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Date: Mon, 17 Jan 2022 16:54:53 +0800
From: Yu Kuai <yukuai3@...wei.com>
To: <axboe@...nel.dk>
CC: <linux-block@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
<yukuai3@...wei.com>, <yi.zhang@...wei.com>
Subject: [PATCH RESEND 1/3] blk-mq: add new interfaces to track if hctx failed to get driver tag
Prepare to allow hardware queue to get more tag while sharing a tag set.
Signed-off-by: Yu Kuai <yukuai3@...wei.com>
---
block/blk-mq-debugfs.c | 2 ++
block/blk-mq-tag.c | 37 +++++++++++++++++++++++++++++++++++++
block/blk-mq-tag.h | 24 +++++++++++++++++++++---
include/linux/blk-mq.h | 12 ++++++++++++
include/linux/blkdev.h | 2 ++
5 files changed, 74 insertions(+), 3 deletions(-)
diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
index 3a790eb4995c..3841fe26cda1 100644
--- a/block/blk-mq-debugfs.c
+++ b/block/blk-mq-debugfs.c
@@ -454,6 +454,8 @@ static void blk_mq_debugfs_tags_show(struct seq_file *m,
seq_printf(m, "nr_reserved_tags=%u\n", tags->nr_reserved_tags);
seq_printf(m, "active_queues=%d\n",
atomic_read(&tags->active_queues));
+ seq_printf(m, "pending_queues=%d\n",
+ atomic_read(&tags->pending_queues));
seq_puts(m, "\nbitmap_tags:\n");
sbitmap_queue_show(&tags->bitmap_tags, m);
diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c
index e55a6834c9a6..77c723bdfd5c 100644
--- a/block/blk-mq-tag.c
+++ b/block/blk-mq-tag.c
@@ -73,6 +73,43 @@ void __blk_mq_tag_idle(struct blk_mq_hw_ctx *hctx)
blk_mq_tag_wakeup_all(tags, false);
}
+/*
+ * Called when hctx failed to get driver tag
+ */
+void __blk_mq_dtag_wait(struct blk_mq_hw_ctx *hctx)
+{
+ if (blk_mq_is_shared_tags(hctx->flags)) {
+ struct request_queue *q = hctx->queue;
+
+ if (!test_bit(QUEUE_FLAG_HCTX_WAIT, &q->queue_flags) &&
+ !test_and_set_bit(QUEUE_FLAG_HCTX_WAIT, &q->queue_flags))
+ atomic_inc(&hctx->tags->pending_queues);
+ } else {
+ if (!test_bit(BLK_MQ_S_DTAG_WAIT, &hctx->state) &&
+ !test_and_set_bit(BLK_MQ_S_DTAG_WAIT, &hctx->state))
+ atomic_inc(&hctx->tags->pending_queues);
+ }
+}
+
+/* Called when busy queue goes inactive */
+void __blk_mq_dtag_idle(struct blk_mq_hw_ctx *hctx)
+{
+ struct blk_mq_tags *tags = hctx->tags;
+
+ if (blk_mq_is_shared_tags(hctx->flags)) {
+ struct request_queue *q = hctx->queue;
+
+ if (!test_and_clear_bit(QUEUE_FLAG_HCTX_WAIT,
+ &q->queue_flags))
+ return;
+ } else {
+ if (!test_and_clear_bit(BLK_MQ_S_DTAG_WAIT, &hctx->state))
+ return;
+ }
+
+ atomic_dec(&tags->pending_queues);
+}
+
static int __blk_mq_get_tag(struct blk_mq_alloc_data *data,
struct sbitmap_queue *bt)
{
diff --git a/block/blk-mq-tag.h b/block/blk-mq-tag.h
index 5668e28be0b7..3fe013aee9a2 100644
--- a/block/blk-mq-tag.h
+++ b/block/blk-mq-tag.h
@@ -47,15 +47,17 @@ enum {
BLK_MQ_TAG_MAX = BLK_MQ_NO_TAG - 1,
};
-extern bool __blk_mq_tag_busy(struct blk_mq_hw_ctx *);
-extern void __blk_mq_tag_idle(struct blk_mq_hw_ctx *);
+extern bool __blk_mq_tag_wait(struct blk_mq_hw_ctx *hctx);
+extern void __blk_mq_tag_idle(struct blk_mq_hw_ctx *hctx);
+extern void __blk_mq_dtag_busy(struct blk_mq_hw_ctx *hctx);
+extern void __blk_mq_dtag_idle(struct blk_mq_hw_ctx *hctx);
static inline bool blk_mq_tag_busy(struct blk_mq_hw_ctx *hctx)
{
if (!(hctx->flags & BLK_MQ_F_TAG_QUEUE_SHARED))
return false;
- return __blk_mq_tag_busy(hctx);
+ return __blk_mq_tag_wait(hctx);
}
static inline void blk_mq_tag_idle(struct blk_mq_hw_ctx *hctx)
@@ -66,6 +68,22 @@ static inline void blk_mq_tag_idle(struct blk_mq_hw_ctx *hctx)
__blk_mq_tag_idle(hctx);
}
+static inline void blk_mq_dtag_wait(struct blk_mq_hw_ctx *hctx)
+{
+ if (!(hctx->flags & BLK_MQ_F_TAG_QUEUE_SHARED))
+ return;
+
+ __blk_mq_dtag_wait(hctx);
+}
+
+static inline void blk_mq_dtag_idle(struct blk_mq_hw_ctx *hctx)
+{
+ if (!(hctx->flags & BLK_MQ_F_TAG_QUEUE_SHARED))
+ return;
+
+ __blk_mq_dtag_idle(hctx);
+}
+
static inline bool blk_mq_tag_is_reserved(struct blk_mq_tags *tags,
unsigned int tag)
{
diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index d319ffa59354..68b1602d9d60 100644
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -666,6 +666,9 @@ enum {
/* hw queue is inactive after all its CPUs become offline */
BLK_MQ_S_INACTIVE = 3,
+ /* hw queue is waiting for driver tag */
+ BLK_MQ_S_DTAG_WAIT = 4,
+
BLK_MQ_MAX_DEPTH = 10240,
BLK_MQ_CPU_WORK_BATCH = 8,
@@ -724,7 +727,16 @@ struct blk_mq_tags {
unsigned int nr_tags;
unsigned int nr_reserved_tags;
+ /*
+ * If multiple queues share a tag set, record the number of queues that
+ * issued io recently.
+ */
atomic_t active_queues;
+ /*
+ * If multiple queues share a tag set, record the number of queues that
+ * can't get driver tag.
+ */
+ atomic_t pending_queues;
struct sbitmap_queue bitmap_tags;
struct sbitmap_queue breserved_tags;
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 9c95df26fc26..787bfb18ce79 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -412,6 +412,8 @@ struct request_queue {
#define QUEUE_FLAG_RQ_ALLOC_TIME 27 /* record rq->alloc_time_ns */
#define QUEUE_FLAG_HCTX_ACTIVE 28 /* at least one blk-mq hctx is active */
#define QUEUE_FLAG_NOWAIT 29 /* device supports NOWAIT */
+#define QUEUE_FLAG_HCTX_WAIT 30 /* at least one blk-mq hctx can't get
+ driver tag */
#define QUEUE_FLAG_MQ_DEFAULT ((1 << QUEUE_FLAG_IO_STAT) | \
(1 << QUEUE_FLAG_SAME_COMP) | \
--
2.31.1
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