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    SubjectRe: [RFC][PATCH 10/11] blkiocg async: Async queue per cfq_group
    Nauman Rafique wrote, on 08/12/2010 09:24 PM:
    > Muuhh,
    > I do not understand the motivation behind making cfq_io_context per
    > cgroup. We can extract cgroup id from bio, use that to lookup cgroup
    > and its async queues. What am I missing?

    What cgroup ID can suggest is only cgroup to which the thread belongs,
    but not the thread itself. This means that IO priority and IO prio-class
    can't be determined by cgroup ID.
    The pointers of async queues are held in cfqg->async_cfqq[class][prio].
    It is impossible to find out which queue is appropriate by only cgroup
    ID if considering IO priority.

    Frankly speaking, I'm not 100% confident if IO priority should be
    applied on async write IOs, but anyway, I made up my mind to keep the
    current scheme.

    Do I make sense? If you have any other idea, I am glad to hear.


    Thanks,
    Muuhh


    >
    > On Thu, Jul 8, 2010 at 8:22 PM, Munehiro Ikeda<m-ikeda@ds.jp.nec.com> wrote:
    >> This is the main body for async capability of blkio controller.
    >> The basic ideas are
    >> - To move async queues from cfq_data to cfq_group, and
    >> - To associate cfq_io_context with cfq_group
    >>
    >> Each cfq_io_context, which was created per an io_context
    >> per a device, is now created per an io_context per a cfq_group.
    >> Each cfq_group is created per a cgroup per a device, so
    >> cfq_io_context is now resulted in to be created per
    >> an io_context per a cgroup per a device.
    >>
    >> To protect link between cfq_io_context and cfq_group,
    >> locking code is modified in several parts.
    >>
    >> ToDo:
    >> - Lock protection still might be imperfect and more investigation
    >> is needed.
    >>
    >> - cic_index of root cfq_group (cfqd->root_group.cic_index) is not
    >> removed and lasts beyond elevator switching.
    >> This issues should be solved.
    >>
    >> Signed-off-by: Munehiro "Muuhh" Ikeda<m-ikeda@ds.jp.nec.com>
    >> ---
    >> block/cfq-iosched.c | 277 ++++++++++++++++++++++++++++-----------------
    >> include/linux/iocontext.h | 2 +-
    >> 2 files changed, 175 insertions(+), 104 deletions(-)
    >>
    >> diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
    >> index 68f76e9..4186c30 100644
    >> --- a/block/cfq-iosched.c
    >> +++ b/block/cfq-iosched.c
    >> @@ -191,10 +191,23 @@ struct cfq_group {
    >> struct cfq_rb_root service_trees[2][3];
    >> struct cfq_rb_root service_tree_idle;
    >>
    >> + /*
    >> + * async queue for each priority case
    >> + */
    >> + struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR];
    >> + struct cfq_queue *async_idle_cfqq;
    >> +
    >> unsigned long saved_workload_slice;
    >> enum wl_type_t saved_workload;
    >> enum wl_prio_t saved_serving_prio;
    >> struct blkio_group blkg;
    >> + struct cfq_data *cfqd;
    >> +
    >> + /* lock for cic_list */
    >> + spinlock_t lock;
    >> + unsigned int cic_index;
    >> + struct list_head cic_list;
    >> +
    >> #ifdef CONFIG_CFQ_GROUP_IOSCHED
    >> struct hlist_node cfqd_node;
    >> atomic_t ref;
    >> @@ -254,12 +267,6 @@ struct cfq_data {
    >> struct cfq_queue *active_queue;
    >> struct cfq_io_context *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;
    >>
    >> /*
    >> @@ -275,8 +282,6 @@ struct cfq_data {
    >> unsigned int cfq_latency;
    >> unsigned int cfq_group_isolation;
    >>
    >> - unsigned int cic_index;
    >> - struct list_head cic_list;
    >>
    >> /*
    >> * Fallback dummy cfqq for extreme OOM conditions
    >> @@ -418,10 +423,16 @@ static inline int cfqg_busy_async_queues(struct cfq_data *cfqd,
    >> }
    >>
    >> static void cfq_dispatch_insert(struct request_queue *, struct request *);
    >> +static void __cfq_exit_single_io_context(struct cfq_data *,
    >> + struct cfq_group *,
    >> + struct cfq_io_context *);
    >> static struct cfq_queue *cfq_get_queue(struct cfq_data *, bool,
