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authorLars Ellenberg <lars.ellenberg@linbit.com>2013-12-20 11:22:13 +0100
committerPhilipp Reisner <philipp.reisner@linbit.com>2014-07-10 18:35:13 +0200
commitad3fee790088d36ad862e31535b5b99c25adeef4 (patch)
tree916a5c23cf57283f9f6a5abf8418364c52249ad9 /drivers/block/drbd/drbd_actlog.c
parentdrbd: add caching oldest request pointers for replication stages (diff)
downloadlinux-ad3fee790088d36ad862e31535b5b99c25adeef4.tar.xz
linux-ad3fee790088d36ad862e31535b5b99c25adeef4.zip
drbd: improve throttling decisions of background resynchronisation
Background resynchronisation does some "side-stepping", or throttles itself, if it detects application IO activity, and the current resync rate estimate is above the configured "cmin-rate". What was not detected: if there is no application IO, because it blocks on activity log transactions. Introduce a new atomic_t ap_actlog_cnt, tracking such blocked requests, and count non-zero as application IO activity. This counter is exposed at proc_details level 2 and above. Also make sure to release the currently locked resync extent if we side-step due to such voluntary throttling. Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com> Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
Diffstat (limited to 'drivers/block/drbd/drbd_actlog.c')
-rw-r--r--drivers/block/drbd/drbd_actlog.c29
1 files changed, 26 insertions, 3 deletions
diff --git a/drivers/block/drbd/drbd_actlog.c b/drivers/block/drbd/drbd_actlog.c
index d7e80663187c..6ce5c76d642b 100644
--- a/drivers/block/drbd/drbd_actlog.c
+++ b/drivers/block/drbd/drbd_actlog.c
@@ -991,6 +991,15 @@ int drbd_try_rs_begin_io(struct drbd_device *device, sector_t sector)
struct lc_element *e;
struct bm_extent *bm_ext;
int i;
+ bool throttle = drbd_rs_should_slow_down(device, sector, true);
+
+ /* If we need to throttle, a half-locked (only marked BME_NO_WRITES,
+ * not yet BME_LOCKED) extent needs to be kicked out explicitly if we
+ * need to throttle. There is at most one such half-locked extent,
+ * which is remembered in resync_wenr. */
+
+ if (throttle && device->resync_wenr != enr)
+ return -EAGAIN;
spin_lock_irq(&device->al_lock);
if (device->resync_wenr != LC_FREE && device->resync_wenr != enr) {
@@ -1014,8 +1023,10 @@ int drbd_try_rs_begin_io(struct drbd_device *device, sector_t sector)
D_ASSERT(device, test_bit(BME_NO_WRITES, &bm_ext->flags));
clear_bit(BME_NO_WRITES, &bm_ext->flags);
device->resync_wenr = LC_FREE;
- if (lc_put(device->resync, &bm_ext->lce) == 0)
+ if (lc_put(device->resync, &bm_ext->lce) == 0) {
+ bm_ext->flags = 0;
device->resync_locked--;
+ }
wake_up(&device->al_wait);
} else {
drbd_alert(device, "LOGIC BUG\n");
@@ -1077,8 +1088,20 @@ proceed:
return 0;
try_again:
- if (bm_ext)
- device->resync_wenr = enr;
+ if (bm_ext) {
+ if (throttle) {
+ D_ASSERT(device, !test_bit(BME_LOCKED, &bm_ext->flags));
+ D_ASSERT(device, test_bit(BME_NO_WRITES, &bm_ext->flags));
+ clear_bit(BME_NO_WRITES, &bm_ext->flags);
+ device->resync_wenr = LC_FREE;
+ if (lc_put(device->resync, &bm_ext->lce) == 0) {
+ bm_ext->flags = 0;
+ device->resync_locked--;
+ }
+ wake_up(&device->al_wait);
+ } else
+ device->resync_wenr = enr;
+ }
spin_unlock_irq(&device->al_lock);
return -EAGAIN;
}