> Il giorno 18 dic 2018, alle ore 19:21, Jens Axboe <[email protected]> ha > scritto: > > On 12/18/18 11:19 AM, Paolo Valente wrote: >> >> >>> Il giorno 18 dic 2018, alle ore 19:08, Jens Axboe <[email protected]> ha >>> scritto: >>> >>> On 12/18/18 11:04 AM, Paolo Valente wrote: >>>> static bool bfq_symmetric_scenario(struct bfq_data *bfqd) >>>> { >>>> - return !bfq_varied_queue_weights_or_active_groups(bfqd); >>>> + /* >>>> + * For queue weights to differ, queue_weights_tree must contain >>>> + * at least two nodes. >>>> + */ >>>> + bool varied_queue_weights = !RB_EMPTY_ROOT(&bfqd->queue_weights_tree) && >>>> + (bfqd->queue_weights_tree.rb_node->rb_left || >>>> + bfqd->queue_weights_tree.rb_node->rb_right); >>>> + >>>> + bool multiple_classes_busy = >>>> + (bfqd->busy_queues[0] & bfqd->busy_queues[1]) | >>>> + (bfqd->busy_queues[0] & bfqd->busy_queues[2]) | >>>> + (bfqd->busy_queues[1] & bfqd->busy_queues[2]); >>> >>> I don't think this does what you want it to, looks like these should be >>> logical AND and OR. >>> >> >> Absolutely, sorry. Fortunately, the end result is still correct :) > > Is it? What if ->busy_queues[0] is 1 and ->busy_queues[1] is 2. You'd > expect the first comparison to be true, but it'd be false. Ditto for > the rest of them, of course. >
S..t. Thank you.
New patch attached, and diffs pasted again. Madhav, you might not see
any difference for your use case, but better if you use the new patch.
block/bfq-iosched.c | 86 ++++++++++++++++++++++++++++-------------------------
block/bfq-iosched.h | 8 +++--
block/bfq-wf2q.c | 12 ++++++--
3 files changed, 59 insertions(+), 47 deletions(-)
diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
index 97337214bec4..6c67b038ede5 100644
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c
@@ -623,26 +623,6 @@ void bfq_pos_tree_add_move(struct bfq_data *bfqd, struct
bfq_queue *bfqq)
bfqq->pos_root = NULL;
}
-/*
- * Tell whether there are active queues with different weights or
- * active groups.
- */
-static bool bfq_varied_queue_weights_or_active_groups(struct bfq_data *bfqd)
-{
- /*
- * For queue weights to differ, queue_weights_tree must contain
- * at least two nodes.
- */
- return (!RB_EMPTY_ROOT(&bfqd->queue_weights_tree) &&
- (bfqd->queue_weights_tree.rb_node->rb_left ||
- bfqd->queue_weights_tree.rb_node->rb_right)
-#ifdef CONFIG_BFQ_GROUP_IOSCHED
- ) ||
- (bfqd->num_groups_with_pending_reqs > 0
-#endif
- );
-}
-
/*
* The following function returns true if every queue must receive the
* same share of the throughput (this condition is used when deciding
@@ -651,25 +631,48 @@ static bool
bfq_varied_queue_weights_or_active_groups(struct bfq_data *bfqd)
*
* Such a scenario occurs when:
* 1) all active queues have the same weight,
- * 2) all active groups at the same level in the groups tree have the same
- * weight,
+ * 2) all active queues belong to the same I/O-priority class,
* 3) all active groups at the same level in the groups tree have the same
+ * weight,
+ * 4) all active groups at the same level in the groups tree have the same
* number of children.
*
* Unfortunately, keeping the necessary state for evaluating exactly
* the last two symmetry sub-conditions above would be quite complex
- * and time consuming. Therefore this function evaluates, instead,
- * only the following stronger two sub-conditions, for which it is
+ * and time consuming. Therefore this function evaluates, instead,
+ * only the following stronger three sub-conditions, for which it is
* much easier to maintain the needed state:
* 1) all active queues have the same weight,
- * 2) there are no active groups.
+ * 2) all active queues belong to the same I/O-priority class,
+ * 3) there are no active groups.
