null_blk: multi queue aware block test driver
A driver that simply completes IO it receives, it does no transfers. Written to fascilitate testing of the blk-mq code. It supports various module options to use either bio queueing, rq queueing, or mq mode. Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Jens Axboe
Родитель
320ae51fee
Коммит
f2298c0403
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@ -15,6 +15,9 @@ menuconfig BLK_DEV
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if BLK_DEV
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config BLK_DEV_NULL_BLK
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tristate "Null test block driver"
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config BLK_DEV_FD
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tristate "Normal floppy disk support"
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depends on ARCH_MAY_HAVE_PC_FDC
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@ -41,6 +41,7 @@ obj-$(CONFIG_BLK_DEV_RBD) += rbd.o
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obj-$(CONFIG_BLK_DEV_PCIESSD_MTIP32XX) += mtip32xx/
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obj-$(CONFIG_BLK_DEV_RSXX) += rsxx/
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obj-$(CONFIG_BLK_DEV_NULL_BLK) += null_blk.o
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nvme-y := nvme-core.o nvme-scsi.o
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swim_mod-y := swim.o swim_asm.o
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@ -0,0 +1,635 @@
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#include <linux/module.h>
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#include <linux/moduleparam.h>
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#include <linux/sched.h>
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#include <linux/fs.h>
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#include <linux/blkdev.h>
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#include <linux/init.h>
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#include <linux/slab.h>
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#include <linux/blk-mq.h>
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#include <linux/hrtimer.h>
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struct nullb_cmd {
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struct list_head list;
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struct llist_node ll_list;
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struct call_single_data csd;
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struct request *rq;
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struct bio *bio;
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unsigned int tag;
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struct nullb_queue *nq;
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};
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struct nullb_queue {
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unsigned long *tag_map;
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wait_queue_head_t wait;
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unsigned int queue_depth;
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struct nullb_cmd *cmds;
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};
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struct nullb {
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struct list_head list;
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unsigned int index;
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struct request_queue *q;
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struct gendisk *disk;
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struct hrtimer timer;
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unsigned int queue_depth;
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spinlock_t lock;
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struct nullb_queue *queues;
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unsigned int nr_queues;
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};
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static LIST_HEAD(nullb_list);
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static struct mutex lock;
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static int null_major;
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static int nullb_indexes;
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struct completion_queue {
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struct llist_head list;
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struct hrtimer timer;
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};
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/*
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* These are per-cpu for now, they will need to be configured by the
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* complete_queues parameter and appropriately mapped.
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*/
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static DEFINE_PER_CPU(struct completion_queue, completion_queues);
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enum {
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NULL_IRQ_NONE = 0,
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NULL_IRQ_SOFTIRQ = 1,
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NULL_IRQ_TIMER = 2,
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NULL_Q_BIO = 0,
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NULL_Q_RQ = 1,
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NULL_Q_MQ = 2,
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};
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static int submit_queues = 1;
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module_param(submit_queues, int, S_IRUGO);
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MODULE_PARM_DESC(submit_queues, "Number of submission queues");
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static int home_node = NUMA_NO_NODE;
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module_param(home_node, int, S_IRUGO);
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MODULE_PARM_DESC(home_node, "Home node for the device");
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static int queue_mode = NULL_Q_MQ;
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module_param(queue_mode, int, S_IRUGO);
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MODULE_PARM_DESC(use_mq, "Use blk-mq interface (0=bio,1=rq,2=multiqueue)");
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static int gb = 250;
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module_param(gb, int, S_IRUGO);
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MODULE_PARM_DESC(gb, "Size in GB");
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static int bs = 512;
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module_param(bs, int, S_IRUGO);
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MODULE_PARM_DESC(bs, "Block size (in bytes)");
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static int nr_devices = 2;
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module_param(nr_devices, int, S_IRUGO);
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MODULE_PARM_DESC(nr_devices, "Number of devices to register");
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static int irqmode = NULL_IRQ_SOFTIRQ;
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module_param(irqmode, int, S_IRUGO);
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MODULE_PARM_DESC(irqmode, "IRQ completion handler. 0-none, 1-softirq, 2-timer");
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static int completion_nsec = 10000;
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module_param(completion_nsec, int, S_IRUGO);
