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Date: Thu, 3 Nov 2022 17:26:19 +0100
From: Paolo Valente <paolo.valente@...aro.org>
To: Jens Axboe <axboe@...nel.dk>
Cc: linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
arie.vanderhoeven@...gate.com, rory.c.chen@...gate.com,
Paolo Valente <paolo.valente@...aro.org>,
Gabriele Felici <felicigb@...il.com>,
Gianmarco Lusvardi <glusvardi@...teo.net>,
Giulio Barabino <giuliobarabino99@...il.com>,
Emiliano Maccaferri <inbox@...lianomaccaferri.com>
Subject: [PATCH V6 4/8] block, bfq: turn bfqq_data into an array in bfq_io_cq
When a bfq_queue Q is merged with another queue, several pieces of
information are saved about Q. These pieces are stored in the
bfqq_data field in the bfq_io_cq data structure of the process
associated with Q.
Yet, with a multi-actuator drive, a process may get associated with
multiple bfq_queues: one queue for each of the N actuators. Each of
these queues may undergo a merge. So, the bfq_io_cq data structure
must be able to accommodate the above information for N queues.
This commit solves this problem by turning the bfqq_data scalar field
into an array of N elements (and by changing code so as to handle
this array).
This solution is written under the assumption that bfq_queues
associated with different actuators cannot be cross-merged. This
assumption holds naturally with basic queue merging: the latter is
triggered by spatial locality, and sectors for different actuators are
not close to each other. As for stable cross-merging, the assumption
here is that it is disabled.
Signed-off-by: Gabriele Felici <felicigb@...il.com>
Signed-off-by: Gianmarco Lusvardi <glusvardi@...teo.net>
Signed-off-by: Giulio Barabino <giuliobarabino99@...il.com>
Signed-off-by: Emiliano Maccaferri <inbox@...lianomaccaferri.com>
Signed-off-by: Paolo Valente <paolo.valente@...aro.org>
---
block/bfq-iosched.c | 72 ++++++++++++++++++++++++---------------------
block/bfq-iosched.h | 12 +++++---
2 files changed, 47 insertions(+), 37 deletions(-)
diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
index 01528182c0c5..f44bac054aaf 100644
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c
@@ -404,7 +404,7 @@ void bic_set_bfqq(struct bfq_io_cq *bic,
* we cancel the stable merge if
* bic->stable_merge_bfqq == bfqq.
*/
- struct bfq_iocq_bfqq_data *bfqq_data = &bic->bfqq_data;
+ struct bfq_iocq_bfqq_data *bfqq_data = &bic->bfqq_data[actuator_idx];
bic->bfqq[is_sync][actuator_idx] = bfqq;
if (bfqq && bfqq_data->stable_merge_bfqq == bfqq) {
@@ -1175,9 +1175,10 @@ static void
bfq_bfqq_resume_state(struct bfq_queue *bfqq, struct bfq_data *bfqd,
struct bfq_io_cq *bic, bool bfq_already_existing)
{
- struct bfq_iocq_bfqq_data *bfqq_data = &bic->bfqq_data;
unsigned int old_wr_coeff = 1;
bool busy = bfq_already_existing && bfq_bfqq_busy(bfqq);
+ unsigned int a_idx = bfqq->actuator_idx;
+ struct bfq_iocq_bfqq_data *bfqq_data = &bic->bfqq_data[a_idx];
if (bfqq_data->saved_has_short_ttime)
bfq_mark_bfqq_has_short_ttime(bfqq);
@@ -1827,6 +1828,16 @@ static bool bfq_bfqq_higher_class_or_weight(struct bfq_queue *bfqq,
return bfqq_weight > in_serv_weight;
}
+/* get the index of the actuator that will serve bio */
+static unsigned int bfq_actuator_index(struct bfq_data *bfqd, struct bio *bio)
+{
+ /*
+ * Multi-actuator support not complete yet, so always return 0
+ * for the moment.
+ */
+ return 0;
+}
+
static bool bfq_better_to_idle(struct bfq_queue *bfqq);
static void bfq_bfqq_handle_idle_busy_switch(struct bfq_data *bfqd,
@@ -1881,7 +1892,9 @@ static void bfq_bfqq_handle_idle_busy_switch(struct bfq_data *bfqd,
wr_or_deserves_wr = bfqd->low_latency &&
(bfqq->wr_coeff > 1 ||
(bfq_bfqq_sync(bfqq) &&
- (bfqq->bic || RQ_BIC(rq)->bfqq_data.stably_merged) &&
+ (bfqq->bic ||
+ RQ_BIC(rq)->bfqq_data[bfq_actuator_index(bfqd, rq->bio)]
+ .stably_merged) &&
(*interactive || soft_rt)));
/*
@@ -2469,16 +2482,6 @@ static void bfq_remove_request(struct request_queue *q,
}
-/* get the index of the actuator that will serve bio */
-static unsigned int bfq_actuator_index(struct bfq_data *bfqd, struct bio *bio)
-{
- /*
- * Multi-actuator support not complete yet, so always return 0
- * for the moment.
