From 380207d08e7c4d1b19c0323777278992b4fbf9d6 Mon Sep 17 00:00:00 2001 From: Philipp Reisner Date: Fri, 11 Nov 2011 12:31:20 +0100 Subject: [PATCH] drbd: Load balancing of read requests New config option for the disk secition "read-balancing", with the values: prefer-local, prefer-remote, round-robin, when-congested-remote. Signed-off-by: Philipp Reisner Signed-off-by: Lars Ellenberg --- drivers/block/drbd/drbd_int.h | 1 + drivers/block/drbd/drbd_receiver.c | 2 +- drivers/block/drbd/drbd_req.c | 57 +++++++++++++++++++++++++++++++++++++- include/linux/drbd.h | 8 ++++++ include/linux/drbd_genl.h | 1 + include/linux/drbd_limits.h | 1 + 6 files changed, 68 insertions(+), 2 deletions(-) diff --git a/drivers/block/drbd/drbd_int.h b/drivers/block/drbd/drbd_int.h index d397681..e2cccb4 100644 --- a/drivers/block/drbd/drbd_int.h +++ b/drivers/block/drbd/drbd_int.h @@ -698,6 +698,7 @@ enum { AHEAD_TO_SYNC_SOURCE, /* Ahead -> SyncSource queued */ B_RS_H_DONE, /* Before resync handler done (already executed) */ DISCARD_MY_DATA, /* discard_my_data flag per volume */ + READ_BALANCE_RR, }; struct drbd_bitmap; /* opaque for drbd_conf */ diff --git a/drivers/block/drbd/drbd_receiver.c b/drivers/block/drbd/drbd_receiver.c index e546dd3..733b8bd 100644 --- a/drivers/block/drbd/drbd_receiver.c +++ b/drivers/block/drbd/drbd_receiver.c @@ -4974,7 +4974,7 @@ static int got_NegDReply(struct drbd_tconn *tconn, struct packet_info *pi) update_peer_seq(mdev, be32_to_cpu(p->seq_num)); - dev_err(DEV, "Got NegDReply; Sector %llus, len %u; Fail original request.\n", + dev_err(DEV, "Got NegDReply; Sector %llus, len %u.\n", (unsigned long long)sector, be32_to_cpu(p->blksize)); return validate_req_change_req_state(mdev, p->block_id, sector, diff --git a/drivers/block/drbd/drbd_req.c b/drivers/block/drbd/drbd_req.c index ceb04a9..98251e2 100644 --- a/drivers/block/drbd/drbd_req.c +++ b/drivers/block/drbd/drbd_req.c @@ -563,6 +563,11 @@ int __req_mod(struct drbd_request *req, enum drbd_req_event what, if (req->rq_state & RQ_NET_SENT && req->rq_state & RQ_WRITE) atomic_sub(req->i.size >> 9, &mdev->ap_in_flight); + if (!(req->rq_state & RQ_WRITE) && + mdev->state.disk == D_UP_TO_DATE && + !IS_ERR_OR_NULL(req->private_bio)) + goto goto_read_retry_local; + /* if it is still queued, we may not complete it here. * it will be canceled soon. */ if (!(req->rq_state & RQ_NET_QUEUED)) @@ -625,10 +630,22 @@ int __req_mod(struct drbd_request *req, enum drbd_req_event what, req->rq_state &= ~(RQ_NET_OK|RQ_NET_PENDING); req->rq_state |= RQ_NET_DONE; + + if (!(req->rq_state & RQ_WRITE) && + mdev->state.disk == D_UP_TO_DATE && + !IS_ERR_OR_NULL(req->private_bio)) + goto goto_read_retry_local; + _req_may_be_done_not_susp(req, m); /* else: done by HANDED_OVER_TO_NETWORK */ break; + goto_read_retry_local: + req->rq_state |= RQ_LOCAL_PENDING; + req->private_bio->bi_bdev = mdev->ldev->backing_bdev; + generic_make_request(req->private_bio); + break; + case FAIL_FROZEN_DISK_IO: if (!