Adding upstream version 14.2.21.upstream/14.2.21upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

4 files changed, 789 insertions, 0 deletions

diff --git a/src/spdk/test/nvme/overhead/.gitignore b/src/spdk/test/nvme/overhead/.gitignore
new file mode 100644
index 00000000..d5a7d6f4
--- /dev/null
+++ b/src/spdk/test/nvme/overhead/.gitignore
@@ -0,0 +1 @@
+overhead
diff --git a/src/spdk/test/nvme/overhead/Makefile b/src/spdk/test/nvme/overhead/Makefile
new file mode 100644
index 00000000..bcb7f38d
--- /dev/null
+++ b/src/spdk/test/nvme/overhead/Makefile
@@ -0,0 +1,44 @@
+#
+#  BSD LICENSE
+#
+#  Copyright (c) Intel Corporation.
+#  All rights reserved.
+#
+#  Redistribution and use in source and binary forms, with or without
+#  modification, are permitted provided that the following conditions
+#  are met:
+#
+#    * Redistributions of source code must retain the above copyright
+#      notice, this list of conditions and the following disclaimer.
+#    * Redistributions in binary form must reproduce the above copyright
+#      notice, this list of conditions and the following disclaimer in
+#      the documentation and/or other materials provided with the
+#      distribution.
+#    * Neither the name of Intel Corporation nor the names of its
+#      contributors may be used to endorse or promote products derived
+#      from this software without specific prior written permission.
+#
+#  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+#  "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+#  LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+#  A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+#  OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+#  SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+#  LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+#  DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+#  THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+#  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+#  OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#
+
+SPDK_ROOT_DIR := $(abspath $(CURDIR)/../../..)
+include $(SPDK_ROOT_DIR)/mk/spdk.common.mk
+
+APP = overhead
+
+ifeq ($(OS),Linux)
+SYS_LIBS += -laio
+CFLAGS += -DHAVE_LIBAIO
+endif
+
+include $(SPDK_ROOT_DIR)/mk/nvme.libtest.mk
diff --git a/src/spdk/test/nvme/overhead/README b/src/spdk/test/nvme/overhead/README
new file mode 100644
index 00000000..b88c4217
--- /dev/null
+++ b/src/spdk/test/nvme/overhead/README
@@ -0,0 +1,24 @@
+This application measures the software overhead of I/O submission
+and completion for both the SPDK NVMe driver and an AIO file handle.
+It runs a random read, queue depth = 1 workload to a single device,
+and captures TSC as follows:
+
+* Submission: capture TSC before and after the I/O submission
+  call (SPDK or AIO).
+* Completion: capture TSC before and after the I/O completion
+  check.  Only record the TSC delta if the I/O completion check
+  resulted in a completed I/O.  Also use heuristics in the AIO
+  case to account for time spent in interrupt handling outside
+  of the actual I/O completion check.
+
+Usage:
+
+To test software overhead for a 4KB I/O over a 10 second period:
+
+SPDK:  overhead -s 4096 -t 10
+AIO:   overhead -s 4096 -t 10 /dev/nvme0n1
+
+Note that for the SPDK case, it will only use the first namespace
+on the first controller found by SPDK.  If a different namespace is
+desired, attach controllers individually to the kernel NVMe driver
+to ensure they will not be enumerated by SPDK.
diff --git a/src/spdk/test/nvme/overhead/overhead.c b/src/spdk/test/nvme/overhead/overhead.c
new file mode 100644
index 00000000..f35247a2
--- /dev/null
+++ b/src/spdk/test/nvme/overhead/overhead.c
@@ -0,0 +1,720 @@
+/*-
+ *   BSD LICENSE
+ *
+ *   Copyright (c) Intel Corporation.
+ *   All rights reserved.
+ *
+ *   Redistribution and use in source and binary forms, with or without
+ *   modification, are permitted provided that the following conditions
+ *   are met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ *       notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above copyright
+ *       notice, this list of conditions and the following disclaimer in
+ *       the documentation and/or other materials provided with the
+ *       distribution.
+ *     * Neither the name of Intel Corporation nor the names of its
+ *       contributors may be used to endorse or promote products derived
+ *       from this software without specific prior written permission.
