diff --git a/include/spdk/ioat.h b/include/spdk/ioat.h
index fc1750957d..9d32eaf0e1 100644
--- a/include/spdk/ioat.h
+++ b/include/spdk/ioat.h
@@ -207,7 +207,7 @@ void spdk_ioat_flush(struct spdk_ioat_chan *chan);
  *
  * \param chan I/OAT channel to check for completions.
  *
- * \return 0 on success, negative errno on failure.
+ * \return number of events handled on success, negative errno on failure.
  */
 int spdk_ioat_process_events(struct spdk_ioat_chan *chan);
 
diff --git a/include/spdk/thread.h b/include/spdk/thread.h
index 27c575b31f..841cf39a82 100644
--- a/include/spdk/thread.h
+++ b/include/spdk/thread.h
@@ -47,6 +47,11 @@
 extern "C" {
 #endif
 
+enum spdk_thread_poller_rc {
+	SPDK_POLLER_IDLE,
+	SPDK_POLLER_BUSY,
+};
+
 /**
  * A stackless, lightweight thread.
  */
diff --git a/lib/bdev/bdev.c b/lib/bdev/bdev.c
index ec4dd3f2df..8430561441 100644
--- a/lib/bdev/bdev.c
+++ b/lib/bdev/bdev.c
@@ -2265,7 +2265,7 @@ bdev_channel_poll_qos(void *arg)
 		 *  timeslice has actually expired.  This should never happen
 		 *  with a well-behaved timer implementation.
 		 */
-		return 0;
+		return SPDK_POLLER_IDLE;
 	}
 
 	/* Reset for next round of rate limiting */
@@ -2457,7 +2457,7 @@ bdev_poll_timeout_io(void *arg)
 	ctx = calloc(1, sizeof(struct poll_timeout_ctx));
 	if (!ctx) {
 		SPDK_ERRLOG("failed to allocate memory\n");
-		return 1;
+		return SPDK_POLLER_BUSY;
 	}
 	ctx->desc = desc;
 	ctx->cb_arg = desc->cb_arg;
@@ -2476,7 +2476,7 @@ bdev_poll_timeout_io(void *arg)
 			      ctx,
 			      bdev_channel_poll_timeout_io_done);
 
-	return 1;
+	return SPDK_POLLER_BUSY;
 }
 
 int
@@ -3114,7 +3114,7 @@ bdev_calculate_measured_queue_depth(void *ctx)
 	bdev->internal.temporary_queue_depth = 0;
 	spdk_for_each_channel(__bdev_to_io_dev(bdev), _calculate_measured_qd, bdev,
 			      _calculate_measured_qd_cpl);
-	return 0;
+	return SPDK_POLLER_BUSY;
 }
 
 void
@@ -6458,12 +6458,12 @@ bdev_lock_lba_range_check_io(void *_i)
 	TAILQ_FOREACH(bdev_io, &ch->io_submitted, internal.ch_link) {
 		if (bdev_io_range_is_locked(bdev_io, range)) {
 			ctx->poller = SPDK_POLLER_REGISTER(bdev_lock_lba_range_check_io, i, 100);
-			return 1;
+			return SPDK_POLLER_BUSY;
 		}
 	}
 
 	spdk_for_each_channel_continue(i, 0);
-	return 1;
+	return SPDK_POLLER_BUSY;
 }
 
 static void
diff --git a/lib/blobfs/blobfs.c b/lib/blobfs/blobfs.c
index fde016f667..96992b6247 100644
--- a/lib/blobfs/blobfs.c
+++ b/lib/blobfs/blobfs.c
@@ -2088,7 +2088,7 @@ _blobfs_cache_pool_reclaim(void *arg)
 	int rc;
 
 	if (!blobfs_cache_pool_need_reclaim()) {
-		return 0;
+		return SPDK_POLLER_IDLE;
 	}
 
 	TAILQ_FOREACH_SAFE(file, &g_caches, cache_tailq, tmp) {
@@ -2099,7 +2099,7 @@ _blobfs_cache_pool_reclaim(void *arg)
 				continue;
 			}
 			if (!blobfs_cache_pool_need_reclaim()) {
-				return 1;
+				return SPDK_POLLER_BUSY;
 			}
 			break;
 		}
@@ -2112,7 +2112,7 @@ _blobfs_cache_pool_reclaim(void *arg)
 				continue;
 			}
 			if (!blobfs_cache_pool_need_reclaim()) {
-				return 1;
+				return SPDK_POLLER_BUSY;
 			}
 			break;
 		}
@@ -2126,7 +2126,7 @@ _blobfs_cache_pool_reclaim(void *arg)
 		break;
 	}
 
-	return 1;
+	return SPDK_POLLER_BUSY;
 }
 
 static void
diff --git a/lib/event/app.c b/lib/event/app.c
index 3d56fb6440..d0031c95bb 100644
--- a/lib/event/app.c
+++ b/lib/event/app.c
@@ -1116,7 +1116,7 @@ rpc_subsystem_init_poller_ctx(void *ctx)
 		free(poller_ctx);
 	}
 
-	return 1;
+	return SPDK_POLLER_BUSY;
 }
 
 static void
diff --git a/lib/event/json_config.c b/lib/event/json_config.c
index b7a5ed80d8..69a95097a3 100644
--- a/lib/event/json_config.c
+++ b/lib/event/json_config.c
@@ -198,10 +198,10 @@ rpc_client_poller(void *arg)
 
 	if (rc == 0) {
 		/* No response yet */
-		return -1;
+		return SPDK_POLLER_BUSY;
 	} else if (rc < 0) {
 		app_json_config_load_done(ctx, rc);
-		return -1;
+		return SPDK_POLLER_BUSY;
 	}
 
 	resp = spdk_jsonrpc_client_get_response(ctx->client_conn);
@@ -235,7 +235,7 @@ rpc_client_poller(void *arg)
 	}
 
