Spdk/examples/nvme/hello_world/hello_world.c

/*-
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 *
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 *       notice, this list of conditions and the following disclaimer.
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 *       notice, this list of conditions and the following disclaimer in
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 *       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
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#include <stdio.h>
#include <string.h>
#include <unistd.h>

#include <rte_config.h>
#include <rte_mempool.h>
#include <rte_malloc.h>

#include "spdk/nvme.h"
#include "spdk/pci.h"

struct ctrlr_entry {
	struct spdk_nvme_ctrlr	*ctrlr;
	struct ctrlr_entry	*next;
	char			name[1024];
};

struct ns_entry {
	struct spdk_nvme_ctrlr	*ctrlr;
	struct spdk_nvme_ns	*ns;
	struct ns_entry		*next;
	struct spdk_nvme_qpair	*qpair;
};

struct rte_mempool *request_mempool;

static struct ctrlr_entry *g_controllers = NULL;
static struct ns_entry *g_namespaces = NULL;

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;

	/*
	 * spdk_nvme_ctrlr is the logical abstraction in SPDK for an NVMe
	 *  controller.  During initialization, the IDENTIFY data for the
	 *  controller is read using an NVMe admin command, and that data
	 *  can be retrieved using spdk_nvme_ctrlr_get_data() to get
	 *  detailed information on the controller.  Refer to the NVMe
	 *  specification for more details on IDENTIFY for NVMe controllers.
	 */
	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;
	}

	entry = malloc(sizeof(struct ns_entry));
	if (entry == NULL) {
		perror("ns_entry malloc");
		exit(1);
	}

	entry->ctrlr = ctrlr;
	entry->ns = ns;
	entry->next = g_namespaces;
	g_namespaces = entry;

	printf("  Namespace ID: %d size: %juGB\n", spdk_nvme_ns_get_id(ns),
	       spdk_nvme_ns_get_size(ns) / 1000000000);
}

struct hello_world_sequence {
	struct ns_entry	*ns_entry;
	char		*buf;
	int		is_completed;
};

static void
read_complete(void *arg, const struct spdk_nvme_cpl *completion)
{
	struct hello_world_sequence *sequence = arg;

	/*
	 * The read I/O has completed.  Print the contents of the
	 *  buffer, free the buffer, then mark the sequence as
	 *  completed.  This will trigger the hello_world() function
	 *  to exit its polling loop.
	 */
	printf("%s", sequence->buf);
	rte_free(sequence->buf);
	sequence->is_completed = 1;
}

static void
write_complete(void *arg, const struct spdk_nvme_cpl *completion)
{
	struct hello_world_sequence	*sequence = arg;
	struct ns_entry			*ns_entry = sequence->ns_entry;
	int				rc;

	/*
	 * The write I/O has completed.  Free the buffer associated with
	 *  the write I/O and allocate a new zeroed buffer for reading
	 *  the data back from the NVMe namespace.
	 */
	rte_free(sequence->buf);
	sequence->buf = rte_zmalloc(NULL, 0x1000, 0x1000);

	rc = spdk_nvme_ns_cmd_read(ns_entry->ns, ns_entry->qpair, sequence->buf,
				   0, /* LBA start */
				   1, /* number of LBAs */
				   read_complete, (void *)sequence, 0);
	if (rc != 0) {
		fprintf(stderr, "starting read I/O failed\n");
		exit(1);
	}
}

static void
hello_world(void)
{
	struct ns_entry			*ns_entry;
	struct hello_world_sequence	sequence;
	int				rc;

	ns_entry = g_namespaces;
	while (ns_entry != NULL) {
		/*
		 * Allocate an I/O qpair that we can use to submit read/write requests
		 *  to namespaces on the controller.  NVMe controllers typically support
		 *  many qpairs per controller.  Any I/O qpair allocated for a controller
		 *  can submit I/O to any namespace on that controller.
		 *
		 * The SPDK NVMe driver provides no synchronization for qpair accesses -
		 *  the application must ensure only a single thread submits I/O to a
		 *  qpair, and that same thread must also check for completions on that
		 *  qpair.  This enables extremely efficient I/O processing by making all
		 *  I/O operations completely lockless.
		 */
		ns_entry->qpair = spdk_nvme_ctrlr_alloc_io_qpair(ns_entry->ctrlr, 0);
		if (ns_entry->qpair == NULL) {
			printf("ERROR: init_ns_worker_ctx() failed\n");
			return;
		}

