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* [PATCH 0/8] bfq: misc updates
@ 2021-04-20 11:20 brookxu
  2021-04-20 11:20 ` [PATCH 1/8] bfq: introduce bfq_entity_to_bfqg helper method brookxu
                   ` (7 more replies)
  0 siblings, 8 replies; 9+ messages in thread
From: brookxu @ 2021-04-20 11:20 UTC (permalink / raw)
  To: paolo.valente, axboe, tj; +Cc: linux-block, linux-kernel

From: Chunguang Xu <brookxu@tencent.com>

Some misc updates, put together mainly to facilitate patch management.

Chunguang Xu (8):
  bfq: introduce bfq_entity_to_bfqg helper method
  bfq: convert the type of bfq_group.bfqd to bfq_data*
  bfq: limit the IO depth of CLASS_IDLE to 1
  bfq: keep the minimun bandwidth for CLASS_BE
  bfq: remove unnecessary initialization logic
  bfq: optimize the calculation of bfq_weight_to_ioprio()
  bfq: reset entity->prio_changed in bfq_init_entity()
  bfq: remove unnecessary BFQ_DEFAULT_GRP_IOPRIO

 block/bfq-cgroup.c  | 13 +++-----
 block/bfq-iosched.c | 17 +++++++++--
 block/bfq-iosched.h | 15 ++++++----
 block/bfq-wf2q.c    | 86 +++++++++++++++++++++++++++++++++++++----------------
 4 files changed, 88 insertions(+), 43 deletions(-)

-- 
1.8.3.1


^ permalink raw reply	[flat|nested] 9+ messages in thread

* [PATCH 1/8] bfq: introduce bfq_entity_to_bfqg helper method
  2021-04-20 11:20 [PATCH 0/8] bfq: misc updates brookxu
@ 2021-04-20 11:20 ` brookxu
  2021-04-20 11:20 ` [PATCH 2/8] bfq: convert the type of bfq_group.bfqd to bfq_data* brookxu
                   ` (6 subsequent siblings)
  7 siblings, 0 replies; 9+ messages in thread
From: brookxu @ 2021-04-20 11:20 UTC (permalink / raw)
  To: paolo.valente, axboe, tj; +Cc: linux-block, linux-kernel

From: Chunguang Xu <brookxu@tencent.com>

Introduce bfq_entity_to_bfqg() to make it easier to obtain the
bfq_group corresponding to the entity.

Signed-off-by: Chunguang Xu <brookxu@tencent.com>
---
 block/bfq-cgroup.c  |  6 ++----
 block/bfq-iosched.h |  1 +
 block/bfq-wf2q.c    | 16 ++++++++++++----
 3 files changed, 15 insertions(+), 8 deletions(-)

diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c
index b791e20..a5f544a 100644
--- a/block/bfq-cgroup.c
+++ b/block/bfq-cgroup.c
@@ -309,8 +309,7 @@ struct bfq_group *bfqq_group(struct bfq_queue *bfqq)
 {
 	struct bfq_entity *group_entity = bfqq->entity.parent;
 
-	return group_entity ? container_of(group_entity, struct bfq_group,
-					   entity) :
+	return group_entity ? bfq_entity_to_bfqg(group_entity) :
 			      bfqq->bfqd->root_group;
 }
 
@@ -610,8 +609,7 @@ struct bfq_group *bfq_find_set_group(struct bfq_data *bfqd,
 	 */
 	entity = &bfqg->entity;
 	for_each_entity(entity) {
-		struct bfq_group *curr_bfqg = container_of(entity,
-						struct bfq_group, entity);
+		struct bfq_group *curr_bfqg = bfq_entity_to_bfqg(entity);
 		if (curr_bfqg != bfqd->root_group) {
 			parent = bfqg_parent(curr_bfqg);
 			if (!parent)
diff --git a/block/bfq-iosched.h b/block/bfq-iosched.h
index b8e793c..a6f98e9 100644
--- a/block/bfq-iosched.h
+++ b/block/bfq-iosched.h
@@ -941,6 +941,7 @@ struct bfq_group {
 #endif
 
 struct bfq_queue *bfq_entity_to_bfqq(struct bfq_entity *entity);
+struct bfq_group *bfq_entity_to_bfqg(struct bfq_entity *entity);
 
