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Diffstat (limited to 'block/blk-mq-sched.c')
-rw-r--r--block/blk-mq-sched.c103
1 files changed, 87 insertions, 16 deletions
diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
index fdcc2c1dd178..a19cdf159b75 100644
--- a/block/blk-mq-sched.c
+++ b/block/blk-mq-sched.c
@@ -7,6 +7,7 @@
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/blk-mq.h>
+#include <linux/list_sort.h>
#include <trace/events/block.h>
@@ -80,6 +81,35 @@ void blk_mq_sched_restart(struct blk_mq_hw_ctx *hctx)
blk_mq_run_hw_queue(hctx, true);
}
+static int sched_rq_cmp(void *priv, struct list_head *a, struct list_head *b)
+{
+ struct request *rqa = container_of(a, struct request, queuelist);
+ struct request *rqb = container_of(b, struct request, queuelist);
+
+ return rqa->mq_hctx > rqb->mq_hctx;
+}
+
+static bool blk_mq_dispatch_hctx_list(struct list_head *rq_list)
+{
+ struct blk_mq_hw_ctx *hctx =
+ list_first_entry(rq_list, struct request, queuelist)->mq_hctx;
+ struct request *rq;
+ LIST_HEAD(hctx_list);
+ unsigned int count = 0;
+
+ list_for_each_entry(rq, rq_list, queuelist) {
+ if (rq->mq_hctx != hctx) {
+ list_cut_before(&hctx_list, rq_list, &rq->queuelist);
+ goto dispatch;
+ }
+ count++;
+ }
+ list_splice_tail_init(rq_list, &hctx_list);
+
+dispatch:
+ return blk_mq_dispatch_rq_list(hctx, &hctx_list, count);
+}
+
#define BLK_MQ_BUDGET_DELAY 3 /* ms units */
/*
@@ -90,12 +120,20 @@ void blk_mq_sched_restart(struct blk_mq_hw_ctx *hctx)
* Returns -EAGAIN if hctx->dispatch was found non-empty and run_work has to
* be run again. This is necessary to avoid starving flushes.
*/
-static int blk_mq_do_dispatch_sched(struct blk_mq_hw_ctx *hctx)
+static int __blk_mq_do_dispatch_sched(struct blk_mq_hw_ctx *hctx)
{
struct request_queue *q = hctx->queue;
struct elevator_queue *e = q->elevator;
+ bool multi_hctxs = false, run_queue = false;
+ bool dispatched = false, busy = false;
+ unsigned int max_dispatch;
LIST_HEAD(rq_list);
- int ret = 0;
+ int count = 0;
+
+ if (hctx->dispatch_busy)
+ max_dispatch = 1;
+ else
+ max_dispatch = hctx->queue->nr_requests;
do {
struct request *rq;
@@ -104,16 +142,16 @@ static int blk_mq_do_dispatch_sched(struct blk_mq_hw_ctx *hctx)
break;
if (!list_empty_careful(&hctx->dispatch)) {
- ret = -EAGAIN;
+ busy = true;
break;
}
- if (!blk_mq_get_dispatch_budget(hctx))
+ if (!blk_mq_get_dispatch_budget(q))
break;
rq = e->type->ops.dispatch_request(hctx);
if (!rq) {
- blk_mq_put_dispatch_budget(hctx);
+ blk_mq_put_dispatch_budget(q);
/*
* We're releasing without dispatching. Holding the
* budget could have blocked any "hctx"s with the
@@ -121,7 +159,7 @@ static int blk_mq_do_dispatch_sched(struct blk_mq_hw_ctx *hctx)
* no guarantee anyone will kick the queue. Kick it
* ourselves.
*/
- blk_mq_delay_run_hw_queues(q, BLK_MQ_BUDGET_DELAY);
+ run_queue = true;
break;
}
@@ -130,8 +168,42 @@ static int blk_mq_do_dispatch_sched(struct blk_mq_hw_ctx *hctx)
* if this rq won't be queued to driver via .queue_rq()
* in blk_mq_dispatch_rq_list().