    >> - struct io_context *, gfp_t);
    >> + struct cfq_io_context *, gfp_t);
    >> static struct cfq_io_context *cfq_cic_lookup(struct cfq_data *,
    >> - struct io_context *);
    >> + struct cfq_group *,
    >> + struct io_context *);
    >> +static void cfq_put_async_queues(struct cfq_group *);
    >> +static int cfq_alloc_cic_index(void);
    >>
    >> static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_context *cic,
    >> bool is_sync)
    >> @@ -438,17 +449,28 @@ static inline void cic_set_cfqq(struct cfq_io_context *cic,
    >> #define CIC_DEAD_KEY 1ul
    >> #define CIC_DEAD_INDEX_SHIFT 1
    >>
    >> -static inline void *cfqd_dead_key(struct cfq_data *cfqd)
    >> +static inline void *cfqg_dead_key(struct cfq_group *cfqg)
    >> {
    >> - return (void *)(cfqd->cic_index<< CIC_DEAD_INDEX_SHIFT | CIC_DEAD_KEY);
    >> + return (void *)(cfqg->cic_index<< CIC_DEAD_INDEX_SHIFT | CIC_DEAD_KEY);
    >> +}
    >> +
    >> +static inline struct cfq_group *cic_to_cfqg(struct cfq_io_context *cic)
    >> +{
    >> + struct cfq_group *cfqg = cic->key;
    >> +
    >> + if (unlikely((unsigned long) cfqg& CIC_DEAD_KEY))
    >> + cfqg = NULL;
    >> +
    >> + return cfqg;
    >> }
    >>
    >> static inline struct cfq_data *cic_to_cfqd(struct cfq_io_context *cic)
    >> {
    >> - struct cfq_data *cfqd = cic->key;
    >> + struct cfq_data *cfqd = NULL;
    >> + struct cfq_group *cfqg = cic_to_cfqg(cic);
    >>
    >> - if (unlikely((unsigned long) cfqd& CIC_DEAD_KEY))
    >> - return NULL;
    >> + if (likely(cfqg))
    >> + cfqd = cfqg->cfqd;
    >>
    >> return cfqd;
    >> }
    >> @@ -959,12 +981,12 @@ cfq_update_blkio_group_weight(struct blkio_group *blkg, unsigned int weight)
    >> }
    >>
    >> static struct cfq_group *
    >> -cfq_find_alloc_cfqg(struct cfq_data *cfqd, struct cgroup *cgroup, int create)
    >> +cfq_find_alloc_cfqg(struct cfq_data *cfqd, struct blkio_cgroup *blkcg,
    >> + int create)
    >> {
    >> - struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgroup);
    >> struct cfq_group *cfqg = NULL;
    >> void *key = cfqd;
    >> - int i, j;
    >> + int i, j, idx;
    >> struct cfq_rb_root *st;
    >> struct backing_dev_info *bdi =&cfqd->queue->backing_dev_info;
    >> unsigned int major, minor;
    >> @@ -978,14 +1000,21 @@ cfq_find_alloc_cfqg(struct cfq_data *cfqd, struct cgroup *cgroup, int create)
    >> if (cfqg || !create)
    >> goto done;
    >>
    >> + idx = cfq_alloc_cic_index();
    >> + if (idx< 0)
    >> + goto done;
    >> +
    >> cfqg = kzalloc_node(sizeof(*cfqg), GFP_ATOMIC, cfqd->queue->node);
    >> if (!cfqg)
    >> - goto done;
    >> + goto err;
    >>
    >> for_each_cfqg_st(cfqg, i, j, st)
    >> *st = CFQ_RB_ROOT;
    >> RB_CLEAR_NODE(&cfqg->rb_node);
    >>
    >> + spin_lock_init(&cfqg->lock);
    >> + INIT_LIST_HEAD(&cfqg->cic_list);
    >> +
    >> /*
    >> * Take the initial reference that will be released on destroy
    >> * This can be thought of a joint reference by cgroup and
    >> @@ -1002,7 +1031,14 @@ cfq_find_alloc_cfqg(struct cfq_data *cfqd, struct cgroup *cgroup, int create)
    >>
    >> /* Add group on cfqd list */
    >> hlist_add_head(&cfqg->cfqd_node,&cfqd->cfqg_list);
    >> + cfqg->cfqd = cfqd;
    >> + cfqg->cic_index = idx;
    >> + goto done;
    >>
    >> +err:
    >> + spin_lock(&cic_index_lock);
    >> + ida_remove(&cic_index_ida, idx);
    >> + spin_unlock(&cic_index_lock);
    >> done:
    >> return cfqg;
    >> }
    >> @@ -1095,10 +1131,6 @@ static inline struct cfq_group *cfq_ref_get_cfqg(struct cfq_group *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 */
    >> atomic_inc(&cfqq->cfqg->ref);
    >> @@ -1114,6 +1146,16 @@ static void cfq_put_cfqg(struct cfq_group *cfqg)
    >> return;
    >> for_each_cfqg_st(cfqg, i, j, st)
    >> BUG_ON(!RB_EMPTY_ROOT(&st->rb) || st->active != NULL);
    >> +
    >> + /**
    >> + * ToDo:
    >> + * root_group never reaches here and cic_index is never
    >> + * removed. Unused cic_index lasts by elevator switching.
