqq = rb_entry(parent, struct cfq_queue, p_node);
if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
return __cfqq;
if (blk_rq_pos(__cfqq->next_rq) < sector)
node = rb_next(&__cfqq->p_node);
else
node = rb_prev(&__cfqq->p_node);
if (!node)
return NULL;
__cfqq = rb_entry(node, struct cfq_queue, p_node);
if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
return __cfqq;
return NULL;
}
/*
* cfqd - obvious
* cur_cfqq - passed in so that we don't decide that the current queue is
* closely cooperating with itself.
*
* So, basically we're assuming that that cur_cfqq has dispatched at least
* one request, and that cfqd->last_position reflects a position on the disk
* associated with the I/O issued by cur_cfqq. I'm not sure this is a valid
* assumption.
*/
static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd,
struct cfq_queue *cur_cfqq)
{
struct cfq_queue *cfqq;
if (cfq_class_idle(cur_cfqq))
return NULL;
if (!cfq_cfqq_sync(cur_cfqq))
return NULL;
if (CFQQ_SEEKY(cur_cfqq))
return NULL;
/*
* Don't search priority tree if it's the only queue in the group.
*/
if (cur_cfqq->cfqg->nr_cfqq == 1)
return NULL;
/*
* We should notice if some of the queues are cooperating, eg
* working closely on the same area of the disk. In that case,
* we can group them together and don't waste time idling.
*/
cfqq = cfqq_close(cfqd, cur_cfqq);
if (!cfqq)
return NULL;
/* If new queue belongs to different cfq_group, don't choose it */
if (cur_cfqq->cfqg != cfqq->cfqg)
return NULL;
/*
* It only makes sense to merge sync queues.
*/
if (!cfq_cfqq_sync(cfqq))
return NULL;
if (CFQQ_SEEKY(cfqq))
return NULL;
/*
* Do not merge queues of different priority classes
*/
if (cfq_class_rt(cfqq) != cfq_class_rt(cur_cfqq))
return NULL;
return cfqq;
}
/*
* Determine whether we should enforce idle window for this queue.
*/
static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq)
{
enum wl_class_t wl_class = cfqq_class(cfqq);
struct cfq_rb_root *st = cfqq->service_tree;
BUG_ON(!st);
BUG_ON(!st->count);
if (!cfqd->cfq_slice_idle)
return false;
/* We never do for idle class queues. */
if (wl_class == IDLE_WORKLOAD)
return false;
/* We do for queues that were marked with idle window flag. */
if (cfq_cfqq_idle_window(cfqq) &&
!(blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag))
return true;
/*
* Otherwise, we do only if they are the last ones
* in their service tree.
*/
if (st->count == 1 && cfq_cfqq_sync(cfqq) &&
!cfq_io_thinktime_big(cfqd, &st->ttime, false))
return true;
cfq_log_cfqq(cfqd, cfqq, "Not idling. st->count:%d", st->count);
return false;
}
static void cfq_arm_slice_timer(struct cfq_data *cfqd)
{
struct cfq_queue *cfqq = cfqd->active_queue;
struct cfq_io_cq *cic;
unsigned long sl, group_idle = 0;
/*
* SSD device without seek penalty, disable idling. But only do so
* for devices that support queuing, otherwise we still have a problem
* with sync vs async workloads.
*/
if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag)
return;
WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list));
WARN_ON(cfq_cfqq_slice_new(cfqq));
/*
* idle is disabled, either manually or by past process history
*/
if (!cfq_should_idle(cfqd, cfqq)) {
/* no queue idling. Check for group idling */
if (cfqd->cfq_group_idle)
group_idle = cfqd->cfq_group_idle;
else
return;
}
/*
* still active requests from this queue, don't idle
*/
if (cfqq->dispatched)
return;
/*
* task has exited, don't wait
*/
cic = cfqd->active_cic;
if (!cic || !atomic_read(&cic->icq.ioc->active_ref))
return;
/*
* If our average think time is larger than the remaining time
* slice, then don't idle. This avoids overrunning the allotted
* time slice.
