1 files changed, 25 insertions, 28 deletions

diff --git a/drivers/md/bcache/writeback.c b/drivers/md/bcache/writeback.c
index 99053b1251be..6c44fe059c27 100644
--- a/drivers/md/bcache/writeback.c
+++ b/drivers/md/bcache/writeback.c
@@ -30,38 +30,40 @@ static void __update_writeback_rate(struct cached_dev *dc)
 
         /* PD controller */
 
-        int change = 0;
-        int64_t error;
         int64_t dirty = bcache_dev_sectors_dirty(&dc->disk);
         int64_t derivative = dirty - dc->disk.sectors_dirty_last;
+        int64_t proportional = dirty - target;
+        int64_t change;
 
         dc->disk.sectors_dirty_last = dirty;
 
-        derivative *= dc->writeback_rate_d_term;
-        derivative = clamp(derivative, -dirty, dirty);
+        /* Scale to sectors per second */
 
-        derivative = ewma_add(dc->disk.sectors_dirty_derivative, derivative,
-                              dc->writeback_rate_d_smooth, 0);
+        proportional *= dc->writeback_rate_update_seconds;
+        proportional = div_s64(proportional, dc->writeback_rate_p_term_inverse);
 
-        /* Avoid divide by zero */
-        if (!target)
-                goto out;
+        derivative = div_s64(derivative, dc->writeback_rate_update_seconds);
 
-        error = div64_s64((dirty + derivative - target) << 8, target);
+        derivative = ewma_add(dc->disk.sectors_dirty_derivative, derivative,
+                              (dc->writeback_rate_d_term /
+                               dc->writeback_rate_update_seconds) ?: 1, 0);
+
+        derivative *= dc->writeback_rate_d_term;
+        derivative = div_s64(derivative, dc->writeback_rate_p_term_inverse);
 
-        change = div_s64((dc->writeback_rate.rate * error) >> 8,
-                         dc->writeback_rate_p_term_inverse);
+        change = proportional + derivative;
 
         /* Don't increase writeback rate if the device isn't keeping up */
         if (change > 0 &&
             time_after64(local_clock(),
-                         dc->writeback_rate.next + 10 * NSEC_PER_MSEC))
+                         dc->writeback_rate.next + NSEC_PER_MSEC))
                 change = 0;
 
         dc->writeback_rate.rate =
-                clamp_t(int64_t, dc->writeback_rate.rate + change,
+                clamp_t(int64_t, (int64_t) dc->writeback_rate.rate + change,
                         1, NSEC_PER_MSEC);
-out:
+
+        dc->writeback_rate_proportional = proportional;
         dc->writeback_rate_derivative = derivative;
         dc->writeback_rate_change = change;
         dc->writeback_rate_target = target;
@@ -87,15 +89,11 @@ static void update_writeback_rate(struct work_struct *work)
 
 static unsigned writeback_delay(struct cached_dev *dc, unsigned sectors)
 {
-        uint64_t ret;
-
         if (test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags) ||
             !dc->writeback_percent)
                 return 0;
 
-        ret = bch_next_delay(&dc->writeback_rate, sectors * 10000000ULL);
-
-        return min_t(uint64_t, ret, HZ);
+        return bch_next_delay(&dc->writeback_rate, sectors);
 }
 
 struct dirty_io {
@@ -241,7 +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_interruptible(delay);
+                                delay = schedule_timeout_uninterruptible(delay);
 
                 dc->last_read   = KEY_OFFSET(&w->key);
 
@@ -438,7 +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_interruptible(delay);
+                                delay = schedule_timeout_uninterruptible(delay);
                 }
         }
 
@@ -476,6 +474,8 @@ void bch_sectors_dirty_init(struct cached_dev *dc)
 
         bch_btree_map_keys(&op.op, dc->disk.c, &KEY(op.inode, 0, 0),
                            sectors_dirty_init_fn, 0);
+
+        dc->disk.sectors_dirty_last = bcache_dev_sectors_dirty(&dc->disk);
 }
 
 int bch_cached_dev_writeback_init(struct cached_dev *dc)
@@ -490,18 +490,15 @@ int bch_cached_dev_writeback_init(struct cached_dev *dc)
         dc->writeback_delay             = 30;
         dc->writeback_rate.rate         = 1024;
 
-        dc->writeback_rate_update_seconds = 30;
-        dc->writeback_rate_d_term       = 16;
-        dc->writeback_rate_p_term_inverse = 64;
-        dc->writeback_rate_d_smooth     = 8;
+        dc->writeback_rate_update_seconds = 5;
+        dc->writeback_rate_d_term       = 30;
+        dc->writeback_rate_p_term_inverse = 6000;
 
         dc->writeback_thread = kthread_create(bch_writeback_thread, dc,
                                               "bcache_writeback");
         if (IS_ERR(dc->writeback_thread))
                 return PTR_ERR(dc->writeback_thread);
 
-        set_task_state(dc->writeback_thread, TASK_INTERRUPTIBLE);
-
         INIT_DELAYED_WORK(&dc->writeback_rate_update, update_writeback_rate);
         schedule_delayed_work(&dc->writeback_rate_update,
                               dc->writeback_rate_update_seconds * HZ);