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, 17 insertions, 8 deletions

diff --git a/drivers/block/drbd/drbd_int.h b/drivers/block/drbd/drbd_int.h
index 72d20475040..0fce3f36fc1 100644
--- a/drivers/block/drbd/drbd_int.h
+++ b/drivers/block/drbd/drbd_int.h
@@ -997,12 +997,16 @@ struct drbd_conf {
 	unsigned long rs_start;
 	/* cumulated time in PausedSyncX state [unit jiffies] */
 	unsigned long rs_paused;
+	/* skipped because csum was equal [unit BM_BLOCK_SIZE] */
+	unsigned long rs_same_csum;
+#define DRBD_SYNC_MARKS 8
+#define DRBD_SYNC_MARK_STEP (3*HZ)
 	/* block not up-to-date at mark [unit BM_BLOCK_SIZE] */
-	unsigned long rs_mark_left;
+	unsigned long rs_mark_left[DRBD_SYNC_MARKS];
 	/* marks's time [unit jiffies] */
-	unsigned long rs_mark_time;
-	/* skipped because csum was equeal [unit BM_BLOCK_SIZE] */
-	unsigned long rs_same_csum;
+	unsigned long rs_mark_time[DRBD_SYNC_MARKS];
+	/* current index into rs_mark_{left,time} */
+	int rs_last_mark;
 
 	/* where does the admin want us to start? (sector) */
 	sector_t ov_start_sector;
@@ -1077,8 +1081,12 @@ struct drbd_conf {
 	u64 ed_uuid; /* UUID of the exposed data */
 	struct mutex state_mutex;
 	char congestion_reason;  /* Why we where congested... */
-	atomic_t rs_sect_in; /* counter to measure the incoming resync data rate */
-	int c_sync_rate; /* current resync rate after delay_probe magic */
+	atomic_t rs_sect_in; /* for incoming resync data rate, SyncTarget */
+	atomic_t rs_sect_ev; /* for submitted resync data rate, both */
+	int rs_last_sect_ev; /* counter to compare with */
+	int rs_last_events;  /* counter of read or write "events" (unit sectors)
+			      * on the lower level device when we last looked. */
+	int c_sync_rate; /* current resync rate after syncer throttle magic */
 	struct fifo_buffer rs_plan_s; /* correction values of resync planer */
 	int rs_in_flight; /* resync sectors in flight (to proxy, in proxy and from proxy) */
 	int rs_planed;    /* resync sectors already planed */
@@ -2072,10 +2080,11 @@ static inline int get_net_conf(struct drbd_conf *mdev)
 
 static inline void put_ldev(struct drbd_conf *mdev)
 {
+	int i = atomic_dec_return(&mdev->local_cnt);
 	__release(local);
-	if (atomic_dec_and_test(&mdev->local_cnt))
+	D_ASSERT(i >= 0);
+	if (i == 0)
 		wake_up(&mdev->misc_wait);
-	D_ASSERT(atomic_read(&mdev->local_cnt) >= 0);
 }
 
 #ifndef __CHECKER__