* In particular, the last condition is always true if hierarchical
* support or the cgroups interface are not enabled, thus no state
* needs to be maintained in this case.
*/
static bool bfq_symmetric_scenario(struct bfq_data *bfqd)
{
- return !bfq_varied_queue_weights_or_active_groups(bfqd);
+ /*
+ * For queue weights to differ, queue_weights_tree must contain
+ * at least two nodes.
+ */
+ bool varied_queue_weights = !RB_EMPTY_ROOT(&bfqd->queue_weights_tree) &&
+ (bfqd->queue_weights_tree.rb_node->rb_left ||
+ bfqd->queue_weights_tree.rb_node->rb_right);
+
+ bool multiple_classes_busy =
+ (bfqd->busy_queues[0] && bfqd->busy_queues[1]) ||
+ (bfqd->busy_queues[0] && bfqd->busy_queues[2]) ||
+ (bfqd->busy_queues[1] && bfqd->busy_queues[2]);
+
+ /*
+ * For queue weights to differ, queue_weights_tree must contain
+ * at least two nodes.
+ */
+ return !(varied_queue_weights || multiple_classes_busy
+#ifdef BFQ_GROUP_IOSCHED_ENABLED
+ || bfqd->num_groups_with_pending_reqs > 0
+#endif
+ );
}
/*
@@ -728,15 +731,14 @@ void bfq_weights_tree_add(struct bfq_data *bfqd, struct
bfq_queue *bfqq,
/*
* In the unlucky event of an allocation failure, we just
* exit. This will cause the weight of queue to not be
- * considered in bfq_varied_queue_weights_or_active_groups,
- * which, in its turn, causes the scenario to be deemed
- * wrongly symmetric in case bfqq's weight would have been
- * the only weight making the scenario asymmetric. On the
- * bright side, no unbalance will however occur when bfqq
- * becomes inactive again (the invocation of this function
- * is triggered by an activation of queue). In fact,
- * bfq_weights_tree_remove does nothing if
- * !bfqq->weight_counter.
+ * considered in bfq_symmetric_scenario, which, in its turn,
+ * causes the scenario to be deemed wrongly symmetric in case
+ * bfqq's weight would have been the only weight making the
+ * scenario asymmetric. On the bright side, no unbalance will
+ * however occur when bfqq becomes inactive again (the
+ * invocation of this function is triggered by an activation
+ * of queue). In fact, bfq_weights_tree_remove does nothing
+ * if !bfqq->weight_counter.
*/
if (unlikely(!bfqq->weight_counter))
return;
@@ -2217,7 +2219,7 @@ bfq_setup_cooperator(struct bfq_data *bfqd, struct
bfq_queue *bfqq,
return NULL;
/* If there is only one backlogged queue, don't search. */
- if (bfqd->busy_queues == 1)
+ if (bfq_tot_busy_queues(bfqd) == 1)
return NULL;
in_service_bfqq = bfqd->in_service_queue;
@@ -3655,7 +3657,8 @@ static bool bfq_better_to_idle(struct bfq_queue *bfqq)
* the requests already queued in the device have been served.
*/
asymmetric_scenario = (bfqq->wr_coeff > 1 &&
- bfqd->wr_busy_queues < bfqd->busy_queues) ||
+ bfqd->wr_busy_queues <
+ bfq_tot_busy_queues(bfqd)) ||
!bfq_symmetric_scenario(bfqd);
/*
@@ -3934,7 +3937,7 @@ static struct request *bfq_dispatch_rq_from_bfqq(struct
bfq_data *bfqd,
* belongs to CLASS_IDLE and other queues are waiting for
* service.
