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Commit 08a1ddab authored by Lars Ellenberg's avatar Lars Ellenberg Committed by Jens Axboe
Browse files

drbd: consolidate as many updates as possible into one AL transaction 



Depending on current IO depth, try to consolidate as many updates
as possible into one activity log transaction.

Signed-off-by: default avatarPhilipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: default avatarLars Ellenberg <lars.ellenberg@linbit.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent cbe5e610

drivers/block/drbd/drbd_actlog.c

+49 −0
Original line number Diff line number Diff line
@@ -359,6 +359,55 @@ void drbd_al_begin_io(struct drbd_conf *mdev, struct drbd_interval *i, bool dele 
		drbd_al_begin_io_commit(mdev, delegate);

}



int drbd_al_begin_io_nonblock(struct drbd_conf *mdev, struct drbd_interval *i)

{

	struct lru_cache *al = mdev->act_log;

	/* for bios crossing activity log extent boundaries,

	 * we may need to activate two extents in one go */

	unsigned first = i->sector >> (AL_EXTENT_SHIFT-9);

	unsigned last = i->size == 0 ? first : (i->sector + (i->size >> 9) - 1) >> (AL_EXTENT_SHIFT-9);

	unsigned nr_al_extents;

	unsigned available_update_slots;

	unsigned enr;



	D_ASSERT(first <= last);



	nr_al_extents = 1 + last - first; /* worst case: all touched extends are cold. */

	available_update_slots = min(al->nr_elements - al->used,

				al->max_pending_changes - al->pending_changes);



	/* We want all necessary updates for a given request within the same transaction

	 * We could first check how many updates are *actually* needed,

	 * and use that instead of the worst-case nr_al_extents */

	if (available_update_slots < nr_al_extents)

		return -EWOULDBLOCK;



	/* Is resync active in this area? */

	for (enr = first; enr <= last; enr++) {

		struct lc_element *tmp;

		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)) {

				if (!test_and_set_bit(BME_PRIORITY, &bm_ext->flags));

					return -EBUSY;

				return -EWOULDBLOCK;

			}

		}

	}



	/* Checkout the refcounts.

	 * Given that we checked for available elements and update slots above,

	 * this has to be successful. */

	for (enr = first; enr <= last; enr++) {

		struct lc_element *al_ext;

		al_ext = lc_get_cumulative(mdev->act_log, enr);

		if (!al_ext)

			dev_info(DEV, "LOGIC BUG for enr=%u\n", enr);

	}

	return 0;

}



void drbd_al_complete_io(struct drbd_conf *mdev, struct drbd_interval *i)

{

	/* for bios crossing activity log extent boundaries,

drivers/block/drbd/drbd_int.h

+2 −0
Original line number Diff line number Diff line
@@ -1611,6 +1611,8 @@ extern const char *drbd_conn_str(enum drbd_conns s); 
extern const char *drbd_role_str(enum drbd_role s);



/* drbd_actlog.c */

extern int drbd_al_begin_io_nonblock(struct drbd_conf *mdev, struct drbd_interval *i);

extern void drbd_al_begin_io_commit(struct drbd_conf *mdev, bool delegate);

extern bool drbd_al_begin_io_fastpath(struct drbd_conf *mdev, struct drbd_interval *i);

extern void drbd_al_begin_io(struct drbd_conf *mdev, struct drbd_interval *i, bool delegate);

extern void drbd_al_complete_io(struct drbd_conf *mdev, struct drbd_interval *i);

drivers/block/drbd/drbd_req.c

+56 −14
Original line number Diff line number Diff line
@@ -1164,32 +1164,74 @@ void __drbd_make_request(struct drbd_conf *mdev, struct bio *bio, unsigned long 
	drbd_send_and_submit(mdev, req);

}



void __drbd_make_request_from_worker(struct drbd_conf *mdev, struct drbd_request *req)

static void submit_fast_path(struct drbd_conf *mdev, struct list_head *incoming)

{

	const int rw = bio_rw(req->master_bio);

	struct drbd_request *req, *tmp;

	list_for_each_entry_safe(req, tmp, incoming, tl_requests) {

		const int rw = bio_data_dir(req->master_bio);



	if (rw == WRITE && req->private_bio && req->i.size

		if (rw == WRITE /* rw != WRITE should not even end up here! */

		&& req->private_bio && req->i.size

		&& !test_bit(AL_SUSPENDED, &mdev->flags)) {

		drbd_al_begin_io(mdev, &req->i, false);

			if (!drbd_al_begin_io_fastpath(mdev, &req->i))

				continue;



			req->rq_state |= RQ_IN_ACT_LOG;

		}



		list_del_init(&req->tl_requests);

		drbd_send_and_submit(mdev, req);

	}

}



static bool prepare_al_transaction_nonblock(struct drbd_conf *mdev,

					    struct list_head *incoming,

					    struct list_head *pending)

{

	struct drbd_request *req, *tmp;

	int wake = 0;

	int err;



	spin_lock_irq(&mdev->al_lock);

	list_for_each_entry_safe(req, tmp, incoming, tl_requests) {

		err = drbd_al_begin_io_nonblock(mdev, &req->i);

		if (err == -EBUSY)

			wake = 1;

		if (err)

			continue;

		req->rq_state |= RQ_IN_ACT_LOG;

		list_move_tail(&req->tl_requests, pending);

	}

	spin_unlock_irq(&mdev->al_lock);

	if (wake)

		wake_up(&mdev->al_wait);



	return !list_empty(pending);

}



void do_submit(struct work_struct *ws)

{

	struct drbd_conf *mdev = container_of(ws, struct drbd_conf, submit.worker);

	LIST_HEAD(writes);

	LIST_HEAD(incoming);

	LIST_HEAD(pending);

	struct drbd_request *req, *tmp;



	for (;;) {

		spin_lock(&mdev->submit.lock);

	list_splice_init(&mdev->submit.writes, &writes);

		list_splice_tail_init(&mdev->submit.writes, &incoming);

		spin_unlock(&mdev->submit.lock);



	list_for_each_entry_safe(req, tmp, &writes, tl_requests) {

		submit_fast_path(mdev, &incoming);

		if (list_empty(&incoming))

			break;



		wait_event(mdev->al_wait, prepare_al_transaction_nonblock(mdev, &incoming, &pending));

		drbd_al_begin_io_commit(mdev, false);



		list_for_each_entry_safe(req, tmp, &pending, tl_requests) {

			list_del_init(&req->tl_requests);

		__drbd_make_request_from_worker(mdev, req);

			drbd_send_and_submit(mdev, req);

		}

	}

}