 /* --------------- main algorithm interface ----------------- */
 
diff --git a/block/bfq-wf2q.c b/block/bfq-wf2q.c
index 070e34a..5ff0028 100644
--- a/block/bfq-wf2q.c
+++ b/block/bfq-wf2q.c
@@ -149,7 +149,7 @@ struct bfq_group *bfq_bfqq_to_bfqg(struct bfq_queue *bfqq)
 	if (!group_entity)
 		group_entity = &bfqq->bfqd->root_group->entity;
 
-	return container_of(group_entity, struct bfq_group, entity);
+	return bfq_entity_to_bfqg(group_entity);
 }
 
 /*
@@ -208,7 +208,7 @@ static bool bfq_no_longer_next_in_service(struct bfq_entity *entity)
 	if (bfq_entity_to_bfqq(entity))
 		return true;
 
-	bfqg = container_of(entity, struct bfq_group, entity);
+	bfqg = bfq_entity_to_bfqg(entity);
 
 	/*
 	 * The field active_entities does not always contain the
@@ -266,6 +266,15 @@ struct bfq_queue *bfq_entity_to_bfqq(struct bfq_entity *entity)
 	return bfqq;
 }
 
+struct bfq_group *bfq_entity_to_bfqg(struct bfq_entity *entity)
+{
+	struct bfq_group *bfqg = NULL;
+
+	if (entity->my_sched_data)
+		bfqg = container_of(entity, struct bfq_group, entity);
+
+	return bfqg;
+}
 
 /**
  * bfq_delta - map service into the virtual time domain.
@@ -1001,8 +1010,7 @@ static void __bfq_activate_entity(struct bfq_entity *entity,
 
 #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_group *bfqg = bfq_entity_to_bfqg(entity);
 		struct bfq_data *bfqd = bfqg->bfqd;
 
 		if (!entity->in_groups_with_pending_reqs) {
-- 
1.8.3.1


^ permalink raw reply	[flat|nested] 9+ messages in thread

* [PATCH 2/8] bfq: convert the type of bfq_group.bfqd to bfq_data*
  2021-04-20 11:20 [PATCH 0/8] bfq: misc updates brookxu
  2021-04-20 11:20 ` [PATCH 1/8] bfq: introduce bfq_entity_to_bfqg helper method brookxu
@ 2021-04-20 11:20 ` brookxu
  2021-04-20 11:20 ` [PATCH 3/8] bfq: limit the IO depth of CLASS_IDLE to 1 brookxu
                   ` (5 subsequent siblings)
  7 siblings, 0 replies; 9+ messages in thread
From: brookxu @ 2021-04-20 11:20 UTC (permalink / raw)
  To: paolo.valente, axboe, tj; +Cc: linux-block, linux-kernel

From: Chunguang Xu <brookxu@tencent.com>

Setting bfq_group.bfqd to void* type does not seem to make much sense.
This will cause unnecessary type conversion. Perhaps it would be better
to change it to bfq_data* type.

Signed-off-by: Chunguang Xu <brookxu@tencent.com>
---
 block/bfq-cgroup.c  | 2 +-
 block/bfq-iosched.h | 2 +-
 block/bfq-wf2q.c    | 6 +++---
 3 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c
index a5f544a..50d06c7 100644
--- a/block/bfq-cgroup.c
+++ b/block/bfq-cgroup.c
@@ -224,7 +224,7 @@ void bfqg_stats_update_io_add(struct bfq_group *bfqg, struct bfq_queue *bfqq,
 {
 	blkg_rwstat_add(&bfqg->stats.queued, op, 1);
 	bfqg_stats_end_empty_time(&bfqg->stats);
-	if (!(bfqq == ((struct bfq_data *)bfqg->bfqd)->in_service_queue))
+	if (!(bfqq == bfqg->bfqd->in_service_queue))
 		bfqg_stats_set_start_group_wait_time(bfqg, bfqq_group(bfqq));
 }
 
diff --git a/block/bfq-iosched.h b/block/bfq-iosched.h
index a6f98e9..28d8590 100644
--- a/block/bfq-iosched.h
+++ b/block/bfq-iosched.h
@@ -914,7 +914,7 @@ struct bfq_group {
 	struct bfq_entity entity;
 	struct bfq_sched_data sched_data;
 