*/
- list_add(&rq->queuelist, &rq_list);
- } while (blk_mq_dispatch_rq_list(q, &rq_list, true));
+ list_add_tail(&rq->queuelist, &rq_list);
+ if (rq->mq_hctx != hctx)
+ multi_hctxs = true;
+ } while (++count < max_dispatch);
+
+ if (!count) {
+ if (run_queue)
+ blk_mq_delay_run_hw_queues(q, BLK_MQ_BUDGET_DELAY);
+ } else if (multi_hctxs) {
+ /*
+ * Requests from different hctx may be dequeued from some
+ * schedulers, such as bfq and deadline.
+ *
+ * Sort the requests in the list according to their hctx,
+ * dispatch batching requests from same hctx at a time.
+ */
+ list_sort(NULL, &rq_list, sched_rq_cmp);
+ do {
+ dispatched |= blk_mq_dispatch_hctx_list(&rq_list);
+ } while (!list_empty(&rq_list));
+ } else {
+ dispatched = blk_mq_dispatch_rq_list(hctx, &rq_list, count);
+ }
+
+ if (busy)
+ return -EAGAIN;
+ return !!dispatched;
+}
+
+static int blk_mq_do_dispatch_sched(struct blk_mq_hw_ctx *hctx)
+{
+ int ret;
+
+ do {
+ ret = __blk_mq_do_dispatch_sched(hctx);
+ } while (ret == 1);
return ret;
}
@@ -153,7 +225,7 @@ static struct blk_mq_ctx *blk_mq_next_ctx(struct blk_mq_hw_ctx *hctx,
* restart queue if .get_budget() returns BLK_STS_NO_RESOURCE.
*
* Returns -EAGAIN if hctx->dispatch was found non-empty and run_work has to
- * to be run again. This is necessary to avoid starving flushes.
+ * be run again. This is necessary to avoid starving flushes.
*/
static int blk_mq_do_dispatch_ctx(struct blk_mq_hw_ctx *hctx)
{
@@ -161,10 +233,9 @@ static int blk_mq_do_dispatch_ctx(struct blk_mq_hw_ctx *hctx)
LIST_HEAD(rq_list);
struct blk_mq_ctx *ctx = READ_ONCE(hctx->dispatch_from);
int ret = 0;
+ struct request *rq;
do {
- struct request *rq;
-
if (!list_empty_careful(&hctx->dispatch)) {
ret = -EAGAIN;
break;
@@ -173,12 +244,12 @@ static int blk_mq_do_dispatch_ctx(struct blk_mq_hw_ctx *hctx)
if (!sbitmap_any_bit_set(&hctx->ctx_map))
break;
- if (!blk_mq_get_dispatch_budget(hctx))
+ if (!blk_mq_get_dispatch_budget(q))
break;
rq = blk_mq_dequeue_from_ctx(hctx, ctx);
if (!rq) {
- blk_mq_put_dispatch_budget(hctx);
+ blk_mq_put_dispatch_budget(q);
/*
* We're releasing without dispatching. Holding the
* budget could have blocked any "hctx"s with the
@@ -200,7 +271,7 @@ static int blk_mq_do_dispatch_ctx(struct blk_mq_hw_ctx *hctx)
/* round robin for fair dispatch */
ctx = blk_mq_next_ctx(hctx, rq->mq_ctx);
- } while (blk_mq_dispatch_rq_list(q, &rq_list, true));
+ } while (blk_mq_dispatch_rq_list(rq->mq_hctx, &rq_list, 1));
WRITE_ONCE(hctx->dispatch_from, ctx);
return ret;
@@ -240,7 +311,7 @@ static int __blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx)
*/
if (!list_empty(&rq_list)) {
blk_mq_sched_mark_restart_hctx(hctx);
- if (blk_mq_dispatch_rq_list(q, &rq_list, false)) {
+ if (blk_mq_dispatch_rq_list(hctx, &rq_list, 0)) {
if (has_sched_dispatch)
ret = blk_mq_do_dispatch_sched(hctx);
else
@@ -253,7 +324,7 @@ static int __blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx)
ret = blk_mq_do_dispatch_ctx(hctx);
} else {
blk_mq_flush_busy_ctxs(hctx, &rq_list);
- blk_mq_dispatch_rq_list(q, &rq_list, false);
+ blk_mq_dispatch_rq_list(hctx, &rq_list, 0);
}
return ret;