diff options
| author | Philipp Reisner <philipp.reisner@linbit.com> | 2010-11-09 12:59:41 (GMT) |
|---|---|---|
| committer | Philipp Reisner <philipp.reisner@linbit.com> | 2011-03-10 10:34:56 (GMT) |
| commit | f91ab6282df251d28aa4ad1bd85194ebe0a0115b (patch) | |
| tree | 1c696b201c9eaea365e8d80bb3956827a0a880e7 | |
| parent | 9d77a5fee9d2a1ea4cd9a841d27b107df5913b33 (diff) | |
| download | linux-f91ab6282df251d28aa4ad1bd85194ebe0a0115b.tar.xz | |
drbd: Implemented side-stepping in drbd_res_begin_io()
Before:
drbd_rs_begin_io() locked app-IO out of an RS extent, and
waited then until all previous app-IO in that area finished.
(But not only until the disk-IO was finished but until the
barrier/epoch ack came in for that == round trip time latency ++)
After:
As soon as a new app-IO waits wants to start new IO on that
RS extent, drbd_rs_begin_io() steps aside (clearing the
BME_NO_WRITES flag again). It retries after 100ms.
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
| -rw-r--r-- | drivers/block/drbd/drbd_actlog.c | 24 |
1 files changed, 19 insertions, 5 deletions
diff --git a/drivers/block/drbd/drbd_actlog.c b/drivers/block/drbd/drbd_actlog.c index 28f85d9..5570d9b 100644 --- a/drivers/block/drbd/drbd_actlog.c +++ b/drivers/block/drbd/drbd_actlog.c @@ -176,14 +176,17 @@ static struct lc_element *_al_get(struct drbd_conf *mdev, unsigned int enr) struct lc_element *al_ext; struct lc_element *tmp; unsigned long al_flags = 0; + int wake; spin_lock_irq(&mdev->al_lock); tmp = lc_find(mdev->resync, enr/AL_EXT_PER_BM_SECT); if (unlikely(tmp != NULL)) { struct bm_extent *bm_ext = lc_entry(tmp, struct bm_extent, lce); if (test_bit(BME_NO_WRITES, &bm_ext->flags)) { - set_bit(BME_PRIORITY, &bm_ext->flags); + wake = !test_and_set_bit(BME_PRIORITY, &bm_ext->flags); spin_unlock_irq(&mdev->al_lock); + if (wake) + wake_up(&mdev->al_wait); return NULL; } } @@ -1135,7 +1138,10 @@ int drbd_rs_begin_io(struct drbd_conf *mdev, sector_t sector) unsigned int enr = BM_SECT_TO_EXT(sector); struct bm_extent *bm_ext; int i, sig; + int sa = 200; /* Step aside 200 times, then grab the extent and let app-IO wait. + 200 times -> 20 seconds. */ +retry: sig = wait_event_interruptible(mdev->al_wait, (bm_ext = _bme_get(mdev, enr))); if (sig) @@ -1146,16 +1152,24 @@ int drbd_rs_begin_io(struct drbd_conf *mdev, sector_t sector) for (i = 0; i < AL_EXT_PER_BM_SECT; i++) { sig = wait_event_interruptible(mdev->al_wait, - !_is_in_al(mdev, enr * AL_EXT_PER_BM_SECT + i)); - if (sig) { + !_is_in_al(mdev, enr * AL_EXT_PER_BM_SECT + i) || + (test_bit(BME_PRIORITY, &bm_ext->flags) && sa)); + + if (sig || (test_bit(BME_PRIORITY, &bm_ext->flags) && sa)) { spin_lock_irq(&mdev->al_lock); if (lc_put(mdev->resync, &bm_ext->lce) == 0) { - clear_bit(BME_NO_WRITES, &bm_ext->flags); + bm_ext->flags = 0; /* clears BME_NO_WRITES and eventually BME_PRIORITY */ mdev->resync_locked--; wake_up(&mdev->al_wait); } spin_unlock_irq(&mdev->al_lock); - return -EINTR; + if (sig) + return -EINTR; + if (schedule_timeout_interruptible(HZ/10)) + return -EINTR; + if (--sa == 0) + dev_warn(DEV,"drbd_rs_begin_io() no longer stepping aside.\n"); + goto retry; } } set_bit(BME_LOCKED, &bm_ext->flags); |