o Littile debugging aid for hierarchical IO scheduling.
o Enabled under CONFIG_DEBUG_GROUP_IOSCHED
o Currently it outputs more debug messages in blktrace output which helps
a great deal in debugging in hierarchical setup. It also creates additional
cgroup interfaces io.disk_queue and io.disk_dequeue to output some more
debugging data.
Signed-off-by: Gui Jianfeng <guijianfeng@xxxxxxxxxxxxxx>
Signed-off-by: Vivek Goyal <vgoyal@xxxxxxxxxx>
---
block/Kconfig.iosched | 8 ++
block/elevator-fq.c | 300 ++++++++++++++++++++++++++++++++++++++++++++++++-
block/elevator-fq.h | 38 ++++++-
3 files changed, 339 insertions(+), 7 deletions(-)
diff --git a/block/Kconfig.iosched b/block/Kconfig.iosched
index a91a807..a7d0bf8 100644
--- a/block/Kconfig.iosched
+++ b/block/Kconfig.iosched
@@ -90,6 +90,14 @@ config DEFAULT_IOSCHED
default "cfq" if DEFAULT_CFQ
default "noop" if DEFAULT_NOOP
+config DEBUG_GROUP_IOSCHED
+ bool "Debug Hierarchical Scheduling support"
+ depends on CGROUPS && GROUP_IOSCHED
+ default n
+ ---help---
+ Enable some debugging hooks for hierarchical scheduling support.
+ Currently it just outputs more information in blktrace output.
+
endmenu
endif
diff --git a/block/elevator-fq.c b/block/elevator-fq.c
index c546962..ca26960 100644
--- a/block/elevator-fq.c
+++ b/block/elevator-fq.c
@@ -153,6 +153,119 @@ static void bfq_find_matching_entity(struct io_entity **entity,
*new_entity = parent_entity(*new_entity);
}
}
+
+static inline struct io_group *io_entity_to_iog(struct io_entity *entity)
+{
+ struct io_group *iog = NULL;
+
+ BUG_ON(entity == NULL);
+ if (entity->my_sched_data != NULL)
+ iog = container_of(entity, struct io_group, entity);
+ return iog;
+}
+
+/* Returns parent group of io group */
+static inline struct io_group *iog_parent(struct io_group *iog)
+{
+ struct io_group *piog;
+
+ if (!iog->entity.sched_data)
+ return NULL;
+
+ /*
+ * Not following entity->parent pointer as for top level groups
+ * this pointer is NULL.
+ */
+ piog = container_of(iog->entity.sched_data, struct io_group,
+ sched_data);
+ return piog;
+}
+
+#ifdef CONFIG_DEBUG_GROUP_IOSCHED
+static void io_group_path(struct io_group *iog, char *buf, int buflen)
+{
+ unsigned short id = iog->iocg_id;
+ struct cgroup_subsys_state *css;
+
+ rcu_read_lock();
+
+ if (!id)
+ goto out;
+
+ css = css_lookup(&io_subsys, id);
+ if (!css)
+ goto out;
+
+ if (!css_tryget(css))
+ goto out;
+
+ cgroup_path(css->cgroup, buf, buflen);
+
+ css_put(css);
+
+ rcu_read_unlock();
+ return;
+out:
+ rcu_read_unlock();
+ buf[0] = '\0';
+ return;
+}
+
+/*
+ * An entity has been freshly added to active tree. Either it came from
+ * idle tree or it was not on any of the trees. Do the accounting.
+ */
+static inline void bfq_account_for_entity_addition(struct io_entity *entity)
+{
+ struct io_group *iog = io_entity_to_iog(entity);
+
+ if (iog) {
+ struct elv_fq_data *efqd;
+
+ /*
+ * Keep track of how many times a group has been added
+ * to active tree.