		/*
		 * Use DPDK rte_zmalloc to allocate a 4KB zeroed buffer.  This memory
		 *  will be allocated from 2MB hugepages and will be pinned.  These are
		 *  both requirements for data buffers used for SPDK NVMe I/O operations.
		 */
		sequence.buf = rte_zmalloc(NULL, 0x1000, 0x1000);
		sequence.is_completed = 0;
		sequence.ns_entry = ns_entry;

		/*
		 * Print "Hello world!" to sequence.buf.  We will write this data to LBA
		 *  0 on the namespace, and then later read it back into a separate buffer
		 *  to demonstrate the full I/O path.
		 */
		sprintf(sequence.buf, "Hello world!\n");

		/*
		 * Write the data buffer to LBA 0 of this namespace.  "write_complete" and
		 *  "&sequence" are specified as the completion callback function and
		 *  argument respectively.  write_complete() will be called with the
		 *  value of &sequence as a parameter when the write I/O is completed.
		 *  This allows users to potentially specify different completion
		 *  callback routines for each I/O, as well as pass a unique handle
		 *  as an argument so the application knows which I/O has completed.
		 *
		 * Note that the SPDK NVMe driver will only check for completions
		 *  when the application calls spdk_nvme_qpair_process_completions().
		 *  It is the responsibility of the application to trigger the polling
		 *  process.
		 */
		rc = spdk_nvme_ns_cmd_write(ns_entry->ns, ns_entry->qpair, sequence.buf,
					    0, /* LBA start */
					    1, /* number of LBAs */
					    write_complete, &sequence, 0);
		if (rc != 0) {
			fprintf(stderr, "starting write I/O failed\n");
			exit(1);
		}

		/*
		 * Poll for completions.  0 here means process all available completions.
		 *  In certain usage models, the caller may specify a positive integer
		 *  instead of 0 to signify the maximum number of completions it should
		 *  process.  This function will never block - if there are no
		 *  completions pending on the specified qpair, it will return immediately.
		 *
		 * When the write I/O completes, write_complete() will submit a new I/O
		 *  to read LBA 0 into a separate buffer, specifying read_complete() as its
		 *  completion routine.  When the read I/O completes, read_complete() will
		 *  print the buffer contents and set sequence.is_completed = 1.  That will
		 *  break this loop and then exit the program.
		 */
		while (!sequence.is_completed) {
			spdk_nvme_qpair_process_completions(ns_entry->qpair, 0);
		}

		/*
		 * Free the I/O qpair.  This typically is done when an application exits.
		 *  But SPDK does support freeing and then reallocating qpairs during
		 *  operation.  It is the responsibility of the caller to ensure all
		 *  pending I/O are completed before trying to free the qpair.
		 */
		spdk_nvme_ctrlr_free_io_qpair(ns_entry->qpair);
		ns_entry = ns_entry->next;
	}
}

static bool
probe_cb(void *cb_ctx, struct spdk_pci_device *dev, struct spdk_nvme_ctrlr_opts *opts)
{
	if (spdk_pci_device_has_non_uio_driver(dev)) {
		/*
		 * If an NVMe controller is found, but it is attached to a non-uio
		 *  driver (i.e. the kernel NVMe driver), we will not try to attach
		 *  to it.
		 */
		fprintf(stderr, "non-uio kernel driver attached to NVMe\n");
		fprintf(stderr, " controller at PCI address %04x:%02x:%02x.%02x\n",
			spdk_pci_device_get_domain(dev),
			spdk_pci_device_get_bus(dev),
			spdk_pci_device_get_dev(dev),
			spdk_pci_device_get_func(dev));
		fprintf(stderr, " skipping...\n");
		return false;
	}

	printf("Attaching to %04x:%02x:%02x.%02x\n",
	       spdk_pci_device_get_domain(dev),
	       spdk_pci_device_get_bus(dev),
	       spdk_pci_device_get_dev(dev),
	       spdk_pci_device_get_func(dev));