*/
if (sample_valid(cic->ttime.ttime_samples) &&
(cfqq->slice_end - jiffies < cic->ttime.ttime_mean)) {
cfq_log_cfqq(cfqd, cfqq, "Not idling. think_time:%lu",
cic->ttime.ttime_mean);
return;
}
/* There are other queues in the group, don't do group idle */
if (group_idle && cfqq->cfqg->nr_cfqq > 1)
return;
cfq_mark_cfqq_wait_request(cfqq);
if (group_idle)
sl = cfqd->cfq_group_idle;
else
sl = cfqd->cfq_slice_idle;
mod_timer(&cfqd->idle_slice_timer, jiffies + sl);
cfqg_stats_set_start_idle_time(cfqq->cfqg);
cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu group_idle: %d", sl,
group_idle ? 1 : 0);
}
/*
* Move request from internal lists to the request queue dispatch list.
*/
static void cfq_dispatch_insert(struct request_queue *q, struct request *rq)
{
struct cfq_data *cfqd = q->elevator->elevator_data;
struct cfq_queue *cfqq = RQ_CFQQ(rq);
cfq_log_cfqq(cfqd, cfqq, "dispatch_insert");
cfqq->next_rq = cfq_find_next_rq(cfqd, cfqq, rq);
cfq_remove_request(rq);
cfqq->dispatched++;
(RQ_CFQG(rq))->dispatched++;
elv_dispatch_sort(q, rq);
cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]++;
cfqq->nr_sectors += blk_rq_sectors(rq);
cfqg_stats_update_dispatch(cfqq->cfqg, blk_rq_bytes(rq), rq->cmd_flags);
}
/*
* return expired entry, or NULL to just start from scratch in rbtree
*/
static struct request *cfq_check_fifo(struct cfq_queue *cfqq)
{
struct request *rq = NULL;
if (cfq_cfqq_fifo_expire(cfqq))
return NULL;
cfq_mark_cfqq_fifo_expire(cfqq);
if (list_empty(&cfqq->fifo))
return NULL;
rq = rq_entry_fifo(cfqq->fifo.next);
if (time_before(jiffies, rq_fifo_time(rq)))
rq = NULL;
cfq_log_cfqq(cfqq->cfqd, cfqq, "fifo=%p", rq);
return rq;
}
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 * (IOPRIO_BE_NR - cfqq->ioprio);
}
/*
* Must be called with the queue_lock held.
*/
static int cfqq_process_refs(struct cfq_queue *cfqq)
{
int process_refs, io_refs;
io_refs = cfqq->allocated[READ] + cfqq->allocated[WRITE];
process_refs = cfqq->ref - io_refs;
BUG_ON(process_refs < 0);
return process_refs;
}
static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq)
{
int process_refs, new_process_refs;
struct cfq_queue *__cfqq;
/*
* If there are no process references on the new_cfqq, then it is
* unsafe to follow the ->new_cfqq chain as other cfqq's in the
* chain may have dropped their last reference (not just their
* last process reference).
*/
if (!cfqq_process_refs(new_cfqq))
return;
/* Avoid a circular list and skip interim queue merges */
while ((__cfqq = new_cfqq->new_cfqq)) {
if (__cfqq == cfqq)
return;
new_cfqq = __cfqq;
}
process_refs = cfqq_process_refs(cfqq);
new_process_refs = cfqq_process_refs(new_cfqq);
/*
* If the process for the cfqq has gone away, there is no
* sense in merging the queues.
*/
if (process_refs == 0 || new_process_refs == 0)
return;
/*
* Merge in the direction of the lesser amount of work.