-	void *bfqd;
+	struct bfq_data *bfqd;
 
 	struct bfq_queue *async_bfqq[2][IOPRIO_BE_NR];
 	struct bfq_queue *async_idle_bfqq;
diff --git a/block/bfq-wf2q.c b/block/bfq-wf2q.c
index 5ff0028..276f225 100644
--- a/block/bfq-wf2q.c
+++ b/block/bfq-wf2q.c
@@ -498,7 +498,7 @@ static void bfq_active_insert(struct bfq_service_tree *st,
 #ifdef CONFIG_BFQ_GROUP_IOSCHED
 	sd = entity->sched_data;
 	bfqg = container_of(sd, struct bfq_group, sched_data);
-	bfqd = (struct bfq_data *)bfqg->bfqd;
+	bfqd = bfqg->bfqd;
 #endif
 	if (bfqq)
 		list_add(&bfqq->bfqq_list, &bfqq->bfqd->active_list);
@@ -597,7 +597,7 @@ static void bfq_active_extract(struct bfq_service_tree *st,
 #ifdef CONFIG_BFQ_GROUP_IOSCHED
 	sd = entity->sched_data;
 	bfqg = container_of(sd, struct bfq_group, sched_data);
-	bfqd = (struct bfq_data *)bfqg->bfqd;
+	bfqd = bfqg->bfqd;
 #endif
 	if (bfqq)
 		list_del(&bfqq->bfqq_list);
@@ -743,7 +743,7 @@ struct bfq_service_tree *
 		else {
 			sd = entity->my_sched_data;
 			bfqg = container_of(sd, struct bfq_group, sched_data);
-			bfqd = (struct bfq_data *)bfqg->bfqd;
+			bfqd = bfqg->bfqd;
 		}
 #endif
 
-- 
1.8.3.1


^ permalink raw reply	[flat|nested] 9+ messages in thread

* [PATCH 3/8] bfq: limit the IO depth of CLASS_IDLE to 1
  2021-04-20 11:20 [PATCH 0/8] bfq: misc updates brookxu
  2021-04-20 11:20 ` [PATCH 1/8] bfq: introduce bfq_entity_to_bfqg helper method brookxu
  2021-04-20 11:20 ` [PATCH 2/8] bfq: convert the type of bfq_group.bfqd to bfq_data* brookxu
@ 2021-04-20 11:20 ` brookxu
  2021-04-20 11:20 ` [PATCH 4/8] bfq: keep the minimun bandwidth for CLASS_BE brookxu
                   ` (4 subsequent siblings)
  7 siblings, 0 replies; 9+ messages in thread
From: brookxu @ 2021-04-20 11:20 UTC (permalink / raw)
  To: paolo.valente, axboe, tj; +Cc: linux-block, linux-kernel

From: Chunguang Xu <brookxu@tencent.com>

The IO depth of queues belong to CLASS_IDLE is limited to 1,
so that it can avoid introducing a larger tail latency under
a device with a larger IO depth. Although limiting the IO
depth may reduce the performance of idle_class, it is
generally not a big problem, because idle_class usually does
not have strict performance requirements.

Signed-off-by: Chunguang Xu <brookxu@tencent.com>
---
 block/bfq-iosched.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
index ec482e6..29940ec 100644
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c
@@ -4808,6 +4808,17 @@ static struct request *__bfq_dispatch_request(struct blk_mq_hw_ctx *hctx)
 	if (!bfqq)
 		goto exit;
 