 
-	return -1;
+	return SPDK_POLLER_BUSY;
 }
 
 static int
@@ -255,9 +255,11 @@ rpc_client_connect_poller(void *_ctx)
 		if (rc) {
 			app_json_config_load_done(ctx, rc);
 		}
+
+		return SPDK_POLLER_IDLE;
 	}
 
-	return -1;
+	return SPDK_POLLER_BUSY;
 }
 
 static int
diff --git a/lib/event/rpc.c b/lib/event/rpc.c
index dc3523a29d..a42d5ebeb4 100644
--- a/lib/event/rpc.c
+++ b/lib/event/rpc.c
@@ -49,7 +49,7 @@ static int
 rpc_subsystem_poll(void *arg)
 {
 	spdk_rpc_accept();
-	return -1;
+	return SPDK_POLLER_BUSY;
 }
 
 void
diff --git a/lib/ftl/ftl_core.c b/lib/ftl/ftl_core.c
index ac7acc08fc..b0b4488065 100644
--- a/lib/ftl/ftl_core.c
+++ b/lib/ftl/ftl_core.c
@@ -2410,7 +2410,7 @@ ftl_io_channel_poll(void *arg)
 	TAILQ_HEAD(, ftl_io) retry_queue;
 
 	if (TAILQ_EMPTY(&ch->write_cmpl_queue) && TAILQ_EMPTY(&ch->retry_queue)) {
-		return 0;
+		return SPDK_POLLER_IDLE;
 	}
 
 	while (!TAILQ_EMPTY(&ch->write_cmpl_queue)) {
@@ -2436,7 +2436,7 @@ ftl_io_channel_poll(void *arg)
 		}
 	}
 
-	return 1;
+	return SPDK_POLLER_BUSY;
 }
 
 int
@@ -2447,14 +2447,14 @@ ftl_task_core(void *ctx)
 	if (dev->halt) {
 		if (ftl_shutdown_complete(dev)) {
 			spdk_poller_unregister(&dev->core_poller);
-			return 0;
+			return SPDK_POLLER_IDLE;
 		}
 	}
 
 	ftl_process_writes(dev);
 	ftl_process_relocs(dev);
 
-	return 0;
+	return SPDK_POLLER_BUSY;
 }
 
 SPDK_LOG_REGISTER_COMPONENT("ftl_core", SPDK_LOG_FTL_CORE)
diff --git a/lib/ftl/ftl_init.c b/lib/ftl/ftl_init.c
index ef75c1a738..8e9ec47df9 100644
--- a/lib/ftl/ftl_init.c
+++ b/lib/ftl/ftl_init.c
@@ -1632,7 +1632,7 @@ ftl_halt_poller(void *ctx)
 		}
 	}
 
-	return 0;
+	return SPDK_POLLER_BUSY;
 }
 
 static void
diff --git a/lib/ioat/ioat.c b/lib/ioat/ioat.c
index ccc16ce11a..bde3290cb5 100644
--- a/lib/ioat/ioat.c
+++ b/lib/ioat/ioat.c
@@ -318,7 +318,7 @@ static int
 ioat_process_channel_events(struct spdk_ioat_chan *ioat)
 {
 	struct ioat_descriptor *desc;
-	uint64_t status, completed_descriptor, hw_desc_phys_addr;
+	uint64_t status, completed_descriptor, hw_desc_phys_addr, events_count = 0;
 	uint32_t tail;
 
 	if (ioat->head == ioat->tail) {
@@ -347,10 +347,12 @@ ioat_process_channel_events(struct spdk_ioat_chan *ioat)
 
 		hw_desc_phys_addr = desc->phys_addr;
 		ioat->tail++;
+		events_count++;
 	} while (hw_desc_phys_addr != completed_descriptor);
 
 	ioat->last_seen = hw_desc_phys_addr;
-	return 0;
+
+	return events_count;
 }
 
 static void
diff --git a/lib/iscsi/conn.c b/lib/iscsi/conn.c
index 4d9bc4cd1d..14bb7dc9b8 100644
--- a/lib/iscsi/conn.c
+++ b/lib/iscsi/conn.c
@@ -512,10 +512,10 @@ iscsi_conn_remove_lun(void *ctx)
 	int lun_id = spdk_scsi_lun_get_id(lun);
 
 	if (!iscsi_conn_check_tasks_for_lun(conn, lun)) {
-		return -1;
+		return SPDK_POLLER_BUSY;
 	}
 	iscsi_conn_close_lun(conn, lun_id);
-	return -1;
+	return SPDK_POLLER_BUSY;
 }
 
 static void
@@ -648,7 +648,7 @@ _iscsi_conn_check_shutdown(void *arg)
 
 	rc = iscsi_conn_free_tasks(conn);
 	if (rc < 0) {
-		return 1;
+		return SPDK_POLLER_BUSY;
 	}
 
 	spdk_poller_unregister(&conn->shutdown_timer);
@@ -656,7 +656,7 @@ _iscsi_conn_check_shutdown(void *arg)
 	iscsi_conn_stop(conn);
 	iscsi_conn_free(conn);
 
-	return 1;
+	return SPDK_POLLER_BUSY;
 }
 
 static void
@@ -688,14 +688,14 @@ _iscsi_conn_check_pending_tasks(void *arg)
 
 	if (conn->dev != NULL &&
 	    spdk_scsi_dev_has_pending_tasks(conn->dev, conn->initiator_port)) {
-		return 1;
+		return SPDK_POLLER_BUSY;
 	}
 
 	spdk_poller_unregister(&conn->shutdown_timer);
 
 	_iscsi_conn_destruct(conn);
 
