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Message-Id: <20231021154806.4019417-3-yukuai1@huaweicloud.com>
Date: Sat, 21 Oct 2023 23:48:00 +0800
From: Yu Kuai <yukuai1@...weicloud.com>
To: bvanassche@....org, hch@....de, kbusch@...nel.org,
ming.lei@...hat.com, axboe@...nel.dk
Cc: linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
yukuai3@...wei.com, yukuai1@...weicloud.com, yi.zhang@...wei.com,
yangerkun@...wei.com
Subject: [PATCH RFC v2 2/8] blk-mq: factor out a structure to store information for tag sharing
From: Yu Kuai <yukuai3@...wei.com>
Tags can be shared by multiple request_queue or hctx, and they both have
a counter to record how many tags is used, 'nr_active_requests_shared_tags'
for request_queue and 'nr_active' for hctx. Factor out a new structure
shared_tag_info to store such information.
Also add new entry debugfs entry 'shared_tag_info' for both queue and
hctx.
This patch prepares for refactoring tag sharing.
Signed-off-by: Yu Kuai <yukuai3@...wei.com>
---
block/blk-core.c | 2 +-
block/blk-mq-debugfs.c | 24 ++++++++++++++++++++++++
block/blk-mq.c | 2 +-
block/blk-mq.h | 23 ++++++++++++-----------
include/linux/blk-mq.h | 11 +++++------
include/linux/blkdev.h | 7 +++++--
6 files changed, 48 insertions(+), 21 deletions(-)
diff --git a/block/blk-core.c b/block/blk-core.c
index 9d51e9894ece..c028b047f5d5 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -414,7 +414,7 @@ struct request_queue *blk_alloc_queue(int node_id)
q->node = node_id;
- atomic_set(&q->nr_active_requests_shared_tags, 0);
+ atomic_set(&q->shared_tag_info.active_tags, 0);
timer_setup(&q->timeout, blk_rq_timed_out_timer, 0);
INIT_WORK(&q->timeout_work, blk_timeout_work);
diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
index f6b77289bc1f..d6ebd8d9d3bb 100644
--- a/block/blk-mq-debugfs.c
+++ b/block/blk-mq-debugfs.c
@@ -155,12 +155,27 @@ static ssize_t queue_state_write(void *data, const char __user *buf,
return count;
}
+static void shared_tag_info_show(struct shared_tag_info *info,
+ struct seq_file *m)
+{
+ seq_printf(m, "%d\n", atomic_read(&info->active_tags));
+}
+
+static int queue_shared_tag_info_show(void *data, struct seq_file *m)
+{
+ struct request_queue *q = data;
+
+ shared_tag_info_show(&q->shared_tag_info, m);
+ return 0;
+}
+
static const struct blk_mq_debugfs_attr blk_mq_debugfs_queue_attrs[] = {
{ "poll_stat", 0400, queue_poll_stat_show },
{ "requeue_list", 0400, .seq_ops = &queue_requeue_list_seq_ops },
{ "pm_only", 0600, queue_pm_only_show, NULL },
{ "state", 0600, queue_state_show, queue_state_write },
{ "zone_wlock", 0400, queue_zone_wlock_show, NULL },
+ { "shared_tag_info", 0400, queue_shared_tag_info_show, NULL },
{ },
};
@@ -512,6 +527,14 @@ static int hctx_dispatch_busy_show(void *data, struct seq_file *m)
return 0;
}
+static int hctx_shared_tag_info_show(void *data, struct seq_file *m)
+{
+ struct blk_mq_hw_ctx *hctx = data;
+
+ shared_tag_info_show(&hctx->shared_tag_info, m);
+ return 0;
+}
+
#define CTX_RQ_SEQ_OPS(name, type) \
static void *ctx_##name##_rq_list_start(struct seq_file *m, loff_t *pos) \
__acquires(&ctx->lock) \
@@ -628,6 +651,7 @@ static const struct blk_mq_debugfs_attr blk_mq_debugfs_hctx_attrs[] = {
{"active", 0400, hctx_active_show},
{"dispatch_busy", 0400, hctx_dispatch_busy_show},
{"type", 0400, hctx_type_show},
+ {"shared_tag_info", 0400, hctx_shared_tag_info_show},
{},
};
diff --git a/block/blk-mq.c b/block/blk-mq.c
index e2d11183f62e..d85b9ad816d0 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -3679,7 +3679,7 @@ blk_mq_alloc_hctx(struct request_queue *q, struct blk_mq_tag_set *set,
if (!zalloc_cpumask_var_node(&hctx->cpumask, gfp, node))
goto free_hctx;
- atomic_set(&hctx->nr_active, 0);
+ atomic_set(&hctx->shared_tag_info.active_tags, 0);
if (node == NUMA_NO_NODE)
node = set->numa_node;
hctx->numa_node = node;
diff --git a/block/blk-mq.h b/block/blk-mq.h
index 363c8f6e13dd..6f332dc122ff 100644
--- a/block/blk-mq.h
+++ b/block/blk-mq.h
@@ -274,10 +274,10 @@ static inline int blk_mq_get_rq_budget_token(struct request *rq)
static inline void __blk_mq_add_active_requests(struct blk_mq_hw_ctx *hctx,
int val)
{
- if (blk_mq_is_shared_tags(hctx->flags))
- atomic_add(val, &hctx->queue->nr_active_requests_shared_tags);
- else
- atomic_add(val, &hctx->nr_active);
+ struct shared_tag_info *info = blk_mq_is_shared_tags(hctx->flags) ?
