On 2021/08/27 1:00, Paolo Valente wrote:
Il giorno 6 ago 2021, alle ore 04:08, Yu Kuai <yukuai3@xxxxxxxxxx> ha scritto:
Add a new member in bfq_data to track number of queues that are in
root_group with any pending requests.
maybe modify the last part of the sentence as: ... and that have some pending request
This will be used in next patch
to optmize queue idle judgment when root_group doesn't have any
pending requests.
Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx>
---
block/bfq-iosched.c | 8 +++++++-
block/bfq-iosched.h | 13 +++++++++++--
block/bfq-wf2q.c | 37 ++++++++++++++++++++++++-------------
3 files changed, 42 insertions(+), 16 deletions(-)
diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
index 727955918563..7c6b412f9a9c 100644
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c
@@ -859,8 +859,14 @@ void __bfq_weights_tree_remove(struct bfq_data *bfqd,
void bfq_weights_tree_remove(struct bfq_data *bfqd,
struct bfq_queue *bfqq)
{
- struct bfq_entity *entity = bfqq->entity.parent;
+ struct bfq_entity *entity = &bfqq->entity;
+
+ if (entity->in_groups_with_pending_reqs) {
+ entity->in_groups_with_pending_reqs = false;
+ bfqd->num_queues_with_pending_reqs_in_root--;
Here you cross the comment "The decrement of
num_groups_with_pending_reqs is not performed immediately upon ...".
Find a way to
- move that comment up, and to make it correct for this slightly
different decrement
- leave a correct comment (probably shorter) in the original position
+ }
+ entity = entity->parent;
for_each_entity(entity) {
struct bfq_sched_data *sd = entity->my_sched_data;
diff --git a/block/bfq-iosched.h b/block/bfq-iosched.h
index 99c2a3cb081e..610769214f72 100644
--- a/block/bfq-iosched.h
+++ b/block/bfq-iosched.h
@@ -195,7 +195,12 @@ struct bfq_entity {
/* flag, set to request a weight, ioprio or ioprio_class change */
int prio_changed;
- /* flag, set if the entity is counted in groups_with_pending_reqs */
+ /*
+ * If entity represents bfq_group, this flag will set
will be set?
if the group is
+ * not root_group and have
has
any pending requests; If entity represents
one more nit: use lowercase after semicolon
+ * bfq_queue, this flag will set
will be set
if the queue is in root_group and have
+ * any pending requests.
+ */
bool in_groups_with_pending_reqs;
The name of the above field follows from the fact that entity is
counted in groups_with_pending_reqs. You change this fact, because,
in your patch, a queue is not counted in groups_with_pending_reqs.
But you leave the same name. This creates confusion.
/* last child queue of entity created (for non-leaf entities) */
@@ -539,7 +544,11 @@ struct bfq_data {
* with no request waiting for completion.
*/
unsigned int num_groups_with_pending_reqs;
-
+ /*
+ * number of queues that are in root_group with at least one request
+ * waiting for completion.
please link somehow this comment to the long comment that comes before it
+ */
+ unsigned int num_queues_with_pending_reqs_in_root;
Why using two counters? I mean, couldn't you simply count also the
root group in num_groups_with_pending_reqs?
Hi, Paolo
Thanks for taking time reviewing these patches
I was doing this too complicated, while counting root group into
num_groups_with_pending_reqs is much easier. I'll do this in next
iteration.
Thanks
Yu Kuai
/*
* Per-class (RT, BE, IDLE) number of bfq_queues containing
* requests (including the queue in service, even if it is
diff --git a/block/bfq-wf2q.c b/block/bfq-wf2q.c
index 7a462df71f68..188c8f907219 100644
--- a/block/bfq-wf2q.c
+++ b/block/bfq-wf2q.c
@@ -946,6 +946,29 @@ static void bfq_update_fin_time_enqueue(struct bfq_entity *entity,
bfq_active_insert(st, entity);
}
+static void bfq_update_groups_with_pending_reqs(struct bfq_entity *entity)
+{
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
+
why do you introduce an extra variable bfqq, instead of doing as in
the original version of the code? In addition, you remove the comment
/* bfq_group */
Thanks,
Paolo
+ if (bfqq) {
+ if (!entity->parent && !entity->in_groups_with_pending_reqs) {
+ entity->in_groups_with_pending_reqs = true;
+ bfqq->bfqd->num_queues_with_pending_reqs_in_root++;
+ }
+ } else {
+ if (!entity->in_groups_with_pending_reqs) {
+ struct bfq_group *bfqg =
+ container_of(entity, struct bfq_group, entity);
+ struct bfq_data *bfqd = bfqg->bfqd;
+
+ entity->in_groups_with_pending_reqs = true;
+ bfqd->num_groups_with_pending_reqs++;
+ }
+ }
+#endif
+}
+
/**
* __bfq_activate_entity - handle activation of entity.
* @entity: the entity being activated.
@@ -999,19 +1022,7 @@ static void __bfq_activate_entity(struct bfq_entity *entity,
entity->on_st_or_in_serv = true;
}
-#ifdef CONFIG_BFQ_GROUP_IOSCHED
- if (!bfq_entity_to_bfqq(entity)) { /* bfq_group */
- struct bfq_group *bfqg =
- container_of(entity, struct bfq_group, entity);
- struct bfq_data *bfqd = bfqg->bfqd;
-
- if (!entity->in_groups_with_pending_reqs) {
- entity->in_groups_with_pending_reqs = true;
- bfqd->num_groups_with_pending_reqs++;
- }
- }
-#endif
-
+ bfq_update_groups_with_pending_reqs(entity);
bfq_update_fin_time_enqueue(entity, st, backshifted);
}
--
2.31.1
.