*/
- if (!(bfqd->busy_queues > 1 && bfq_class_idle(bfqq)))
+ if (!(bfq_tot_busy_queues(bfqd) > 1 && bfq_class_idle(bfqq)))
goto return_rq;
bfq_bfqq_expire(bfqd, bfqq, false, BFQQE_BUDGET_EXHAUSTED);
@@ -3952,7 +3955,7 @@ static bool bfq_has_work(struct blk_mq_hw_ctx *hctx)
* most a call to dispatch for nothing
*/
return !list_empty_careful(&bfqd->dispatch) ||
- bfqd->busy_queues > 0;
+ bfq_tot_busy_queues(bfqd) > 0;
}
static struct request *__bfq_dispatch_request(struct blk_mq_hw_ctx *hctx)
@@ -4006,9 +4009,10 @@ static struct request *__bfq_dispatch_request(struct
blk_mq_hw_ctx *hctx)
goto start_rq;
}
- bfq_log(bfqd, "dispatch requests: %d busy queues", bfqd->busy_queues);
+ bfq_log(bfqd, "dispatch requests: %d busy queues",
+ bfq_tot_busy_queues(bfqd));
- if (bfqd->busy_queues == 0)
+ if (bfq_tot_busy_queues(bfqd) == 0)
goto exit;
/*
diff --git a/block/bfq-iosched.h b/block/bfq-iosched.h
index 0b02bf302de0..30be669be465 100644
--- a/block/bfq-iosched.h
+++ b/block/bfq-iosched.h
@@ -501,10 +501,11 @@ struct bfq_data {
unsigned int num_groups_with_pending_reqs;
/*
- * Number of bfq_queues containing requests (including the
- * queue in service, even if it is idling).
+ * Per-class (RT, BE, IDLE) number of bfq_queues containing
+ * requests (including the queue in service, even if it is
+ * idling).
*/
- int busy_queues;
+ unsigned int busy_queues[3];
/* number of weight-raised busy @bfq_queues */
int wr_busy_queues;
/* number of queued requests */
@@ -974,6 +975,7 @@ extern struct blkcg_policy blkcg_policy_bfq;
struct bfq_group *bfq_bfqq_to_bfqg(struct bfq_queue *bfqq);
struct bfq_queue *bfq_entity_to_bfqq(struct bfq_entity *entity);
+unsigned int bfq_tot_busy_queues(struct bfq_data *bfqd);
struct bfq_service_tree *bfq_entity_service_tree(struct bfq_entity *entity);
struct bfq_entity *bfq_entity_of(struct rb_node *node);
unsigned short bfq_ioprio_to_weight(int ioprio);
diff --git a/block/bfq-wf2q.c b/block/bfq-wf2q.c
index 63e0f12be7c9..7119207cae3c 100644
--- a/block/bfq-wf2q.c
+++ b/block/bfq-wf2q.c
@@ -44,6 +44,12 @@ static unsigned int bfq_class_idx(struct bfq_entity *entity)
BFQ_DEFAULT_GRP_CLASS - 1;
}
+unsigned int bfq_tot_busy_queues(struct bfq_data *bfqd)
+{
+ return bfqd->busy_queues[0] + bfqd->busy_queues[1] +
+ bfqd->busy_queues[2];
+}
+
static struct bfq_entity *bfq_lookup_next_entity(struct bfq_sched_data *sd,
bool expiration);
@@ -1514,7 +1520,7 @@ struct bfq_queue *bfq_get_next_queue(struct bfq_data
*bfqd)
struct bfq_sched_data *sd;
struct bfq_queue *bfqq;
- if (bfqd->busy_queues == 0)
+ if (bfq_tot_busy_queues(bfqd) == 0)
return NULL;
/*
@@ -1666,7 +1672,7 @@ void bfq_del_bfqq_busy(struct bfq_data *bfqd, struct
bfq_queue *bfqq,
bfq_clear_bfqq_busy(bfqq);
- bfqd->busy_queues--;
+ bfqd->busy_queues[bfqq->ioprio_class - 1]--;
if (!bfqq->dispatched)
bfq_weights_tree_remove(bfqd, bfqq);
@@ -1689,7 +1695,7 @@ void bfq_add_bfqq_busy(struct bfq_data *bfqd, struct
bfq_queue *bfqq)
bfq_activate_bfqq(bfqd, bfqq);
bfq_mark_bfqq_busy(bfqq);
- bfqd->busy_queues++;
+ bfqd->busy_queues[bfqq->ioprio_class - 1]++;
if (!bfqq->dispatched)
if (bfqq->wr_coeff == 1)
Thanks,
Paolo
0001-consider-also-ioprio-classes-for-symmetry-detection.patch.gz
Description: GNU Zip compressed data
