int nr_cfqq;
/*
- * Per group busy queus average. Useful for workload slice calc. We
+ * 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.
/* List of cfq groups being managed on this device*/
struct hlist_head cfqg_list;
- struct rcu_head rcu;
+
+ /* Number of groups which are on blkcg->blkg_list */
+ unsigned int nr_blkcg_linked_grps;
};
static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd);
#define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
blk_add_trace_msg((cfqd)->queue, "cfq%d%c %s " fmt, (cfqq)->pid, \
cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \
- blkg_path(&(cfqq)->cfqg->blkg), ##args);
+ blkg_path(&(cfqq)->cfqg->blkg), ##args)
#define cfq_log_cfqg(cfqd, cfqg, fmt, args...) \
blk_add_trace_msg((cfqd)->queue, "%s " fmt, \
- blkg_path(&(cfqg)->blkg), ##args); \
+ blkg_path(&(cfqg)->blkg), ##args) \
#else
#define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args)
-#define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do {} while (0);
+#define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do {} while (0)
#endif
#define cfq_log(cfqd, fmt, args...) \
blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args)
if (rq2 == NULL)
return rq1;
- if (rq_is_sync(rq1) && !rq_is_sync(rq2))
- return rq1;
- else if (rq_is_sync(rq2) && !rq_is_sync(rq1))
- return rq2;
- if ((rq1->cmd_flags & REQ_META) && !(rq2->cmd_flags & REQ_META))
- return rq1;
- else if ((rq2->cmd_flags & REQ_META) &&
- !(rq1->cmd_flags & REQ_META))
- return rq2;
+ if (rq_is_sync(rq1) != rq_is_sync(rq2))
+ return rq_is_sync(rq1) ? rq1 : rq2;
+
+ if ((rq1->cmd_flags ^ rq2->cmd_flags) & REQ_META)
+ return rq1->cmd_flags & REQ_META ? rq1 : rq2;
s1 = blk_rq_pos(rq1);
s2 = blk_rq_pos(rq2);
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=%u", used_sl, cfqq->slice_dispatch, charge,
- iops_mode(cfqd), cfqq->nr_sectors);
+ 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);
cfq_blkiocg_update_timeslice_used(&cfqg->blkg, used_sl,
unaccounted_sl);
cfq_blkiocg_set_start_empty_time(&cfqg->blkg);
cfqg->needs_update = true;
}
-static struct cfq_group * cfq_find_alloc_cfqg(struct cfq_data *cfqd,
- struct blkio_cgroup *blkcg, int create)
+static void cfq_init_add_cfqg_lists(struct cfq_data *cfqd,
+ struct cfq_group *cfqg, struct blkio_cgroup *blkcg)
{
- struct cfq_group *cfqg = NULL;
- void *key = cfqd;
- int i, j;
- struct cfq_rb_root *st;
struct backing_dev_info *bdi = &cfqd->queue->backing_dev_info;
unsigned int major, minor;
- cfqg = cfqg_of_blkg(blkiocg_lookup_group(blkcg, key));
- if (cfqg && !cfqg->blkg.dev && bdi->dev && dev_name(bdi->dev)) {
+ /*
+ * Add group onto cgroup list. It might happen that bdi->dev is
+ * not initialized yet. Initialize this new group without major
+ * and minor info and this info will be filled in once a new thread
+ * comes for IO.
+ */
+ if (bdi->dev) {
sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor);
- cfqg->blkg.dev = MKDEV(major, minor);
- goto done;
- }
- if (cfqg || !create)
- goto done;
+ cfq_blkiocg_add_blkio_group(blkcg, &cfqg->blkg,
+ (void *)cfqd, MKDEV(major, minor));
+ } else
+ cfq_blkiocg_add_blkio_group(blkcg, &cfqg->blkg,
+ (void *)cfqd, 0);
+
+ cfqd->nr_blkcg_linked_grps++;
+ cfqg->weight = blkcg_get_weight(blkcg, cfqg->blkg.dev);
+
+ /* Add group on cfqd list */
+ hlist_add_head(&cfqg->cfqd_node, &cfqd->cfqg_list);
+}
+
+/*
+ * Should be called from sleepable context. No request queue lock as per
+ * cpu stats are allocated dynamically and alloc_percpu needs to be called
+ * from sleepable context.