*/
if (new_process_refs >= process_refs) {
cfqq->new_cfqq = new_cfqq;
new_cfqq->ref += process_refs;
} else {
new_cfqq->new_cfqq = cfqq;
cfqq->ref += new_process_refs;
}
}
static enum wl_type_t cfq_choose_wl_type(struct cfq_data *cfqd,
struct cfq_group *cfqg, enum wl_class_t wl_class)
{
struct cfq_queue *queue;
int i;
bool key_valid = false;
unsigned long lowest_key = 0;
enum wl_type_t cur_best = SYNC_NOIDLE_WORKLOAD;
for (i = 0; i <= SYNC_WORKLOAD; ++i) {
/* select the one with lowest rb_key */
queue = cfq_rb_first(st_for(cfqg, wl_class, i));
if (queue &&
(!key_valid || time_before(queue->rb_key, lowest_key))) {
lowest_key = queue->rb_key;
cur_best = i;
key_valid = true;
}
}
return cur_best;
}
static void
choose_wl_class_and_type(struct cfq_data *cfqd, struct cfq_group *cfqg)
{
unsigned slice;
unsigned count;
struct cfq_rb_root *st;
unsigned group_slice;
enum wl_class_t original_class = cfqd->serving_wl_class;
/* Choose next priority. RT > BE > IDLE */
if (cfq_group_busy_queues_wl(RT_WORKLOAD, cfqd, cfqg))
cfqd->serving_wl_class = RT_WORKLOAD;
else if (cfq_group_busy_queues_wl(BE_WORKLOAD, cfqd, cfqg))
cfqd->serving_wl_class = BE_WORKLOAD;
else {
cfqd->serving_wl_class = IDLE_WORKLOAD;
cfqd->workload_expires = jiffies + 1;
return;
}
if (original_class != cfqd->serving_wl_class)
goto new_workload;
/*
* For RT and BE, we have to choose also the type
* (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload
* expiration time
*/
st = st_for(cfqg, cfqd->serving_wl_class, cfqd->serving_wl_type);
count = st->count;
/*
* check workload expiration, and that we still have other queues ready
*/
if (count && !time_after(jiffies, cfqd->workload_expires))
return;
new_workload:
/* otherwise select new workload type */
cfqd->serving_wl_type = cfq_choose_wl_type(cfqd, cfqg,
cfqd->serving_wl_class);
st = st_for(cfqg, cfqd->serving_wl_class, cfqd->serving_wl_type);
count = st->count;
/*
* the workload slice is computed as a fraction of target latency
* proportional to the number of queues in that workload, over
* all the queues in the same priority class
*/
group_slice = cfq_group_slice(cfqd, cfqg);
slice = group_slice * count /
max_t(unsigned, cfqg->busy_queues_avg[cfqd->serving_wl_class],
cfq_group_busy_queues_wl(cfqd->serving_wl_class, cfqd,
cfqg));
if (cfqd->serving_wl_type == ASYNC_WORKLOAD) {
unsigned int tmp;
/*
* Async queues are currently system wide. Just taking
* proportion of queues with-in same group will lead to higher
* async ratio system wide as generally root group is going
* to have higher weight. A more accurate thing would be to
* calculate system wide asnc/sync ratio.
*/
tmp = cfqd->cfq_target_latency *
cfqg_busy_async_queues(cfqd, cfqg);
tmp = tmp/cfqd->busy_queues;
slice = min_t(unsigned, slice, tmp);
/* async workload slice is scaled down according to
* the sync/async slice ratio. */
slice = slice * cfqd->cfq_slice[0] / cfqd->cfq_slice[1];
} else
/* sync workload slice is at least 2 * cfq_slice_idle */
slice = max(slice, 2 * cfqd->cfq_slice_idle);
slice = max_t(unsigned, slice, CFQ_MIN_TT);
cfq_log(cfqd, "workload slice:%d", slice);
cfqd->workload_expires = jiffies + slice;
}
static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd)
{
struct cfq_rb_root *st = &cfqd->grp_service_tree;
struct cfq_group *cfqg;
if (RB_EMPTY_ROOT(&st->rb))
return NULL;
cfqg = cfq_rb_first_group(st);
update_min_vdisktime(st);
return cfqg;
}
static void cfq_choose_cfqg(struct cfq_data *cfqd)
{
struct cfq_group *cfqg = cfq_get_next_cfqg(cfqd);
cfqd->serving_group = cfqg;
/* Restore the workload type data */
if (cfqg->saved_wl_slice) {
cfqd->workload_expires = jiffies + cfqg->saved_wl_slice;
cfqd->serving_wl_type = cfqg->saved_wl_type;
cfqd->serving_wl_class = cfqg->saved_wl_class;
} else
cfqd->workload_expires = jiffies - 1;
choose_wl_class_and_type(cfqd, cfqg);
}
/*
* Select a queue for service. If we have a current active queue,
* check whether to continue servicing it, or retrieve and set a new one.