+	/*
+	 * Here, the IO depth of queues belong to CLASS_IDLE is limited
+	 * to 1, so that it can avoid introducing a larger tail latency
+	 * under a device with a larger IO depth. Although limiting the
+	 * IO depth may reduce the performance of idle_class, it is
+	 * generally not a big problem, because idle_class usually
+	 * does not have strict performance requirements.
+	 */
+	if (bfq_class_idle(bfqq) && bfqq->dispatched)
+		goto exit;
+
 	rq = bfq_dispatch_rq_from_bfqq(bfqd, bfqq);
 
 	if (rq) {
-- 
1.8.3.1


^ permalink raw reply	[flat|nested] 9+ messages in thread

* [PATCH 4/8] bfq: keep the minimun bandwidth for CLASS_BE
  2021-04-20 11:20 [PATCH 0/8] bfq: misc updates brookxu
                   ` (2 preceding siblings ...)
  2021-04-20 11:20 ` [PATCH 3/8] bfq: limit the IO depth of CLASS_IDLE to 1 brookxu
@ 2021-04-20 11:20 ` brookxu
  2021-04-20 11:20 ` [PATCH 5/8] bfq: remove unnecessary initialization logic brookxu
                   ` (3 subsequent siblings)
  7 siblings, 0 replies; 9+ messages in thread
From: brookxu @ 2021-04-20 11:20 UTC (permalink / raw)
  To: paolo.valente, axboe, tj; +Cc: linux-block, linux-kernel

From: Chunguang Xu <brookxu@tencent.com>

CLASS_RT will preempt other classes, which may starve. At
present, CLASS_IDLE has alleviated the starvation problem
through the minimum bandwidth mechanism. Similarly, we
should do the same for CLASS_BE.

Signed-off-by: Chunguang Xu <brookxu@tencent.com>
---
 block/bfq-iosched.c |  6 ++++--
 block/bfq-iosched.h | 11 ++++++----
 block/bfq-wf2q.c    | 59 ++++++++++++++++++++++++++++++++++++++---------------
 3 files changed, 53 insertions(+), 23 deletions(-)

diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
index 29940ec..89d4646 100644
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c
@@ -6537,9 +6537,11 @@ static void bfq_init_root_group(struct bfq_group *root_group,
 	root_group->bfqd = bfqd;
 #endif
 	root_group->rq_pos_tree = RB_ROOT;
-	for (i = 0; i < BFQ_IOPRIO_CLASSES; i++)
+	for (i = 0; i < BFQ_IOPRIO_CLASSES; i++) {
 		root_group->sched_data.service_tree[i] = BFQ_SERVICE_TREE_INIT;
-	root_group->sched_data.bfq_class_idle_last_service = jiffies;
+		root_group->sched_data.bfq_class_last_service[i] = jiffies;
+	}
+	root_group->sched_data.class_timeout_last_check = jiffies;
 }
 
 static int bfq_init_queue(struct request_queue *q, struct elevator_type *e)
diff --git a/block/bfq-iosched.h b/block/bfq-iosched.h
index 28d8590..da636a8 100644
--- a/block/bfq-iosched.h
+++ b/block/bfq-iosched.h
@@ -13,7 +13,7 @@
 #include "blk-cgroup-rwstat.h"
 
 #define BFQ_IOPRIO_CLASSES	3
-#define BFQ_CL_IDLE_TIMEOUT	(HZ/5)
+#define BFQ_CLASS_TIMEOUT	(HZ/5)
 
 #define BFQ_MIN_WEIGHT			1
 #define BFQ_MAX_WEIGHT			1000
@@ -97,9 +97,12 @@ struct bfq_sched_data {
 	struct bfq_entity *next_in_service;
 	/* array of service trees, one per ioprio_class */
 	struct bfq_service_tree service_tree[BFQ_IOPRIO_CLASSES];
-	/* last time CLASS_IDLE was served */
-	unsigned long bfq_class_idle_last_service;
-
+	/* last time the class was served */
+	unsigned long bfq_class_last_service[BFQ_IOPRIO_CLASSES];
+	/* last time class timeout was checked */
+	unsigned long class_timeout_last_check;
+	/* next index to check class timeout */
+	unsigned int next_class_index;
 };
 
 /**
diff --git a/block/bfq-wf2q.c b/block/bfq-wf2q.c
index 276f225..619ed21 100644
--- a/block/bfq-wf2q.c
+++ b/block/bfq-wf2q.c
@@ -1168,6 +1168,7 @@ bool __bfq_deactivate_entity(struct bfq_entity *entity, bool ins_into_idle_tree)
 {
 	struct bfq_sched_data *sd = entity->sched_data;
 	struct bfq_service_tree *st;
+	int idx = bfq_class_idx(entity);
 	bool is_in_service;
 
 	if (!entity->on_st_or_in_serv) /*
@@ -1207,6 +1208,7 @@ bool __bfq_deactivate_entity(struct bfq_entity *entity, bool ins_into_idle_tree)
 	else
 		bfq_idle_insert(st, entity);
 