+ */
+static struct cfq_group * cfq_alloc_cfqg(struct cfq_data *cfqd)
+{
+ struct cfq_group *cfqg = NULL;
+ int i, j, ret;
+ struct cfq_rb_root *st;
cfqg = kzalloc_node(sizeof(*cfqg), GFP_ATOMIC, cfqd->queue->node);
if (!cfqg)
- goto done;
+ return NULL;
for_each_cfqg_st(cfqg, i, j, st)
*st = CFQ_RB_ROOT;
*/
cfqg->ref = 1;
+ ret = blkio_alloc_blkg_stats(&cfqg->blkg);
+ if (ret) {
+ kfree(cfqg);
+ return NULL;
+ }
+
+ return cfqg;
+}
+
+static struct cfq_group *
+cfq_find_cfqg(struct cfq_data *cfqd, struct blkio_cgroup *blkcg)
+{
+ struct cfq_group *cfqg = NULL;
+ void *key = cfqd;
+ struct backing_dev_info *bdi = &cfqd->queue->backing_dev_info;
+ unsigned int major, minor;
+
/*
- * Add group onto cgroup list. It might happen that bdi->dev is
- * not initialized yet. Initialize this new group without major
- * and minor info and this info will be filled in once a new thread
- * comes for IO. See code above.
+ * This is the common case when there are no blkio cgroups.
+ * Avoid lookup in this case
*/
- if (bdi->dev) {
- sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor);
- cfq_blkiocg_add_blkio_group(blkcg, &cfqg->blkg, (void *)cfqd,
- MKDEV(major, minor));
- } else
- cfq_blkiocg_add_blkio_group(blkcg, &cfqg->blkg, (void *)cfqd,
- 0);
-
- cfqg->weight = blkcg_get_weight(blkcg, cfqg->blkg.dev);
+ if (blkcg == &blkio_root_cgroup)
+ cfqg = &cfqd->root_group;
+ else
+ cfqg = cfqg_of_blkg(blkiocg_lookup_group(blkcg, key));
- /* Add group on cfqd list */
- hlist_add_head(&cfqg->cfqd_node, &cfqd->cfqg_list);
+ if (cfqg && !cfqg->blkg.dev && bdi->dev && dev_name(bdi->dev)) {
+ sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor);
+ cfqg->blkg.dev = MKDEV(major, minor);
+ }
-done:
return cfqg;
}
/*
- * Search for the cfq group current task belongs to. If create = 1, then also
- * create the cfq group if it does not exist. request_queue lock must be held.
+ * Search for the cfq group current task belongs to. request_queue lock must
+ * be held.
*/
-static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd, int create)
+static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd)
{
struct blkio_cgroup *blkcg;
- struct cfq_group *cfqg = NULL;
+ struct cfq_group *cfqg = NULL, *__cfqg = NULL;
+ struct request_queue *q = cfqd->queue;
+
+ rcu_read_lock();
+ blkcg = task_blkio_cgroup(current);
+ cfqg = cfq_find_cfqg(cfqd, blkcg);
+ if (cfqg) {
+ rcu_read_unlock();
+ return cfqg;
+ }
+
+ /*
+ * Need to allocate a group. Allocation of group also needs allocation
+ * of per cpu stats which in-turn takes a mutex() and can block. Hence
+ * we need to drop rcu lock and queue_lock before we call alloc.
+ *
+ * Not taking any queue reference here and assuming that queue is
+ * around by the time we return. CFQ queue allocation code does
+ * the same. It might be racy though.
+ */
+
+ rcu_read_unlock();
+ spin_unlock_irq(q->queue_lock);
+
+ cfqg = cfq_alloc_cfqg(cfqd);
+
+ spin_lock_irq(q->queue_lock);
rcu_read_lock();
blkcg = task_blkio_cgroup(current);
- cfqg = cfq_find_alloc_cfqg(cfqd, blkcg, create);
- if (!cfqg && create)
+
+ /*
+ * If some other thread already allocated the group while we were
+ * not holding queue lock, free up the group
+ */
+ __cfqg = cfq_find_cfqg(cfqd, blkcg);
+
+ if (__cfqg) {
+ kfree(cfqg);
+ rcu_read_unlock();
+ return __cfqg;
+ }
+
+ if (!cfqg)
cfqg = &cfqd->root_group;
+
+ cfq_init_add_cfqg_lists(cfqd, cfqg, blkcg);
rcu_read_unlock();
return cfqg;
}
return;
for_each_cfqg_st(cfqg, i, j, st)
BUG_ON(!RB_EMPTY_ROOT(&st->rb));
+ free_percpu(cfqg->blkg.stats_cpu);
kfree(cfqg);
}
}
#else /* GROUP_IOSCHED */
-static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd, int create)
+static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd)
{
return &cfqd->root_group;
}
struct cfq_rb_root *service_tree;
int left;
int new_cfqq = 1;
- int group_changed = 0;
service_tree = service_tree_for(cfqq->cfqg, cfqq_prio(cfqq),
cfqq_type(cfqq));
rb_link_node(&cfqq->rb_node, parent, p);
