diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
index 653100fb719eb80e1bb11e9ef7761f14f960623f..d94838bcc135e11936b952815686679e26356308 100644
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c
@@ -3182,6 +3182,13 @@ static unsigned long bfq_bfqq_softrt_next_start(struct bfq_data *bfqd,
jiffies + nsecs_to_jiffies(bfqq->bfqd->bfq_slice_idle) + 4);
}
+static bool bfq_bfqq_injectable(struct bfq_queue *bfqq)
+{
+ return BFQQ_SEEKY(bfqq) && bfqq->wr_coeff == 1 &&
+ blk_queue_nonrot(bfqq->bfqd->queue) &&
+ bfqq->bfqd->hw_tag;
+}
+
/**
* bfq_bfqq_expire - expire a queue.
* @bfqd: device owning the queue.
@@ -3291,6 +3298,8 @@ void bfq_bfqq_expire(struct bfq_data *bfqd,
if (ref == 1) /* bfqq is gone, no more actions on it */
return;
+ bfqq->injected_service = 0;
+
/* mark bfqq as waiting a request only if a bic still points to it */
if (!bfq_bfqq_busy(bfqq) &&
reason != BFQQE_BUDGET_TIMEOUT &&
@@ -3629,6 +3638,30 @@ static bool bfq_bfqq_must_idle(struct bfq_queue *bfqq)
return RB_EMPTY_ROOT(&bfqq->sort_list) && bfq_better_to_idle(bfqq);
}
+static struct bfq_queue *bfq_choose_bfqq_for_injection(struct bfq_data *bfqd)
+{
+ struct bfq_queue *bfqq;
+
+ /*
+ * A linear search; but, with a high probability, very few
+ * steps are needed to find a candidate queue, i.e., a queue
+ * with enough budget left for its next request. In fact:
+ * - BFQ dynamically updates the budget of every queue so as
+ * to accommodate the expected backlog of the queue;
+ * - if a queue gets all its requests dispatched as injected
+ * service, then the queue is removed from the active list
+ * (and re-added only if it gets new requests, but with
+ * enough budget for its new backlog).
+ */
+ list_for_each_entry(bfqq, &bfqd->active_list, bfqq_list)
+ if (!RB_EMPTY_ROOT(&bfqq->sort_list) &&
+ bfq_serv_to_charge(bfqq->next_rq, bfqq) <=
+ bfq_bfqq_budget_left(bfqq))
+ return bfqq;
+
+ return NULL;
+}
+
/*
* Select a queue for service. If we have a current queue in service,
* check whether to continue servicing it, or retrieve and set a new one.
@@ -3710,10 +3743,19 @@ static struct bfq_queue *bfq_select_queue(struct bfq_data *bfqd)
* No requests pending. However, if the in-service queue is idling
* for a new request, or has requests waiting for a completion and
* may idle after their completion, then keep it anyway.
+ *
+ * Yet, to boost throughput, inject service from other queues if
+ * possible.
*/
if (bfq_bfqq_wait_request(bfqq) ||
(bfqq->dispatched != 0 && bfq_better_to_idle(bfqq))) {
- bfqq = NULL;
+ if (bfq_bfqq_injectable(bfqq) &&
+ bfqq->injected_service * bfqq->inject_coeff <
+ bfqq->entity.service * 10)
+ bfqq = bfq_choose_bfqq_for_injection(bfqd);
+ else
+ bfqq = NULL;
+
goto keep_queue;
}
@@ -3803,6 +3845,14 @@ static struct request *bfq_dispatch_rq_from_bfqq(struct bfq_data *bfqd,
bfq_dispatch_remove(bfqd->queue, rq);
+ if (bfqq != bfqd->in_service_queue) {
+ if (likely(bfqd->in_service_queue))
+ bfqd->in_service_queue->injected_service +=
+ bfq_serv_to_charge(rq, bfqq);
+
+ goto return_rq;
+ }
+
/*
* If weight raising has to terminate for bfqq, then next
* function causes an immediate update of bfqq's weight,
@@ -3821,13 +3871,12 @@ 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))
- goto expire;
-
- return rq;
+ if (!(bfqd->busy_queues > 1 && bfq_class_idle(bfqq)))
+ goto return_rq;
-expire:
bfq_bfqq_expire(bfqd, bfqq, false, BFQQE_BUDGET_EXHAUSTED);
+
+return_rq:
return rq;
}
@@ -4232,6 +4281,13 @@ static void bfq_init_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq,
bfq_mark_bfqq_has_short_ttime(bfqq);
bfq_mark_bfqq_sync(bfqq);
bfq_mark_bfqq_just_created(bfqq);
+ /*
+ * Aggressively inject a lot of service: up to 90%.
+ * This coefficient remains constant during bfqq life,
+ * but this behavior might be changed, after enough
+ * testing and tuning.
+ */
+ bfqq->inject_coeff = 1;
} else
bfq_clear_bfqq_sync(bfqq);
diff --git a/block/bfq-iosched.h b/block/bfq-iosched.h
index a8a2e5aca4d48f328dbb1c14bff88f1aaa485a2c..37d627afdc2e5fe21f2b830755c4e672433ee0fc 100644
--- a/block/bfq-iosched.h
+++ b/block/bfq-iosched.h
@@ -351,6 +351,32 @@ struct bfq_queue {
unsigned long split_time; /* time of last split */
unsigned long first_IO_time; /* time of first I/O for this queue */
+
+ /* max service rate measured so far */
+ u32 max_service_rate;
+ /*
+ * Ratio between the service received by bfqq while it is in
+ * service, and the cumulative service (of requests of other
+ * queues) that may be injected while bfqq is empty but still
+ * in service. To increase precision, the coefficient is
+ * measured in tenths of unit. Here are some example of (1)
+ * ratios, (2) resulting percentages of service injected
+ * w.r.t. to the total service dispatched while bfqq is in
+ * service, and (3) corresponding values of the coefficient:
+ * 1 (50%) -> 10
+ * 2 (33%) -> 20
+ * 10 (9%) -> 100
+ * 9.9 (9%) -> 99
+ * 1.5 (40%) -> 15
+ * 0.5 (66%) -> 5
+ * 0.1 (90%) -> 1
+ *
+ * So, if the coefficient is lower than 10, then
+ * injected service is more than bfqq service.
+ */
+ unsigned int inject_coeff;
+ /* amount of service injected in current service slot */
+ unsigned int injected_service;
};
/**