o This patch introduces core changes in fair queuing scheduler to support
hierarhical/group scheduling. It is enabled by CONFIG_GROUP_IOSCHED.
Signed-off-by: Fabio Checconi <fa...@gandalf.sssup.it>
Signed-off-by: Paolo Valente <paolo.vale...@unimore.it>
Signed-off-by: Nauman Rafique <nau...@google.com>
Signed-off-by: Vivek Goyal <vgo...@redhat.com>
---
block/elevator-fq.c | 158 ++++++++++++++++++++++++++++++++++++++++++++++++---
block/elevator-fq.h | 19 ++++++
init/Kconfig | 8 +++
3 files changed, 177 insertions(+), 8 deletions(-)
diff --git a/block/elevator-fq.c b/block/elevator-fq.c
index 1ca7b4a..6546df0 100644
--- a/block/elevator-fq.c
+++ b/block/elevator-fq.c
@@ -137,6 +137,88 @@ static inline struct io_group *iog_of(struct io_entity
*entity)
return NULL;
}
+#ifdef CONFIG_GROUP_IOSCHED
+/* check for entity->parent so that loop is not executed for root entity. */
+#define for_each_entity(entity) \
+ for (; entity && entity->parent; entity = entity->parent)
+
+/* Do the two (enqueued) entities belong to the same group ? */
+static inline int
+is_same_group(struct io_entity *entity, struct io_entity *new_entity)
+{
+ if (parent_entity(entity) == parent_entity(new_entity))
+ return 1;
+
+ return 0;
+}
+
+/* return depth at which a io entity is present in the hierarchy */
+static inline int depth_entity(struct io_entity *entity)
+{
+ int depth = 0;
+
+ for_each_entity(entity)
+ depth++;
+
+ return depth;
+}
+
+static void find_matching_io_entity(struct io_entity **entity,
+ struct io_entity **new_entity)
+{
+ int entity_depth, new_entity_depth;
+
+ /*
+ * preemption test can be made between sibling entities who are in the
+ * same group i.e who have a common parent. Walk up the hierarchy of
+ * both entities until we find their ancestors who are siblings of
+ * common parent.
+ */
+
+ /* First walk up until both entities are at same depth */
+ entity_depth = depth_entity(*entity);
+ new_entity_depth = depth_entity(*new_entity);
+
+ while (entity_depth > new_entity_depth) {
+ entity_depth--;
+ *entity = parent_entity(*entity);
+ }
+
+ while (new_entity_depth > entity_depth) {
+ new_entity_depth--;
+ *new_entity = parent_entity(*new_entity);
+ }
+
+ while (!is_same_group(*entity, *new_entity)) {
+ *entity = parent_entity(*entity);
+ *new_entity = parent_entity(*new_entity);
+ }
+}
+struct io_group *ioq_to_io_group(struct io_queue *ioq)
+{
+ return iog_of(parent_entity(&ioq->entity));
+}
+EXPORT_SYMBOL(ioq_to_io_group);
+
+static inline struct io_sched_data *
+io_entity_sched_data(struct io_entity *entity)
+{
+ return &iog_of(parent_entity(entity))->sched_data;
+}
+
+#else /* GROUP_IOSCHED */
+#define for_each_entity(entity) \
+ for (; entity != NULL; entity = NULL)
+
+static void find_matching_io_entity(struct io_entity **entity,
+ struct io_entity **new_entity) { }
+
+static inline int
+is_same_group(struct io_entity *entity, struct io_entity *new_entity)
+{
+ return 1;
+}
+
static inline struct elv_fq_data *efqd_of(struct io_entity *entity)
{
return ioq_of(entity)->efqd;
@@ -155,6 +237,7 @@ io_entity_sched_data(struct io_entity *entity)
return &efqd->root_group->sched_data;
}
+#endif /* GROUP_IOSCHED */
static inline void
init_io_entity_service_tree(struct io_entity *entity, struct io_entity *parent)
@@ -171,8 +254,10 @@ static void
entity_served(struct io_entity *entity, unsigned long served,
unsigned long nr_sectors)
{
- entity->vdisktime += elv_delta_fair(served, entity);
- update_min_vdisktime(entity->st);
+ for_each_entity(entity) {
+ entity->vdisktime += elv_delta_fair(served, entity);
+ update_min_vdisktime(entity->st);
+ }
}
static void place_entity(struct io_service_tree *st, struct io_entity *entity,
@@ -388,14 +473,23 @@ static void put_prev_ioq(struct io_queue *ioq)
{
struct io_entity *entity = &ioq->entity;
- put_prev_io_entity(entity);
+ for_each_entity(entity) {
+ put_prev_io_entity(entity);
+ }
}
static void dequeue_ioq(struct io_queue *ioq)
{
struct io_entity *entity = &ioq->entity;