+ *
+ *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ *   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ *   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ *   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ *   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ *   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ *   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ *   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "spdk/stdinc.h"
+
+#include "spdk/barrier.h"
+#include "spdk/fd.h"
+#include "spdk/nvme.h"
+#include "spdk/env.h"
+#include "spdk/string.h"
+#include "spdk/nvme_intel.h"
+#include "spdk/histogram_data.h"
+
+#if HAVE_LIBAIO
+#include <libaio.h>
+#endif
+
+struct ctrlr_entry {
+	struct spdk_nvme_ctrlr			*ctrlr;
+	struct ctrlr_entry			*next;
+	char					name[1024];
+};
+
+enum entry_type {
+	ENTRY_TYPE_NVME_NS,
+	ENTRY_TYPE_AIO_FILE,
+};
+
+struct ns_entry {
+	enum entry_type		type;
+
+	union {
+		struct {
+			struct spdk_nvme_ctrlr	*ctrlr;
+			struct spdk_nvme_ns	*ns;
+			struct spdk_nvme_qpair	*qpair;
+		} nvme;
+#if HAVE_LIBAIO
+		struct {
+			int			fd;
+			struct io_event		*events;
+			io_context_t		ctx;
+		} aio;
+#endif
+	} u;
+
+	uint32_t		io_size_blocks;
+	uint64_t		size_in_ios;
+	bool			is_draining;
+	uint32_t		current_queue_depth;
+	char			name[1024];
+	struct ns_entry		*next;
+
+	struct spdk_histogram_data	*submit_histogram;
+	struct spdk_histogram_data	*complete_histogram;
+};
+
+struct perf_task {
+	void			*buf;
+	uint64_t		submit_tsc;
+#if HAVE_LIBAIO
+	struct iocb		iocb;
+#endif
+};
+
+static bool g_enable_histogram = false;
+
+static struct ctrlr_entry *g_ctrlr = NULL;
+static struct ns_entry *g_ns = NULL;
+
+static uint64_t g_tsc_rate;
+
+static uint32_t g_io_size_bytes;
+static int g_time_in_sec;
+
+static int g_aio_optind; /* Index of first AIO filename in argv */
+
+struct perf_task *g_task;
+uint64_t g_tsc_submit = 0;
+uint64_t g_tsc_submit_min = UINT64_MAX;
+uint64_t g_tsc_submit_max = 0;
+uint64_t g_tsc_complete = 0;
+uint64_t g_tsc_complete_min = UINT64_MAX;
+uint64_t g_tsc_complete_max = 0;
+uint64_t g_io_completed = 0;
+
+static void
+register_ns(struct spdk_nvme_ctrlr *ctrlr, struct spdk_nvme_ns *ns)
+{
+	struct ns_entry *entry;
+	const struct spdk_nvme_ctrlr_data *cdata;
+
+	cdata = spdk_nvme_ctrlr_get_data(ctrlr);
+
+	if (!spdk_nvme_ns_is_active(ns)) {
+		printf("Controller %-20.20s (%-20.20s): Skipping inactive NS %u\n",
+		       cdata->mn, cdata->sn,
+		       spdk_nvme_ns_get_id(ns));
+		return;
+	}
+
+	if (spdk_nvme_ns_get_size(ns) < g_io_size_bytes ||
+	    spdk_nvme_ns_get_sector_size(ns) > g_io_size_bytes) {
+		printf("WARNING: controller %-20.20s (%-20.20s) ns %u has invalid "
+		       "ns size %" PRIu64 " / block size %u for I/O size %u\n",
+		       cdata->mn, cdata->sn, spdk_nvme_ns_get_id(ns),
+		       spdk_nvme_ns_get_size(ns), spdk_nvme_ns_get_sector_size(ns), g_io_size_bytes);
+		return;
+	}
+
+	entry = calloc(1, sizeof(struct ns_entry));
+	if (entry == NULL) {
+		perror("ns_entry malloc");
+		exit(1);
+	}
+
+	entry->type = ENTRY_TYPE_NVME_NS;
+	entry->u.nvme.ctrlr = ctrlr;
+	entry->u.nvme.ns = ns;
+
+	entry->size_in_ios = spdk_nvme_ns_get_size(ns) /
+			     g_io_size_bytes;
