Commit 0f0601f4 authored by Lars Ellenberg's avatar Lars Ellenberg Committed by Philipp Reisner

drbd: new configuration parameter c-min-rate

We now track the data rate of locally submitted resync related requests,
and can thus detect non-resync activity on the lower level device.

If the current sync rate is above c-min-rate, and the lower level device
appears to be busy, we throttle the resyncer.
Signed-off-by: default avatarPhilipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: default avatarLars Ellenberg <lars.ellenberg@linbit.com>
parent 80a40e43
......@@ -1513,6 +1513,7 @@ extern int w_restart_disk_io(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_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);
......
......@@ -1098,6 +1098,8 @@ int __drbd_set_state(struct drbd_conf *mdev,
mdev->ov_left = mdev->rs_total
- BM_SECT_TO_BIT(mdev->ov_position);
mdev->rs_start = now;
mdev->rs_last_events = 0;
mdev->rs_last_sect_ev = 0;
mdev->ov_last_oos_size = 0;
mdev->ov_last_oos_start = 0;
......@@ -2706,7 +2708,8 @@ static void drbd_set_defaults(struct drbd_conf *mdev)
/* .c_plan_ahead = */ DRBD_C_PLAN_AHEAD_DEF,
/* .c_delay_target = */ DRBD_C_DELAY_TARGET_DEF,
/* .c_fill_target = */ DRBD_C_FILL_TARGET_DEF,
/* .c_max_rate = */ DRBD_C_MAX_RATE_DEF
/* .c_max_rate = */ DRBD_C_MAX_RATE_DEF,
/* .c_min_rate = */ DRBD_C_MIN_RATE_DEF
};
/* Have to use that way, because the layout differs between
......@@ -2742,6 +2745,7 @@ void drbd_init_set_defaults(struct drbd_conf *mdev)
atomic_set(&mdev->packet_seq, 0);
atomic_set(&mdev->pp_in_use, 0);
atomic_set(&mdev->rs_sect_in, 0);
atomic_set(&mdev->rs_sect_ev, 0);
mutex_init(&mdev->md_io_mutex);
mutex_init(&mdev->data.mutex);
......@@ -2819,6 +2823,7 @@ void drbd_mdev_cleanup(struct drbd_conf *mdev)
mdev->rs_total =
mdev->rs_failed = 0;
mdev->rs_last_events = 0;
mdev->rs_last_sect_ev = 0;
for (i = 0; i < DRBD_SYNC_MARKS; i++) {
mdev->rs_mark_left[i] = 0;
mdev->rs_mark_time[i] = 0;
......
......@@ -1604,7 +1604,8 @@ static int drbd_nl_syncer_conf(struct drbd_conf *mdev, struct drbd_nl_cfg_req *n
sc.c_plan_ahead = DRBD_C_PLAN_AHEAD_DEF;
sc.c_delay_target = DRBD_C_DELAY_TARGET_DEF;
sc.c_fill_target = DRBD_C_FILL_TARGET_DEF;
sc.c_max_rate = DRBD_C_MAX_RATE_DEF;
sc.c_max_rate = DRBD_C_MAX_RATE_DEF;
sc.c_min_rate = DRBD_C_MIN_RATE_DEF;
} else
memcpy(&sc, &mdev->sync_conf, sizeof(struct syncer_conf));
......
......@@ -1561,6 +1561,7 @@ static int recv_resync_read(struct drbd_conf *mdev, sector_t sector, int data_si
list_add(&e->w.list, &mdev->sync_ee);
spin_unlock_irq(&mdev->req_lock);
atomic_add(data_size >> 9, &mdev->rs_sect_ev);
if (drbd_submit_ee(mdev, e, WRITE, DRBD_FAULT_RS_WR) == 0)
return TRUE;
......@@ -2017,17 +2018,66 @@ out_interrupted:
return FALSE;
}
/* We may throttle resync, if the lower device seems to be busy,
* and current sync rate is above c_min_rate.
