diff options
author | Lars Ellenberg <lars.ellenberg@linbit.com> | 2013-12-20 14:22:13 +0400 |
---|---|---|
committer | Philipp Reisner <philipp.reisner@linbit.com> | 2014-07-10 20:35:13 +0400 |
commit | ad3fee790088d36ad862e31535b5b99c25adeef4 (patch) | |
tree | 916a5c23cf57283f9f6a5abf8418364c52249ad9 /drivers/block/drbd/drbd_actlog.c | |
parent | 7753a4c17f9e305ed19d8851e1a3154c8c9abaaf (diff) | |
download | linux-ad3fee790088d36ad862e31535b5b99c25adeef4.tar.xz |
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.c | 29 |
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; } |