    >> + */
    >> + spin_lock(&cic_index_lock);
    >> + ida_remove(&cic_index_ida, cfqg->cic_index);
    >> + spin_unlock(&cic_index_lock);
    >> +
    >> kfree(cfqg);
    >> }
    >>
    >> @@ -1122,6 +1164,15 @@ static void cfq_destroy_cfqg(struct cfq_data *cfqd, struct cfq_group *cfqg)
    >> /* Something wrong if we are trying to remove same group twice */
    >> BUG_ON(hlist_unhashed(&cfqg->cfqd_node));
    >>
    >> + while (!list_empty(&cfqg->cic_list)) {
    >> + struct cfq_io_context *cic = list_entry(cfqg->cic_list.next,
    >> + struct cfq_io_context,
    >> + group_list);
    >> +
    >> + __cfq_exit_single_io_context(cfqd, cfqg, cic);
    >> + }
    >> +
    >> + cfq_put_async_queues(cfqg);
    >> hlist_del_init(&cfqg->cfqd_node);
    >>
    >> /*
    >> @@ -1497,10 +1548,12 @@ static struct request *
    >> cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio)
    >> {
    >> struct task_struct *tsk = current;
    >> + struct cfq_group *cfqg;
    >> struct cfq_io_context *cic;
    >> struct cfq_queue *cfqq;
    >>
    >> - cic = cfq_cic_lookup(cfqd, tsk->io_context);
    >> + cfqg = cfq_get_cfqg(cfqd, bio, 0);
    >> + cic = cfq_cic_lookup(cfqd, cfqg, tsk->io_context);
    >> if (!cic)
    >> return NULL;
    >>
    >> @@ -1611,6 +1664,7 @@ 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_group *cfqg;
    >> struct cfq_io_context *cic;
    >> struct cfq_queue *cfqq;
    >>
    >> @@ -1624,7 +1678,8 @@ static int cfq_allow_merge(struct request_queue *q, struct request *rq,
    >> * Lookup the cfqq that this bio will be queued with. Allow
    >> * merge only if rq is queued there.