+	entry->io_size_blocks = g_io_size_bytes / spdk_nvme_ns_get_sector_size(ns);
+	entry->submit_histogram = spdk_histogram_data_alloc();
+	entry->complete_histogram = spdk_histogram_data_alloc();
+
+	snprintf(entry->name, 44, "%-20.20s (%-20.20s)", cdata->mn, cdata->sn);
+
+	entry->next = g_ns;
+	g_ns = entry;
+}
+
+static void
+register_ctrlr(struct spdk_nvme_ctrlr *ctrlr)
+{
+	int num_ns;
+	struct ctrlr_entry *entry = malloc(sizeof(struct ctrlr_entry));
+	const struct spdk_nvme_ctrlr_data *cdata = spdk_nvme_ctrlr_get_data(ctrlr);
+
+	if (entry == NULL) {
+		perror("ctrlr_entry malloc");
+		exit(1);
+	}
+
+	snprintf(entry->name, sizeof(entry->name), "%-20.20s (%-20.20s)", cdata->mn, cdata->sn);
+
+	entry->ctrlr = ctrlr;
+
+	entry->next = g_ctrlr;
+	g_ctrlr = entry;
+
+	num_ns = spdk_nvme_ctrlr_get_num_ns(ctrlr);
+	/* Only register the first namespace. */
+	if (num_ns < 1) {
+		fprintf(stderr, "controller found with no namespaces\n");
+		exit(1);
+	}
+
+	register_ns(ctrlr, spdk_nvme_ctrlr_get_ns(ctrlr, 1));
+}
+
+#if HAVE_LIBAIO
+static int
+register_aio_file(const char *path)
+{
+	struct ns_entry *entry;
+
+	int fd;
+	uint64_t size;
+	uint32_t blklen;
+
+	fd = open(path, O_RDWR | O_DIRECT);
+	if (fd < 0) {
+		fprintf(stderr, "Could not open AIO device %s: %s\n", path, strerror(errno));
+		return -1;
+	}
+
+	size = spdk_fd_get_size(fd);
+	if (size == 0) {
+		fprintf(stderr, "Could not determine size of AIO device %s\n", path);
+		close(fd);
+		return -1;
+	}
+
+	blklen = spdk_fd_get_blocklen(fd);
+	if (blklen == 0) {
+		fprintf(stderr, "Could not determine block size of AIO device %s\n", path);
+		close(fd);
+		return -1;
+	}
+
+	entry = calloc(1, sizeof(struct ns_entry));
+	if (entry == NULL) {
+		close(fd);
+		perror("aio ns_entry malloc");
+		return -1;
+	}
+
+	entry->type = ENTRY_TYPE_AIO_FILE;
+	entry->u.aio.fd = fd;
+	entry->size_in_ios = size / g_io_size_bytes;
+	entry->io_size_blocks = g_io_size_bytes / blklen;
+	entry->submit_histogram = spdk_histogram_data_alloc();
+	entry->complete_histogram = spdk_histogram_data_alloc();
+
+	snprintf(entry->name, sizeof(entry->name), "%s", path);
+
+	g_ns = entry;
+
+	return 0;
+}
+
+static int
+aio_submit(io_context_t aio_ctx, struct iocb *iocb, int fd, enum io_iocb_cmd cmd, void *buf,
+	   unsigned long nbytes, uint64_t offset, void *cb_ctx)
+{
+	iocb->aio_fildes = fd;
+	iocb->aio_reqprio = 0;
+	iocb->aio_lio_opcode = cmd;
+	iocb->u.c.buf = buf;
+	iocb->u.c.nbytes = nbytes;
+	iocb->u.c.offset = offset;
+	iocb->data = cb_ctx;
+
+	if (io_submit(aio_ctx, 1, &iocb) < 0) {
+		printf("io_submit");
+		return -1;
+	}
+
+	return 0;
+}
+
+static void
+aio_check_io(void)
+{
+	int count, i;
+	struct timespec timeout;
+
+	timeout.tv_sec = 0;
+	timeout.tv_nsec = 0;
+
+	count = io_getevents(g_ns->u.aio.ctx, 1, 1, g_ns->u.aio.events, &timeout);
+	if (count < 0) {
+		fprintf(stderr, "io_getevents error\n");
+		exit(1);
+	}
+
+	for (i = 0; i < count; i++) {
+		g_ns->current_queue_depth--;
+	}
+}
+#endif /* HAVE_LIBAIO */
+
+static void io_complete(void *ctx, const struct spdk_nvme_cpl *completion);
+
+static __thread unsigned int seed = 0;
+
+static void
+submit_single_io(void)
+{
+	uint64_t		offset_in_ios;
+	uint64_t		start;
+	int			rc;