-	return 1;
+	return SPDK_POLLER_BUSY;
 }
 
 void
@@ -783,14 +783,14 @@ static int
 iscsi_conn_check_shutdown(void *arg)
 {
 	if (iscsi_get_active_conns(NULL) != 0) {
-		return 1;
+		return SPDK_POLLER_BUSY;
 	}
 
 	spdk_poller_unregister(&g_shutdown_timer);
 
 	spdk_thread_send_msg(spdk_get_thread(), iscsi_conn_check_shutdown_cb, NULL);
 
-	return 1;
+	return SPDK_POLLER_BUSY;
 }
 
 static void
@@ -826,7 +826,7 @@ logout_request_timeout(void *arg)
 		conn->state = ISCSI_CONN_STATE_EXITING;
 	}
 
-	return -1;
+	return SPDK_POLLER_BUSY;
 }
 
 /* If the connection is running and logout is not requested yet, request logout
@@ -1647,7 +1647,7 @@ logout_timeout(void *arg)
 		conn->state = ISCSI_CONN_STATE_EXITING;
 	}
 
-	return -1;
+	return SPDK_POLLER_BUSY;
 }
 
 void
diff --git a/lib/iscsi/iscsi.c b/lib/iscsi/iscsi.c
index a54617dc43..5f9b200cb2 100644
--- a/lib/iscsi/iscsi.c
+++ b/lib/iscsi/iscsi.c
@@ -3589,12 +3589,12 @@ _iscsi_op_abort_task(void *arg)
 
 	rc = iscsi_conn_abort_queued_datain_task(task->conn, task->scsi.abort_id);
 	if (rc != 0) {
-		return 1;
+		return SPDK_POLLER_BUSY;
 	}
 
 	spdk_poller_unregister(&task->mgmt_poller);
 	iscsi_queue_mgmt_task(task->conn, task);
-	return 1;
+	return SPDK_POLLER_BUSY;
 }
 
 static void
@@ -3614,12 +3614,12 @@ _iscsi_op_abort_task_set(void *arg)
 	rc = iscsi_conn_abort_queued_datain_tasks(task->conn, task->scsi.lun,
 			task->pdu);
 	if (rc != 0) {
-		return 1;
+		return SPDK_POLLER_BUSY;
 	}
 
 	spdk_poller_unregister(&task->mgmt_poller);
 	iscsi_queue_mgmt_task(task->conn, task);
-	return 1;
+	return SPDK_POLLER_BUSY;
 }
 
 void
diff --git a/lib/iscsi/iscsi_subsystem.c b/lib/iscsi/iscsi_subsystem.c
index 66831e32cb..0e12b9e943 100644
--- a/lib/iscsi/iscsi_subsystem.c
+++ b/lib/iscsi/iscsi_subsystem.c
@@ -1189,7 +1189,7 @@ iscsi_poll_group_poll(void *ctx)
 	int rc;
 
 	if (spdk_unlikely(STAILQ_EMPTY(&group->connections))) {
-		return 0;
+		return SPDK_POLLER_IDLE;
 	}
 
 	rc = spdk_sock_group_poll(group->sock_group);
@@ -1203,7 +1203,7 @@ iscsi_poll_group_poll(void *ctx)
 		}
 	}
 
-	return rc;
+	return rc != 0 ? SPDK_POLLER_BUSY : SPDK_POLLER_IDLE;
 }
 
 static int
@@ -1216,7 +1216,7 @@ iscsi_poll_group_handle_nop(void *ctx)
 		iscsi_conn_handle_nop(conn);
 	}
 
-	return -1;
+	return SPDK_POLLER_BUSY;
 }
 
 static int
diff --git a/lib/iscsi/tgt_node.c b/lib/iscsi/tgt_node.c
index f07b8d1d53..d810fdc445 100644
--- a/lib/iscsi/tgt_node.c
+++ b/lib/iscsi/tgt_node.c
@@ -656,14 +656,14 @@ iscsi_tgt_node_check_active_conns(void *arg)
 	struct spdk_iscsi_tgt_node *target = arg;
 
 	if (iscsi_get_active_conns(target) != 0) {
-		return 1;
+		return SPDK_POLLER_BUSY;
 	}
 
 	spdk_poller_unregister(&target->destruct_poller);
 
 	spdk_scsi_dev_destruct(target->dev, _iscsi_tgt_node_destruct, target);
 
-	return 1;
+	return SPDK_POLLER_BUSY;
 }
 
 static void
diff --git a/lib/nbd/nbd.c b/lib/nbd/nbd.c
index 2854946582..0465390e58 100644
--- a/lib/nbd/nbd.c
+++ b/lib/nbd/nbd.c
@@ -818,7 +818,7 @@ nbd_poll(void *arg)
 		spdk_nbd_stop(nbd);
 	}
 
-	return -1;
+	return SPDK_POLLER_BUSY;
 }
 
 static void *
@@ -942,7 +942,7 @@ nbd_enable_kernel(void *arg)
 								   NBD_BUSY_POLLING_INTERVAL_US);
 			}
 			/* If the kernel is busy, check back later */
-			return 0;
+			return SPDK_POLLER_BUSY;
 		}
 
 		SPDK_ERRLOG("ioctl(NBD_SET_SOCK) failed: %s\n", spdk_strerror(errno));
@@ -957,7 +957,7 @@ nbd_enable_kernel(void *arg)
 		}
 
 		free(ctx);
-		return 1;
+		return SPDK_POLLER_BUSY;
 	}
 
 	if (ctx->poller) {
@@ -966,7 +966,7 @@ nbd_enable_kernel(void *arg)
 
 	nbd_start_complete(ctx);
 