+ */
+ iog->queue++;
+ iog->queue_start = jiffies;
+
+ /* Log group addition event */
+ rcu_read_lock();
+ efqd = rcu_dereference(iog->key);
+ if (efqd)
+ elv_log_iog(efqd, iog, "add group weight=%u",
+ iog->entity.weight);
+ rcu_read_unlock();
+ }
+}
+
+/*
+ * An entity got removed from active tree and either went to idle tree or
+ * not is on any of the tree. Do the accouting
+ */
+static inline void bfq_account_for_entity_deletion(struct io_entity *entity)
+{
+ struct io_group *iog = io_entity_to_iog(entity);
+
+ if (iog) {
+ struct elv_fq_data *efqd;
+
+ iog->dequeue++;
+ /* Keep a track of how long group was on active tree */
+ iog->queue_duration += jiffies_to_msecs(jiffies -
+ iog->queue_start);
+ iog->queue_start = 0;
+
+ /* Log group deletion event */
+ rcu_read_lock();
+ efqd = rcu_dereference(iog->key);
+ if (efqd)
+ elv_log_iog(efqd, iog, "del group weight=%u",
+ iog->entity.weight);
+ rcu_read_unlock();
+ }
+}
+#endif /* DEBUG_GROUP_IOSCHED */
#else /* GROUP_IOSCHED */
#define for_each_entity(entity) \
for (; entity != NULL; entity = NULL)
@@ -186,6 +299,11 @@ is_same_group(struct io_entity *entity, struct io_entity *new_entity)
{
return 1;
}
+
+static inline struct io_group *io_entity_to_iog(struct io_entity *entity)
+{
+ return NULL;
+}
#endif /* GROUP_IOSCHED */
static inline int elv_prio_slice(struct elv_fq_data *efqd, int sync,
@@ -426,6 +544,7 @@ static void bfq_active_insert(struct io_service_tree *st,
struct rb_node *node = &entity->rb_node;
bfq_insert(&st->active, entity);
+ entity->sched_data->nr_active++;
if (node->rb_left != NULL)
node = node->rb_left;
@@ -485,6 +604,7 @@ static void bfq_active_remove(struct io_service_tree *st,
node = bfq_find_deepest(&entity->rb_node);
bfq_remove(&st->active, entity);
+ entity->sched_data->nr_active--;
if (node != NULL)
bfq_update_active_tree(node);
@@ -571,6 +691,21 @@ static void bfq_forget_idle(struct io_service_tree *st)
bfq_put_idle_entity(st, first_idle);
}
+/*
+ * Returns the number of active entities a particular io group has. This
+ * includes number of active entities on service tree as well as the active
+ * entity which is being served currently, if any.
+ */
+
+static inline int elv_iog_nr_active(struct io_group *iog)
+{
+ struct io_sched_data *sd = &iog->sched_data;
+
+ if (sd->active_entity)
+ return sd->nr_active + 1;
+ else
+ return sd->nr_active;
+}
static struct io_service_tree *
__bfq_entity_update_prio(struct io_service_tree *old_st,
@@ -752,6 +887,7 @@ static void __bfq_activate_entity(struct io_entity *entity, int add_front)
{
struct io_sched_data *sd = entity->sched_data;
struct io_service_tree *st = io_entity_service_tree(entity);
+ int newly_added = 0;
if (entity == sd->active_entity) {
BUG_ON(entity->tree != NULL);
@@ -778,6 +914,7 @@ static void __bfq_activate_entity(struct io_entity *entity, int add_front)
bfq_idle_remove(st, entity);
entity->start = bfq_gt(st->vtime, entity->finish) ?