    >> */
    >> - cic = cfq_cic_lookup(cfqd, current->io_context);
    >> + cfqg = cfq_get_cfqg(cfqd, bio, 0);
    >> + cic = cfq_cic_lookup(cfqd, cfqg, current->io_context);
    >> if (!cic)
    >> return false;
    >>
    >> @@ -2667,17 +2722,18 @@ static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
    >> }
    >>
    >> static void __cfq_exit_single_io_context(struct cfq_data *cfqd,
    >> + struct cfq_group *cfqg,
    >> struct cfq_io_context *cic)
    >> {
    >> struct io_context *ioc = cic->ioc;
    >>
    >> - list_del_init(&cic->queue_list);
    >> + list_del_init(&cic->group_list);
    >>
    >> /*
    >> * Make sure dead mark is seen for dead queues
    >> */
    >> smp_wmb();
    >> - cic->key = cfqd_dead_key(cfqd);
    >> + cic->key = cfqg_dead_key(cfqg);
    >>
    >> if (ioc->ioc_data == cic)
    >> rcu_assign_pointer(ioc->ioc_data, NULL);
    >> @@ -2696,23 +2752,23 @@ static void __cfq_exit_single_io_context(struct cfq_data *cfqd,
    >> static void cfq_exit_single_io_context(struct io_context *ioc,
    >> struct cfq_io_context *cic)
    >> {
    >> - struct cfq_data *cfqd = cic_to_cfqd(cic);
    >> + struct cfq_group *cfqg = cic_to_cfqg(cic);
    >>
    >> - if (cfqd) {
    >> - struct request_queue *q = cfqd->queue;
    >> + if (cfqg) {
    >> + struct cfq_data *cfqd = cfqg->cfqd;
    >> unsigned long flags;
    >>
    >> - spin_lock_irqsave(q->queue_lock, flags);
    >> + spin_lock_irqsave(&cfqg->lock, flags);
    >>
    >> /*
    >> * Ensure we get a fresh copy of the ->key to prevent
    >> * race between exiting task and queue
    >> */
    >> smp_read_barrier_depends();
    >> - if (cic->key == cfqd)
    >> - __cfq_exit_single_io_context(cfqd, cic);
    >> + if (cic->key == cfqg)
    >> + __cfq_exit_single_io_context(cfqd, cfqg, cic);
    >>
    >> - spin_unlock_irqrestore(q->queue_lock, flags);
    >> + spin_unlock_irqrestore(&cfqg->lock, flags);
    >> }
    >> }
    >>
    >> @@ -2734,7 +2790,7 @@ cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
    >> cfqd->queue->node);
    >> if (cic) {
    >> cic->last_end_request = jiffies;
    >> - INIT_LIST_HEAD(&cic->queue_list);
    >> + INIT_LIST_HEAD(&cic->group_list);
    >> INIT_HLIST_NODE(&cic->cic_list);
    >> cic->dtor = cfq_free_io_context;
    >> cic->exit = cfq_exit_io_context;
    >> @@ -2801,8 +2857,7 @@ static void changed_ioprio(struct io_context *ioc, struct cfq_io_context *cic)
    >> cfqq = cic->cfqq[BLK_RW_ASYNC];
    >> if (cfqq) {
    >> struct cfq_queue *new_cfqq;
    >> - new_cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic->ioc,
    >> - GFP_ATOMIC);
    >> + new_cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic, GFP_ATOMIC);
    >> if (new_cfqq) {
    >> cic->cfqq[BLK_RW_ASYNC] = new_cfqq;
    >> cfq_put_queue(cfqq);
    >> @@ -2879,16 +2934,14 @@ static void cfq_ioc_set_cgroup(struct io_context *ioc)
    >>
    >> static struct cfq_queue *
    >> cfq_find_alloc_queue(struct cfq_data *cfqd, bool is_sync,
    >> - struct io_context *ioc, gfp_t gfp_mask)
    >> + struct cfq_io_context *cic, gfp_t gfp_mask)
    >> {
    >> struct cfq_queue *cfqq, *new_cfqq = NULL;
    >> - struct cfq_io_context *cic;
    >> + struct io_context *ioc = cic->ioc;
    >> struct cfq_group *cfqg;
    >>
    >> retry:
    >> - cfqg = cfq_get_cfqg(cfqd, NULL, 1);
    >> - cic = cfq_cic_lookup(cfqd, ioc);
    >> - /* cic always exists here */
    >> + cfqg = cic_to_cfqg(cic);
    >> cfqq = cic_to_cfqq(cic, is_sync);
    >>
    >> /*
    >> @@ -2930,36 +2983,38 @@ retry:
    >> }
    >>
    >> static struct cfq_queue **
    >> -cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio)
    >> +cfq_async_queue_prio(struct cfq_group *cfqg, int ioprio_class, int ioprio)
    >> {
    >> switch (ioprio_class) {
    >> case IOPRIO_CLASS_RT:
    >> - return&cfqd->async_cfqq[0][ioprio];
    >> + return&cfqg->async_cfqq[0][ioprio];
    >> case IOPRIO_CLASS_BE:
    >> - return&cfqd->async_cfqq[1][ioprio];
    >> + return&cfqg->async_cfqq[1][ioprio];
    >> case IOPRIO_CLASS_IDLE:
    >> - return&cfqd->async_idle_cfqq;
    >> + return&cfqg->async_idle_cfqq;
    >> default:
    >> BUG();
    >> }
    >> }
    >>
    >> static struct cfq_queue *
    >> -cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct io_context *ioc,
    >> +cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct cfq_io_context *cic,
    >> gfp_t gfp_mask)
    >> {
    >> + struct io_context *ioc = cic->ioc;
    >> const int ioprio = task_ioprio(ioc);
    >> const int ioprio_class = task_ioprio_class(ioc);
    >> + struct cfq_group *cfqg = cic_to_cfqg(cic);
    >> struct cfq_queue **async_cfqq = NULL;
    >> struct cfq_queue *cfqq = NULL;
    >>
    >> if (!is_sync) {
    >> - async_cfqq = cfq_async_queue_prio(cfqd, ioprio_class, ioprio);
    >> + async_cfqq = cfq_async_queue_prio(cfqg, ioprio_class, ioprio);
    >> cfqq = *async_cfqq;
    >> }
    >>
    >> if (!cfqq)
    >> - cfqq = cfq_find_alloc_queue(cfqd, is_sync, ioc, gfp_mask);
    >> + cfqq = cfq_find_alloc_queue(cfqd, is_sync, cic, gfp_mask);
    >>
    >> /*
    >> * pin the queue now that it's allocated, scheduler exit will prune it
    >> @@ -2977,19 +3032,19 @@ cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct io_context *ioc,
    >> * We drop cfq io contexts lazily, so we may find a dead one.