	return true;
}

static void
attach_cb(void *cb_ctx, struct spdk_pci_device *dev, struct spdk_nvme_ctrlr *ctrlr,
	  const struct spdk_nvme_ctrlr_opts *opts)
{
	int nsid, num_ns;
	struct ctrlr_entry *entry;
	const struct spdk_nvme_ctrlr_data *cdata = spdk_nvme_ctrlr_get_data(ctrlr);

	entry = malloc(sizeof(struct ctrlr_entry));
	if (entry == NULL) {
		perror("ctrlr_entry malloc");
		exit(1);
	}

	printf("Attached to %04x:%02x:%02x.%02x\n",
	       spdk_pci_device_get_domain(dev),
	       spdk_pci_device_get_bus(dev),
	       spdk_pci_device_get_dev(dev),
	       spdk_pci_device_get_func(dev));

	snprintf(entry->name, sizeof(entry->name), "%-20.20s (%-20.20s)", cdata->mn, cdata->sn);

	entry->ctrlr = ctrlr;
	entry->next = g_controllers;
	g_controllers = entry;

	/*
	 * Each controller has one of more namespaces.  An NVMe namespace is basically
	 *  equivalent to a SCSI LUN.  The controller's IDENTIFY data tells us how
	 *  many namespaces exist on the controller.  For Intel(R) P3X00 controllers,
	 *  it will just be one namespace.
	 *
	 * Note that in NVMe, namespace IDs start at 1, not 0.
	 */
	num_ns = spdk_nvme_ctrlr_get_num_ns(ctrlr);
	printf("Using controller %s with %d namespaces.\n", entry->name, num_ns);
	for (nsid = 1; nsid <= num_ns; nsid++) {
		register_ns(ctrlr, spdk_nvme_ctrlr_get_ns(ctrlr, nsid));
	}
}

static void
cleanup(void)
{
	struct ns_entry *ns_entry = g_namespaces;
	struct ctrlr_entry *ctrlr_entry = g_controllers;

	while (ns_entry) {
		struct ns_entry *next = ns_entry->next;
		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;
	}
}

static char *ealargs[] = {
	"hello_world",
	"-c 0x1",
};

int main(int argc, char **argv)
{
	int rc;

	/*
	 * By default, the SPDK NVMe driver uses DPDK for huge page-based
	 *  memory management and NVMe request buffer pools.  Huge pages can
	 *  be either 2MB or 1GB in size (instead of 4KB) and are pinned in
	 *  memory.  Pinned memory is important to ensure DMA operations
	 *  never target swapped out memory.
	 *
	 * So first we must initialize DPDK.  "-c 0x1" indicates to only use
	 *  core 0.
	 */
	rc = rte_eal_init(sizeof(ealargs) / sizeof(ealargs[0]), ealargs);
	if (rc < 0) {
		fprintf(stderr, "could not initialize dpdk\n");
		return 1;
	}

	/*
	 * Create the NVMe request buffer pool.  This will be used internally
	 *  by the SPDK NVMe driver to allocate an spdk_nvme_request data
	 *  structure for each I/O request.  This is implicitly passed to
	 *  the SPDK NVMe driver via an extern declaration in nvme_impl.h.
	 */
	request_mempool = rte_mempool_create("nvme_request", 8192,
					     spdk_nvme_request_size(), 128, 0,
					     NULL, NULL, NULL, NULL,
					     SOCKET_ID_ANY, 0);

	if (request_mempool == NULL) {
		fprintf(stderr, "could not initialize request mempool\n");
		return 1;
	}

	printf("Initializing NVMe Controllers\n");

	/*
	 * Start the SPDK NVMe enumeration process.  probe_cb will be called
	 *  for each NVMe controller found, giving our application a choice on
	 *  whether to attach to each controller.  attach_cb will then be
	 *  called for each controller after the SPDK NVMe driver has completed
	 *  initializing the controller we chose to attach.
	 */
	rc = spdk_nvme_probe(NULL, probe_cb, attach_cb, NULL);
	if (rc != 0) {
		fprintf(stderr, "spdk_nvme_probe() failed\n");
		cleanup();
		return 1;
	}

	printf("Initialization complete.\n");
	hello_world();
	cleanup();
	return 0;
}