*
* To decide whether or not the lower device is busy, we use a scheme similar
* to MD RAID is_mddev_idle(): if the partition stats reveal "significant"
* (more than 64 sectors) of activity we cannot account for with our own resync
* activity, it obviously is "busy".
*
* 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)
{
struct gendisk *disk = mdev->ldev->backing_bdev->bd_contains->bd_disk;
unsigned long db, dt, dbdt;
int curr_events;
int throttle = 0;
/* feature disabled? */
if (mdev->sync_conf.c_min_rate == 0)
return 0;
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;
mdev->rs_last_events = curr_events;
/* sync speed average over the last 2*DRBD_SYNC_MARK_STEP,
* approx. */
i = (mdev->rs_last_mark + DRBD_SYNC_MARKS-2) % DRBD_SYNC_MARKS;
rs_left = drbd_bm_total_weight(mdev) - mdev->rs_failed;
dt = ((long)jiffies - (long)mdev->rs_mark_time[i]) / HZ;
if (!dt)
dt++;
db = mdev->rs_mark_left[i] - rs_left;
dbdt = Bit2KB(db/dt);
if (dbdt > mdev->sync_conf.c_min_rate)
throttle = 1;
}
return throttle;
}
static int receive_DataRequest(struct drbd_conf *mdev, struct p_header *h)
{
sector_t sector;
const sector_t capacity = drbd_get_capacity(mdev->this_bdev);
struct drbd_epoch_entry *e;
struct digest_info *di = NULL;
struct p_block_req *p = (struct p_block_req *)h;
const int brps = sizeof(*p)-sizeof(*h);
int size, digest_size;
unsigned int fault_type;
struct p_block_req *p =
(struct p_block_req *)h;
const int brps = sizeof(*p)-sizeof(*h);
if (drbd_recv(mdev, h->payload, brps) != brps)
return FALSE;
......@@ -2099,8 +2149,9 @@ static int receive_DataRequest(struct drbd_conf *mdev, struct p_header *h)
} else if (h->command == P_OV_REPLY) {
e->w.cb = w_e_end_ov_reply;
dec_rs_pending(mdev);
/* drbd_rs_begin_io done when we sent this request */
goto submit;
/* drbd_rs_begin_io done when we sent this request,
* but accounting still needs to be done. */
goto submit_for_resync;
}
break;
......@@ -2128,9 +2179,36 @@ static int receive_DataRequest(struct drbd_conf *mdev, struct p_header *h)
goto out_free_e;
}
/* Throttle, drbd_rs_begin_io and submit should become asynchronous
* wrt the receiver, but it is not as straightforward as it may seem.
* Various places in the resync start and stop logic assume resync
* requests are processed in order, requeuing this on the worker thread
* introduces a bunch of new code for synchronization between threads.
*
* Unlimited throttling before drbd_rs_begin_io may stall the resync
* "forever", throttling after drbd_rs_begin_io will lock that extent
* for application writes for the same time. For now, just throttle
* here, where the rest of the code expects the receiver to sleep for
* a while, anyways.
*/
/* Throttle before drbd_rs_begin_io, as that locks out application IO;
* this defers syncer requests for some time, before letting at least
* on request through. The resync controller on the receiving side
* will adapt to the incoming rate accordingly.
*
* We cannot throttle here if remote is Primary/SyncTarget:
* 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))
goto out_free_e;
submit_for_resync:
atomic_add(size >> 9, &mdev->rs_sect_ev);
submit:
inc_unacked(mdev);
spin_lock_irq(&mdev->req_lock);
......
