summaryrefslogtreecommitdiffstats
path: root/block
diff options
context:
space:
mode:
authorMing Lei <ming.lei@redhat.com>2021-12-03 14:15:32 +0100
committerJens Axboe <axboe@kernel.dk>2021-12-03 22:51:29 +0100
commit704b914f15fb7daaf517e3acc4bed472b50ca19e (patch)
tree5fffc1140fef4ddceeaae58e44fbb65333c33861 /block
parentblk-mq: remove hctx_lock and hctx_unlock (diff)
downloadlinux-704b914f15fb7daaf517e3acc4bed472b50ca19e.tar.xz
linux-704b914f15fb7daaf517e3acc4bed472b50ca19e.zip
blk-mq: move srcu from blk_mq_hw_ctx to request_queue
In case of BLK_MQ_F_BLOCKING, per-hctx srcu is used to protect dispatch critical area. However, this srcu instance stays at the end of hctx, and it often takes standalone cacheline, often cold. Inside srcu_read_lock() and srcu_read_unlock(), WRITE is always done on the indirect percpu variable which is allocated from heap instead of being embedded, srcu->srcu_idx is read only in srcu_read_lock(). It doesn't matter if srcu structure stays in hctx or request queue. So switch to per-request-queue srcu for protecting dispatch, and this way simplifies quiesce a lot, not mention quiesce is always done on the request queue wide. Signed-off-by: Ming Lei <ming.lei@redhat.com> Link: https://lore.kernel.org/r/20211203131534.3668411-3-ming.lei@redhat.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block')
-rw-r--r--block/blk-core.c27
-rw-r--r--block/blk-mq-sysfs.c2
-rw-r--r--block/blk-mq.c37
-rw-r--r--block/blk-mq.h4
-rw-r--r--block/blk-sysfs.c3
-rw-r--r--block/blk.h10
-rw-r--r--block/genhd.c2
7 files changed, 44 insertions, 41 deletions
diff --git a/block/blk-core.c b/block/blk-core.c
index b0660c9df852..10619fd83c1b 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -66,6 +66,7 @@ DEFINE_IDA(blk_queue_ida);
* For queue allocation
*/
struct kmem_cache *blk_requestq_cachep;
+struct kmem_cache *blk_requestq_srcu_cachep;
/*
* Controlling structure to kblockd
@@ -437,21 +438,27 @@ static void blk_timeout_work(struct work_struct *work)
{
}
-struct request_queue *blk_alloc_queue(int node_id)
+struct request_queue *blk_alloc_queue(int node_id, bool alloc_srcu)
{
struct request_queue *q;
int ret;
- q = kmem_cache_alloc_node(blk_requestq_cachep,
- GFP_KERNEL | __GFP_ZERO, node_id);
+ q = kmem_cache_alloc_node(blk_get_queue_kmem_cache(alloc_srcu),
+ GFP_KERNEL | __GFP_ZERO, node_id);
if (!q)
return NULL;
+ if (alloc_srcu) {
+ blk_queue_flag_set(QUEUE_FLAG_HAS_SRCU, q);
+ if (init_srcu_struct(q->srcu) != 0)
+ goto fail_q;
+ }
+
q->last_merge = NULL;
q->id = ida_simple_get(&blk_queue_ida, 0, 0, GFP_KERNEL);
if (q->id < 0)
- goto fail_q;
+ goto fail_srcu;
ret = bioset_init(&q->bio_split, BIO_POOL_SIZE, 0, 0);
if (ret)
@@ -508,8 +515,11 @@ fail_split:
bioset_exit(&q->bio_split);
fail_id:
ida_simple_remove(&blk_queue_ida, q->id);
+fail_srcu:
+ if (alloc_srcu)
+ cleanup_srcu_struct(q->srcu);
fail_q:
- kmem_cache_free(blk_requestq_cachep, q);
+ kmem_cache_free(blk_get_queue_kmem_cache(alloc_srcu), q);
