drbd: The new, smarter resync speed controller
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
diff --git a/drivers/block/drbd/drbd_worker.c b/drivers/block/drbd/drbd_worker.c
index d94720f..fd3e1e9 100644
--- a/drivers/block/drbd/drbd_worker.c
+++ b/drivers/block/drbd/drbd_worker.c
@@ -422,6 +422,89 @@
drbd_queue_work(&mdev->data.work, &mdev->resync_work);
}
+static void fifo_set(struct fifo_buffer *fb, int value)
+{
+ int i;
+
+ for (i = 0; i < fb->size; i++)
+ fb->values[i] += value;
+}
+
+static int fifo_push(struct fifo_buffer *fb, int value)
+{
+ int ov;
+
+ ov = fb->values[fb->head_index];
+ fb->values[fb->head_index++] = value;
+
+ if (fb->head_index >= fb->size)
+ fb->head_index = 0;
+
+ return ov;
+}
+
+static void fifo_add_val(struct fifo_buffer *fb, int value)
+{
+ int i;
+
+ for (i = 0; i < fb->size; i++)
+ fb->values[i] += value;
+}
+
+int drbd_rs_controller(struct drbd_conf *mdev)
+{
+ unsigned int sect_in; /* Number of sectors that came in since the last turn */
+ unsigned int want; /* The number of sectors we want in the proxy */
+ int req_sect; /* Number of sectors to request in this turn */
+ int correction; /* Number of sectors more we need in the proxy*/
+ int cps; /* correction per invocation of drbd_rs_controller() */
+ int steps; /* Number of time steps to plan ahead */
+ int curr_corr;
+ int max_sect;
+
+ sect_in = atomic_xchg(&mdev->rs_sect_in, 0); /* Number of sectors that came in */
+ mdev->rs_in_flight -= sect_in;
+
+ spin_lock(&mdev->peer_seq_lock); /* get an atomic view on mdev->rs_plan_s */
+
+ steps = mdev->rs_plan_s.size; /* (mdev->sync_conf.c_plan_ahead * 10 * SLEEP_TIME) / HZ; */
+
+ if (mdev->rs_in_flight + sect_in == 0) { /* At start of resync */
+ want = ((mdev->sync_conf.rate * 2 * SLEEP_TIME) / HZ) * steps;
+ } else { /* normal path */
+ want = mdev->sync_conf.c_fill_target ? mdev->sync_conf.c_fill_target :
+ sect_in * mdev->sync_conf.c_delay_target * HZ / (SLEEP_TIME * 10);
+ }
+
+ correction = want - mdev->rs_in_flight - mdev->rs_planed;
+
+ /* Plan ahead */
+ cps = correction / steps;
+ fifo_add_val(&mdev->rs_plan_s, cps);
+ mdev->rs_planed += cps * steps;
+
+ /* What we do in this step */
+ curr_corr = fifo_push(&mdev->rs_plan_s, 0);
+ spin_unlock(&mdev->peer_seq_lock);
+ mdev->rs_planed -= curr_corr;
+
+ req_sect = sect_in + curr_corr;
+ if (req_sect < 0)
+ req_sect = 0;
+
+ max_sect = (mdev->sync_conf.c_max_rate * 2 * SLEEP_TIME) / HZ;
+ if (req_sect > max_sect)
+ req_sect = max_sect;
+
+ /*
+ dev_warn(DEV, "si=%u if=%d wa=%u co=%d st=%d cps=%d pl=%d cc=%d rs=%d\n",
+ sect_in, mdev->rs_in_flight, want, correction,
+ steps, cps, mdev->rs_planed, curr_corr, req_sect);
+ */
+
+ return req_sect;
+}
+
int w_make_resync_request(struct drbd_conf *mdev,
struct drbd_work *w, int cancel)
{
@@ -459,7 +542,13 @@
max_segment_size = mdev->agreed_pro_version < 94 ?
queue_max_segment_size(mdev->rq_queue) : DRBD_MAX_SEGMENT_SIZE;
- number = SLEEP_TIME * mdev->sync_conf.rate / ((BM_BLOCK_SIZE / 1024) * HZ);
+ if (mdev->rs_plan_s.size) { /* mdev->sync_conf.c_plan_ahead */
+ number = drbd_rs_controller(mdev) >> (BM_BLOCK_SHIFT - 9);
+ mdev->c_sync_rate = number * HZ * (BM_BLOCK_SIZE / 1024) / SLEEP_TIME;
+ } else {
+ mdev->c_sync_rate = mdev->sync_conf.rate;
+ number = SLEEP_TIME * mdev->c_sync_rate / ((BM_BLOCK_SIZE / 1024) * HZ);
+ }
pe = atomic_read(&mdev->rs_pending_cnt);
mutex_lock(&mdev->data.mutex);
@@ -593,6 +682,7 @@
}
requeue:
+ mdev->rs_in_flight += (i << (BM_BLOCK_SHIFT - 9));
mod_timer(&mdev->resync_timer, jiffies + SLEEP_TIME);
put_ldev(mdev);
return 1;
@@ -1419,6 +1509,12 @@
drbd_resync_finished(mdev);
}
+ atomic_set(&mdev->rs_sect_in, 0);
+ mdev->rs_in_flight = 0;
+ mdev->rs_planed = 0;
+ spin_lock(&mdev->peer_seq_lock);
+ fifo_set(&mdev->rs_plan_s, 0);
+ spin_unlock(&mdev->peer_seq_lock);
/* ns.conn may already be != mdev->state.conn,
* we may have been paused in between, or become paused until
* the timer triggers.