......@@ -215,10 +215,8 @@ void drbd_endio_sec(struct bio *bio, int error)
*/
void drbd_endio_pri(struct bio *bio, int error)
{
unsigned long flags;
struct drbd_request *req = bio->bi_private;
struct drbd_conf *mdev = req->mdev;
struct bio_and_error m;
enum drbd_req_event what;
int uptodate = bio_flagged(bio, BIO_UPTODATE);
......@@ -244,12 +242,7 @@ void drbd_endio_pri(struct bio *bio, int error)
bio_put(req->private_bio);
req->private_bio = ERR_PTR(error);
spin_lock_irqsave(&mdev->req_lock, flags);
__req_mod(req, what, &m);
spin_unlock_irqrestore(&mdev->req_lock, flags);
if (m.bio)
complete_master_bio(mdev, &m);
req_mod(req, what);
}
int w_read_retry_remote(struct drbd_conf *mdev, struct drbd_work *w, int cancel)
......@@ -376,6 +369,9 @@ 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))
goto defer;
/* GFP_TRY, because if there is no memory available right now, this may
* be rescheduled for later. It is "only" background resync, after all. */
e = drbd_alloc_ee(mdev, DRBD_MAGIC+0xbeef, sector, size, GFP_TRY);
......@@ -387,6 +383,7 @@ static int read_for_csum(struct drbd_conf *mdev, sector_t sector, int size)
list_add(&e->w.list, &mdev->read_ee);
spin_unlock_irq(&mdev->req_lock);
atomic_add(size >> 9, &mdev->rs_sect_ev);
if (drbd_submit_ee(mdev, e, READ, DRBD_FAULT_RS_RD) == 0)
return 0;
......@@ -512,8 +509,9 @@ int w_make_resync_request(struct drbd_conf *mdev,
sector_t sector;
const sector_t capacity = drbd_get_capacity(mdev->this_bdev);
int max_segment_size;
int number, i, rollback_i, size, pe, mx;
int number, rollback_i, size, pe, mx;
int align, queued, sndbuf;
int i = 0;
if (unlikely(cancel))
return 1;
......@@ -549,7 +547,14 @@ int w_make_resync_request(struct drbd_conf *mdev,
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);
/* 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 (drbd_rs_should_slow_down(mdev))
goto requeue;
mutex_lock(&mdev->data.mutex);
if (mdev->data.socket)
......@@ -563,6 +568,7 @@ int w_make_resync_request(struct drbd_conf *mdev,
mx = number;
/* Limit the number of pending RS requests to no more than the peer's receive buffer */
pe = atomic_read(&mdev->rs_pending_cnt);
if ((pe + number) > mx) {
number = mx - pe;
}
......@@ -1492,6 +1498,8 @@ void drbd_start_resync(struct drbd_conf *mdev, enum drbd_conns side)
mdev->rs_failed = 0;
mdev->rs_paused = 0;
mdev->rs_same_csum = 0;
mdev->rs_last_events = 0;
mdev->rs_last_sect_ev = 0;
mdev->rs_total = tw;
mdev->rs_start = now;
for (i = 0; i < DRBD_SYNC_MARKS; i++) {
......@@ -1516,6 +1524,7 @@ void drbd_start_resync(struct drbd_conf *mdev, enum drbd_conns side)
}
atomic_set(&mdev->rs_sect_in, 0);
atomic_set(&mdev->rs_sect_ev, 0);
mdev->rs_in_flight = 0;
mdev->rs_planed = 0;
spin_lock(&mdev->peer_seq_lock);
......
......@@ -150,5 +150,9 @@
#define DRBD_C_MAX_RATE_MAX (4 << 20)
#define DRBD_C_MAX_RATE_DEF 102400
#define DRBD_C_MIN_RATE_MIN 0 /* kByte/sec */
#define DRBD_C_MIN_RATE_MAX (4 << 20)
#define DRBD_C_MIN_RATE_DEF 4096
#undef RANGE
#endif
......@@ -92,6 +92,7 @@ NL_PACKET(syncer_conf, 8,
NL_INTEGER( 77, T_MAY_IGNORE, c_delay_target)
NL_INTEGER( 78, T_MAY_IGNORE, c_fill_target)
NL_INTEGER( 79, T_MAY_IGNORE, c_max_rate)
NL_INTEGER( 80, T_MAY_IGNORE, c_min_rate)
)
NL_PACKET(invalidate, 9, )
......
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