st->vtime : entity->finish;
+ newly_added = 1;
} else {
/*
* The finish time of the entity may be invalid, and
@@ -790,6 +927,7 @@ static void __bfq_activate_entity(struct io_entity *entity, int add_front)
BUG_ON(entity->on_st);
entity->on_st = 1;
+ newly_added = 1;
}
st = __bfq_entity_update_prio(st, entity);
@@ -831,6 +969,11 @@ static void __bfq_activate_entity(struct io_entity *entity, int add_front)
bfq_calc_finish(entity, entity->budget);
}
bfq_active_insert(st, entity);
+
+#ifdef CONFIG_DEBUG_GROUP_IOSCHED
+ if (newly_added)
+ bfq_account_for_entity_addition(entity);
+#endif
}
/**
@@ -872,7 +1015,7 @@ static int __bfq_deactivate_entity(struct io_entity *entity, int requeue)
struct io_sched_data *sd = entity->sched_data;
struct io_service_tree *st = io_entity_service_tree(entity);
int was_active = entity == sd->active_entity;
- int ret = 0;
+ int ret = 0, active_removed = 0;
if (!entity->on_st)
return 0;
@@ -882,9 +1025,11 @@ static int __bfq_deactivate_entity(struct io_entity *entity, int requeue)
if (was_active) {
bfq_calc_finish(entity, entity->service);
sd->active_entity = NULL;
- } else if (entity->tree == &st->active)
+ active_removed = 1;
+ } else if (entity->tree == &st->active) {
bfq_active_remove(st, entity);
- else if (entity->tree == &st->idle)
+ active_removed = 1;
+ } else if (entity->tree == &st->idle)
bfq_idle_remove(st, entity);
else if (entity->tree != NULL)
BUG();
@@ -899,6 +1044,10 @@ static int __bfq_deactivate_entity(struct io_entity *entity, int requeue)
BUG_ON(sd->active_entity == entity);
BUG_ON(sd->next_active == entity);
+#ifdef CONFIG_DEBUG_GROUP_IOSCHED
+ if (active_removed)
+ bfq_account_for_entity_deletion(entity);
+#endif
return ret;
}
@@ -1208,6 +1357,67 @@ static int io_cgroup_disk_sectors_read(struct cgroup *cgroup,
return 0;
}
+#ifdef CONFIG_DEBUG_GROUP_IOSCHED
+static int io_cgroup_disk_queue_read(struct cgroup *cgroup,
+ struct cftype *cftype, struct seq_file *m)
+{
+ struct io_cgroup *iocg = NULL;
+ struct io_group *iog = NULL;
+ struct hlist_node *n;
+
+ if (!cgroup_lock_live_group(cgroup))
+ return -ENODEV;
+
+ iocg = cgroup_to_io_cgroup(cgroup);
+ rcu_read_lock();
+ /* Loop through all the io groups and print statistics */
+ hlist_for_each_entry_rcu(iog, n, &iocg->group_data, group_node) {
+ /*
+ * There might be groups which are not functional and
+ * waiting to be reclaimed upon cgoup deletion.
+ */
+ if (iog->key) {
+ seq_printf(m, "%u:%u %lu %lu\n", MAJOR(iog->dev),
+ MINOR(iog->dev), iog->queue,
+ iog->queue_duration);
+ }
+ }
+ rcu_read_unlock();
+ cgroup_unlock();
+
+ return 0;
+}
+
+static int io_cgroup_disk_dequeue_read(struct cgroup *cgroup,
+ struct cftype *cftype, struct seq_file *m)
+{
+ struct io_cgroup *iocg = NULL;
+ struct io_group *iog = NULL;
+ struct hlist_node *n;
+
+ if (!cgroup_lock_live_group(cgroup))
+ return -ENODEV;
+
+ iocg = cgroup_to_io_cgroup(cgroup);
+ spin_lock_irq(&iocg->lock);
+ /* Loop through all the io groups and print statistics */
+ hlist_for_each_entry_rcu(iog, n, &iocg->group_data, group_node) {
+ /*
+ * There might be groups which are not functional and
+ * waiting to be reclaimed upon cgoup deletion.