    >> */
    >> static void
    >> -cfq_drop_dead_cic(struct cfq_data *cfqd, struct io_context *ioc,
    >> - struct cfq_io_context *cic)
    >> +cfq_drop_dead_cic(struct cfq_data *cfqd, struct cfq_group *cfqg,
    >> + struct io_context *ioc, struct cfq_io_context *cic)
    >> {
    >> unsigned long flags;
    >>
    >> - WARN_ON(!list_empty(&cic->queue_list));
    >> - BUG_ON(cic->key != cfqd_dead_key(cfqd));
    >> + WARN_ON(!list_empty(&cic->group_list));
    >> + BUG_ON(cic->key != cfqg_dead_key(cfqg));
    >>
    >> spin_lock_irqsave(&ioc->lock, flags);
    >>
    >> BUG_ON(ioc->ioc_data == cic);
    >>
    >> - radix_tree_delete(&ioc->radix_root, cfqd->cic_index);
    >> + radix_tree_delete(&ioc->radix_root, cfqg->cic_index);
    >> hlist_del_rcu(&cic->cic_list);
    >> spin_unlock_irqrestore(&ioc->lock, flags);
    >>
    >> @@ -2997,11 +3052,14 @@ cfq_drop_dead_cic(struct cfq_data *cfqd, struct io_context *ioc,
    >> }
    >>
    >> static struct cfq_io_context *
    >> -cfq_cic_lookup(struct cfq_data *cfqd, struct io_context *ioc)
    >> +cfq_cic_lookup(struct cfq_data *cfqd, struct cfq_group *cfqg,
    >> + struct io_context *ioc)
    >> {
    >> struct cfq_io_context *cic;
    >> unsigned long flags;
    >>
    >> + if (!cfqg)
    >> + return NULL;
    >> if (unlikely(!ioc))
    >> return NULL;
    >>
    >> @@ -3011,18 +3069,18 @@ cfq_cic_lookup(struct cfq_data *cfqd, struct io_context *ioc)
    >> * we maintain a last-hit cache, to avoid browsing over the tree
    >> */
    >> cic = rcu_dereference(ioc->ioc_data);
    >> - if (cic&& cic->key == cfqd) {
    >> + if (cic&& cic->key == cfqg) {
    >> rcu_read_unlock();
    >> return cic;
    >> }
    >>
    >> do {
    >> - cic = radix_tree_lookup(&ioc->radix_root, cfqd->cic_index);
    >> + cic = radix_tree_lookup(&ioc->radix_root, cfqg->cic_index);
    >> rcu_read_unlock();
    >> if (!cic)
    >> break;
    >> - if (unlikely(cic->key != cfqd)) {
    >> - cfq_drop_dead_cic(cfqd, ioc, cic);
    >> + if (unlikely(cic->key != cfqg)) {
    >> + cfq_drop_dead_cic(cfqd, cfqg, ioc, cic);
    >> rcu_read_lock();
    >> continue;
    >> }
    >> @@ -3037,24 +3095,25 @@ cfq_cic_lookup(struct cfq_data *cfqd, struct io_context *ioc)
    >> }
    >>
    >> /*
    >> - * Add cic into ioc, using cfqd as the search key. This enables us to lookup
    >> + * Add cic into ioc, using cfqg as the search key. This enables us to lookup
    >> * the process specific cfq io context when entered from the block layer.