-	return 1;
+	return SPDK_POLLER_BUSY;
 }
 
 void
diff --git a/lib/nvmf/ctrlr.c b/lib/nvmf/ctrlr.c
index 2159895084..ddcd817ae9 100644
--- a/lib/nvmf/ctrlr.c
+++ b/lib/nvmf/ctrlr.c
@@ -181,7 +181,7 @@ nvmf_ctrlr_keep_alive_poll(void *ctx)
 		}
 	}
 
-	return 1;
+	return SPDK_POLLER_BUSY;
 }
 
 static void
diff --git a/lib/nvmf/nvmf.c b/lib/nvmf/nvmf.c
index 570a448dce..bd996774c5 100644
--- a/lib/nvmf/nvmf.c
+++ b/lib/nvmf/nvmf.c
@@ -99,12 +99,12 @@ nvmf_poll_group_poll(void *ctx)
 	TAILQ_FOREACH(tgroup, &group->tgroups, link) {
 		rc = nvmf_transport_poll_group_poll(tgroup);
 		if (rc < 0) {
-			return -1;
+			return SPDK_POLLER_BUSY;
 		}
 		count += rc;
 	}
 
-	return count;
+	return count > 0 ? SPDK_POLLER_BUSY : SPDK_POLLER_IDLE;
 }
 
 static int
diff --git a/lib/nvmf/rdma.c b/lib/nvmf/rdma.c
index 488030260b..6a515e2aa0 100644
--- a/lib/nvmf/rdma.c
+++ b/lib/nvmf/rdma.c
@@ -3542,7 +3542,7 @@ nvmf_rdma_destroy_defunct_qpair(void *ctx)
 	nvmf_rdma_qpair_process_pending(rtransport, rqpair, true);
 	nvmf_rdma_qpair_destroy(rqpair);
 
-	return 0;
+	return SPDK_POLLER_BUSY;
 }
 
 static void
diff --git a/lib/nvmf/tcp.c b/lib/nvmf/tcp.c
index d39486b8a7..79b7cb6505 100644
--- a/lib/nvmf/tcp.c
+++ b/lib/nvmf/tcp.c
@@ -1056,7 +1056,7 @@ nvmf_tcp_qpair_handle_timeout(void *ctx)
 		    SPDK_NVME_TCP_QPAIR_EXIT_TIMEOUT);
 
 	nvmf_tcp_qpair_disconnect(tqpair);
-	return 0;
+	return SPDK_POLLER_BUSY;
 }
 
 static void
diff --git a/lib/scsi/lun.c b/lib/scsi/lun.c
index b14911b6e8..262137d808 100644
--- a/lib/scsi/lun.c
+++ b/lib/scsi/lun.c
@@ -95,12 +95,12 @@ scsi_lun_reset_check_outstanding_tasks(void *arg)
 	struct spdk_scsi_lun *lun = task->lun;
 
 	if (scsi_lun_has_outstanding_tasks(lun)) {
-		return 0;
+		return SPDK_POLLER_BUSY;
 	}
 	spdk_poller_unregister(&lun->reset_poller);
 
 	scsi_lun_complete_mgmt_task(lun, task);
-	return 1;
+	return SPDK_POLLER_BUSY;
 }
 
 void
@@ -299,12 +299,12 @@ scsi_lun_check_io_channel(void *arg)
 	struct spdk_scsi_lun *lun = (struct spdk_scsi_lun *)arg;
 
 	if (lun->io_channel) {
-		return -1;
+		return SPDK_POLLER_BUSY;
 	}
 	spdk_poller_unregister(&lun->hotremove_poller);
 
 	scsi_lun_remove(lun);
-	return -1;
+	return SPDK_POLLER_BUSY;
 }
 
 static void
@@ -339,12 +339,12 @@ scsi_lun_check_outstanding_tasks(void *arg)
 
 	if (scsi_lun_has_outstanding_tasks(lun) ||
 	    scsi_lun_has_outstanding_mgmt_tasks(lun)) {
-		return -1;
+		return SPDK_POLLER_BUSY;
 	}
 	spdk_poller_unregister(&lun->hotremove_poller);
 
 	scsi_lun_notify_hot_remove(lun);
-	return -1;
+	return SPDK_POLLER_BUSY;
 }
 
 static void
diff --git a/lib/vhost/vhost_blk.c b/lib/vhost/vhost_blk.c
index 10ab3896cd..51a45098bf 100644
--- a/lib/vhost/vhost_blk.c
+++ b/lib/vhost/vhost_blk.c
@@ -688,7 +688,7 @@ vdev_worker(void *arg)
 
 	vhost_session_used_signal(vsession);
 
-	return -1;
+	return SPDK_POLLER_BUSY;
 }
 
 static void
@@ -776,7 +776,7 @@ no_bdev_vdev_worker(void *arg)
 		bvsession->io_channel = NULL;
 	}
 
-	return -1;
+	return SPDK_POLLER_BUSY;
 }
 
 static struct spdk_vhost_blk_session *
@@ -972,11 +972,11 @@ destroy_session_poller_cb(void *arg)
 	int i;
 
 	if (vsession->task_cnt > 0) {
-		return -1;
+		return SPDK_POLLER_BUSY;
 	}
 
 	if (spdk_vhost_trylock() != 0) {
-		return -1;
+		return SPDK_POLLER_BUSY;
 	}
 
 	for (i = 0; i < vsession->max_queues; i++) {
@@ -997,7 +997,7 @@ destroy_session_poller_cb(void *arg)
 	vhost_session_stop_done(vsession, 0);
 
 	spdk_vhost_unlock();
-	return -1;
+	return SPDK_POLLER_BUSY;
 }
 
 static int
diff --git a/lib/vhost/vhost_nvme.c b/lib/vhost/vhost_nvme.c
index 47b3ccb363..10f53baf92 100644
--- a/lib/vhost/vhost_nvme.c
+++ b/lib/vhost/vhost_nvme.c
@@ -583,11 +583,11 @@ nvme_worker(void *arg)
 	int count = -1;
 