*/
static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
{
struct cfq_queue *cfqq, *new_cfqq = NULL;
cfqq = cfqd->active_queue;
if (!cfqq)
goto new_queue;
if (!cfqd->rq_queued)
return NULL;
/*
* We were waiting for group to get backlogged. Expire the queue
*/
if (cfq_cfqq_wait_busy(cfqq) && !RB_EMPTY_ROOT(&cfqq->sort_list))
goto expire;
/*
* The active queue has run out of time, expire it and select new.
*/
if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq)) {
/*
* If slice had not expired at the completion of last request
* we might not have turned on wait_busy flag. Don't expire
* the queue yet. Allow the group to get backlogged.
*
* The very fact that we have used the slice, that means we
* have been idling all along on this queue and it should be
* ok to wait for this request to complete.
*/
if (cfqq->cfqg->nr_cfqq == 1 && RB_EMPTY_ROOT(&cfqq->sort_list)
&& cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
cfqq = NULL;
goto keep_queue;
} else
goto check_group_idle;
}
/*
* The active queue has requests and isn't expired, allow it to
* dispatch.
*/
if (!RB_EMPTY_ROOT(&cfqq->sort_list))
goto keep_queue;
/*
* If another queue has a request waiting within our mean seek
* distance, let it run. The expire code will check for close
* cooperators and put the close queue at the front of the service
* tree. If possible, merge the expiring queue with the new cfqq.
*/
new_cfqq = cfq_close_cooperator(cfqd, cfqq);
if (new_cfqq) {
if (!cfqq->new_cfqq)
cfq_setup_merge(cfqq, new_cfqq);
goto expire;
}
/*
* No requests pending. If the active queue still has requests in
* flight or is idling for a new request, allow either of these
* conditions to happen (or time out) before selecting a new queue.
*/
if (timer_pending(&cfqd->idle_slice_timer)) {
cfqq = NULL;
goto keep_queue;
}
/*
* This is a deep seek queue, but the device is much faster than
* the queue can deliver, don't idle
**/
if (CFQQ_SEEKY(cfqq) && cfq_cfqq_idle_window(cfqq) &&
(cfq_cfqq_slice_new(cfqq) ||
(cfqq->slice_end - jiffies > jiffies - cfqq->slice_start))) {
cfq_clear_cfqq_deep(cfqq);
cfq_clear_cfqq_idle_window(cfqq);
}
if (cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
cfqq = NULL;
goto keep_queue;
}
/*
* If group idle is enabled and there are requests dispatched from
* this group, wait for requests to complete.
*/
check_group_idle:
if (cfqd->cfq_group_idle && cfqq->cfqg->nr_cfqq == 1 &&
cfqq->cfqg->dispatched &&
!cfq_io_thinktime_big(cfqd, &cfqq->cfqg->ttime, true)) {
cfqq = NULL;
goto keep_queue;
}
expire:
cfq_slice_expired(cfqd, 0);
new_queue:
/*
* Current queue expired. Check if we have to switch to a new
* service tree
*/
if (!new_cfqq)
cfq_choose_cfqg(cfqd);
cfqq = cfq_set_active_queue(cfqd, new_cfqq);