    >> - * Also adds the cic to a per-cfqd list, used when this queue is removed.
    >> + * Also adds the cic to a per-cfqg list, used when the group is removed.
    >> + * request_queue lock must be held.
    >> */
    >> -static int cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc,
    >> - struct cfq_io_context *cic, gfp_t gfp_mask)
    >> +static int cfq_cic_link(struct cfq_data *cfqd, struct cfq_group *cfqg,
    >> + struct io_context *ioc, struct cfq_io_context *cic)
    >> {
    >> unsigned long flags;
    >> int ret;
    >>
    >> - ret = radix_tree_preload(gfp_mask);
    >> + ret = radix_tree_preload(GFP_ATOMIC);
    >> if (!ret) {
    >> cic->ioc = ioc;
    >> - cic->key = cfqd;
    >> + cic->key = cfqg;
    >>
    >> spin_lock_irqsave(&ioc->lock, flags);
    >> ret = radix_tree_insert(&ioc->radix_root,
    >> - cfqd->cic_index, cic);
    >> + cfqg->cic_index, cic);
    >> if (!ret)
    >> hlist_add_head_rcu(&cic->cic_list,&ioc->cic_list);
    >> spin_unlock_irqrestore(&ioc->lock, flags);
    >> @@ -3062,9 +3121,9 @@ static int cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc,
    >> radix_tree_preload_end();
    >>
    >> if (!ret) {
    >> - spin_lock_irqsave(cfqd->queue->queue_lock, flags);
    >> - list_add(&cic->queue_list,&cfqd->cic_list);
    >> - spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
    >> + spin_lock_irqsave(&cfqg->lock, flags);
    >> + list_add(&cic->group_list,&cfqg->cic_list);
    >> + spin_unlock_irqrestore(&cfqg->lock, flags);
    >> }
    >> }
    >>
    >> @@ -3080,10 +3139,12 @@ static int cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc,
    >> * than one device managed by cfq.
    >> */
    >> static struct cfq_io_context *
    >> -cfq_get_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
    >> +cfq_get_io_context(struct cfq_data *cfqd, struct bio *bio, gfp_t gfp_mask)
    >> {
    >> struct io_context *ioc = NULL;
    >> struct cfq_io_context *cic;
    >> + struct cfq_group *cfqg, *cfqg2;
    >> + unsigned long flags;
    >>
    >> might_sleep_if(gfp_mask& __GFP_WAIT);
    >>
    >> @@ -3091,18 +3152,38 @@ cfq_get_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
    >> if (!ioc)
    >> return NULL;
    >>
    >> - cic = cfq_cic_lookup(cfqd, ioc);
    >> + spin_lock_irqsave(cfqd->queue->queue_lock, flags);
    >> +retry_cfqg:
    >> + cfqg = cfq_get_cfqg(cfqd, bio, 1);
    >> +retry_cic:
    >> + cic = cfq_cic_lookup(cfqd, cfqg, ioc);
    >> if (cic)
    >> goto out;
    >> + spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
    >>
    >> cic = cfq_alloc_io_context(cfqd, gfp_mask);
    >> if (cic == NULL)
    >> goto err;
    >>
    >> - if (cfq_cic_link(cfqd, ioc, cic, gfp_mask))
    >> + spin_lock_irqsave(cfqd->queue->queue_lock, flags);
    >> +
    >> + /* check the consistency breakage during unlock period */
    >> + cfqg2 = cfq_get_cfqg(cfqd, bio, 0);
    >> + if (cfqg != cfqg2) {
    >> + cfq_cic_free(cic);
    >> + if (!cfqg2)
    >> + goto retry_cfqg;
    >> + else {
    >> + cfqg = cfqg2;
    >> + goto retry_cic;
    >> + }
    >> + }
    >> +
    >> + if (cfq_cic_link(cfqd, cfqg, ioc, cic))
    >> goto err_free;
    >>
    >> out:
    >> + spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
    >> smp_read_barrier_depends();
    >> if (unlikely(ioc->ioprio_changed))
