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-rw-r--r--block/kyber-iosched.c190
1 files changed, 158 insertions, 32 deletions
diff --git a/block/kyber-iosched.c b/block/kyber-iosched.c
index 5b33dc3..a1660ba 100644
--- a/block/kyber-iosched.c
+++ b/block/kyber-iosched.c
@@ -72,6 +72,19 @@ static const unsigned int kyber_batch_size[] = {
[KYBER_OTHER] = 8,
};
+/*
+ * There is a same mapping between ctx & hctx and kcq & khd,
+ * we use request->mq_ctx->index_hw to index the kcq in khd.
+ */
+struct kyber_ctx_queue {
+ /*
+ * Used to ensure operations on rq_list and kcq_map to be an atmoic one.
+ * Also protect the rqs on rq_list when merge.
+ */
+ spinlock_t lock;
+ struct list_head rq_list[KYBER_NUM_DOMAINS];
+} ____cacheline_aligned_in_smp;
+
struct kyber_queue_data {
struct request_queue *q;
@@ -99,6 +112,8 @@ struct kyber_hctx_data {
struct list_head rqs[KYBER_NUM_DOMAINS];
unsigned int cur_domain;
unsigned int batching;
+ struct kyber_ctx_queue *kcqs;
+ struct sbitmap kcq_map[KYBER_NUM_DOMAINS];
wait_queue_entry_t domain_wait[KYBER_NUM_DOMAINS];
struct sbq_wait_state *domain_ws[KYBER_NUM_DOMAINS];
atomic_t wait_index[KYBER_NUM_DOMAINS];
@@ -107,10 +122,8 @@ struct kyber_hctx_data {
static int kyber_domain_wake(wait_queue_entry_t *wait, unsigned mode, int flags,
void *key);
-static int rq_sched_domain(const struct request *rq)
+static unsigned int kyber_sched_domain(unsigned int op)
{
- unsigned int op = rq->cmd_flags;
-
if ((op & REQ_OP_MASK) == REQ_OP_READ)
return KYBER_READ;
else if ((op & REQ_OP_MASK) == REQ_OP_WRITE && op_is_sync(op))
@@ -284,6 +297,11 @@ static unsigned int kyber_sched_tags_shift(struct kyber_queue_data *kqd)
return kqd->q->queue_hw_ctx[0]->sched_tags->bitmap_tags.sb.shift;
}
+static int kyber_bucket_fn(const struct request *rq)
+{
+ return kyber_sched_domain(rq->cmd_flags);
+}
+
static struct kyber_queue_data *kyber_queue_data_alloc(struct request_queue *q)
{
struct kyber_queue_data *kqd;
@@ -297,7 +315,7 @@ static struct kyber_queue_data *kyber_queue_data_alloc(struct request_queue *q)
goto err;
kqd->q = q;
- kqd->cb = blk_stat_alloc_callback(kyber_stat_timer_fn, rq_sched_domain,
+ kqd->cb = blk_stat_alloc_callback(kyber_stat_timer_fn, kyber_bucket_fn,
KYBER_NUM_DOMAINS, kqd);
if (!kqd->cb)
goto err_kqd;
@@ -376,6 +394,15 @@ static void kyber_exit_sched(struct elevator_queue *e)
kfree(kqd);
}
+static void kyber_ctx_queue_init(struct kyber_ctx_queue *kcq)
+{
+ unsigned int i;
+
+ spin_lock_init(&kcq->lock);
+ for (i = 0; i < KYBER_NUM_DOMAINS; i++)
+ INIT_LIST_HEAD(&kcq->rq_list[i]);
+}
+
static int kyber_init_hctx(struct blk_mq_hw_ctx *hctx, unsigned int hctx_idx)
{
struct kyber_queue_data *kqd = hctx->queue->elevator->elevator_data;
@@ -386,6 +413,24 @@ static int kyber_init_hctx(struct blk_mq_hw_ctx *hctx, unsigned int hctx_idx)
if (!khd)
return -ENOMEM;
+ khd->kcqs = kmalloc_array_node(hctx->nr_ctx,
+ sizeof(struct kyber_ctx_queue),
+ GFP_KERNEL, hctx->numa_node);
+ if (!khd->kcqs)
+ goto err_khd;
+
+ for (i = 0; i < hctx->nr_ctx; i++)
+ kyber_ctx_queue_init(&khd->kcqs[i]);
+
+ for (i = 0; i < KYBER_NUM_DOMAINS; i++) {
+ if (sbitmap_init_node(&khd->kcq_map[i], hctx->nr_ctx,
+ ilog2(8), GFP_KERNEL, hctx->numa_node)) {
+ while (--i >= 0)
+ sbitmap_free(&khd->kcq_map[i]);
+ goto err_kcqs;
+ }
+ }
+
spin_lock_init(&khd->lock);
for (i = 0; i < KYBER_NUM_DOMAINS; i++) {
@@ -405,10 +450,22 @@ static int kyber_init_hctx(struct blk_mq_hw_ctx *hctx, unsigned int hctx_idx)
kqd->async_depth);
return 0;
+
+err_kcqs:
+ kfree(khd->kcqs);
+err_khd:
+ kfree(khd);
+ return -ENOMEM;
}
static void kyber_exit_hctx(struct blk_mq_hw_ctx *hctx, unsigned int hctx_idx)
{
+ struct kyber_hctx_data *khd = hctx->sched_data;
+ int i;
+
+ for (i = 0; i < KYBER_NUM_DOMAINS; i++)
+ sbitmap_free(&khd->kcq_map[i]);
+ kfree(khd->kcqs);
kfree(hctx->sched_data);
}
@@ -430,7 +487,7 @@ static void rq_clear_domain_token(struct kyber_queue_data *kqd,
nr = rq_get_domain_token(rq);
if (nr != -1) {
- sched_domain = rq_sched_domain(rq);