- */
- return 0;
-}
-
static bool bfq_bio_merge(struct request_queue *q, struct bio *bio,
unsigned int nr_segs)
{
@@ -2905,7 +2908,8 @@ bfq_setup_cooperator(struct bfq_data *bfqd, struct bfq_queue *bfqq,
void *io_struct, bool request, struct bfq_io_cq *bic)
{
struct bfq_queue *in_service_bfqq, *new_bfqq;
- struct bfq_iocq_bfqq_data *bfqq_data = &bic->bfqq_data;
+ unsigned int a_idx = bfqq->actuator_idx;
+ struct bfq_iocq_bfqq_data *bfqq_data = &bic->bfqq_data[a_idx];
/* if a merge has already been setup, then proceed with that first */
if (bfqq->new_bfqq)
@@ -2952,8 +2956,9 @@ bfq_setup_cooperator(struct bfq_data *bfqd, struct bfq_queue *bfqq,
if (new_bfqq) {
bfqq_data->stably_merged = true;
if (new_bfqq->bic)
- new_bfqq->bic->bfqq_data.stably_merged =
- true;
+ new_bfqq->bic->bfqq_data
+ [new_bfqq->actuator_idx]
+ .stably_merged = true;
}
return new_bfqq;
} else
@@ -3052,7 +3057,9 @@ bfq_setup_cooperator(struct bfq_data *bfqd, struct bfq_queue *bfqq,
static void bfq_bfqq_save_state(struct bfq_queue *bfqq)
{
struct bfq_io_cq *bic = bfqq->bic;
- struct bfq_iocq_bfqq_data *bfqq_data = &bic->bfqq_data;
+ /* State must be saved for the right queue index. */
+ unsigned int a_idx = bfqq->actuator_idx;
+ struct bfq_iocq_bfqq_data *bfqq_data = &bic->bfqq_data[a_idx];
/*
* If !bfqq->bic, the queue is already shared or its requests
@@ -3063,7 +3070,7 @@ static void bfq_bfqq_save_state(struct bfq_queue *bfqq)
return;
bfqq_data->saved_last_serv_time_ns = bfqq->last_serv_time_ns;
- bfqq_data->saved_inject_limit = bfqq->inject_limit;
+ bfqq_data->saved_inject_limit = bfqq->inject_limit;
bfqq_data->saved_decrease_time_jif = bfqq->decrease_time_jif;
bfqq_data->saved_weight = bfqq->entity.orig_weight;
@@ -5425,7 +5432,7 @@ static void bfq_exit_icq(struct io_cq *icq)
unsigned long flags;
unsigned int act_idx;
unsigned int num_actuators;
- struct bfq_iocq_bfqq_data *bfqq_data = &bic->bfqq_data;
+ struct bfq_iocq_bfqq_data *bfqq_data = bic->bfqq_data;
/*
* bfqd is NULL if scheduler already exited, and in that case
@@ -5445,10 +5452,10 @@ static void bfq_exit_icq(struct io_cq *icq)
num_actuators = BFQ_MAX_ACTUATORS;
}
- if (bfqq_data->stable_merge_bfqq)
- bfq_put_stable_ref(bfqq_data->stable_merge_bfqq);
-
for (act_idx = 0; act_idx < num_actuators; act_idx++) {
+ if (bfqq_data[act_idx].stable_merge_bfqq)
+ bfq_put_stable_ref(bfqq_data[act_idx].stable_merge_bfqq);
+
bfq_exit_icq_bfqq(bic, true, act_idx);
bfq_exit_icq_bfqq(bic, false, act_idx);
}
@@ -5635,16 +5642,16 @@ bfq_do_early_stable_merge(struct bfq_data *bfqd, struct bfq_queue *bfqq,
struct bfq_io_cq *bic,
struct bfq_queue *last_bfqq_created)
{
+ unsigned int a_idx = last_bfqq_created->actuator_idx;
struct bfq_queue *new_bfqq =
bfq_setup_merge(bfqq, last_bfqq_created);
- struct bfq_iocq_bfqq_data *bfqq_data = &bic->bfqq_data;
if (!new_bfqq)
return bfqq;
if (new_bfqq->bic)
- new_bfqq->bic->bfqq_data.stably_merged = true;
- bfqq_data->stably_merged = true;
+ new_bfqq->bic->bfqq_data[a_idx].stably_merged = true;
+ bic->bfqq_data[a_idx].stably_merged = true;
/*
* Reusing merge functions. This implies that
@@ -5713,7 +5720,6 @@ static struct bfq_queue *bfq_do_or_sched_stable_merge(struct bfq_data *bfqd,
&bfqd->last_bfqq_created;
struct bfq_queue *last_bfqq_created = *source_bfqq;
- struct bfq_iocq_bfqq_data *bfqq_data = &bic->bfqq_data;
/*
* If last_bfqq_created has not been set yet, then init it. If
@@ -5775,7 +5781,8 @@ static struct bfq_queue *bfq_do_or_sched_stable_merge(struct bfq_data *bfqd,
/*
* Record the bfqq to merge to.
