block, bfq: move io_cq-persistent bfqq data into a dedicated struct

With a multi-actuator drive, a process may get associated with multiple
bfq_queues: one queue for each of the N actuators. So, the bfq_io_cq
data structure must be able to accommodate its per-queue persistent
information for N queues. Currently it stores this information for
just one queue, in several scalar fields.

This is a preparatory commit for moving to accommodating persistent
information for N queues. In particular, this commit packs all the
above scalar fields into a single data structure. Then there is now
only one field, in bfq_io_cq, that stores all the above information. This
scalar field will then be turned into an array by a following commit.

Suggested-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Reviewed-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Signed-off-by: Gianmarco Lusvardi <glusvardi@posteo.net>
Signed-off-by: Giulio Barabino <giuliobarabino99@gmail.com>
Signed-off-by: Emiliano Maccaferri <inbox@emilianomaccaferri.com>
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Link: https://lore.kernel.org/r/20230103145503.71712-4-paolo.valente@linaro.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
index b21ca91..cefd16b 100644 (file)
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c
@@ -395,10 +395,6 @@ void bic_set_bfqq(struct bfq_io_cq *bic,
 {
        struct bfq_queue *old_bfqq = bic->bfqq[is_sync][actuator_idx];
 
-       /* Clear bic pointer if bfqq is detached from this bic */
-       if (old_bfqq && old_bfqq->bic == bic)
-               old_bfqq->bic = NULL;
-
        /*
         * If bfqq != NULL, then a non-stable queue merge between
         * bic->bfqq and bfqq is happening here. This causes troubles
@@ -412,12 +408,18 @@ 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;
+
+       /* Clear bic pointer if bfqq is detached from this bic */
+       if (old_bfqq && old_bfqq->bic == bic)
+               old_bfqq->bic = NULL;
+
        if (is_sync)
                bic->bfqq[1][actuator_idx] = bfqq;
        else
                bic->bfqq[0][actuator_idx] = bfqq;
 
-       if (bfqq && bic->stable_merge_bfqq == bfqq) {
+       if (bfqq && bfqq_data->stable_merge_bfqq == bfqq) {
                /*
                 * Actually, these same instructions are executed also
                 * in bfq_setup_cooperator, in case of abort or actual
@@ -426,9 +428,9 @@ void bic_set_bfqq(struct bfq_io_cq *bic,
                 * did so, we would nest even more complexity in this
                 * function.
                 */
-               bfq_put_stable_ref(bic->stable_merge_bfqq);
+               bfq_put_stable_ref(bfqq_data->stable_merge_bfqq);
 
-               bic->stable_merge_bfqq = NULL;
+               bfqq_data->stable_merge_bfqq = NULL;
        }
 }
 
@@ -1133,38 +1135,40 @@ 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);
 
-       if (bic->saved_has_short_ttime)
+       if (bfqq_data->saved_has_short_ttime)
                bfq_mark_bfqq_has_short_ttime(bfqq);
        else
                bfq_clear_bfqq_has_short_ttime(bfqq);
 
-       if (bic->saved_IO_bound)
+       if (bfqq_data->saved_IO_bound)
                bfq_mark_bfqq_IO_bound(bfqq);
        else
                bfq_clear_bfqq_IO_bound(bfqq);
 
-       bfqq->last_serv_time_ns = bic->saved_last_serv_time_ns;
-       bfqq->inject_limit = bic->saved_inject_limit;
-       bfqq->decrease_time_jif = bic->saved_decrease_time_jif;
+       bfqq->last_serv_time_ns = bfqq_data->saved_last_serv_time_ns;
+       bfqq->inject_limit = bfqq_data->saved_inject_limit;
+       bfqq->decrease_time_jif = bfqq_data->saved_decrease_time_jif;
 
