Skip to content

Commit

Permalink
block, bfq: move io_cq-persistent bfqq data into a dedicated struct
Browse files Browse the repository at this point in the history 
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>
  • Loading branch information
Paolo Valente authored and Jens Axboe committed Jan 29, 2023
1 parent b752989 commit a612304
Show file tree
Hide file tree
Showing 2 changed files with 110 additions and 80 deletions.
138 changes: 79 additions & 59 deletions block/bfq-iosched.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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
Expand All @@ -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
Expand All @@ -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;
}
}

Expand Down Expand Up @@ -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 +
Expand Down Expand Up @@ -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)));

/*
Expand Down Expand Up @@ -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)
Expand All @@ -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) {
Expand All @@ -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
Expand Down Expand Up @@ -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
Expand All @@ -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)) {
Expand All @@ -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;
}
}

Expand Down Expand Up @@ -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
Expand All @@ -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);
Expand Down Expand Up @@ -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
Expand Down Expand Up @@ -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
Expand Down Expand Up @@ -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;
}
}

Expand Down Expand Up @@ -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;
Expand All @@ -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
Expand Down Expand Up @@ -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;
Expand All @@ -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;
Expand Down
52 changes: 31 additions & 21 deletions block/bfq-iosched.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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
Expand Down Expand Up @@ -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 */
};

Expand Down

0 comments on commit a612304

Please sign in to comment.