+	struct ns_entry		*entry = g_ns;
+	uint64_t		tsc_submit;
+
+	offset_in_ios = rand_r(&seed) % entry->size_in_ios;
+
+	start = spdk_get_ticks();
+	spdk_rmb();
+#if HAVE_LIBAIO
+	if (entry->type == ENTRY_TYPE_AIO_FILE) {
+		rc = aio_submit(g_ns->u.aio.ctx, &g_task->iocb, entry->u.aio.fd, IO_CMD_PREAD, g_task->buf,
+				g_io_size_bytes, offset_in_ios * g_io_size_bytes, g_task);
+	} else
+#endif
+	{
+		rc = spdk_nvme_ns_cmd_read(entry->u.nvme.ns, g_ns->u.nvme.qpair, g_task->buf,
+					   offset_in_ios * entry->io_size_blocks,
+					   entry->io_size_blocks, io_complete, g_task, 0);
+	}
+
+	spdk_rmb();
+	tsc_submit = spdk_get_ticks() - start;
+	g_tsc_submit += tsc_submit;
+	if (tsc_submit < g_tsc_submit_min) {
+		g_tsc_submit_min = tsc_submit;
+	}
+	if (tsc_submit > g_tsc_submit_max) {
+		g_tsc_submit_max = tsc_submit;
+	}
+	if (g_enable_histogram) {
+		spdk_histogram_data_tally(entry->submit_histogram, tsc_submit);
+	}
+
+	if (rc != 0) {
+		fprintf(stderr, "starting I/O failed\n");
+	}
+
+	g_ns->current_queue_depth++;
+}
+
+static void
+io_complete(void *ctx, const struct spdk_nvme_cpl *completion)
+{
+	g_ns->current_queue_depth--;
+}
+
+uint64_t g_complete_tsc_start;
+
+static uint64_t
+check_io(void)
+{
+	uint64_t end, tsc_complete;
+
+	spdk_rmb();
+#if HAVE_LIBAIO
+	if (g_ns->type == ENTRY_TYPE_AIO_FILE) {
+		aio_check_io();
+	} else
+#endif
+	{
+		spdk_nvme_qpair_process_completions(g_ns->u.nvme.qpair, 0);
+	}
+	spdk_rmb();
+	end = spdk_get_ticks();
+	if (g_ns->current_queue_depth == 1) {
+		/*
+		 * Account for race condition in AIO case where interrupt occurs
+		 *  after checking for queue depth.  If the timestamp capture
+		 *  is too big compared to the last capture, assume that an
+		 *  interrupt fired, and do not bump the start tsc forward.  This
+		 *  will ensure this extra time is accounted for next time through
+		 *  when we see current_queue_depth drop to 0.
+		 */
+		if (g_ns->type == ENTRY_TYPE_NVME_NS || (end - g_complete_tsc_start) < 500) {
+			g_complete_tsc_start = end;
+		}
+	} else {
+		tsc_complete = end - g_complete_tsc_start;
+		g_tsc_complete += tsc_complete;
+		if (tsc_complete < g_tsc_complete_min) {
+			g_tsc_complete_min = tsc_complete;
+		}
+		if (tsc_complete > g_tsc_complete_max) {
+			g_tsc_complete_max = tsc_complete;
+		}
+		if (g_enable_histogram) {
+			spdk_histogram_data_tally(g_ns->complete_histogram, tsc_complete);
+		}
+		g_io_completed++;
+		if (!g_ns->is_draining) {
+			submit_single_io();
+		}
+		end = g_complete_tsc_start = spdk_get_ticks();
+	}
+
+	return end;
+}
+
+static void
+drain_io(void)
+{
+	g_ns->is_draining = true;
+	while (g_ns->current_queue_depth > 0) {
+		check_io();
+	}
+}
+
+static int
+init_ns_worker_ctx(void)
+{
+	if (g_ns->type == ENTRY_TYPE_AIO_FILE) {
+#ifdef HAVE_LIBAIO
+		g_ns->u.aio.events = calloc(1, sizeof(struct io_event));
+		if (!g_ns->u.aio.events) {
+			return -1;
+		}
+		g_ns->u.aio.ctx = 0;
+		if (io_setup(1, &g_ns->u.aio.ctx) < 0) {
+			free(g_ns->u.aio.events);
+			perror("io_setup");
+			return -1;
+		}
+#endif
+	} else {
+		/*
+		 * TODO: If a controller has multiple namespaces, they could all use the same queue.
+		 *  For now, give each namespace/thread combination its own queue.