    >> cfq_ioc_set_ioprio(ioc);
    >> @@ -3113,6 +3194,7 @@ out:
    >> #endif
    >> return cic;
    >> err_free:
    >> + spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
    >> cfq_cic_free(cic);
    >> err:
    >> put_io_context(ioc);
    >> @@ -3537,6 +3619,7 @@ static inline int __cfq_may_queue(struct cfq_queue *cfqq)
    >> static int cfq_may_queue(struct request_queue *q, struct bio *bio, int rw)
    >> {
    >> struct cfq_data *cfqd = q->elevator->elevator_data;
    >> + struct cfq_group *cfqg;
    >> struct task_struct *tsk = current;
    >> struct cfq_io_context *cic;
    >> struct cfq_queue *cfqq;
    >> @@ -3547,7 +3630,8 @@ static int cfq_may_queue(struct request_queue *q, struct bio *bio, int rw)
    >> * so just lookup a possibly existing queue, or return 'may queue'
    >> * if that fails
    >> */
    >> - cic = cfq_cic_lookup(cfqd, tsk->io_context);
    >> + cfqg = cfq_get_cfqg(cfqd, bio, 0);
    >> + cic = cfq_cic_lookup(cfqd, cfqg, tsk->io_context);
    >> if (!cic)
    >> return ELV_MQUEUE_MAY;
    >>
    >> @@ -3636,7 +3720,7 @@ cfq_set_request(struct request_queue *q, struct request *rq, struct bio *bio,
    >>
    >> might_sleep_if(gfp_mask& __GFP_WAIT);
    >>
    >> - cic = cfq_get_io_context(cfqd, gfp_mask);
    >> + cic = cfq_get_io_context(cfqd, bio, gfp_mask);
    >>
    >> spin_lock_irqsave(q->queue_lock, flags);
    >>
    >> @@ -3646,7 +3730,7 @@ cfq_set_request(struct request_queue *q, struct request *rq, struct bio *bio,
    >> new_queue:
    >> cfqq = cic_to_cfqq(cic, is_sync);
    >> if (!cfqq || cfqq ==&cfqd->oom_cfqq) {
    >> - cfqq = cfq_get_queue(cfqd, is_sync, cic->ioc, gfp_mask);
    >> + cfqq = cfq_get_queue(cfqd, is_sync, cic, gfp_mask);
    >> cic_set_cfqq(cic, cfqq, is_sync);
    >> } else {
    >> /*
    >> @@ -3762,19 +3846,19 @@ static void cfq_shutdown_timer_wq(struct cfq_data *cfqd)
    >> cancel_work_sync(&cfqd->unplug_work);
    >> }
    >>
    >> -static void cfq_put_async_queues(struct cfq_data *cfqd)
    >> +static void cfq_put_async_queues(struct cfq_group *cfqg)
    >> {
    >> int i;
    >>
    >> for (i = 0; i< IOPRIO_BE_NR; i++) {
    >> - if (cfqd->async_cfqq[0][i])
    >> - cfq_put_queue(cfqd->async_cfqq[0][i]);
    >> - if (cfqd->async_cfqq[1][i])
    >> - cfq_put_queue(cfqd->async_cfqq[1][i]);
    >> + if (cfqg->async_cfqq[0][i])
    >> + cfq_put_queue(cfqg->async_cfqq[0][i]);
    >> + if (cfqg->async_cfqq[1][i])
    >> + cfq_put_queue(cfqg->async_cfqq[1][i]);
    >> }
    >>
    >> - if (cfqd->async_idle_cfqq)
    >> - cfq_put_queue(cfqd->async_idle_cfqq);
    >> + if (cfqg->async_idle_cfqq)
    >> + cfq_put_queue(cfqg->async_idle_cfqq);
    >> }
    >>
    >> static void cfq_cfqd_free(struct rcu_head *head)
    >> @@ -3794,15 +3878,6 @@ static void cfq_exit_queue(struct elevator_queue *e)
    >> if (cfqd->active_queue)
    >> __cfq_slice_expired(cfqd, cfqd->active_queue, 0);
    >>
    >> - while (!list_empty(&cfqd->cic_list)) {
    >> - struct cfq_io_context *cic = list_entry(cfqd->cic_list.next,
    >> - struct cfq_io_context,
    >> - queue_list);
    >> -
    >> - __cfq_exit_single_io_context(cfqd, cic);
    >> - }
    >> -
    >> - cfq_put_async_queues(cfqd);
    >> cfq_release_cfq_groups(cfqd);
    >> cfq_blkiocg_del_blkio_group(&cfqd->root_group.blkg);
