| From 0e29284793e52fd086da2fed409b0af9bca03b53 Mon Sep 17 00:00:00 2001 |
| From: Kai Krakow <kai@kaishome.de> |
| Date: Fri, 29 Jan 2021 17:40:05 +0100 |
| Subject: [PATCH 3/5] Revert "bcache: Kill btree_io_wq" |
| |
| This reverts commit 56b30770b27d54d68ad51eccc6d888282b568cee. |
| |
| With the btree using the `system_wq`, I seem to see a lot more desktop |
| latency than I should. |
| |
| After some more investigation, it looks like the original assumption |
| of 56b3077 no longer is true, and bcache has a very high potential of |
| congesting the `system_wq`. In turn, this introduces laggy desktop |
| performance, IO stalls (at least with btrfs), and input events may be |
| delayed. |
| |
| So let's revert this. It's important to note that the semantics of |
| using `system_wq` previously mean that `btree_io_wq` should be created |
| before and destroyed after other bcache wqs to keep the same |
| assumptions. |
| |
| Cc: Coly Li <colyli@suse.de> |
| Cc: stable@vger.kernel.org # 5.4+ |
| Signed-off-by: Kai Krakow <kai@kaishome.de> |
| Signed-off-by: Coly Li <colyli@suse.de> |
| --- |
| drivers/md/bcache/bcache.h | 2 ++ |
| drivers/md/bcache/btree.c | 21 +++++++++++++++++++-- |
| drivers/md/bcache/super.c | 4 ++++ |
| 3 files changed, 25 insertions(+), 2 deletions(-) |
| |
| diff --git a/drivers/md/bcache/bcache.h b/drivers/md/bcache/bcache.h |
| index d7a84327b7f1..2b8c7dd2cfae 100644 |
| --- a/drivers/md/bcache/bcache.h |
| +++ b/drivers/md/bcache/bcache.h |
| @@ -1046,5 +1046,7 @@ void bch_debug_exit(void); |
| void bch_debug_init(void); |
| void bch_request_exit(void); |
| int bch_request_init(void); |
| +void bch_btree_exit(void); |
| +int bch_btree_init(void); |
| |
| #endif /* _BCACHE_H */ |
| diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c |
| index 910df242c83d..952f022db5a5 100644 |
| --- a/drivers/md/bcache/btree.c |
| +++ b/drivers/md/bcache/btree.c |
| @@ -99,6 +99,8 @@ |
| #define PTR_HASH(c, k) \ |
| (((k)->ptr[0] >> c->bucket_bits) | PTR_GEN(k, 0)) |
| |
| +static struct workqueue_struct *btree_io_wq; |
| + |
| #define insert_lock(s, b) ((b)->level <= (s)->lock) |
| |
| |
| @@ -308,7 +310,7 @@ static void __btree_node_write_done(struct closure *cl) |
| btree_complete_write(b, w); |
| |
| if (btree_node_dirty(b)) |
| - schedule_delayed_work(&b->work, 30 * HZ); |
| + queue_delayed_work(btree_io_wq, &b->work, 30 * HZ); |
| |
| closure_return_with_destructor(cl, btree_node_write_unlock); |
| } |
| @@ -481,7 +483,7 @@ static void bch_btree_leaf_dirty(struct btree *b, atomic_t *journal_ref) |
| BUG_ON(!i->keys); |
| |
| if (!btree_node_dirty(b)) |
| - schedule_delayed_work(&b->work, 30 * HZ); |
| + queue_delayed_work(btree_io_wq, &b->work, 30 * HZ); |
| |
| set_btree_node_dirty(b); |
| |
| @@ -2764,3 +2766,18 @@ void bch_keybuf_init(struct keybuf *buf) |
| spin_lock_init(&buf->lock); |
| array_allocator_init(&buf->freelist); |
| } |
| + |
| +void bch_btree_exit(void) |
| +{ |
| + if (btree_io_wq) |
| + destroy_workqueue(btree_io_wq); |
| +} |
| + |
| +int __init bch_btree_init(void) |
| +{ |
| + btree_io_wq = create_singlethread_workqueue("bch_btree_io"); |
| + if (!btree_io_wq) |
| + return -ENOMEM; |
| + |
| + return 0; |
| +} |
| diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c |
| index e7d1b52c5cc8..85a44a0cffe0 100644 |
| --- a/drivers/md/bcache/super.c |
| +++ b/drivers/md/bcache/super.c |
| @@ -2821,6 +2821,7 @@ static void bcache_exit(void) |
| destroy_workqueue(bcache_wq); |
| if (bch_journal_wq) |
| destroy_workqueue(bch_journal_wq); |
| + bch_btree_exit(); |
| |
| if (bcache_major) |
| unregister_blkdev(bcache_major, "bcache"); |
| @@ -2876,6 +2877,9 @@ static int __init bcache_init(void) |
| return bcache_major; |
| } |
| |
| + if (bch_btree_init()) |
| + goto err; |
| + |
| bcache_wq = alloc_workqueue("bcache", WQ_MEM_RECLAIM, 0); |
| if (!bcache_wq) |
| goto err; |
| -- |
| 2.26.2 |
| |