+		 */
+		g_ns->u.nvme.qpair = spdk_nvme_ctrlr_alloc_io_qpair(g_ns->u.nvme.ctrlr, NULL, 0);
+		if (!g_ns->u.nvme.qpair) {
+			printf("ERROR: spdk_nvme_ctrlr_alloc_io_qpair failed\n");
+			return -1;
+		}
+	}
+
+	return 0;
+}
+
+static void
+cleanup_ns_worker_ctx(void)
+{
+	if (g_ns->type == ENTRY_TYPE_AIO_FILE) {
+#ifdef HAVE_LIBAIO
+		io_destroy(g_ns->u.aio.ctx);
+		free(g_ns->u.aio.events);
+#endif
+	} else {
+		spdk_nvme_ctrlr_free_io_qpair(g_ns->u.nvme.qpair);
+	}
+}
+
+static int
+work_fn(void)
+{
+	uint64_t tsc_end, current;
+
+	/* Allocate a queue pair for each namespace. */
+	if (init_ns_worker_ctx() != 0) {
+		printf("ERROR: init_ns_worker_ctx() failed\n");
+		return 1;
+	}
+
+	tsc_end = spdk_get_ticks() + g_time_in_sec * g_tsc_rate;
+
+	/* Submit initial I/O for each namespace. */
+	submit_single_io();
+	g_complete_tsc_start = spdk_get_ticks();
+
+	while (1) {
+		/*
+		 * Check for completed I/O for each controller. A new
+		 * I/O will be submitted in the io_complete callback
+		 * to replace each I/O that is completed.
+		 */
+		current = check_io();
+
+		if (current > tsc_end) {
+			break;
+		}
+	}
+
+	drain_io();
+	cleanup_ns_worker_ctx();
+
+	return 0;
+}
+
+static void usage(char *program_name)
+{
+	printf("%s options", program_name);
+#if HAVE_LIBAIO
+	printf(" [AIO device(s)]...");
+#endif
+	printf("\n");
+	printf("\t[-s io size in bytes]\n");
+	printf("\t[-t time in seconds]\n");
+	printf("\t\t(default: 1)]\n");
+	printf("\t[-H enable histograms]\n");
+}
+
+static void
+print_bucket(void *ctx, uint64_t start, uint64_t end, uint64_t count,
+	     uint64_t total, uint64_t so_far)
+{
+	double so_far_pct;
+
+	if (count == 0) {
+		return;
+	}
+
+	so_far_pct = (double)so_far * 100 / total;
+
+	printf("%9.3f - %9.3f: %9.4f%%  (%9ju)\n",
+	       (double)start * 1000 * 1000 / g_tsc_rate,
+	       (double)end * 1000 * 1000 / g_tsc_rate,
+	       so_far_pct, count);
+}
+
+static void
+print_stats(void)
+{
+	double divisor = (double)g_tsc_rate / (1000 * 1000 * 1000);
+
+	printf("submit (in ns)   avg, min, max = %8.1f, %8.1f, %8.1f\n",
+	       (double)g_tsc_submit / g_io_completed / divisor,
+	       (double)g_tsc_submit_min / divisor,
+	       (double)g_tsc_submit_max / divisor);
+	printf("complete (in ns) avg, min, max = %8.1f, %8.1f, %8.1f\n",
+	       (double)g_tsc_complete / g_io_completed / divisor,
+	       (double)g_tsc_complete_min / divisor,
+	       (double)g_tsc_complete_max / divisor);
+
+	if (!g_enable_histogram) {
+		return;
+	}
+
+	printf("\n");
+	printf("Submit histogram\n");
+	printf("================\n");
+	printf("       Range in us     Cumulative     Count\n");
+	spdk_histogram_data_iterate(g_ns->submit_histogram, print_bucket, NULL);
+	printf("\n");
+
+	printf("Complete histogram\n");
+	printf("==================\n");
+	printf("       Range in us     Cumulative     Count\n");
+	spdk_histogram_data_iterate(g_ns->complete_histogram, print_bucket, NULL);
+	printf("\n");
+
+}
+
+static int
+parse_args(int argc, char **argv)
+{
+	int op;
+
+	/* default value */
+	g_io_size_bytes = 0;
+	g_time_in_sec = 0;
+
+	while ((op = getopt(argc, argv, "hs:t:H")) != -1) {
+		switch (op) {
+		case 'h':
+			usage(argv[0]);
+			exit(0);
