nvme/rdma: Introduce transport_ack_timeout

Add transport_ack_timeout parameter to nvme controller opts.
This parameter allows to configure RDMA ACK timeout according
to the formula 4.096 * 2^(transport_ack_timeout) usec.
The parameter should be in range 0..31 where 0 means use
driver-specific default value.

Change-Id: I0c8a5a636aa9d816bda5c1ba58f56a00a585b060
Signed-off-by: Alexey Marchuk <alexeymar@mellanox.com>
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/502
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Ben Walker <benjamin.walker@intel.com>
Reviewed-by: Shuhei Matsumoto <shuhei.matsumoto.xt@hitachi.com>

CHANGELOG.md

@@ -156,6 +156,9 @@ the target expects the initiator to send both the compare command and write comm
 SPDK initiator currently respects this requirement, but this note is included as a flag for other initiators attempting
 compatibility with this version of SPDK.
 
+The `spdk_nvme_ctrlr_opts` struct has been extended with new field `transport_ack_timeout` which allows
+to configure transport ACK timeout. Applicable for RDMA transport only.
+
 ### rpc
 
 A new RPC, `bdev_zone_block_create`, enables creating an emulated zoned bdev on top of a standard block device.

CONFIG

@@ -93,6 +93,7 @@ CONFIG_FIO_SOURCE_DIR=/usr/src/fio
 # Requires ibverbs development libraries.
 CONFIG_RDMA=n
 CONFIG_RDMA_SEND_WITH_INVAL=n
+CONFIG_RDMA_SET_ACK_TIMEOUT=n
 
 # Enable NVMe Character Devices.
 CONFIG_NVME_CUSE=n

configure

@@ -569,6 +569,16 @@ of libibverbs, so Linux kernel NVMe-oF initiators based on kernels greater
 than or equal to 4.14 will see significantly reduced performance.
 *******************************************************************************"
 	fi
+
+	if echo -e '#include <rdma/rdma_cma.h>\n' \
+		'int main(void) { return !!RDMA_OPTION_ID_ACK_TIMEOUT; }\n' \
+		| ${BUILD_CMD[@]} -c - 2>/dev/null; then
+		CONFIG[RDMA_SET_ACK_TIMEOUT]="y"
+	else
+		CONFIG[RDMA_SET_ACK_TIMEOUT]="n"
+		echo "RDMA_OPTION_ID_ACK_TIMEOUT is not supported"
+	fi
+
 fi
 
 if [[ "${CONFIG[FC]}" = "y" ]]; then

include/spdk/nvme.h

@@ -2,7 +2,7 @@
  *   BSD LICENSE
  *
  *   Copyright (c) Intel Corporation. All rights reserved.
- *   Copyright (c) 2019 Mellanox Technologies LTD. All rights reserved.
+ *   Copyright (c) 2019, 2020 Mellanox Technologies LTD. All rights reserved.
  *
  *   Redistribution and use in source and binary forms, with or without
  *   modification, are permitted provided that the following conditions
@@ -220,6 +220,20 @@ struct spdk_nvme_ctrlr_opts {
 	 * Defaults to 'false' (errors are logged).
 	 */
 	bool disable_error_logging;
+
+	/**
+	 * It is used for RDMA transport
+	 * Specify the transport ACK timeout. The value should be in range 0-31 where 0 means
+	 * use driver-specific default value. The value is applied to each RDMA qpair
+	 * and affects the time that qpair waits for transport layer acknowledgement
+	 * until it retransmits a packet. The value should be chosen empirically
+	 * to meet the needs of a particular application. A low value means less time
+	 * the qpair waits for ACK which can increase the number of retransmissions.
+	 * A large value can increase the time the connection is closed.
+	 * The value of ACK timeout is calculated according to the formula
+	 * 4.096 * 2^(transport_ack_timeout) usec.
+	 */
+	uint8_t transport_ack_timeout;
 };
 