-       bfqq->entity.new_weight = bic->saved_weight;
-       bfqq->ttime = bic->saved_ttime;
-       bfqq->io_start_time = bic->saved_io_start_time;
-       bfqq->tot_idle_time = bic->saved_tot_idle_time;
+       bfqq->entity.new_weight = bfqq_data->saved_weight;
+       bfqq->ttime = bfqq_data->saved_ttime;
+       bfqq->io_start_time = bfqq_data->saved_io_start_time;
+       bfqq->tot_idle_time = bfqq_data->saved_tot_idle_time;
        /*
         * Restore weight coefficient only if low_latency is on
         */
        if (bfqd->low_latency) {
                old_wr_coeff = bfqq->wr_coeff;
-               bfqq->wr_coeff = bic->saved_wr_coeff;
+               bfqq->wr_coeff = bfqq_data->saved_wr_coeff;
        }
-       bfqq->service_from_wr = bic->saved_service_from_wr;
-       bfqq->wr_start_at_switch_to_srt = bic->saved_wr_start_at_switch_to_srt;
-       bfqq->last_wr_start_finish = bic->saved_last_wr_start_finish;
-       bfqq->wr_cur_max_time = bic->saved_wr_cur_max_time;
+       bfqq->service_from_wr = bfqq_data->saved_service_from_wr;
+       bfqq->wr_start_at_switch_to_srt =
+               bfqq_data->saved_wr_start_at_switch_to_srt;
+       bfqq->last_wr_start_finish = bfqq_data->saved_last_wr_start_finish;
+       bfqq->wr_cur_max_time = bfqq_data->saved_wr_cur_max_time;
 
        if (bfqq->wr_coeff > 1 && (bfq_bfqq_in_large_burst(bfqq) ||
            time_is_before_jiffies(bfqq->last_wr_start_finish +
@@ -1849,7 +1853,7 @@ 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)->stably_merged) &&
+                 (bfqq->bic || RQ_BIC(rq)->bfqq_data.stably_merged) &&
                   (*interactive || soft_rt)));
 
        /*
@@ -2849,6 +2853,7 @@ 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;
 
        /* if a merge has already been setup, then proceed with that first */
        if (bfqq->new_bfqq)
@@ -2870,21 +2875,21 @@ bfq_setup_cooperator(struct bfq_data *bfqd, struct bfq_queue *bfqq,
                 * stable merging) also if bic is associated with a
                 * sync queue, but this bfqq is async
                 */
-               if (bfq_bfqq_sync(bfqq) && bic->stable_merge_bfqq &&
+               if (bfq_bfqq_sync(bfqq) && bfqq_data->stable_merge_bfqq &&
                    !bfq_bfqq_just_created(bfqq) &&
                    time_is_before_jiffies(bfqq->split_time +
                                          msecs_to_jiffies(bfq_late_stable_merging)) &&
                    time_is_before_jiffies(bfqq->creation_time +
                                           msecs_to_jiffies(bfq_late_stable_merging))) {
                        struct bfq_queue *stable_merge_bfqq =
-                               bic->stable_merge_bfqq;
+                               bfqq_data->stable_merge_bfqq;
                        int proc_ref = min(bfqq_process_refs(bfqq),
                                           bfqq_process_refs(stable_merge_bfqq));
 
                        /* deschedule stable merge, because done or aborted here */
                        bfq_put_stable_ref(stable_merge_bfqq);
 
-                       bic->stable_merge_bfqq = NULL;
+                       bfqq_data->stable_merge_bfqq = NULL;
 
                        if (!idling_boosts_thr_without_issues(bfqd, bfqq) &&
                            proc_ref > 0) {
@@ -2893,10 +2898,10 @@ bfq_setup_cooperator(struct bfq_data *bfqd, struct bfq_queue *bfqq,
                                        bfq_setup_merge(bfqq, stable_merge_bfqq);
 
                                if (new_bfqq) {
-                                       bic->stably_merged = true;
+                                       bfqq_data->stably_merged = true;
                                        if (new_bfqq->bic)
-                                               new_bfqq->bic->stably_merged =
-                                                                       true;
+                                               new_bfqq->bic->bfqq_data.stably_merged =
+                                                       true;
                                }
                                return new_bfqq;
                        } else
@@ -2995,6 +3000,7 @@ 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;
 
        /*
         * If !bfqq->bic, the queue is already shared or its requests
@@ -3004,18 +3010,21 @@ static void bfq_bfqq_save_state(struct bfq_queue *bfqq)
        if (!bic)
                return;
 