+ &hctx->queue->shared_tag_info : &hctx->shared_tag_info;
+
+ atomic_add(val, &info->active_tags);
}
static inline void __blk_mq_inc_active_requests(struct blk_mq_hw_ctx *hctx)
@@ -288,10 +288,10 @@ static inline void __blk_mq_inc_active_requests(struct blk_mq_hw_ctx *hctx)
static inline void __blk_mq_sub_active_requests(struct blk_mq_hw_ctx *hctx,
int val)
{
- if (blk_mq_is_shared_tags(hctx->flags))
- atomic_sub(val, &hctx->queue->nr_active_requests_shared_tags);
- else
- atomic_sub(val, &hctx->nr_active);
+ struct shared_tag_info *info = blk_mq_is_shared_tags(hctx->flags) ?
+ &hctx->queue->shared_tag_info : &hctx->shared_tag_info;
+
+ atomic_sub(val, &info->active_tags);
}
static inline void __blk_mq_dec_active_requests(struct blk_mq_hw_ctx *hctx)
@@ -327,9 +327,10 @@ static inline void blk_mq_dec_active_requests(struct blk_mq_hw_ctx *hctx)
static inline int __blk_mq_active_requests(struct blk_mq_hw_ctx *hctx)
{
- if (blk_mq_is_shared_tags(hctx->flags))
- return atomic_read(&hctx->queue->nr_active_requests_shared_tags);
- return atomic_read(&hctx->nr_active);
+ struct shared_tag_info *info = blk_mq_is_shared_tags(hctx->flags) ?
+ &hctx->queue->shared_tag_info : &hctx->shared_tag_info;
+
+ return atomic_read(&info->active_tags);
}
static inline void __blk_mq_put_driver_tag(struct blk_mq_hw_ctx *hctx,
struct request *rq)
diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index 5a08527c53b9..4301226f311b 100644
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -384,6 +384,11 @@ struct blk_mq_hw_ctx {
* assigned when a request is dispatched from a hardware queue.
*/
struct blk_mq_tags *tags;
+ /**
+ * @shared_tag_info: Only used when a tag set is shared across request
+ * queues.
+ */
+ struct shared_tag_info shared_tag_info;
/**
* @sched_tags: Tags owned by I/O scheduler. If there is an I/O
* scheduler associated with a request queue, a tag is assigned when
@@ -399,12 +404,6 @@ struct blk_mq_hw_ctx {
/** @queue_num: Index of this hardware queue. */
unsigned int queue_num;
- /**
- * @nr_active: Number of active requests. Only used when a tag set is
- * shared across request queues.
- */
- atomic_t nr_active;
-
/** @cpuhp_online: List to store request if CPU is going to die */
struct hlist_node cpuhp_online;
/** @cpuhp_dead: List to store request if some CPU die. */
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 51fa7ffdee83..645a8e245add 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -375,6 +375,10 @@ struct blk_independent_access_ranges {
struct blk_independent_access_range ia_range[];
};
+struct shared_tag_info {
+ atomic_t active_tags;
+};
+
struct request_queue {
struct request *last_merge;
struct elevator_queue *elevator;
@@ -455,8 +459,6 @@ struct request_queue {
struct timer_list timeout;
struct work_struct timeout_work;
- atomic_t nr_active_requests_shared_tags;
-
struct blk_mq_tags *sched_shared_tags;
struct list_head icq_list;
@@ -513,6 +515,7 @@ struct request_queue {
struct blk_mq_tag_set *tag_set;
struct list_head tag_set_list;
+ struct shared_tag_info shared_tag_info;
struct dentry *debugfs_dir;
struct dentry *sched_debugfs_dir;
--
2.39.2
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