 /**

lib/nvme/nvme_ctrlr.c

@@ -174,6 +174,10 @@ spdk_nvme_ctrlr_get_default_ctrlr_opts(struct spdk_nvme_ctrlr_opts *opts, size_t
 	if (FIELD_OK(disable_error_logging)) {
 		opts->disable_error_logging = false;
 	}
+
+	if (FIELD_OK(transport_ack_timeout)) {
+		opts->transport_ack_timeout = SPDK_NVME_DEFAULT_TRANSPORT_ACK_TIMEOUT;
+	}
 #undef FIELD_OK
 }
 

lib/nvme/nvme_internal.h

@@ -159,6 +159,9 @@ extern pid_t g_spdk_nvme_pid;
 
 #define SPDK_NVME_DEFAULT_RETRY_COUNT	(4)
 
+#define SPDK_NVME_TRANSPORT_ACK_TIMEOUT_DISABLED	(0)
+#define SPDK_NVME_DEFAULT_TRANSPORT_ACK_TIMEOUT	SPDK_NVME_TRANSPORT_ACK_TIMEOUT_DISABLED
+
 #define MIN_KEEP_ALIVE_TIMEOUT_IN_MS	(10000)
 
 /* We want to fit submission and completion rings each in a single 2MB

lib/nvme/nvme_rdma.c

@@ -51,6 +51,7 @@
 #include "spdk/string.h"
 #include "spdk/endian.h"
 #include "spdk/likely.h"
+#include "spdk/config.h"
 
 #include "nvme_internal.h"
 
@@ -84,6 +85,11 @@
  */
 #define NVME_RDMA_CTRLR_MAX_TRANSPORT_RETRY_COUNT	7
 
+/*
+ * Maximum value of transport_ack_timeout used by RDMA controller
+ */
+#define NVME_RDMA_CTRLR_MAX_TRANSPORT_ACK_TIMEOUT	31
+
 struct spdk_nvmf_cmd {
 	struct spdk_nvme_cmd cmd;
 	struct spdk_nvme_sgl_descriptor sgl[NVME_RDMA_MAX_SGL_DESCRIPTORS];
@@ -859,6 +865,21 @@ nvme_rdma_resolve_addr(struct nvme_rdma_qpair *rqpair,
 		return -1;
 	}
 
+	if (rqpair->qpair.ctrlr->opts.transport_ack_timeout != SPDK_NVME_TRANSPORT_ACK_TIMEOUT_DISABLED) {
+#ifdef SPDK_CONFIG_RDMA_SET_ACK_TIMEOUT
+		uint8_t timeout = rqpair->qpair.ctrlr->opts.transport_ack_timeout;
+		ret = rdma_set_option(rqpair->cm_id, RDMA_OPTION_ID,
+				      RDMA_OPTION_ID_ACK_TIMEOUT,
+				      &timeout, sizeof(timeout));
+		if (ret) {
+			SPDK_NOTICELOG("Can't apply RDMA_OPTION_ID_ACK_TIMEOUT %d, ret %d\n", timeout, ret);
+		}
+#else
+		SPDK_DEBUGLOG(SPDK_LOG_NVME, "transport_ack_timeout is not supported\n");
+#endif
+	}
+
+
 	ret = rdma_resolve_route(rqpair->cm_id, NVME_RDMA_TIME_OUT_IN_MS);
 	if (ret) {
 		SPDK_ERRLOG("rdma_resolve_route\n");
@@ -1732,6 +1753,11 @@ static struct spdk_nvme_ctrlr *nvme_rdma_ctrlr_construct(const struct spdk_nvme_
 			       NVME_RDMA_CTRLR_MAX_TRANSPORT_RETRY_COUNT);
 		rctrlr->ctrlr.opts.transport_retry_count = NVME_RDMA_CTRLR_MAX_TRANSPORT_RETRY_COUNT;
 	}
+	if (rctrlr->ctrlr.opts.transport_ack_timeout > NVME_RDMA_CTRLR_MAX_TRANSPORT_ACK_TIMEOUT) {
+		SPDK_NOTICELOG("transport_ack_timeout exceeds max value %d, use max value\n",
+			       NVME_RDMA_CTRLR_MAX_TRANSPORT_ACK_TIMEOUT);
+		rctrlr->ctrlr.opts.transport_ack_timeout = NVME_RDMA_CTRLR_MAX_TRANSPORT_ACK_TIMEOUT;
+	}
 
 	contexts = rdma_get_devices(NULL);
 	if (contexts == NULL) {