+	sd->bfq_class_last_service[idx] = jiffies;
 	return true;
 }
 
@@ -1435,6 +1437,45 @@ static struct bfq_entity *bfq_first_active_entity(struct bfq_service_tree *st,
 	return entity;
 }
 
+static int bfq_select_next_class(struct bfq_sched_data *sd)
+{
+	struct bfq_service_tree *st = sd->service_tree;
+	unsigned long last_check, last_serve;
+	int i, class_idx, next_class = 0;
+	bool found = false;
+
+	/*
+	 * we needed to guarantee a minimum bandwidth for each class (if
+	 * there is some active entity in this class). This should also
+	 * mitigate priority-inversion problems in case a low priority
+	 * task is holding file system resources.
+	 */
+	last_check = sd->class_timeout_last_check;
+	if (time_is_after_jiffies(last_check + BFQ_CLASS_TIMEOUT))
+		return next_class;
+
+	sd->class_timeout_last_check = jiffies;
+	for (i = 0; i < BFQ_IOPRIO_CLASSES; i++) {
+		class_idx = (sd->next_class_index + i) % BFQ_IOPRIO_CLASSES;
+		last_serve = sd->bfq_class_last_service[class_idx];
+
+		if (time_is_after_jiffies(last_serve + BFQ_CLASS_TIMEOUT))
+			continue;
+
+		if (!RB_EMPTY_ROOT(&(st + class_idx)->active)) {
+			if (found)
+				continue;
+
+			next_class = class_idx++;
+			class_idx %= BFQ_IOPRIO_CLASSES;
+			sd->next_class_index = class_idx;
+			found = true;
+		}
+		sd->bfq_class_last_service[class_idx] = jiffies;
+	}
+	return next_class;
+}
+
 /**
  * bfq_lookup_next_entity - return the first eligible entity in @sd.
  * @sd: the sched_data.
@@ -1448,24 +1489,8 @@ static struct bfq_entity *bfq_lookup_next_entity(struct bfq_sched_data *sd,
 						 bool expiration)
 {
 	struct bfq_service_tree *st = sd->service_tree;
-	struct bfq_service_tree *idle_class_st = st + (BFQ_IOPRIO_CLASSES - 1);
 	struct bfq_entity *entity = NULL;
-	int class_idx = 0;
-
-	/*
-	 * Choose from idle class, if needed to guarantee a minimum
-	 * bandwidth to this class (and if there is some active entity
-	 * in idle class). This should also mitigate
-	 * priority-inversion problems in case a low priority task is
-	 * holding file system resources.
-	 */
-	if (time_is_before_jiffies(sd->bfq_class_idle_last_service +
-				   BFQ_CL_IDLE_TIMEOUT)) {
-		if (!RB_EMPTY_ROOT(&idle_class_st->active))
-			class_idx = BFQ_IOPRIO_CLASSES - 1;
-		/* About to be served if backlogged, or not yet backlogged */
-		sd->bfq_class_idle_last_service = jiffies;
-	}
+	int class_idx = bfq_select_next_class(sd);
 
 	/*
 	 * Find the next entity to serve for the highest-priority
-- 
1.8.3.1


^ permalink raw reply	[flat|nested] 9+ messages in thread

* [PATCH 5/8] bfq: remove unnecessary initialization logic
  2021-04-20 11:20 [PATCH 0/8] bfq: misc updates brookxu
                   ` (3 preceding siblings ...)
  2021-04-20 11:20 ` [PATCH 4/8] bfq: keep the minimun bandwidth for CLASS_BE brookxu
@ 2021-04-20 11:20 ` brookxu
  2021-04-20 11:20 ` [PATCH 6/8] bfq: optimize the calculation of bfq_weight_to_ioprio() brookxu
                   ` (2 subsequent siblings)
  7 siblings, 0 replies; 9+ messages in thread
From: brookxu @ 2021-04-20 11:20 UTC (permalink / raw)
  To: paolo.valente, axboe, tj; +Cc: linux-block, linux-kernel

From: Chunguang Xu <brookxu@tencent.com>

Since we will initialize sched_data.service_tree[] in
bfq_init_root_group(), bfq_create_group_hierarchy() can
ignore this part of the initialization, which can avoid
repeated initialization.