 	if (spdk_unlikely(!nvme->num_sqs)) {
-		return -1;
+		return SPDK_POLLER_IDLE;
 	}
 
 	if (spdk_unlikely(!nvme->dataplane_started && !nvme->bar)) {
-		return -1;
+		return SPDK_POLLER_IDLE;
 	}
 
 	for (qid = 1; qid <= MAX_IO_QUEUES; qid++) {
@@ -598,7 +598,7 @@ nvme_worker(void *arg)
 		}
 		cq = vhost_nvme_get_cq_from_qid(nvme, sq->cqid);
 		if (spdk_unlikely(!cq)) {
-			return -1;
+			return SPDK_POLLER_BUSY;
 		}
 		cq->guest_signaled_cq_head = vhost_nvme_get_queue_head(nvme, cq_offset(sq->cqid, 1));
 		if (spdk_unlikely(!STAILQ_EMPTY(&cq->cq_full_waited_tasks) &&
@@ -620,7 +620,7 @@ nvme_worker(void *arg)
 				task = STAILQ_FIRST(&nvme->free_tasks);
 				STAILQ_REMOVE_HEAD(&nvme->free_tasks, stailq);
 			} else {
-				return -1;
+				return SPDK_POLLER_BUSY;
 			}
 
 			task->cmd = sq->sq_cmd[sq->sq_head];
@@ -1113,7 +1113,7 @@ destroy_device_poller_cb(void *arg)
 	/* FIXME wait for pending I/Os to complete */
 
 	if (spdk_vhost_trylock() != 0) {
-		return -1;
+		return SPDK_POLLER_BUSY;
 	}
 
 	for (i = 0; i < nvme->num_ns; i++) {
@@ -1137,7 +1137,7 @@ destroy_device_poller_cb(void *arg)
 	vhost_session_stop_done(nvme->vsession, 0);
 
 	spdk_vhost_unlock();
-	return -1;
+	return SPDK_POLLER_BUSY;
 }
 
 static int
diff --git a/lib/vhost/vhost_scsi.c b/lib/vhost/vhost_scsi.c
index e7634926eb..49e49dc76f 100644
--- a/lib/vhost/vhost_scsi.c
+++ b/lib/vhost/vhost_scsi.c
@@ -769,7 +769,7 @@ vdev_mgmt_worker(void *arg)
 	process_vq(svsession, &vsession->virtqueue[VIRTIO_SCSI_CONTROLQ]);
 	vhost_vq_used_signal(vsession, &vsession->virtqueue[VIRTIO_SCSI_CONTROLQ]);
 
-	return -1;
+	return SPDK_POLLER_BUSY;
 }
 
 static int
@@ -785,7 +785,7 @@ vdev_worker(void *arg)
 
 	vhost_session_used_signal(vsession);
 
-	return -1;
+	return SPDK_POLLER_BUSY;
 }
 
 static struct spdk_vhost_scsi_dev *
@@ -1364,11 +1364,11 @@ destroy_session_poller_cb(void *arg)
 	uint32_t i;
 
 	if (vsession->task_cnt > 0) {
-		return -1;
+		return SPDK_POLLER_BUSY;
 	}
 
 	if (spdk_vhost_trylock() != 0) {
-		return -1;
+		return SPDK_POLLER_BUSY;
 	}
 
 	for (i = 0; i < vsession->max_queues; i++) {
@@ -1408,7 +1408,7 @@ destroy_session_poller_cb(void *arg)
 	vhost_session_stop_done(vsession, 0);
 
 	spdk_vhost_unlock();
-	return -1;
+	return SPDK_POLLER_BUSY;
 }
 
 static int
diff --git a/module/accel/ioat/accel_engine_ioat.c b/module/accel/ioat/accel_engine_ioat.c
index a485878b7b..41f8cc94ac 100644
--- a/module/accel/ioat/accel_engine_ioat.c
+++ b/module/accel/ioat/accel_engine_ioat.c
@@ -184,9 +184,8 @@ ioat_poll(void *arg)
 {
 	struct spdk_ioat_chan *chan = arg;
 
-	spdk_ioat_process_events(chan);
-
-	return -1;
+	return spdk_ioat_process_events(chan) != 0 ? SPDK_POLLER_BUSY :
+	       SPDK_POLLER_IDLE;
 }
 
 static struct spdk_io_channel *ioat_get_io_channel(void);
diff --git a/module/bdev/aio/bdev_aio.c b/module/bdev/aio/bdev_aio.c
index 5eb63f69e0..5813aa8fa6 100644
--- a/module/bdev/aio/bdev_aio.c
+++ b/module/bdev/aio/bdev_aio.c
@@ -323,7 +323,7 @@ bdev_aio_group_poll(void *arg)
 	nr = bdev_user_io_getevents(group_ch->io_ctx, SPDK_AIO_QUEUE_DEPTH, events);
 
 	if (nr < 0) {
-		return -1;
+		return SPDK_POLLER_IDLE;
 	}
 
 	for (i = 0; i < nr; i++) {
@@ -338,7 +338,7 @@ bdev_aio_group_poll(void *arg)
 		aio_task->ch->io_inflight--;
 	}
 
-	return nr;
+	return nr > 0 ? SPDK_POLLER_BUSY : SPDK_POLLER_IDLE;
 }
 
 static void
@@ -384,7 +384,7 @@ bdev_aio_reset_retry_timer(void *arg)
 			      fdisk,
 			      _bdev_aio_get_io_inflight_done);
 