rb_insert_color(&cfqq->rb_node, &service_tree->rb);
service_tree->count++;
- if ((add_front || !new_cfqq) && !group_changed)
+ if (add_front || !new_cfqq)
return;
cfq_group_notify_queue_add(cfqd, cfqq->cfqg);
}
*/
if (sample_valid(cic->ttime_samples) &&
(cfqq->slice_end - jiffies < cic->ttime_mean)) {
- cfq_log_cfqq(cfqd, cfqq, "Not idling. think_time:%d",
- cic->ttime_mean);
+ cfq_log_cfqq(cfqd, cfqq, "Not idling. think_time:%lu",
+ cic->ttime_mean);
return;
}
WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR);
- return 2 * (base_rq + base_rq * (CFQ_PRIO_LISTS - 1 - cfqq->ioprio));
+ return 2 * base_rq * (IOPRIO_BE_NR - cfqq->ioprio);
}
/*
smp_wmb();
cic->key = cfqd_dead_key(cfqd);
- if (ioc->ioc_data == cic)
+ if (rcu_dereference(ioc->ioc_data) == cic) {
+ spin_lock(&ioc->lock);
rcu_assign_pointer(ioc->ioc_data, NULL);
+ spin_unlock(&ioc->lock);
+ }
if (cic->cfqq[BLK_RW_ASYNC]) {
cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]);
struct cfq_group *cfqg;
retry:
- cfqg = cfq_get_cfqg(cfqd, 1);
+ cfqg = cfq_get_cfqg(cfqd);
cic = cfq_cic_lookup(cfqd, ioc);
/* cic always exists here */
cfqq = cic_to_cfqq(cic, is_sync);
return 0;
queue_fail:
- if (cic)
- put_io_context(cic->ioc);
-
cfq_schedule_dispatch(cfqd);
spin_unlock_irqrestore(q->queue_lock, flags);
cfq_log(cfqd, "set_request fail");
cfq_put_queue(cfqd->async_idle_cfqq);
}
-static void cfq_cfqd_free(struct rcu_head *head)
-{
- kfree(container_of(head, struct cfq_data, rcu));
-}
-
static void cfq_exit_queue(struct elevator_queue *e)
{
struct cfq_data *cfqd = e->elevator_data;
struct request_queue *q = cfqd->queue;
+ bool wait = false;
cfq_shutdown_timer_wq(cfqd);
cfq_put_async_queues(cfqd);
cfq_release_cfq_groups(cfqd);
- cfq_blkiocg_del_blkio_group(&cfqd->root_group.blkg);
+
+ /*
+ * If there are groups which we could not unlink from blkcg list,
+ * wait for a rcu period for them to be freed.
+ */
+ if (cfqd->nr_blkcg_linked_grps)
+ wait = true;
spin_unlock_irq(q->queue_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);
+ /*
+ * Wait for cfqg->blkg->key accessors to exit their grace periods.
+ * Do this wait only if there are other unlinked groups out
+ * there. This can happen if cgroup deletion path claimed the
+ * responsibility of cleaning up a group before queue cleanup code
+ * get to the group.
+ *
+ * Do not call synchronize_rcu() unconditionally as there are drivers
+ * which create/delete request queue hundreds of times during scan/boot
+ * and synchronize_rcu() can take significant time and slow down boot.
+ */
+ if (wait)
+ synchronize_rcu();
+
+#ifdef CONFIG_CFQ_GROUP_IOSCHED
+ /* Free up per cpu stats for root group */
+ free_percpu(cfqd->root_group.blkg.stats_cpu);
+#endif
+ kfree(cfqd);
}
static int cfq_alloc_cic_index(void)
return NULL;
cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node);
- if (!cfqd)
+ if (!cfqd) {
+ spin_lock(&cic_index_lock);
+ ida_remove(&cic_index_ida, i);
+ spin_unlock(&cic_index_lock);
return NULL;
+ }
/*
* Don't need take queue_lock in the routine, since we are
#ifdef CONFIG_CFQ_GROUP_IOSCHED
/*
- * Take a reference to root group which we never drop. This is just
- * to make sure that cfq_put_cfqg() does not try to kfree root group
+ * Set root group reference to 2. One reference will be dropped when
+ * all groups on cfqd->cfqg_list are being deleted during queue exit.
+ * Other reference will remain there as we don't want to delete this
+ * group as it is statically allocated and gets destroyed when
+ * throtl_data goes away.
*/
- cfqg->ref = 1;
+ cfqg->ref = 2;
+
+ if (blkio_alloc_blkg_stats(&cfqg->blkg)) {
+ kfree(cfqg);
+ kfree(cfqd);
+ return NULL;
+ }
+
rcu_read_lock();
+
cfq_blkiocg_add_blkio_group(&blkio_root_cgroup, &cfqg->blkg,
(void *)cfqd, 0);
rcu_read_unlock();
+ cfqd->nr_blkcg_linked_grps++;
+
+ /* Add group on cfqd->cfqg_list */
+ hlist_add_head(&cfqg->cfqd_node, &cfqd->cfqg_list);
#endif
/*
* Not strictly needed (since RB_ROOT just clears the node and we
git.openpandora.org / pandora-kernel.git / blobdiff