return NULL;
}
@@ -1301,6 +1311,9 @@ int __init blk_dev_init(void)
sizeof_field(struct request, cmd_flags));
BUILD_BUG_ON(REQ_OP_BITS + REQ_FLAG_BITS > 8 *
sizeof_field(struct bio, bi_opf));
+ BUILD_BUG_ON(ALIGN(offsetof(struct request_queue, srcu),
+ __alignof__(struct request_queue)) !=
+ sizeof(struct request_queue));
/* used for unplugging and affects IO latency/throughput - HIGHPRI */
kblockd_workqueue = alloc_workqueue("kblockd",
@@ -1311,6 +1324,10 @@ int __init blk_dev_init(void)
blk_requestq_cachep = kmem_cache_create("request_queue",
sizeof(struct request_queue), 0, SLAB_PANIC, NULL);
+ blk_requestq_srcu_cachep = kmem_cache_create("request_queue_srcu",
+ sizeof(struct request_queue) +
+ sizeof(struct srcu_struct), 0, SLAB_PANIC, NULL);
+
blk_debugfs_root = debugfs_create_dir("block", NULL);
return 0;
diff --git a/block/blk-mq-sysfs.c b/block/blk-mq-sysfs.c
index 253c857cba47..674786574075 100644
--- a/block/blk-mq-sysfs.c
+++ b/block/blk-mq-sysfs.c
@@ -36,8 +36,6 @@ static void blk_mq_hw_sysfs_release(struct kobject *kobj)
struct blk_mq_hw_ctx *hctx = container_of(kobj, struct blk_mq_hw_ctx,
kobj);
- if (hctx->flags & BLK_MQ_F_BLOCKING)
- cleanup_srcu_struct(hctx->srcu);
blk_free_flush_queue(hctx->fq);
sbitmap_free(&hctx->ctx_map);
free_cpumask_var(hctx->cpumask);
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 494da31dc1a5..6a2c2704454e 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -260,17 +260,9 @@ EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue_nowait);
*/
void blk_mq_wait_quiesce_done(struct request_queue *q)
{
- struct blk_mq_hw_ctx *hctx;
- unsigned int i;
- bool rcu = false;
-
- queue_for_each_hw_ctx(q, hctx, i) {
- if (hctx->flags & BLK_MQ_F_BLOCKING)
- synchronize_srcu(hctx->srcu);
- else
- rcu = true;
- }
- if (rcu)
+ if (blk_queue_has_srcu(q))
+ synchronize_srcu(q->srcu);
+ else
synchronize_rcu();
}
EXPORT_SYMBOL_GPL(blk_mq_wait_quiesce_done);
@@ -3400,20 +3392,6 @@ static void blk_mq_exit_hw_queues(struct request_queue *q,
}
}
-static int blk_mq_hw_ctx_size(struct blk_mq_tag_set *tag_set)
-{
- int hw_ctx_size = sizeof(struct blk_mq_hw_ctx);
-
- BUILD_BUG_ON(ALIGN(offsetof(struct blk_mq_hw_ctx, srcu),
- __alignof__(struct blk_mq_hw_ctx)) !=
- sizeof(struct blk_mq_hw_ctx));
-
- if (tag_set->flags & BLK_MQ_F_BLOCKING)
- hw_ctx_size += sizeof(struct srcu_struct);
-
- return hw_ctx_size;
-}
-
static int blk_mq_init_hctx(struct request_queue *q,
struct blk_mq_tag_set *set,
struct blk_mq_hw_ctx *hctx, unsigned hctx_idx)
@@ -3451,7 +3429,7 @@ blk_mq_alloc_hctx(struct request_queue *q, struct blk_mq_tag_set *set,
struct blk_mq_hw_ctx *hctx;
gfp_t gfp = GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY;
- hctx = kzalloc_node(blk_mq_hw_ctx_size(set), gfp, node);
+ hctx = kzalloc_node(sizeof(struct blk_mq_hw_ctx), gfp, node);
if (!hctx)
goto fail_alloc_hctx;
@@ -3493,8 +3471,6 @@ blk_mq_alloc_hctx(struct request_queue *q, struct blk_mq_tag_set *set,
