blk-mq: allow changing of queue depth through sysfs
For request_fn based devices, the block layer exports a 'nr_requests'
file through sysfs to allow adjusting of queue depth on the fly.
Currently this returns -EINVAL for blk-mq, since it's not wired up.
Wire this up for blk-mq, so that it now also always dynamic
adjustments of the allowed queue depth for any given block device
managed by blk-mq.
Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c
index e6b3fba..f6dea96 100644
--- a/block/blk-mq-tag.c
+++ b/block/blk-mq-tag.c
@@ -57,23 +57,13 @@
}
/*
- * If a previously busy queue goes inactive, potential waiters could now
- * be allowed to queue. Wake them up and check.
+ * Wakeup all potentially sleeping on normal (non-reserved) tags
*/
-void __blk_mq_tag_idle(struct blk_mq_hw_ctx *hctx)
+static void blk_mq_tag_wakeup_all(struct blk_mq_tags *tags)
{
- struct blk_mq_tags *tags = hctx->tags;
struct blk_mq_bitmap_tags *bt;
int i, wake_index;
- if (!test_and_clear_bit(BLK_MQ_S_TAG_ACTIVE, &hctx->state))
- return;
-
- atomic_dec(&tags->active_queues);
-
- /*
- * Will only throttle depth on non-reserved tags
- */
bt = &tags->bitmap_tags;
wake_index = bt->wake_index;
for (i = 0; i < BT_WAIT_QUEUES; i++) {
@@ -87,6 +77,22 @@
}
/*
+ * If a previously busy queue goes inactive, potential waiters could now
+ * be allowed to queue. Wake them up and check.
+ */
+void __blk_mq_tag_idle(struct blk_mq_hw_ctx *hctx)
+{
+ struct blk_mq_tags *tags = hctx->tags;
+
+ if (!test_and_clear_bit(BLK_MQ_S_TAG_ACTIVE, &hctx->state))
+ return;
+
+ atomic_dec(&tags->active_queues);
+
+ blk_mq_tag_wakeup_all(tags);
+}
+
+/*
* For shared tag users, we track the number of currently active users
* and attempt to provide a fair share of the tag depth for each of them.
*/
@@ -408,6 +414,28 @@
return bt->depth - used;
}
+static void bt_update_count(struct blk_mq_bitmap_tags *bt,
+ unsigned int depth)
+{
+ unsigned int tags_per_word = 1U << bt->bits_per_word;
+ unsigned int map_depth = depth;
+
+ if (depth) {
+ int i;
+
+ for (i = 0; i < bt->map_nr; i++) {
+ bt->map[i].depth = min(map_depth, tags_per_word);
+ map_depth -= bt->map[i].depth;
+ }
+ }
+
+ bt->wake_cnt = BT_WAIT_BATCH;
+ if (bt->wake_cnt > depth / 4)
+ bt->wake_cnt = max(1U, depth / 4);
+
+ bt->depth = depth;
+}
+
static int bt_alloc(struct blk_mq_bitmap_tags *bt, unsigned int depth,
int node, bool reserved)
{
@@ -420,7 +448,7 @@
* condition.
*/
if (depth) {
- unsigned int nr, i, map_depth, tags_per_word;
+ unsigned int nr, tags_per_word;
tags_per_word = (1 << bt->bits_per_word);
@@ -444,11 +472,6 @@
return -ENOMEM;
bt->map_nr = nr;
- map_depth = depth;
- for (i = 0; i < nr; i++) {
- bt->map[i].depth = min(map_depth, tags_per_word);
- map_depth -= tags_per_word;
- }
}
bt->bs = kzalloc(BT_WAIT_QUEUES * sizeof(*bt->bs), GFP_KERNEL);
@@ -460,11 +483,7 @@
for (i = 0; i < BT_WAIT_QUEUES; i++)
init_waitqueue_head(&bt->bs[i].wait);
- bt->wake_cnt = BT_WAIT_BATCH;
- if (bt->wake_cnt > depth / 4)
- bt->wake_cnt = max(1U, depth / 4);
-
- bt->depth = depth;
+ bt_update_count(bt, depth);
return 0;
}
@@ -525,6 +544,21 @@
*tag = prandom_u32() % depth;
}
+int blk_mq_tag_update_depth(struct blk_mq_tags *tags, unsigned int tdepth)
+{
+ tdepth -= tags->nr_reserved_tags;
+ if (tdepth > tags->nr_tags)
+ return -EINVAL;
+
+ /*
+ * Don't need (or can't) update reserved tags here, they remain
+ * static and should never need resizing.
+ */
+ bt_update_count(&tags->bitmap_tags, tdepth);
+ blk_mq_tag_wakeup_all(tags);
+ return 0;
+}
+
ssize_t blk_mq_tag_sysfs_show(struct blk_mq_tags *tags, char *page)
{
char *orig_page = page;