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drbd: Implemented priority inheritance for resync requests

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We only issue resync requests if there is no significant application IO
going on. = Application IO has higher priority than resnyc IO.

If application IO can not be started because the resync process locked
an resync_lru entry, start the IO operations necessary to release the
lock ASAP.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
This commit is contained in:
Philipp Reisner 2010-11-07 15:56:29 +01:00
parent 59817f4fab
commit e3555d8545
4 changed files with 27 additions and 20 deletions
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4
drivers/block/drbd/drbd_actlog.c
View File

@ -182,6 +182,7 @@ static struct lc_element *_al_get(struct drbd_conf *mdev, unsigned int enr)
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);
spin_unlock_irq(&mdev->al_lock);
return NULL;
}
@ -1297,8 +1298,7 @@ void drbd_rs_complete_io(struct drbd_conf *mdev, sector_t sector)
}
if (lc_put(mdev->resync, &bm_ext->lce) == 0) {
clear_bit(BME_LOCKED, &bm_ext->flags);
clear_bit(BME_NO_WRITES, &bm_ext->flags);
bm_ext->flags = 0; /* clear BME_LOCKED, BME_NO_WRITES and BME_PRIORITY */
mdev->resync_locked--;
wake_up(&mdev->al_wait);
}

3
drivers/block/drbd/drbd_int.h
View File

@ -1326,6 +1326,7 @@ struct bm_extent {
#define BME_NO_WRITES 0 /* bm_extent.flags: no more requests on this one! */
#define BME_LOCKED 1 /* bm_extent.flags: syncer active on this one. */
#define BME_PRIORITY 2 /* finish resync IO on this extent ASAP! App IO waiting! */
/* drbd_bitmap.c */
/*
@ -1552,7 +1553,7 @@ extern int w_start_resync(struct drbd_conf *, struct drbd_work *, int);
extern void resync_timer_fn(unsigned long data);
/* drbd_receiver.c */
extern int drbd_rs_should_slow_down(struct drbd_conf *mdev);
extern int drbd_rs_should_slow_down(struct drbd_conf *mdev, sector_t sector);
extern int drbd_submit_ee(struct drbd_conf *mdev, struct drbd_epoch_entry *e,
const unsigned rw, const int fault_type);
extern int drbd_release_ee(struct drbd_conf *mdev, struct list_head *list);

22
drivers/block/drbd/drbd_receiver.c
View File

@ -1862,10 +1862,11 @@ out_interrupted:
* The current sync rate used here uses only the most recent two step marks,
* to have a short time average so we can react faster.
*/
int drbd_rs_should_slow_down(struct drbd_conf *mdev)
int drbd_rs_should_slow_down(struct drbd_conf *mdev, sector_t sector)
{
struct gendisk *disk = mdev->ldev->backing_bdev->bd_contains->bd_disk;
unsigned long db, dt, dbdt;
struct lc_element *tmp;
int curr_events;
int throttle = 0;
@ -1873,9 +1874,22 @@ int drbd_rs_should_slow_down(struct drbd_conf *mdev)
if (mdev->sync_conf.c_min_rate == 0)
return 0;
spin_lock_irq(&mdev->al_lock);
tmp = lc_find(mdev->resync, BM_SECT_TO_EXT(sector));
if (tmp) {
struct bm_extent *bm_ext = lc_entry(tmp, struct bm_extent, lce);
if (test_bit(BME_PRIORITY, &bm_ext->flags)) {
spin_unlock_irq(&mdev->al_lock);
return 0;
}
/* Do not slow down if app IO is already waiting for this extent */
}
spin_unlock_irq(&mdev->al_lock);
curr_events = (int)part_stat_read(&disk->part0, sectors[0]) +
(int)part_stat_read(&disk->part0, sectors[1]) -
atomic_read(&mdev->rs_sect_ev);
if (!mdev->rs_last_events || curr_events - mdev->rs_last_events > 64) {
unsigned long rs_left;
int i;
@ -2060,9 +2074,9 @@ static int receive_DataRequest(struct drbd_conf *mdev, enum drbd_packets cmd, un
* we would also throttle its application reads.
* In that case, throttling is done on the SyncTarget only.
*/
if (mdev->state.peer != R_PRIMARY && drbd_rs_should_slow_down(mdev))
msleep(100);
if (drbd_rs_begin_io(mdev, e->sector))
if (mdev->state.peer != R_PRIMARY && drbd_rs_should_slow_down(mdev, sector))
schedule_timeout_uninterruptible(HZ/10);
if (drbd_rs_begin_io(mdev, sector))
goto out_free_e;
submit_for_resync:

18
drivers/block/drbd/drbd_worker.c
View File

@ -355,7 +355,7 @@ static int read_for_csum(struct drbd_conf *mdev, sector_t sector, int size)
if (!get_ldev(mdev))
return -EIO;
if (drbd_rs_should_slow_down(mdev))
if (drbd_rs_should_slow_down(mdev, sector))
goto defer;
/* GFP_TRY, because if there is no memory available right now, this may
@ -503,16 +503,6 @@ int drbd_rs_number_requests(struct drbd_conf *mdev)
number = SLEEP_TIME * mdev->c_sync_rate / ((BM_BLOCK_SIZE / 1024) * HZ);
}
/* Throttle resync on lower level disk activity, which may also be
* caused by application IO on Primary/SyncTarget.
* Keep this after the call to drbd_rs_controller, as that assumes
* to be called as precisely as possible every SLEEP_TIME,
* and would be confused otherwise. */
if (number && drbd_rs_should_slow_down(mdev)) {
mdev->c_sync_rate = 1;
number = 0;
}
/* ignore the amount of pending requests, the resync controller should
* throttle down to incoming reply rate soon enough anyways. */
return number;
@ -594,7 +584,8 @@ next_sector:
sector = BM_BIT_TO_SECT(bit);
if (drbd_try_rs_begin_io(mdev, sector)) {
if (drbd_rs_should_slow_down(mdev, sector) ||
drbd_try_rs_begin_io(mdev, sector)) {
mdev->bm_resync_fo = bit;
goto requeue;
}
@ -719,7 +710,8 @@ static int w_make_ov_request(struct drbd_conf *mdev, struct drbd_work *w, int ca
size = BM_BLOCK_SIZE;
if (drbd_try_rs_begin_io(mdev, sector)) {
if (drbd_rs_should_slow_down(mdev, sector) ||
drbd_try_rs_begin_io(mdev, sector)) {
mdev->ov_position = sector;
goto requeue;
}