if (!hctx->fq)
goto free_bitmap;
- if (hctx->flags & BLK_MQ_F_BLOCKING)
- init_srcu_struct(hctx->srcu);
blk_mq_hctx_kobj_init(hctx);
return hctx;
@@ -3830,7 +3806,7 @@ static struct request_queue *blk_mq_init_queue_data(struct blk_mq_tag_set *set,
struct request_queue *q;
int ret;
- q = blk_alloc_queue(set->numa_node);
+ q = blk_alloc_queue(set->numa_node, set->flags & BLK_MQ_F_BLOCKING);
if (!q)
return ERR_PTR(-ENOMEM);
q->queuedata = queuedata;
@@ -3979,6 +3955,9 @@ static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set *set,
int blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
struct request_queue *q)
{
+ WARN_ON_ONCE(blk_queue_has_srcu(q) !=
+ !!(set->flags & BLK_MQ_F_BLOCKING));
+
/* mark the queue as mq asap */
q->mq_ops = set->ops;
diff --git a/block/blk-mq.h b/block/blk-mq.h
index e4c396204928..792f0b29c6eb 100644
--- a/block/blk-mq.h
+++ b/block/blk-mq.h
@@ -385,9 +385,9 @@ do { \
int srcu_idx; \
\
might_sleep(); \
- srcu_idx = srcu_read_lock((hctx)->srcu); \
+ srcu_idx = srcu_read_lock((hctx)->queue->srcu); \
(dispatch_ops); \
- srcu_read_unlock((hctx)->srcu, srcu_idx); \
+ srcu_read_unlock((hctx)->queue->srcu, srcu_idx); \
} \
} while (0)
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 4622da4bb992..3e6357321225 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -735,7 +735,8 @@ static void blk_free_queue_rcu(struct rcu_head *rcu_head)
{
struct request_queue *q = container_of(rcu_head, struct request_queue,
rcu_head);
- kmem_cache_free(blk_requestq_cachep, q);
+
+ kmem_cache_free(blk_get_queue_kmem_cache(blk_queue_has_srcu(q)), q);
}
/* Unconfigure the I/O scheduler and dissociate from the cgroup controller. */
diff --git a/block/blk.h b/block/blk.h
index 24d8b333bb03..7ccb7c7d86b3 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -27,6 +27,7 @@ struct blk_flush_queue {
};
extern struct kmem_cache *blk_requestq_cachep;
+extern struct kmem_cache *blk_requestq_srcu_cachep;
extern struct kobj_type blk_queue_ktype;
extern struct ida blk_queue_ida;
@@ -424,7 +425,14 @@ int bio_add_hw_page(struct request_queue *q, struct bio *bio,
struct page *page, unsigned int len, unsigned int offset,
unsigned int max_sectors, bool *same_page);
-struct request_queue *blk_alloc_queue(int node_id);
+static inline struct kmem_cache *blk_get_queue_kmem_cache(bool srcu)
+{
+ if (srcu)
+ return blk_requestq_srcu_cachep;
+ return blk_requestq_cachep;
+}
+struct request_queue *blk_alloc_queue(int node_id, bool alloc_srcu);
+
int disk_scan_partitions(struct gendisk *disk, fmode_t mode);
int disk_alloc_events(struct gendisk *disk);
diff --git a/block/genhd.c b/block/genhd.c
index 5179a4f00fba..3c139a1b6f04 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -1338,7 +1338,7 @@ struct gendisk *__blk_alloc_disk(int node, struct lock_class_key *lkclass)
struct request_queue *q;
struct gendisk *disk;
- q = blk_alloc_queue(node);
+ q = blk_alloc_queue(node, false);
if (!q)
return NULL;