- dequeue_io_entity(entity);
+ for_each_entity(entity) {
+ struct io_sched_data *sd = io_entity_sched_data(entity);
+
+ dequeue_io_entity(entity);
+ /* Don't dequeue parent if it has other entities besides us */
+ if (sd->nr_active)
+ break;
+ }
elv_put_ioq(ioq);
return;
}
@@ -406,7 +500,12 @@ static void enqueue_ioq(struct io_queue *ioq)
struct io_entity *entity = &ioq->entity;
elv_get_ioq(ioq);
- enqueue_io_entity(entity);
+
+ for_each_entity(entity) {
+ if (entity->on_st)
+ break;
+ enqueue_io_entity(entity);
+ }
}
static inline void
@@ -638,6 +737,38 @@ void elv_io_group_set_async_queue(struct io_group *iog,
int ioprio_class,
}
EXPORT_SYMBOL(elv_io_group_set_async_queue);
+#ifdef CONFIG_GROUP_IOSCHED
+
+static void io_free_root_group(struct elevator_queue *e)
+{
+ struct io_group *iog = e->efqd->root_group;
+
+ put_io_group_queues(e, iog);
+ kfree(iog);
+}
+
+static struct io_group *io_alloc_root_group(struct request_queue *q,
+ struct elevator_queue *e, void *key)
+{
+ struct io_group *iog;
+ int i;
+
+ iog = kmalloc_node(sizeof(*iog), GFP_KERNEL | __GFP_ZERO, q->node);
+ if (iog == NULL)
+ return NULL;
+
+ iog->entity.parent = NULL;
+ iog->entity.my_sd = &iog->sched_data;
+ iog->key = key;
+
+ for (i = 0; i < IO_IOPRIO_CLASSES; i++)
+ iog->sched_data.service_tree[i] = ELV_SERVICE_TREE_INIT;
+
+ return iog;
+}
+
+#else /* CONFIG_GROUP_IOSCHED */
+
static struct io_group *io_alloc_root_group(struct request_queue *q,
struct elevator_queue *e, void *key)
{
@@ -666,6 +797,8 @@ static void io_free_root_group(struct elevator_queue *e)
kfree(iog);
}
+#endif /* CONFIG_GROUP_IOSCHED */
+
/*
* Should be called after ioq prio and class has been initialized as prio
* class data will be used to determine which service tree in the group
@@ -691,9 +824,11 @@ static struct io_queue *elv_get_next_ioq(struct
request_queue *q)
return NULL;
sd = &efqd->root_group->sched_data;
- entity = lookup_next_io_entity(sd);
- if (!entity)
- return NULL;
+ for (; sd != NULL; sd = entity->my_sd) {
+ entity = lookup_next_io_entity(sd);
+ if (!entity)
+ return NULL;
+ }
ioq = ioq_of(entity);
return ioq;
@@ -894,6 +1029,13 @@ static int elv_should_preempt(struct request_queue *q,
struct io_queue *new_ioq,
new_entity = &new_ioq->entity;
/*
+ * In hierarchical setup, one need to traverse up the hierarchy
+ * till both the queues are children of same parent to make a
+ * decision whether to do the preemption or not.
+ */
+ find_matching_io_entity(&entity, &new_entity);
+
+ /*
* Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
*/
diff --git a/block/elevator-fq.h b/block/elevator-fq.h
index 6d3809f..776f429 100644
--- a/block/elevator-fq.h
+++ b/block/elevator-fq.h
@@ -86,6 +86,23 @@ struct io_queue {
void *sched_queue;
};
+#ifdef CONFIG_GROUP_IOSCHED /* CONFIG_GROUP_IOSCHED */
+struct io_group {
+ struct io_entity entity;
+ atomic_t ref;
+ struct io_sched_data sched_data;
+ /*
+ * async queue for each priority case for RT and BE class.
+ * Used only for cfq.
+ */
+
+ struct io_queue *async_queue[2][IOPRIO_BE_NR];
+ struct io_queue *async_idle_queue;
+ void *key;
+};
+
+#else /* CONFIG_GROUP_IOSCHED */
+
struct io_group {
struct io_entity entity;
struct io_sched_data sched_data;
@@ -99,6 +116,8 @@ struct io_group {
void *key;
};
+#endif /* CONFIG_GROUP_IOSCHED */
+
struct elv_fq_data {
struct io_group *root_group;
diff --git a/init/Kconfig b/init/Kconfig
index 3f7e609..29f701d 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -612,6 +612,14 @@ config CGROUP_MEM_RES_CTLR_SWAP
Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
size is 4096bytes, 512k per 1Gbytes of swap.
+config GROUP_IOSCHED
+ bool "Group IO Scheduler"
+ depends on CGROUPS && ELV_FAIR_QUEUING
+ default n
+ ---help---
+ This feature lets IO scheduler recognize task groups and control
+ disk bandwidth allocation to such task groups.
+
endif # CGROUPS
config MM_OWNER
--
1.6.0.6
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