+ */
+ if (iog->key) {
+ seq_printf(m, "%u:%u %lu\n", MAJOR(iog->dev),
+ MINOR(iog->dev), iog->dequeue);
+ }
+ }
+ spin_unlock_irq(&iocg->lock);
+ cgroup_unlock();
+
+ return 0;
+}
+#endif
+
struct cftype bfqio_files[] = {
{
.name = "weight",
@@ -1227,6 +1437,16 @@ struct cftype bfqio_files[] = {
.name = "disk_sectors",
.read_seq_string = io_cgroup_disk_sectors_read,
},
+#ifdef CONFIG_DEBUG_GROUP_IOSCHED
+ {
+ .name = "disk_queue",
+ .read_seq_string = io_cgroup_disk_queue_read,
+ },
+ {
+ .name = "disk_dequeue",
+ .read_seq_string = io_cgroup_disk_dequeue_read,
+ },
+#endif
};
static int iocg_populate(struct cgroup_subsys *subsys, struct cgroup *cgroup)
@@ -1367,6 +1587,11 @@ io_group_chain_alloc(struct request_queue *q, void *key, struct cgroup *cgroup)
*/
elv_get_iog(iog);
+#ifdef CONFIG_DEBUG_GROUP_IOSCHED
+ io_group_path(iog, iog->path, sizeof(iog->path));
+#endif
+
+
if (leaf == NULL) {
leaf = iog;
prev = leaf;
@@ -1947,6 +2172,22 @@ EXPORT_SYMBOL(elv_del_idle_slice_timer);
static void elv_ioq_served(struct io_queue *ioq, unsigned long served)
{
entity_served(&ioq->entity, served, ioq->nr_sectors);
+
+#ifdef CONFIG_DEBUG_GROUP_IOSCHED
+ {
+ struct elv_fq_data *efqd = ioq->efqd;
+ struct io_group *iog = ioq_to_io_group(ioq);
+ elv_log_ioq(efqd, ioq, "ioq served: QSt=0x%lx QSs=0x%lx"
+ " QTt=0x%lx QTs=0x%lx GTt=0x%lx "
+ " GTs=0x%lx rq_queued=%d",
+ served, ioq->nr_sectors,
+ ioq->entity.total_service,
+ ioq->entity.total_sector_service,
+ iog->entity.total_service,
+ iog->entity.total_sector_service,
+ ioq->nr_queued);
+ }
+#endif
}
/*
@@ -2238,10 +2479,29 @@ static void __elv_set_active_ioq(struct elv_fq_data *efqd, struct io_queue *ioq,
if (ioq) {
struct io_group *iog = ioq_to_io_group(ioq);
elv_log_ioq(efqd, ioq, "set_active, busy=%d ioprio=%d"
- " weight=%u group_weight=%u",
+ " weight=%u rq_queued=%d group_weight=%u",
efqd->busy_queues,
ioq->entity.ioprio, ioq->entity.weight,
- iog_weight(iog));
+ ioq->nr_queued, iog_weight(iog));
+#ifdef CONFIG_DEBUG_GROUP_IOSCHED
+ {
+ int nr_active = 0;
+ struct io_group *parent = NULL;
+
+ parent = iog_parent(iog);
+ if (parent)
+ nr_active = elv_iog_nr_active(parent);
+
+ elv_log_ioq(efqd, ioq, "set_active, ioq"
+ " nrgrps=%d QTt=0x%lx QTs=0x%lx GTt=0x%lx "
+ " GTs=0x%lx rq_queued=%d", nr_active,
+ ioq->entity.total_service,
+ ioq->entity.total_sector_service,
+ iog->entity.total_service,
+ iog->entity.total_sector_service,
+ ioq->nr_queued);
+ }
+#endif
ioq->slice_end = 0;
ioq->slice_start = jiffies;
@@ -2301,10 +2561,23 @@ static void elv_add_ioq_busy(struct elv_fq_data *efqd, struct io_queue *ioq)
{
BUG_ON(elv_ioq_busy(ioq));
BUG_ON(ioq == efqd->active_queue);
- elv_log_ioq(efqd, ioq, "add to busy");
elv_activate_ioq(ioq, 0);
elv_mark_ioq_busy(ioq);
efqd->busy_queues++;
+#ifdef CONFIG_DEBUG_GROUP_IOSCHED
+ {
+ struct io_group *iog = ioq_to_io_group(ioq);
+ elv_log_ioq(efqd, ioq, "add to busy: QTt=0x%lx QTs=0x%lx"
+ " GTt=0x%lx GTs=0x%lx rq_queued=%d",
+ ioq->entity.total_service,
+ ioq->entity.total_sector_service,
+ iog->entity.total_service,
+ iog->entity.total_sector_service,
+ ioq->nr_queued);
+ }
+#else