Signed-off-by: Chunguang Xu <brookxu@tencent.com>
---
 block/bfq-cgroup.c | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c
index 50d06c7..c8c68dc 100644
--- a/block/bfq-cgroup.c
+++ b/block/bfq-cgroup.c
@@ -1429,15 +1429,11 @@ void bfqg_and_blkg_put(struct bfq_group *bfqg) {}
 struct bfq_group *bfq_create_group_hierarchy(struct bfq_data *bfqd, int node)
 {
 	struct bfq_group *bfqg;
-	int i;
 
 	bfqg = kmalloc_node(sizeof(*bfqg), GFP_KERNEL | __GFP_ZERO, node);
 	if (!bfqg)
 		return NULL;
 
-	for (i = 0; i < BFQ_IOPRIO_CLASSES; i++)
-		bfqg->sched_data.service_tree[i] = BFQ_SERVICE_TREE_INIT;
-
 	return bfqg;
 }
 #endif	/* CONFIG_BFQ_GROUP_IOSCHED */
-- 
1.8.3.1


^ permalink raw reply	[flat|nested] 9+ messages in thread

* [PATCH 6/8] bfq: optimize the calculation of bfq_weight_to_ioprio()
  2021-04-20 11:20 [PATCH 0/8] bfq: misc updates brookxu
                   ` (4 preceding siblings ...)
  2021-04-20 11:20 ` [PATCH 5/8] bfq: remove unnecessary initialization logic brookxu
@ 2021-04-20 11:20 ` brookxu
  2021-04-20 11:20 ` [PATCH 7/8] bfq: reset entity->prio_changed in bfq_init_entity() brookxu
  2021-04-20 11:20 ` [PATCH 8/8] bfq: remove unnecessary BFQ_DEFAULT_GRP_IOPRIO brookxu
  7 siblings, 0 replies; 9+ messages in thread
From: brookxu @ 2021-04-20 11:20 UTC (permalink / raw)
  To: paolo.valente, axboe, tj; +Cc: linux-block, linux-kernel

From: Chunguang Xu <brookxu@tencent.com>

The value range of ioprio is [0, 7], but the result of
bfq_weight_to_ioprio() may exceed this range, so simple
optimization is required.

Signed-off-by: Chunguang Xu <brookxu@tencent.com>
---
 block/bfq-wf2q.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/block/bfq-wf2q.c b/block/bfq-wf2q.c
index 619ed21..ea5b90d 100644
--- a/block/bfq-wf2q.c
+++ b/block/bfq-wf2q.c
@@ -527,8 +527,9 @@ unsigned short bfq_ioprio_to_weight(int ioprio)
  */
 static unsigned short bfq_weight_to_ioprio(int weight)
 {
-	return max_t(int, 0,
-		     IOPRIO_BE_NR * BFQ_WEIGHT_CONVERSION_COEFF - weight);
+	int ioprio = IOPRIO_BE_NR  - weight / BFQ_WEIGHT_CONVERSION_COEFF;
+
+	return ioprio < 0 ? 0 : min_t(int, ioprio, IOPRIO_BE_NR - 1);
 }
 
 static void bfq_get_entity(struct bfq_entity *entity)
-- 
1.8.3.1


^ permalink raw reply	[flat|nested] 9+ messages in thread

* [PATCH 7/8] bfq: reset entity->prio_changed in bfq_init_entity()
  2021-04-20 11:20 [PATCH 0/8] bfq: misc updates brookxu
                   ` (5 preceding siblings ...)
  2021-04-20 11:20 ` [PATCH 6/8] bfq: optimize the calculation of bfq_weight_to_ioprio() brookxu
@ 2021-04-20 11:20 ` brookxu
  2021-04-20 11:20 ` [PATCH 8/8] bfq: remove unnecessary BFQ_DEFAULT_GRP_IOPRIO brookxu
  7 siblings, 0 replies; 9+ messages in thread
From: brookxu @ 2021-04-20 11:20 UTC (permalink / raw)
  To: paolo.valente, axboe, tj; +Cc: linux-block, linux-kernel

From: Chunguang Xu <brookxu@tencent.com>

Since weight, ioprio, ioprio_class will be updated in bfq_init_entity(),
st->wsum will be updated in __bfq_activate_entity(), so when it is first
active, it seems that __bfq_entity_update_weight_prio() has nothing to
do. By resetting entity->prio_change in bfq_init_entity(), we can avoid
unnecessary logic calls.