-	return -1;
+	return SPDK_POLLER_BUSY;
 }
 
 static void
diff --git a/module/bdev/compress/vbdev_compress.c b/module/bdev/compress/vbdev_compress.c
index 336f0484ca..399a695b4b 100644
--- a/module/bdev/compress/vbdev_compress.c
+++ b/module/bdev/compress/vbdev_compress.c
@@ -702,7 +702,7 @@ comp_dev_poller(void *args)
 			}
 		}
 	}
-	return 0;
+	return num_deq == 0 ? SPDK_POLLER_IDLE : SPDK_POLLER_BUSY;
 }
 
 /* Entry point for reduce lib to issue a compress operation. */
diff --git a/module/bdev/delay/vbdev_delay.c b/module/bdev/delay/vbdev_delay.c
index 2b3cd0face..ecee65049c 100644
--- a/module/bdev/delay/vbdev_delay.c
+++ b/module/bdev/delay/vbdev_delay.c
@@ -199,7 +199,7 @@ _delay_finish_io(void *arg)
 	_process_io_stailq(&delay_ch->p99_read_io, ticks);
 	_process_io_stailq(&delay_ch->p99_write_io, ticks);
 
-	return 0;
+	return SPDK_POLLER_BUSY;
 }
 
 /* Completion callback for IO that were issued from this bdev. The original bdev_io
diff --git a/module/bdev/iscsi/bdev_iscsi.c b/module/bdev/iscsi/bdev_iscsi.c
index 99792733f8..18e8e00902 100644
--- a/module/bdev/iscsi/bdev_iscsi.c
+++ b/module/bdev/iscsi/bdev_iscsi.c
@@ -378,27 +378,29 @@ bdev_iscsi_poll_lun(void *_lun)
 
 	if (poll(&pfd, 1, 0) < 0) {
 		SPDK_ERRLOG("poll failed\n");
-		return -1;
+		return SPDK_POLLER_IDLE;
 	}
 
 	if (pfd.revents != 0) {
 		if (iscsi_service(lun->context, pfd.revents) < 0) {
 			SPDK_ERRLOG("iscsi_service failed: %s\n", iscsi_get_error(lun->context));
 		}
+
+		return SPDK_POLLER_BUSY;
 	}
 
-	return -1;
+	return SPDK_POLLER_IDLE;
 }
 
 static int
 bdev_iscsi_no_master_ch_poll(void *arg)
 {
 	struct bdev_iscsi_lun *lun = arg;
-	int rc = 0;
+	enum spdk_thread_poller_rc rc = SPDK_POLLER_IDLE;
 
 	if (pthread_mutex_trylock(&lun->mutex)) {
 		/* Don't care about the error code here. */
-		return -1;
+		return SPDK_POLLER_IDLE;
 	}
 
 	if (lun->ch_count == 0) {
@@ -754,6 +756,10 @@ iscsi_bdev_conn_poll(void *arg)
 	struct pollfd pfd;
 	struct iscsi_context *context;
 
+	if (TAILQ_EMPTY(&g_iscsi_conn_req)) {
+		return SPDK_POLLER_IDLE;
+	}
+
 	TAILQ_FOREACH_SAFE(req, &g_iscsi_conn_req, link, tmp) {
 		context = req->context;
 		pfd.fd = iscsi_get_fd(context);
@@ -761,7 +767,7 @@ iscsi_bdev_conn_poll(void *arg)
 		pfd.revents = 0;
 		if (poll(&pfd, 1, 0) < 0) {
 			SPDK_ERRLOG("poll failed\n");
-			return -1;
+			return SPDK_POLLER_BUSY;
 		}
 
 		if (pfd.revents != 0) {
@@ -784,7 +790,7 @@ iscsi_bdev_conn_poll(void *arg)
 			_bdev_iscsi_conn_req_free(req);
 		}
 	}
-	return -1;
+	return SPDK_POLLER_BUSY;
 }
 
 int
diff --git a/module/bdev/null/bdev_null.c b/module/bdev/null/bdev_null.c
index ee9480c50b..97aa8b03f3 100644
--- a/module/bdev/null/bdev_null.c
+++ b/module/bdev/null/bdev_null.c
@@ -368,7 +368,7 @@ null_io_poll(void *arg)
 	TAILQ_SWAP(&ch->io, &io, spdk_bdev_io, module_link);
 
 	if (TAILQ_EMPTY(&io)) {
-		return 0;
+		return SPDK_POLLER_IDLE;
 	}
 
 	while (!TAILQ_EMPTY(&io)) {
@@ -377,7 +377,7 @@ null_io_poll(void *arg)
 		spdk_bdev_io_complete(bdev_io, SPDK_BDEV_IO_STATUS_SUCCESS);
 	}
 
-	return 1;
+	return SPDK_POLLER_BUSY;
 }
 
 static int
diff --git a/module/bdev/nvme/bdev_nvme.c b/module/bdev/nvme/bdev_nvme.c
index 0ba6944595..487e354e21 100644
--- a/module/bdev/nvme/bdev_nvme.c
+++ b/module/bdev/nvme/bdev_nvme.c
@@ -258,7 +258,7 @@ bdev_nvme_poll(void *arg)
 		}
 	}
 
-	return num_completions;
+	return num_completions > 0 ? SPDK_POLLER_BUSY : SPDK_POLLER_IDLE;
 }
 
 static int
@@ -276,7 +276,7 @@ bdev_nvme_poll_adminq(void *arg)
 		bdev_nvme_reset(nvme_bdev_ctrlr, NULL, true);
 	}
 
-	return rc;
+	return rc == 0 ? SPDK_POLLER_IDLE : SPDK_POLLER_BUSY;
 }
 
 static int
@@ -1569,17 +1569,16 @@ bdev_nvme_hotplug(void *arg)
 				      hotplug_probe_cb,
 				      attach_cb, remove_cb);
 		if (!g_hotplug_probe_ctx) {
-			return -1;
+			return SPDK_POLLER_BUSY;
 		}
 	}
 
 	done = spdk_nvme_probe_poll_async(g_hotplug_probe_ctx);
 	if (done != -EAGAIN) {
 		g_hotplug_probe_ctx = NULL;
-		return 1;
 	}
 