    >>
    >> @@ -3810,10 +3885,6 @@ static void cfq_exit_queue(struct elevator_queue *e)
    >>
    >> cfq_shutdown_timer_wq(cfqd);
    >>
    >> - spin_lock(&cic_index_lock);
    >> - ida_remove(&cic_index_ida, cfqd->cic_index);
    >> - spin_unlock(&cic_index_lock);
    >> -
    >> /* Wait for cfqg->blkg->key accessors to exit their grace periods. */
    >> call_rcu(&cfqd->rcu, cfq_cfqd_free);
    >> }
    >> @@ -3823,7 +3894,7 @@ static int cfq_alloc_cic_index(void)
    >> int index, error;
    >>
    >> do {
    >> - if (!ida_pre_get(&cic_index_ida, GFP_KERNEL))
    >> + if (!ida_pre_get(&cic_index_ida, GFP_ATOMIC))
    >> return -ENOMEM;
    >>
    >> spin_lock(&cic_index_lock);
    >> @@ -3839,20 +3910,18 @@ static int cfq_alloc_cic_index(void)
    >> static void *cfq_init_queue(struct request_queue *q)
    >> {
    >> struct cfq_data *cfqd;
    >> - int i, j;
    >> + int i, j, idx;
    >> struct cfq_group *cfqg;
    >> struct cfq_rb_root *st;
    >>
    >> - i = cfq_alloc_cic_index();
    >> - if (i< 0)
    >> + idx = cfq_alloc_cic_index();
    >> + if (idx< 0)
    >> return NULL;
    >>
    >> cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node);
    >> if (!cfqd)
    >> return NULL;
    >>
    >> - cfqd->cic_index = i;
    >> -
    >> /* Init root service tree */
    >> cfqd->grp_service_tree = CFQ_RB_ROOT;
    >>
    >> @@ -3861,6 +3930,9 @@ static void *cfq_init_queue(struct request_queue *q)
    >> for_each_cfqg_st(cfqg, i, j, st)
    >> *st = CFQ_RB_ROOT;
    >> RB_CLEAR_NODE(&cfqg->rb_node);
    >> + cfqg->cfqd = cfqd;
    >> + cfqg->cic_index = idx;
    >> + INIT_LIST_HEAD(&cfqg->cic_list);
    >>
    >> /* Give preference to root group over other groups */
    >> cfqg->weight = 2*BLKIO_WEIGHT_DEFAULT;
    >> @@ -3874,6 +3946,7 @@ static void *cfq_init_queue(struct request_queue *q)
    >> rcu_read_lock();
    >> cfq_blkiocg_add_blkio_group(&blkio_root_cgroup,&cfqg->blkg,
    >> (void *)cfqd, 0);
    >> + hlist_add_head(&cfqg->cfqd_node,&cfqd->cfqg_list);
    >> rcu_read_unlock();
    >> #endif
    >> /*
    >> @@ -3893,8 +3966,6 @@ static void *cfq_init_queue(struct request_queue *q)
    >> atomic_inc(&cfqd->oom_cfqq.ref);
    >> cfq_link_cfqq_cfqg(&cfqd->oom_cfqq,&cfqd->root_group);
    >>
    >> - INIT_LIST_HEAD(&cfqd->cic_list);
    >> -
    >> cfqd->queue = q;
    >>
    >> init_timer(&cfqd->idle_slice_timer);
    >> diff --git a/include/linux/iocontext.h b/include/linux/iocontext.h
    >> index 64d5291..6c05b54 100644
    >> --- a/include/linux/iocontext.h
    >> +++ b/include/linux/iocontext.h
    >> @@ -18,7 +18,7 @@ struct cfq_io_context {
    >> unsigned long ttime_samples;
    >> unsigned long ttime_mean;
    >>
    >> - struct list_head queue_list;
    >> + struct list_head group_list;
    >> struct hlist_node cic_list;
    >>
    >> void (*dtor)(struct io_context *); /* destructor */
    >> --
    >> 1.6.2.5
    >> --
    >> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    >> the body of a message to majordomo@vger.kernel.org
    >> More majordomo info at http://vger.kernel.org/majordomo-info.html
    >> Please read the FAQ at http://www.tux.org/lkml/
    >>
    >

    --
    IKEDA, Munehiro
    NEC Corporation of America
    m-ikeda@ds.jp.nec.com



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