drbd: use rolling marks for resync speed calculation

The current resync speed as displayed in /proc/drbd fluctuates a lot.
Using an array of rolling marks makes this calculation much more stable.
We used to have this (a long time ago with 0.7), but it got lost somehow.

If "stalled", do not discard the rest of the information, just add a
" (stalled)" tag to the progress line.

This patch also shortens a spinlock critical section somewhat, and
reduces the number of atomic operations in put_ldev.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>

1 files changed, 15 insertions, 14 deletions

diff --git a/drivers/block/drbd/drbd_actlog.c b/drivers/block/drbd/drbd_actlog.c
index 9400845d602e..b895470e53d7 100644
--- a/drivers/block/drbd/drbd_actlog.c
+++ b/drivers/block/drbd/drbd_actlog.c
@@ -965,29 +965,30 @@ void __drbd_set_in_sync(struct drbd_conf *mdev, sector_t sector, int size,
          * ok, (capacity & 7) != 0 sometimes, but who cares...
          * we count rs_{total,left} in bits, not sectors.
          */
-        spin_lock_irqsave(&mdev->al_lock, flags);
         count = drbd_bm_clear_bits(mdev, sbnr, ebnr);
-        if (count) {
-                /* we need the lock for drbd_try_clear_on_disk_bm */
-                if (jiffies - mdev->rs_mark_time > HZ*10) {
-                        /* should be rolling marks,
-                         * but we estimate only anyways. */
-                        if (mdev->rs_mark_left != drbd_bm_total_weight(mdev) &&
+        if (count && get_ldev(mdev)) {
+                unsigned long now = jiffies;
+                unsigned long last = mdev->rs_mark_time[mdev->rs_last_mark];
+                int next = (mdev->rs_last_mark + 1) % DRBD_SYNC_MARKS;
+                if (time_after_eq(now, last + DRBD_SYNC_MARK_STEP)) {
+                        unsigned long tw = drbd_bm_total_weight(mdev);
+                        if (mdev->rs_mark_left[mdev->rs_last_mark] != tw &&
                             mdev->state.conn != C_PAUSED_SYNC_T &&
                             mdev->state.conn != C_PAUSED_SYNC_S) {
-                                mdev->rs_mark_time = jiffies;
-                                mdev->rs_mark_left = drbd_bm_total_weight(mdev);
+                                mdev->rs_mark_time[next] = now;
+                                mdev->rs_mark_left[next] = tw;
+                                mdev->rs_last_mark = next;
                         }
                 }
-                if (get_ldev(mdev)) {
-                        drbd_try_clear_on_disk_bm(mdev, sector, count, TRUE);
-                        put_ldev(mdev);
-                }
+                spin_lock_irqsave(&mdev->al_lock, flags);
+                drbd_try_clear_on_disk_bm(mdev, sector, count, TRUE);
+                spin_unlock_irqrestore(&mdev->al_lock, flags);
+
                 /* just wake_up unconditional now, various lc_chaged(),
                  * lc_put() in drbd_try_clear_on_disk_bm(). */
                 wake_up = 1;
+                put_ldev(mdev);
         }
-        spin_unlock_irqrestore(&mdev->al_lock, flags);
         if (wake_up)
                 wake_up(&mdev->al_wait);
 }