-	return -1;
+	return SPDK_POLLER_BUSY;
 }
 
 void
@@ -1740,7 +1739,7 @@ bdev_nvme_async_poll(void *arg)
 		free(ctx);
 	}
 
-	return 1;
+	return SPDK_POLLER_BUSY;
 }
 
 int
diff --git a/module/bdev/nvme/bdev_ocssd.c b/module/bdev/nvme/bdev_ocssd.c
index ddbc240c72..35f665f404 100644
--- a/module/bdev/nvme/bdev_ocssd.c
+++ b/module/bdev/nvme/bdev_ocssd.c
@@ -942,7 +942,7 @@ bdev_ocssd_poll_mm(void *ctx)
 		}
 	}
 
-	return 0;
+	return SPDK_POLLER_BUSY;
 }
 
 void
diff --git a/module/bdev/nvme/common.c b/module/bdev/nvme/common.c
index c3ac457d67..40ea3afee0 100644
--- a/module/bdev/nvme/common.c
+++ b/module/bdev/nvme/common.c
@@ -157,14 +157,14 @@ nvme_bdev_ctrlr_destruct(struct nvme_bdev_ctrlr *nvme_bdev_ctrlr)
 	/* If we have already registered a poller, let that one take care of it. */
 	if (nvme_bdev_ctrlr->destruct_poller != NULL) {
 		pthread_mutex_unlock(&g_bdev_nvme_mutex);
-		return 1;
+		return SPDK_POLLER_IDLE;
 	}
 
 	if (nvme_bdev_ctrlr->resetting) {
 		nvme_bdev_ctrlr->destruct_poller =
 			SPDK_POLLER_REGISTER((spdk_poller_fn)nvme_bdev_ctrlr_destruct, nvme_bdev_ctrlr, 1000);
 		pthread_mutex_unlock(&g_bdev_nvme_mutex);
-		return 1;
+		return SPDK_POLLER_BUSY;
 	}
 	pthread_mutex_unlock(&g_bdev_nvme_mutex);
 
@@ -179,7 +179,7 @@ nvme_bdev_ctrlr_destruct(struct nvme_bdev_ctrlr *nvme_bdev_ctrlr)
 	}
 
 	spdk_io_device_unregister(nvme_bdev_ctrlr, nvme_bdev_unregister_cb);
-	return 1;
+	return SPDK_POLLER_BUSY;
 }
 
 void
diff --git a/module/bdev/ocf/ctx.c b/module/bdev/ocf/ctx.c
index 3bcb422ad4..5bf4c8fee7 100644
--- a/module/bdev/ocf/ctx.c
+++ b/module/bdev/ocf/ctx.c
@@ -342,13 +342,13 @@ cleaner_poll(void *arg)
 
 	if (spdk_get_ticks() >= priv->next_run) {
 		ocf_cleaner_run(cleaner, priv->queue);
-		return 1;
+		return SPDK_POLLER_BUSY;
 	}
 
 	if (iono > 0) {
-		return 1;
+		return SPDK_POLLER_BUSY;
 	} else {
-		return 0;
+		return SPDK_POLLER_IDLE;
 	}
 }
 
diff --git a/module/bdev/ocf/vbdev_ocf.c b/module/bdev/ocf/vbdev_ocf.c
index 4a714b9418..35ffe3e957 100644
--- a/module/bdev/ocf/vbdev_ocf.c
+++ b/module/bdev/ocf/vbdev_ocf.c
@@ -783,9 +783,9 @@ queue_poll(void *opaque)
 	}
 
 	if (iono > 0) {
-		return 1;
+		return SPDK_POLLER_BUSY;
 	} else {
-		return 0;
+		return SPDK_POLLER_IDLE;
 	}
 }
 
@@ -891,9 +891,9 @@ mngt_queue_poll(void *opaque)
 	}
 
 	if (iono > 0) {
-		return 1;
+		return SPDK_POLLER_BUSY;
 	} else {
-		return 0;
+		return SPDK_POLLER_IDLE;
 	}
 }
 
diff --git a/module/bdev/rbd/bdev_rbd.c b/module/bdev/rbd/bdev_rbd.c
index 01fad34854..f3b2547c4d 100644
--- a/module/bdev/rbd/bdev_rbd.c
+++ b/module/bdev/rbd/bdev_rbd.c
@@ -347,7 +347,7 @@ bdev_rbd_reset_timer(void *arg)
 	spdk_poller_unregister(&disk->reset_timer);
 	disk->reset_bdev_io = NULL;
 
-	return -1;
+	return SPDK_POLLER_BUSY;
 }
 
 static int
@@ -468,7 +468,7 @@ bdev_rbd_io_poll(void *arg)
 
 	/* check the return value of poll since we have only one fd for each channel */
 	if (rc != 1) {
-		return 0;
+		return SPDK_POLLER_BUSY;
 	}
 
 	rc = rbd_poll_io_events(ch->image, comps, SPDK_RBD_QUEUE_DEPTH);
@@ -504,7 +504,7 @@ bdev_rbd_io_poll(void *arg)
 		}
 	}
 
-	return rc;
+	return rc > 0 ? SPDK_POLLER_BUSY : SPDK_POLLER_IDLE;
 }
 
 static void
diff --git a/module/bdev/uring/bdev_uring.c b/module/bdev/uring/bdev_uring.c
index d535cee325..494cc47940 100644
--- a/module/bdev/uring/bdev_uring.c
+++ b/module/bdev/uring/bdev_uring.c
@@ -261,7 +261,7 @@ bdev_uring_group_poll(void *arg)
 	}
 
 	if (ret < 0) {
-		return 1;
+		return SPDK_POLLER_BUSY;
 	}
 
 	count = 0;
@@ -269,7 +269,11 @@ bdev_uring_group_poll(void *arg)
 		count = bdev_uring_reap(&group_ch->uring, to_complete);
 	}
 