-       bic->saved_last_serv_time_ns = bfqq->last_serv_time_ns;
-       bic->saved_inject_limit = bfqq->inject_limit;
-       bic->saved_decrease_time_jif = bfqq->decrease_time_jif;
-
-       bic->saved_weight = bfqq->entity.orig_weight;
-       bic->saved_ttime = bfqq->ttime;
-       bic->saved_has_short_ttime = bfq_bfqq_has_short_ttime(bfqq);
-       bic->saved_IO_bound = bfq_bfqq_IO_bound(bfqq);
-       bic->saved_io_start_time = bfqq->io_start_time;
-       bic->saved_tot_idle_time = bfqq->tot_idle_time;
-       bic->saved_in_large_burst = bfq_bfqq_in_large_burst(bfqq);
-       bic->was_in_burst_list = !hlist_unhashed(&bfqq->burst_list_node);
+       bfqq_data->saved_last_serv_time_ns = bfqq->last_serv_time_ns;
+       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;
+       bfqq_data->saved_ttime = bfqq->ttime;
+       bfqq_data->saved_has_short_ttime =
+               bfq_bfqq_has_short_ttime(bfqq);
+       bfqq_data->saved_IO_bound = bfq_bfqq_IO_bound(bfqq);
+       bfqq_data->saved_io_start_time = bfqq->io_start_time;
+       bfqq_data->saved_tot_idle_time = bfqq->tot_idle_time;
+       bfqq_data->saved_in_large_burst = bfq_bfqq_in_large_burst(bfqq);
+       bfqq_data->was_in_burst_list =
+               !hlist_unhashed(&bfqq->burst_list_node);
+
        if (unlikely(bfq_bfqq_just_created(bfqq) &&
                     !bfq_bfqq_in_large_burst(bfqq) &&
                     bfqq->bfqd->low_latency)) {
@@ -3028,17 +3037,21 @@ static void bfq_bfqq_save_state(struct bfq_queue *bfqq)
                 * to bfqq, so that to avoid that bfqq unjustly fails
                 * to enjoy weight raising if split soon.
                 */
-               bic->saved_wr_coeff = bfqq->bfqd->bfq_wr_coeff;
-               bic->saved_wr_start_at_switch_to_srt = bfq_smallest_from_now();
-               bic->saved_wr_cur_max_time = bfq_wr_duration(bfqq->bfqd);
-               bic->saved_last_wr_start_finish = jiffies;
+               bfqq_data->saved_wr_coeff = bfqq->bfqd->bfq_wr_coeff;
+               bfqq_data->saved_wr_start_at_switch_to_srt =
+                       bfq_smallest_from_now();
+               bfqq_data->saved_wr_cur_max_time =
+                       bfq_wr_duration(bfqq->bfqd);
+               bfqq_data->saved_last_wr_start_finish = jiffies;
        } else {
-               bic->saved_wr_coeff = bfqq->wr_coeff;
-               bic->saved_wr_start_at_switch_to_srt =
+               bfqq_data->saved_wr_coeff = bfqq->wr_coeff;
+               bfqq_data->saved_wr_start_at_switch_to_srt =
                        bfqq->wr_start_at_switch_to_srt;
-               bic->saved_service_from_wr = bfqq->service_from_wr;
-               bic->saved_last_wr_start_finish = bfqq->last_wr_start_finish;
-               bic->saved_wr_cur_max_time = bfqq->wr_cur_max_time;
+               bfqq_data->saved_service_from_wr =
+                       bfqq->service_from_wr;
+               bfqq_data->saved_last_wr_start_finish =
+                       bfqq->last_wr_start_finish;
+               bfqq_data->saved_wr_cur_max_time = bfqq->wr_cur_max_time;
        }
 }
 
@@ -5364,6 +5377,7 @@ static void bfq_exit_icq(struct io_cq *icq)
         * therefore on its unused per-actuator fields being NULL.
         */
        unsigned int num_actuators = BFQ_MAX_ACTUATORS;
+       struct bfq_iocq_bfqq_data *bfqq_data = &bic->bfqq_data;
 
        /*
         * bfqd is NULL if scheduler already exited, and in that case
@@ -5374,8 +5388,8 @@ static void bfq_exit_icq(struct io_cq *icq)
                num_actuators = bfqd->num_actuators;
        }
 
-       if (bic->stable_merge_bfqq)
-               bfq_put_stable_ref(bic->stable_merge_bfqq);
+       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++) {
                bfq_exit_icq_bfqq(bic, true, act_idx);
@@ -5566,13 +5580,14 @@ bfq_do_early_stable_merge(struct bfq_data *bfqd, struct bfq_queue *bfqq,
 {
        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->stably_merged = true;
-       bic->stably_merged = true;
+               new_bfqq->bic->bfqq_data.stably_merged = true;
+       bfqq_data->stably_merged = true;
 