(req->rq_state & RQ_LOCAL_COMPLETED)) break; @@ -689,6 +706,11 @@ int __req_mod(struct drbd_request *req, enum drbd_req_event what, dec_ap_pending(mdev); req->rq_state &= ~RQ_NET_PENDING; req->rq_state |= (RQ_NET_OK|RQ_NET_DONE); + if (!IS_ERR_OR_NULL(req->private_bio)) { + bio_put(req->private_bio); + req->private_bio = NULL; + put_ldev(mdev); + } _req_may_be_done_not_susp(req, m); break; }; @@ -723,6 +745,35 @@ static bool drbd_may_do_local_read(struct drbd_conf *mdev, sector_t sector, int return drbd_bm_count_bits(mdev, sbnr, ebnr) == 0; } +static bool remote_due_to_read_balancing(struct drbd_conf *mdev) +{ + enum drbd_read_balancing rbm; + struct backing_dev_info *bdi; + + if (mdev->state.pdsk < D_UP_TO_DATE) + return false; + + rcu_read_lock(); + rbm = rcu_dereference(mdev->ldev->disk_conf)->read_balancing; + rcu_read_unlock(); + + switch (rbm) { + case RB_CONGESTED_REMOTE: + bdi = &mdev->ldev->backing_bdev->bd_disk->queue->backing_dev_info; + return bdi_read_congested(bdi); + case RB_LEAST_PENDING: + return atomic_read(&mdev->local_cnt) > + atomic_read(&mdev->ap_pending_cnt) + atomic_read(&mdev->rs_pending_cnt); + case RB_ROUND_ROBIN: + return test_and_change_bit(READ_BALANCE_RR, &mdev->flags); + case RB_PREFER_REMOTE: + return true; + case RB_PREFER_LOCAL: + default: + return false; + } +} + /* * complete_conflicting_writes - wait for any conflicting write requests * @@ -790,6 +841,10 @@ int __drbd_make_request(struct drbd_conf *mdev, struct bio *bio, unsigned long s bio_put(req->private_bio); req->private_bio = NULL; put_ldev(mdev); + } else if (remote_due_to_read_balancing(mdev)) { + /* Keep the private bio in case we need it + for a local retry */ + local = 0; } } remote = !local && mdev->state.pdsk >= D_UP_TO_DATE; @@ -1017,7 +1072,7 @@ fail_free_complete: if (req->rq_state & RQ_IN_ACT_LOG) drbd_al_complete_io(mdev, &req->i); fail_and_free_req: - if (local) { + if (!IS_ERR_OR_NULL(req->private_bio)) { bio_put(req->private_bio); req->private_bio = NULL; put_ldev(mdev); diff --git a/include/linux/drbd.h b/include/linux/drbd.h index 1e9f754..157ba3d 100644 --- a/include/linux/drbd.h +++ b/include/linux/drbd.h @@ -102,6 +102,14 @@ enum drbd_on_congestion { OC_DISCONNECT, }; +enum drbd_read_balancing { + RB_PREFER_LOCAL, + RB_PREFER_REMOTE, + RB_ROUND_ROBIN, + RB_LEAST_PENDING, + RB_CONGESTED_REMOTE, +}; + /* KEEP the order, do not delete or insert. Only append. */ enum drbd_ret_code { ERR_CODE_BASE = 100, diff --git a/include/linux/drbd_genl.h b/include/linux/drbd_genl.h index 2e6cefe..826008f 100644 --- a/include/linux/drbd_genl.h +++ b/include/linux/drbd_genl.h @@ -129,6 +129,7 @@ GENL_struct(DRBD_NLA_DISK_CONF, 3, disk_conf, __flg_field_def(18, DRBD_GENLA_F_MANDATORY, disk_drain, DRBD_DISK_DRAIN_DEF) __flg_field_def(19, DRBD_GENLA_F_MANDATORY, md_flushes, DRBD_MD_FLUSHES_DEF) __u32_field_def(20, DRBD_GENLA_F_MANDATORY, disk_timeout, DRBD_DISK_TIMEOUT_DEF) + __u32_field_def(21, 0 /* OPTIONAL */, read_balancing, DRBD_READ_BALANCING_DEF) ) GENL_struct(DRBD_NLA_RESOURCE_OPTS, 4, res_opts, diff --git a/include/linux/drbd_limits.h b/include/linux/drbd_limits.h index 6d0a243..17ef66a5 100644 --- a/include/linux/drbd_limits.h +++ b/include/linux/drbd_limits.h @@ -161,6 +161,7 @@ #define DRBD_RR_CONFLICT_DEF ASB_DISCONNECT #define DRBD_ON_NO_DATA_DEF OND_IO_ERROR #define DRBD_ON_CONGESTION_DEF OC_BLOCK +#define DRBD_READ_BALANCING_DEF RB_PREFER_LOCAL #define DRBD_MAX_BIO_BVECS_MIN 0 #define DRBD_MAX_BIO_BVECS_MAX 128 -- 2.7.4