From 695185fce22928dfc9bacd7d7eb976c9ec2fcef3 Mon Sep 17 00:00:00 2001 From: Kai Krakow Date: Wed, 10 Feb 2021 13:07:27 +0800 Subject: [PATCH] bcache: Move journal work to new flush wq commit afe78ab46f638ecdf80a35b122ffc92c20d9ae5d upstream. This is potentially long running and not latency sensitive, let's get it out of the way of other latency sensitive events. As observed in the previous commit, the `system_wq` comes easily congested by bcache, and this fixes a few more stalls I was observing every once in a while. Let's not make this `WQ_MEM_RECLAIM` as it showed to reduce performance of boot and file system operations in my tests. Also, without `WQ_MEM_RECLAIM`, I no longer see desktop stalls. This matches the previous behavior as `system_wq` also does no memory reclaim: > // workqueue.c: > system_wq = alloc_workqueue("events", 0, 0); Cc: Coly Li Cc: stable@vger.kernel.org # 5.4+ Signed-off-by: Kai Krakow Signed-off-by: Coly Li Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman --- drivers/md/bcache/bcache.h | 1 + drivers/md/bcache/journal.c | 4 ++-- drivers/md/bcache/super.c | 16 ++++++++++++++++ 3 files changed, 19 insertions(+), 2 deletions(-) diff --git a/drivers/md/bcache/bcache.h b/drivers/md/bcache/bcache.h index b1ed16c7a534..e8bf4f752e8b 100644 --- a/drivers/md/bcache/bcache.h +++ b/drivers/md/bcache/bcache.h @@ -1001,6 +1001,7 @@ void bch_write_bdev_super(struct cached_dev *dc, struct closure *parent); extern struct workqueue_struct *bcache_wq; extern struct workqueue_struct *bch_journal_wq; +extern struct workqueue_struct *bch_flush_wq; extern struct mutex bch_register_lock; extern struct list_head bch_cache_sets; diff --git a/drivers/md/bcache/journal.c b/drivers/md/bcache/journal.c index aefbdb7e003b..c6613e817333 100644 --- a/drivers/md/bcache/journal.c +++ b/drivers/md/bcache/journal.c @@ -932,8 +932,8 @@ atomic_t *bch_journal(struct cache_set *c, journal_try_write(c); } else if (!w->dirty) { w->dirty = true; - schedule_delayed_work(&c->journal.work, - msecs_to_jiffies(c->journal_delay_ms)); + queue_delayed_work(bch_flush_wq, &c->journal.work, + msecs_to_jiffies(c->journal_delay_ms)); spin_unlock(&c->journal.lock); } else { spin_unlock(&c->journal.lock); diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c index 69901175b4f4..248bda63f085 100644 --- a/drivers/md/bcache/super.c +++ b/drivers/md/bcache/super.c @@ -49,6 +49,7 @@ static int bcache_major; static DEFINE_IDA(bcache_device_idx); static wait_queue_head_t unregister_wait; struct workqueue_struct *bcache_wq; +struct workqueue_struct *bch_flush_wq; struct workqueue_struct *bch_journal_wq; @@ -2833,6 +2834,8 @@ static void bcache_exit(void) destroy_workqueue(bcache_wq); if (bch_journal_wq) destroy_workqueue(bch_journal_wq); + if (bch_flush_wq) + destroy_workqueue(bch_flush_wq); bch_btree_exit(); if (bcache_major) @@ -2896,6 +2899,19 @@ static int __init bcache_init(void) if (!bcache_wq) goto err; + /* + * Let's not make this `WQ_MEM_RECLAIM` for the following reasons: + * + * 1. It used `system_wq` before which also does no memory reclaim. + * 2. With `WQ_MEM_RECLAIM` desktop stalls, increased boot times, and + * reduced throughput can be observed. + * + * We still want to user our own queue to not congest the `system_wq`. + */ + bch_flush_wq = alloc_workqueue("bch_flush", 0, 0); + if (!bch_flush_wq) + goto err; + bch_journal_wq = alloc_workqueue("bch_journal", WQ_MEM_RECLAIM, 0); if (!bch_journal_wq) goto err;