        /*
         * Reusing merge functions. This implies that
@@ -5641,6 +5656,7 @@ 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
@@ -5702,7 +5718,7 @@ static struct bfq_queue *bfq_do_or_sched_stable_merge(struct bfq_data *bfqd,
                        /*
                         * Record the bfqq to merge to.
                         */
-                       bic->stable_merge_bfqq = last_bfqq_created;
+                       bfqq_data->stable_merge_bfqq = last_bfqq_created;
                }
        }
 
@@ -6623,6 +6639,7 @@ 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;
 
        if (likely(bfqq && bfqq != &bfqd->oom_bfqq))
                return bfqq;
@@ -6636,12 +6653,12 @@ static struct bfq_queue *bfq_get_bfqq_handle_split(struct bfq_data *bfqd,
 
        bic_set_bfqq(bic, bfqq, is_sync, act_idx);
        if (split && is_sync) {
-               if ((bic->was_in_burst_list && bfqd->large_burst) ||
-                   bic->saved_in_large_burst)
+               if ((bfqq_data->was_in_burst_list && bfqd->large_burst) ||
+                   bfqq_data->saved_in_large_burst)
                        bfq_mark_bfqq_in_large_burst(bfqq);
                else {
                        bfq_clear_bfqq_in_large_burst(bfqq);
-                       if (bic->was_in_burst_list)
+                       if (bfqq_data->was_in_burst_list)
                                /*
                                 * If bfqq was in the current
                                 * burst list before being
@@ -6730,6 +6747,7 @@ 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;
 
        if (unlikely(!rq->elv.icq))
                return NULL;
@@ -6753,15 +6771,17 @@ 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) &&
-                       !bic->stably_merged) {
+                       !bfqq_data->stably_merged) {
                        struct bfq_queue *old_bfqq = bfqq;
 
                        /* Update bic before losing reference to bfqq */
                        if (bfq_bfqq_in_large_burst(bfqq))
-                               bic->saved_in_large_burst = true;
+                               bfqq_data->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 645bc01..33d43d6 100644 (file)
--- a/block/bfq-iosched.h
+++ b/block/bfq-iosched.h
@@ -413,27 +413,9 @@ struct bfq_queue {
 };
 
 /**
- * struct bfq_io_cq - per (request_queue, io_context) structure.
- */
-struct bfq_io_cq {
-       /* associated io_cq structure */
-       struct io_cq icq; /* must be the first member */
-       /*
-        * Matrix of associated process queues: first row for async
-        * queues, second row sync queues. Each row contains one
-        * column for each actuator. An I/O request generated by the
-        * process is inserted into the queue pointed by bfqq[i][j] if
-        * the request is to be served by the j-th actuator of the
-        * drive, where i==0 or i==1, depending on whether the request
-        * is async or sync. So there is a distinct queue for each
-        * actuator.
-        */
-       struct bfq_queue *bfqq[2][BFQ_MAX_ACTUATORS];
-       /* per (request_queue, blkcg) ioprio */
-       int ioprio;
-#ifdef CONFIG_BFQ_GROUP_IOSCHED
-       uint64_t blkcg_serial_nr; /* the current blkcg serial */
-#endif
+* struct bfq_data - bfqq data unique and persistent for associated bfq_io_cq
+*/
+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
@@ -488,6 +470,34 @@ struct bfq_io_cq {
        struct bfq_queue *stable_merge_bfqq;
 
        bool stably_merged;     /* non splittable if true */
+};
+
+/**
+ * struct bfq_io_cq - per (request_queue, io_context) structure.
+ */
+struct bfq_io_cq {
+       /* associated io_cq structure */
+       struct io_cq icq; /* must be the first member */
+       /*
+        * Matrix of associated process queues: first row for async
+        * queues, second row sync queues. Each row contains one
+        * column for each actuator. An I/O request generated by the
+        * process is inserted into the queue pointed by bfqq[i][j] if
+        * the request is to be served by the j-th actuator of the
+        * drive, where i==0 or i==1, depending on whether the request
+        * is async or sync. So there is a distinct queue for each
+        * actuator.
+        */
+       struct bfq_queue *bfqq[2][BFQ_MAX_ACTUATORS];
+       /* per (request_queue, blkcg) ioprio */
+       int ioprio;
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+       uint64_t blkcg_serial_nr; /* the current blkcg serial */
+#endif
+
+       /* persistent data for associated synchronous process queue */
+       struct bfq_iocq_bfqq_data bfqq_data;
+
        unsigned int requests;  /* Number of requests this process has in flight */
 };