Signed-off-by: Chunguang Xu <brookxu@tencent.com>
---
 block/bfq-cgroup.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c
index c8c68dc..79a5aaa 100644
--- a/block/bfq-cgroup.c
+++ b/block/bfq-cgroup.c
@@ -426,6 +426,7 @@ void bfq_init_entity(struct bfq_entity *entity, struct bfq_group *bfqg)
 
 	entity->weight = entity->new_weight;
 	entity->orig_weight = entity->new_weight;
+	entity->prio_changed = 0;
 	if (bfqq) {
 		bfqq->ioprio = bfqq->new_ioprio;
 		bfqq->ioprio_class = bfqq->new_ioprio_class;
-- 
1.8.3.1


^ permalink raw reply	[flat|nested] 9+ messages in thread

* [PATCH 8/8] bfq: remove unnecessary BFQ_DEFAULT_GRP_IOPRIO
  2021-04-20 11:20 [PATCH 0/8] bfq: misc updates brookxu
                   ` (6 preceding siblings ...)
  2021-04-20 11:20 ` [PATCH 7/8] bfq: reset entity->prio_changed in bfq_init_entity() brookxu
@ 2021-04-20 11:20 ` brookxu
  7 siblings, 0 replies; 9+ messages in thread
From: brookxu @ 2021-04-20 11:20 UTC (permalink / raw)
  To: paolo.valente, axboe, tj; +Cc: linux-block, linux-kernel

From: Chunguang Xu <brookxu@tencent.com>

BFQ_DEFAULT_GRP_IOPRIO seems to be unused, maybe we can remove it.

Signed-off-by: Chunguang Xu <brookxu@tencent.com>
---
 block/bfq-iosched.h | 1 -
 1 file changed, 1 deletion(-)

diff --git a/block/bfq-iosched.h b/block/bfq-iosched.h
index da636a8..91c8654 100644
--- a/block/bfq-iosched.h
+++ b/block/bfq-iosched.h
@@ -22,7 +22,6 @@
 #define BFQ_DEFAULT_QUEUE_IOPRIO	4
 
 #define BFQ_WEIGHT_LEGACY_DFL	100
-#define BFQ_DEFAULT_GRP_IOPRIO	0
 #define BFQ_DEFAULT_GRP_CLASS	IOPRIO_CLASS_BE
 
 #define MAX_PID_STR_LENGTH 12
-- 
1.8.3.1


^ permalink raw reply	[flat|nested] 9+ messages in thread

end of thread, back to index

Thread overview: 9+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-04-20 11:20 [PATCH 0/8] bfq: misc updates brookxu
2021-04-20 11:20 ` [PATCH 1/8] bfq: introduce bfq_entity_to_bfqg helper method brookxu
2021-04-20 11:20 ` [PATCH 2/8] bfq: convert the type of bfq_group.bfqd to bfq_data* brookxu
2021-04-20 11:20 ` [PATCH 3/8] bfq: limit the IO depth of CLASS_IDLE to 1 brookxu
2021-04-20 11:20 ` [PATCH 4/8] bfq: keep the minimun bandwidth for CLASS_BE brookxu
2021-04-20 11:20 ` [PATCH 5/8] bfq: remove unnecessary initialization logic brookxu
2021-04-20 11:20 ` [PATCH 6/8] bfq: optimize the calculation of bfq_weight_to_ioprio() brookxu
2021-04-20 11:20 ` [PATCH 7/8] bfq: reset entity->prio_changed in bfq_init_entity() brookxu
2021-04-20 11:20 ` [PATCH 8/8] bfq: remove unnecessary BFQ_DEFAULT_GRP_IOPRIO brookxu

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