+ elv_log_ioq(efqd, ioq, "add to busy");
+#endif
}
static void elv_del_ioq_busy(struct elevator_queue *e, struct io_queue *ioq,
@@ -2314,7 +2587,21 @@ static void elv_del_ioq_busy(struct elevator_queue *e, struct io_queue *ioq,
BUG_ON(!elv_ioq_busy(ioq));
BUG_ON(ioq->nr_queued);
+#ifdef CONFIG_DEBUG_GROUP_IOSCHED
+ {
+ struct io_group *iog = ioq_to_io_group(ioq);
+ elv_log_ioq(efqd, ioq, "del from busy: QTt=0x%lx "
+ "QTs=0x%lx ioq GTt=0x%lx GTs=0x%lx "
+ "rq_queued=%d",
+ ioq->entity.total_service,
+ ioq->entity.total_sector_service,
+ iog->entity.total_service,
+ iog->entity.total_sector_service,
+ ioq->nr_queued);
+ }
+#else
elv_log_ioq(efqd, ioq, "del from busy");
+#endif
elv_clear_ioq_busy(ioq);
BUG_ON(efqd->busy_queues == 0);
efqd->busy_queues--;
@@ -2503,6 +2790,7 @@ void elv_ioq_request_add(struct request_queue *q, struct request *rq)
BUG_ON(!efqd);
BUG_ON(!ioq);
ioq->nr_queued++;
+ elv_log_ioq(efqd, ioq, "add rq: rq_queued=%d", ioq->nr_queued);
if (!elv_ioq_busy(ioq))
elv_add_ioq_busy(efqd, ioq);
diff --git a/block/elevator-fq.h b/block/elevator-fq.h
index b7f9f82..1da7ecc 100644
--- a/block/elevator-fq.h
+++ b/block/elevator-fq.h
@@ -75,6 +75,7 @@ struct io_service_tree {
struct io_sched_data {
struct io_entity *active_entity;
struct io_entity *next_active;
+ int nr_active;
struct io_service_tree service_tree[IO_IOPRIO_CLASSES];
};
@@ -243,6 +244,23 @@ struct io_group {
/* The device MKDEV(major, minor), this group has been created for */
dev_t dev;
+
+#ifdef CONFIG_DEBUG_GROUP_IOSCHED
+ /* How many times this group has been added to active tree */
+ unsigned long queue;
+
+ /* How long this group remained on active tree, in ms */
+ unsigned long queue_duration;
+
+ /* When was this group added to active tree */
+ unsigned long queue_start;
+
+ /* How many times this group has been removed from active tree */
+ unsigned long dequeue;
+
+ /* Store cgroup path */
+ char path[128];
+#endif
};
/**
@@ -303,10 +321,29 @@ struct elv_fq_data {
};
/* Logging facilities. */
+#ifdef CONFIG_DEBUG_GROUP_IOSCHED
+#define elv_log_ioq(efqd, ioq, fmt, args...) \
+{ \
+ blk_add_trace_msg((efqd)->queue, "elv%d%c %s " fmt, (ioq)->pid, \
+ elv_ioq_sync(ioq) ? 'S' : 'A', \
+ ioq_to_io_group(ioq)->path, ##args); \
+}
+
+#define elv_log_iog(efqd, iog, fmt, args...) \
+{ \
+ blk_add_trace_msg((efqd)->queue, "elv %s " fmt, (iog)->path, ##args); \
+}
+
+#else
#define elv_log_ioq(efqd, ioq, fmt, args...) \
blk_add_trace_msg((efqd)->queue, "elv%d%c " fmt, (ioq)->pid, \
elv_ioq_sync(ioq) ? 'S' : 'A', ##args)
+#define elv_log_iog(efqd, iog, fmt, args...) \
+ blk_add_trace_msg((efqd)->queue, "elv " fmt, ##args)
+
+#endif
+
#define elv_log(efqd, fmt, args...) \
blk_add_trace_msg((efqd)->queue, "elv " fmt, ##args)
@@ -443,7 +480,6 @@ static inline struct io_group *ioq_to_io_group(struct io_queue *ioq)
#ifdef CONFIG_GROUP_IOSCHED
extern int io_group_allow_merge(struct request *rq, struct bio *bio);
extern void elv_put_iog(struct io_group *iog);
-
static inline void elv_get_iog(struct io_group *iog)
{
atomic_inc(&iog->ref);
--
1.6.0.6
--
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