-	return (count + to_submit);
+	if (count + to_submit > 0) {
+		return SPDK_POLLER_BUSY;
+	} else {
+		return SPDK_POLLER_IDLE;
+	}
 }
 
 static void bdev_uring_get_buf_cb(struct spdk_io_channel *ch, struct spdk_bdev_io *bdev_io,
diff --git a/module/bdev/virtio/bdev_virtio_scsi.c b/module/bdev/virtio/bdev_virtio_scsi.c
index de65b15d7f..520b8a17d9 100644
--- a/module/bdev/virtio/bdev_virtio_scsi.c
+++ b/module/bdev/virtio/bdev_virtio_scsi.c
@@ -811,7 +811,7 @@ bdev_virtio_poll(void *arg)
 		if (spdk_unlikely(scan_ctx && io[i] == &scan_ctx->io_ctx)) {
 			if (svdev->removed) {
 				_virtio_scsi_dev_scan_finish(scan_ctx, -EINTR);
-				return -1;
+				return SPDK_POLLER_BUSY;
 			}
 
 			if (scan_ctx->restart) {
@@ -831,9 +831,9 @@ bdev_virtio_poll(void *arg)
 	if (spdk_unlikely(scan_ctx && scan_ctx->needs_resend)) {
 		if (svdev->removed) {
 			_virtio_scsi_dev_scan_finish(scan_ctx, -EINTR);
-			return -1;
+			return SPDK_POLLER_BUSY;
 		} else if (cnt == 0) {
-			return 0;
+			return SPDK_POLLER_IDLE;
 		}
 
 		rc = send_scan_io(scan_ctx);
diff --git a/module/event/subsystems/nvmf/nvmf_tgt.c b/module/event/subsystems/nvmf/nvmf_tgt.c
index 22354cff0a..8227a86fd9 100644
--- a/module/event/subsystems/nvmf/nvmf_tgt.c
+++ b/module/event/subsystems/nvmf/nvmf_tgt.c
@@ -111,7 +111,11 @@ acceptor_poll(void *arg)
 
 	count = spdk_nvmf_tgt_accept(tgt);
 
-	return count;
+	if (count > 0) {
+		return SPDK_POLLER_BUSY;
+	} else {
+		return SPDK_POLLER_IDLE;
+	}
 }
 
 static void
diff --git a/module/sock/vpp/vpp.c b/module/sock/vpp/vpp.c
index 237c65fbb9..89a92e9d10 100644
--- a/module/sock/vpp/vpp.c
+++ b/module/sock/vpp/vpp.c
@@ -517,7 +517,7 @@ vpp_queue_poller(void *ctx)
 		vl_msg_api_handler((void *)msg);
 	}
 
-	return 0;
+	return SPDK_POLLER_BUSY;
 }
 
 static int
@@ -532,7 +532,7 @@ app_queue_poller(void *ctx)
 		handle_mq_event(e);
 		svm_msg_q_free_msg(g_svm.app_event_queue, &msg);
 	}
-	return 0;
+	return SPDK_POLLER_BUSY;
 }
 
 /* This is required until sock.c API changes to asynchronous */
@@ -1449,7 +1449,7 @@ vpp_application_detached_timeout(void *arg)
 		/* We need to finish detach on initial thread */
 		spdk_thread_send_msg(g_svm.init_thread, vpp_application_detached, NULL);
 	}
-	return 0;
+	return SPDK_POLLER_BUSY;
 }
 
 static void
diff --git a/test/unit/lib/bdev/compress.c/compress_ut.c b/test/unit/lib/bdev/compress.c/compress_ut.c
index c0abb28083..53c14310ca 100644
--- a/test/unit/lib/bdev/compress.c/compress_ut.c
+++ b/test/unit/lib/bdev/compress.c/compress_ut.c
@@ -923,7 +923,7 @@ test_poller(void)
 	CU_ASSERT(TAILQ_EMPTY(&g_comp_bdev.queued_comp_ops) == true);
 	rc = comp_dev_poller((void *)&g_comp_bdev);
 	CU_ASSERT(TAILQ_EMPTY(&g_comp_bdev.queued_comp_ops) == true);
-	CU_ASSERT(rc == 0);
+	CU_ASSERT(rc == SPDK_POLLER_BUSY);
 
 	/* Success from dequeue, 2 ops. nothing needing to be resubmitted.
 	 */
@@ -942,7 +942,7 @@ test_poller(void)
 	CU_ASSERT(TAILQ_EMPTY(&g_comp_bdev.queued_comp_ops) == true);
 	rc = comp_dev_poller((void *)&g_comp_bdev);
 	CU_ASSERT(TAILQ_EMPTY(&g_comp_bdev.queued_comp_ops) == true);
-	CU_ASSERT(rc == 0);
+	CU_ASSERT(rc == SPDK_POLLER_BUSY);
 
 	/* Success from dequeue, one op to be resubmitted.
 	 */
@@ -970,7 +970,7 @@ test_poller(void)
 	CU_ASSERT(TAILQ_EMPTY(&g_comp_bdev.queued_comp_ops) == false);
 	rc = comp_dev_poller((void *)&g_comp_bdev);
 	CU_ASSERT(TAILQ_EMPTY(&g_comp_bdev.queued_comp_ops) == true);
-	CU_ASSERT(rc == 0);
+	CU_ASSERT(rc == SPDK_POLLER_BUSY);
 
 	/* op_to_queue is freed in code under test */
 	free(cb_args);