+ sched_domain = kyber_sched_domain(rq->cmd_flags);
sbitmap_queue_clear(&kqd->domain_tokens[sched_domain], nr,
rq->mq_ctx->cpu);
}
@@ -449,11 +506,51 @@ static void kyber_limit_depth(unsigned int op, struct blk_mq_alloc_data *data)
}
}
+static bool kyber_bio_merge(struct blk_mq_hw_ctx *hctx, struct bio *bio)
+{
+ struct kyber_hctx_data *khd = hctx->sched_data;
+ struct blk_mq_ctx *ctx = blk_mq_get_ctx(hctx->queue);
+ struct kyber_ctx_queue *kcq = &khd->kcqs[ctx->index_hw];
+ unsigned int sched_domain = kyber_sched_domain(bio->bi_opf);
+ struct list_head *rq_list = &kcq->rq_list[sched_domain];
+ bool merged;
+
+ spin_lock(&kcq->lock);
+ merged = blk_mq_bio_list_merge(hctx->queue, rq_list, bio);
+ spin_unlock(&kcq->lock);
+ blk_mq_put_ctx(ctx);
+
+ return merged;
+}
+
static void kyber_prepare_request(struct request *rq, struct bio *bio)
{
rq_set_domain_token(rq, -1);
}
+static void kyber_insert_requests(struct blk_mq_hw_ctx *hctx,
+ struct list_head *rq_list, bool at_head)
+{
+ struct kyber_hctx_data *khd = hctx->sched_data;
+ struct request *rq, *next;
+
+ list_for_each_entry_safe(rq, next, rq_list, queuelist) {
+ unsigned int sched_domain = kyber_sched_domain(rq->cmd_flags);
+ struct kyber_ctx_queue *kcq = &khd->kcqs[rq->mq_ctx->index_hw];
+ struct list_head *head = &kcq->rq_list[sched_domain];
+
+ spin_lock(&kcq->lock);
+ if (at_head)
+ list_move(&rq->queuelist, head);
+ else
+ list_move_tail(&rq->queuelist, head);
+ sbitmap_set_bit(&khd->kcq_map[sched_domain],
+ rq->mq_ctx->index_hw);
+ blk_mq_sched_request_inserted(rq);
+ spin_unlock(&kcq->lock);
+ }
+}
+
static void kyber_finish_request(struct request *rq)
{
struct kyber_queue_data *kqd = rq->q->elevator->elevator_data;
@@ -472,7 +569,7 @@ static void kyber_completed_request(struct request *rq)
* Check if this request met our latency goal. If not, quickly gather
* some statistics and start throttling.
*/
- sched_domain = rq_sched_domain(rq);
+ sched_domain = kyber_sched_domain(rq->cmd_flags);
switch (sched_domain) {
case KYBER_READ:
target = kqd->read_lat_nsec;
@@ -498,19 +595,38 @@ static void kyber_completed_request(struct request *rq)
blk_stat_activate_msecs(kqd->cb, 10);
}
-static void kyber_flush_busy_ctxs(struct kyber_hctx_data *khd,
- struct blk_mq_hw_ctx *hctx)
+struct flush_kcq_data {
+ struct kyber_hctx_data *khd;
+ unsigned int sched_domain;
+ struct list_head *list;
+};
+
+static bool flush_busy_kcq(struct sbitmap *sb, unsigned int bitnr, void *data)
{
- LIST_HEAD(rq_list);
- struct request *rq, *next;
+ struct flush_kcq_data *flush_data = data;
+ struct kyber_ctx_queue *kcq = &flush_data->khd->kcqs[bitnr];
- blk_mq_flush_busy_ctxs(hctx, &rq_list);
- list_for_each_entry_safe(rq, next, &rq_list, queuelist) {
- unsigned int sched_domain;
+ spin_lock(&kcq->lock);
+ list_splice_tail_init(&kcq->rq_list[flush_data->sched_domain],
+ flush_data->list);
+ sbitmap_clear_bit(sb, bitnr);
+ spin_unlock(&kcq->lock);
- sched_domain = rq_sched_domain(rq);
- list_move_tail(&rq->queuelist, &khd->rqs[sched_domain]);
- }
+ return true;
+}
+
+static void kyber_flush_busy_kcqs(struct kyber_hctx_data *khd,
+ unsigned int sched_domain,
+ struct list_head *list)
+{
+ struct flush_kcq_data data = {
+ .khd = khd,
+ .sched_domain = sched_domain,
+ .list = list,
+ };
+
+ sbitmap_for_each_set(&khd->kcq_map[sched_domain],
+ flush_busy_kcq, &data);
}
static int kyber_domain_wake(wait_queue_entry_t *wait, unsigned mode, int flags,
@@ -573,26 +689,23 @@ static int kyber_get_domain_token(struct kyber_queue_data *kqd,
static struct request *
kyber_dispatch_cur_domain(struct kyber_queue_data *kqd,
struct kyber_hctx_data *khd,
- struct blk_mq_hw_ctx *hctx,
- bool *flushed)
+ struct blk_mq_hw_ctx *hctx)
{
struct list_head *rqs;
struct request *rq;
int nr;
rqs = &khd->rqs[khd->cur_domain];
- rq = list_first_entry_or_null(rqs, struct request, queuelist);
/*
- * If there wasn't already a pending request and we haven't flushed the
- * software queues yet, flush the software queues and check again.