*/
- bfqq_data->stable_merge_bfqq = last_bfqq_created;
+ bic->bfqq_data[last_bfqq_created->actuator_idx].stable_merge_bfqq =
+ last_bfqq_created;
}
}
@@ -6696,7 +6703,7 @@ static struct bfq_queue *bfq_get_bfqq_handle_split(struct bfq_data *bfqd,
{
unsigned int act_idx = bfq_actuator_index(bfqd, bio);
struct bfq_queue *bfqq = bic_to_bfqq(bic, is_sync, act_idx);
- struct bfq_iocq_bfqq_data *bfqq_data = &bic->bfqq_data;
+ struct bfq_iocq_bfqq_data *bfqq_data = &bic->bfqq_data[act_idx];
if (likely(bfqq && bfqq != &bfqd->oom_bfqq))
return bfqq;
@@ -6804,7 +6811,7 @@ static struct bfq_queue *bfq_init_rq(struct request *rq)
struct bfq_queue *bfqq;
bool new_queue = false;
bool bfqq_already_existing = false, split = false;
- struct bfq_iocq_bfqq_data *bfqq_data;
+ unsigned int a_idx = bfq_actuator_index(bfqd, bio);
if (unlikely(!rq->elv.icq))
return NULL;
@@ -6828,17 +6835,16 @@ static struct bfq_queue *bfq_init_rq(struct request *rq)
bfqq = bfq_get_bfqq_handle_split(bfqd, bic, bio, false, is_sync,
&new_queue);
- bfqq_data = &bic->bfqq_data;
-
if (likely(!new_queue)) {
/* If the queue was seeky for too long, break it apart. */
if (bfq_bfqq_coop(bfqq) && bfq_bfqq_split_coop(bfqq) &&
- !bfqq_data->stably_merged) {
+ !bic->bfqq_data[a_idx].stably_merged) {
struct bfq_queue *old_bfqq = bfqq;
/* Update bic before losing reference to bfqq */
if (bfq_bfqq_in_large_burst(bfqq))
- bfqq_data->saved_in_large_burst = true;
+ bic->bfqq_data[a_idx].saved_in_large_burst =
+ true;
bfqq = bfq_split_bfqq(bic, bfqq);
split = true;
diff --git a/block/bfq-iosched.h b/block/bfq-iosched.h
index f2e8ab91951c..e27897d66a0f 100644
--- a/block/bfq-iosched.h
+++ b/block/bfq-iosched.h
@@ -416,7 +416,7 @@ struct bfq_queue {
struct bfq_iocq_bfqq_data {
/*
* Snapshot of the has_short_time flag before merging; taken
- * to remember its value while the queue is merged, so as to
+ * to remember its values while the queue is merged, so as to
* be able to restore it in case of split.
*/
bool saved_has_short_ttime;
@@ -430,7 +430,7 @@ struct bfq_iocq_bfqq_data {
u64 saved_tot_idle_time;
/*
- * Same purpose as the previous fields for the value of the
+ * Same purpose as the previous fields for the values of the
* field keeping the queue's belonging to a large burst
*/
bool saved_in_large_burst;
@@ -493,8 +493,12 @@ struct bfq_io_cq {
uint64_t blkcg_serial_nr; /* the current blkcg serial */
#endif
- /* persistent data for associated synchronous process queue */
- struct bfq_iocq_bfqq_data bfqq_data;
+ /*
+ * Persistent data for associated synchronous process queues
+ * (one queue per actuator, see field bfqq above). In
+ * particular, each of these queues may undergo a merge.
+ */
+ struct bfq_iocq_bfqq_data bfqq_data[BFQ_MAX_ACTUATORS];
unsigned int requests; /* Number of requests this process has in flight */
};
--
2.20.1
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