There were two issues here:
- writeback thread did not start until the device first became dirty
- writeback thread used uninterruptible sleep once running
Without this patch I see kernel warnings printed and a load average of
1.52 after booting my test VM. With this patch the warnings are gone and
the load average is near 0.00 as expected.
---
drivers/md/bcache/super.c | 3 +++
drivers/md/bcache/writeback.c | 13 +++++++++----
drivers/md/bcache/writeback.h | 3 ++-
3 files changed, 14 insertions(+), 5 deletions(-)
diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index 926ded8..3ebe829 100644
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -1041,6 +1041,9 @@ int bch_cached_dev_attach(struct cached_dev *dc, struct cache_set *c)
*/
atomic_set(&dc->count, 1);
+ if (bch_cached_dev_writeback_start(dc))
+ return -ENOMEM;
+
if (BDEV_STATE(&dc->sb) == BDEV_STATE_DIRTY) {
bch_sectors_dirty_init(dc);
atomic_set(&dc->has_dirty, 1);
diff --git a/drivers/md/bcache/writeback.c b/drivers/md/bcache/writeback.c
index f4300e4..08c1abb 100644
--- a/drivers/md/bcache/writeback.c
+++ b/drivers/md/bcache/writeback.c
@@ -239,7 +239,7 @@ static void read_dirty(struct cached_dev *dc)
if (KEY_START(&w->key) != dc->last_read ||
jiffies_to_msecs(delay) > 50)
while (!kthread_should_stop() && delay)
- delay = schedule_timeout_uninterruptible(delay);
+ delay = schedule_timeout_interruptible(delay);
dc->last_read = KEY_OFFSET(&w->key);
@@ -436,7 +436,7 @@ static int bch_writeback_thread(void *arg)
while (delay &&
!kthread_should_stop() &&
!test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags))
- delay = schedule_timeout_uninterruptible(delay);
+ delay = schedule_timeout_interruptible(delay);
}
}
@@ -478,7 +478,7 @@ void bch_sectors_dirty_init(struct cached_dev *dc)
dc->disk.sectors_dirty_last = bcache_dev_sectors_dirty(&dc->disk);
}
-int bch_cached_dev_writeback_init(struct cached_dev *dc)
+void bch_cached_dev_writeback_init(struct cached_dev *dc)
{
sema_init(&dc->in_flight, 64);
init_rwsem(&dc->writeback_lock);
@@ -494,14 +494,19 @@ int bch_cached_dev_writeback_init(struct cached_dev *dc)
dc->writeback_rate_d_term = 30;
dc->writeback_rate_p_term_inverse = 6000;
+ INIT_DELAYED_WORK(&dc->writeback_rate_update, update_writeback_rate);
+}
+
+int bch_cached_dev_writeback_start(struct cached_dev *dc)
+{
dc->writeback_thread = kthread_create(bch_writeback_thread, dc,
"bcache_writeback");
if (IS_ERR(dc->writeback_thread))
return PTR_ERR(dc->writeback_thread);
- INIT_DELAYED_WORK(&dc->writeback_rate_update, update_writeback_rate);
schedule_delayed_work(&dc->writeback_rate_update,
dc->writeback_rate_update_seconds * HZ);
+ bch_writeback_queue(dc);
return 0;
}
diff --git a/drivers/md/bcache/writeback.h b/drivers/md/bcache/writeback.h
index e2f8598..0a9dab1 100644
--- a/drivers/md/bcache/writeback.h
+++ b/drivers/md/bcache/writeback.h
@@ -85,6 +85,7 @@ static inline void bch_writeback_add(struct cached_dev *dc)
void bcache_dev_sectors_dirty_add(struct cache_set *, unsigned, uint64_t, int);
void bch_sectors_dirty_init(struct cached_dev *dc);
-int bch_cached_dev_writeback_init(struct cached_dev *);
+void bch_cached_dev_writeback_init(struct cached_dev *);
+int bch_cached_dev_writeback_start(struct cached_dev *);
#endif
--
2.0.0.rc0
--
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