+			break;
+		case 's':
+			g_io_size_bytes = atoi(optarg);
+			break;
+		case 't':
+			g_time_in_sec = atoi(optarg);
+			break;
+		case 'H':
+			g_enable_histogram = true;
+			break;
+		default:
+			usage(argv[0]);
+			return 1;
+		}
+	}
+
+	if (!g_io_size_bytes) {
+		usage(argv[0]);
+		return 1;
+	}
+	if (!g_time_in_sec) {
+		usage(argv[0]);
+		return 1;
+	}
+
+	g_aio_optind = optind;
+
+	return 0;
+}
+
+static bool
+probe_cb(void *cb_ctx, const struct spdk_nvme_transport_id *trid,
+	 struct spdk_nvme_ctrlr_opts *opts)
+{
+	static uint32_t ctrlr_found = 0;
+
+	if (ctrlr_found == 1) {
+		fprintf(stderr, "only attaching to one controller, so skipping\n");
+		fprintf(stderr, " controller at PCI address %s\n",
+			trid->traddr);
+		return false;
+	}
+	ctrlr_found = 1;
+
+	printf("Attaching to %s\n", trid->traddr);
+
+	return true;
+}
+
+static void
+attach_cb(void *cb_ctx, const struct spdk_nvme_transport_id *trid,
+	  struct spdk_nvme_ctrlr *ctrlr, const struct spdk_nvme_ctrlr_opts *opts)
+{
+	printf("Attached to %s\n", trid->traddr);
+
+	register_ctrlr(ctrlr);
+}
+
+static int
+register_controllers(void)
+{
+	printf("Initializing NVMe Controllers\n");
+
+	if (spdk_nvme_probe(NULL, NULL, probe_cb, attach_cb, NULL) != 0) {
+		fprintf(stderr, "spdk_nvme_probe() failed\n");
+		return 1;
+	}
+
+	if (g_ns == NULL) {
+		fprintf(stderr, "no NVMe controller found - check that device is bound to uio/vfio\n");
+		return 1;
+	}
+
+	return 0;
+}
+
+static void
+cleanup(void)
+{
+	struct ns_entry *ns_entry = g_ns;
+	struct ctrlr_entry *ctrlr_entry = g_ctrlr;
+
+	while (ns_entry) {
+		struct ns_entry *next = ns_entry->next;
+
+		spdk_histogram_data_free(ns_entry->submit_histogram);
+		spdk_histogram_data_free(ns_entry->complete_histogram);
+		free(ns_entry);
+		ns_entry = next;
+	}
+
+	while (ctrlr_entry) {
+		struct ctrlr_entry *next = ctrlr_entry->next;
+
+		spdk_nvme_detach(ctrlr_entry->ctrlr);
+		free(ctrlr_entry);
+		ctrlr_entry = next;
+	}
+}
+
+int main(int argc, char **argv)
+{
+	int			rc;
+	struct spdk_env_opts	opts;
+
+	rc = parse_args(argc, argv);
+	if (rc != 0) {
+		return rc;
+	}
+
+	spdk_env_opts_init(&opts);
+	opts.name = "overhead";
+	opts.core_mask = "0x1";
+	opts.shm_id = 0;
+	if (spdk_env_init(&opts) < 0) {
+		fprintf(stderr, "Unable to initialize SPDK env\n");
+		return 1;
+	}
+
+	g_task = spdk_dma_zmalloc(sizeof(struct perf_task), 0, NULL);
+	if (g_task == NULL) {
+		fprintf(stderr, "g_task alloc failed\n");
+		exit(1);
+	}
+
+	g_task->buf = spdk_dma_zmalloc(g_io_size_bytes, 0x1000, NULL);
+	if (g_task->buf == NULL) {
+		fprintf(stderr, "g_task->buf spdk_dma_zmalloc failed\n");
+		exit(1);
+	}
+
+	g_tsc_rate = spdk_get_ticks_hz();
+
+#if HAVE_LIBAIO
+	if (g_aio_optind < argc) {
+		printf("Measuring overhead for AIO device %s.\n", argv[g_aio_optind]);
+		if (register_aio_file(argv[g_aio_optind]) != 0) {
+			cleanup();
+			return -1;
+		}
+	} else
+#endif
+	{
+		if (register_controllers() != 0) {
+			cleanup();
+			return -1;
+		}
+	}
+
+	printf("Initialization complete. Launching workers.\n");
+
+	rc = work_fn();
+
+	print_stats();
+
+	cleanup();
+
+	if (rc != 0) {
+		fprintf(stderr, "%s: errors occured\n", argv[0]);
+	}
+
+	return rc;
+}