+ * If we already have a flushed request, then we just need to get a
+ * token for it. Otherwise, if there are pending requests in the kcqs,
+ * flush the kcqs, but only if we can get a token. If not, we should
+ * leave the requests in the kcqs so that they can be merged. Note that
+ * khd->lock serializes the flushes, so if we observed any bit set in
+ * the kcq_map, we will always get a request.
*/
- if (!rq && !*flushed) {
- kyber_flush_busy_ctxs(khd, hctx);
- *flushed = true;
- rq = list_first_entry_or_null(rqs, struct request, queuelist);
- }
-
+ rq = list_first_entry_or_null(rqs, struct request, queuelist);
if (rq) {
nr = kyber_get_domain_token(kqd, khd, hctx);
if (nr >= 0) {
@@ -601,6 +714,16 @@ kyber_dispatch_cur_domain(struct kyber_queue_data *kqd,
list_del_init(&rq->queuelist);
return rq;
}
+ } else if (sbitmap_any_bit_set(&khd->kcq_map[khd->cur_domain])) {
+ nr = kyber_get_domain_token(kqd, khd, hctx);
+ if (nr >= 0) {
+ kyber_flush_busy_kcqs(khd, khd->cur_domain, rqs);
+ rq = list_first_entry(rqs, struct request, queuelist);
+ khd->batching++;
+ rq_set_domain_token(rq, nr);
+ list_del_init(&rq->queuelist);
+ return rq;
+ }
}
/* There were either no pending requests or no tokens. */
@@ -611,7 +734,6 @@ static struct request *kyber_dispatch_request(struct blk_mq_hw_ctx *hctx)
{
struct kyber_queue_data *kqd = hctx->queue->elevator->elevator_data;
struct kyber_hctx_data *khd = hctx->sched_data;
- bool flushed = false;
struct request *rq;
int i;
@@ -622,7 +744,7 @@ static struct request *kyber_dispatch_request(struct blk_mq_hw_ctx *hctx)
* from the batch.
*/
if (khd->batching < kyber_batch_size[khd->cur_domain]) {
- rq = kyber_dispatch_cur_domain(kqd, khd, hctx, &flushed);
+ rq = kyber_dispatch_cur_domain(kqd, khd, hctx);
if (rq)
goto out;
}
@@ -643,7 +765,7 @@ static struct request *kyber_dispatch_request(struct blk_mq_hw_ctx *hctx)
else
khd->cur_domain++;
- rq = kyber_dispatch_cur_domain(kqd, khd, hctx, &flushed);
+ rq = kyber_dispatch_cur_domain(kqd, khd, hctx);
if (rq)
goto out;
}
@@ -660,10 +782,12 @@ static bool kyber_has_work(struct blk_mq_hw_ctx *hctx)
int i;
for (i = 0; i < KYBER_NUM_DOMAINS; i++) {
- if (!list_empty_careful(&khd->rqs[i]))
+ if (!list_empty_careful(&khd->rqs[i]) ||
+ sbitmap_any_bit_set(&khd->kcq_map[i]))
return true;
}
- return sbitmap_any_bit_set(&hctx->ctx_map);
+
+ return false;
}
#define KYBER_LAT_SHOW_STORE(op) \
@@ -834,7 +958,9 @@ static struct elevator_type kyber_sched = {
.init_hctx = kyber_init_hctx,
.exit_hctx = kyber_exit_hctx,
.limit_depth = kyber_limit_depth,
+ .bio_merge = kyber_bio_merge,
.prepare_request = kyber_prepare_request,
+ .insert_requests = kyber_insert_requests,
.finish_request = kyber_finish_request,
.requeue_request = kyber_finish_request,
.completed_request = kyber_completed_request,