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MODULE_PARM_DESC(completion_nsec, "Time in ns to complete a request in hardware. Default: 10,000ns");
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static int hw_queue_depth = 64;
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module_param(hw_queue_depth, int, S_IRUGO);
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MODULE_PARM_DESC(hw_queue_depth, "Queue depth for each hardware queue. Default: 64");
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static bool use_per_node_hctx = true;
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module_param(use_per_node_hctx, bool, S_IRUGO);
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MODULE_PARM_DESC(use_per_node_hctx, "Use per-node allocation for hardware context queues. Default: true");
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static void put_tag(struct nullb_queue *nq, unsigned int tag)
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{
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clear_bit_unlock(tag, nq->tag_map);
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if (waitqueue_active(&nq->wait))
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wake_up(&nq->wait);
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}
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static unsigned int get_tag(struct nullb_queue *nq)
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{
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unsigned int tag;
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do {
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tag = find_first_zero_bit(nq->tag_map, nq->queue_depth);
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if (tag >= nq->queue_depth)
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return -1U;
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} while (test_and_set_bit_lock(tag, nq->tag_map));
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return tag;
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}
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static void free_cmd(struct nullb_cmd *cmd)
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{
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put_tag(cmd->nq, cmd->tag);
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}
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static struct nullb_cmd *__alloc_cmd(struct nullb_queue *nq)
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{
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struct nullb_cmd *cmd;
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unsigned int tag;
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tag = get_tag(nq);
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if (tag != -1U) {
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cmd = &nq->cmds[tag];
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cmd->tag = tag;
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cmd->nq = nq;
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return cmd;
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}
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return NULL;
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}
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static struct nullb_cmd *alloc_cmd(struct nullb_queue *nq, int can_wait)
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{
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struct nullb_cmd *cmd;
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DEFINE_WAIT(wait);
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cmd = __alloc_cmd(nq);
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if (cmd || !can_wait)
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return cmd;
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do {
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prepare_to_wait(&nq->wait, &wait, TASK_UNINTERRUPTIBLE);
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cmd = __alloc_cmd(nq);
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if (cmd)
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break;
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io_schedule();
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} while (1);
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finish_wait(&nq->wait, &wait);
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return cmd;
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}
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static void end_cmd(struct nullb_cmd *cmd)
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{
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if (cmd->rq) {
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if (queue_mode == NULL_Q_MQ)
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blk_mq_end_io(cmd->rq, 0);
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else {
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INIT_LIST_HEAD(&cmd->rq->queuelist);
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blk_end_request_all(cmd->rq, 0);
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}
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} else if (cmd->bio)
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bio_endio(cmd->bio, 0);
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if (queue_mode != NULL_Q_MQ)
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free_cmd(cmd);
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}
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static enum hrtimer_restart null_cmd_timer_expired(struct hrtimer *timer)
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{
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struct completion_queue *cq;
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struct llist_node *entry;
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struct nullb_cmd *cmd;
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cq = &per_cpu(completion_queues, smp_processor_id());
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while ((entry = llist_del_all(&cq->list)) != NULL) {
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do {
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cmd = container_of(entry, struct nullb_cmd, ll_list);
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end_cmd(cmd);
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entry = entry->next;
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} while (entry);
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}
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return HRTIMER_NORESTART;
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}
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static void null_cmd_end_timer(struct nullb_cmd *cmd)
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{
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struct completion_queue *cq = &per_cpu(completion_queues, get_cpu());
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cmd->ll_list.next = NULL;
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if (llist_add(&cmd->ll_list, &cq->list)) {
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ktime_t kt = ktime_set(0, completion_nsec);
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hrtimer_start(&cq->timer, kt, HRTIMER_MODE_REL);
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}
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put_cpu();
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}
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static void null_softirq_done_fn(struct request *rq)
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{
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blk_end_request_all(rq, 0);
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}
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#if defined(CONFIG_SMP) && defined(CONFIG_USE_GENERIC_SMP_HELPERS)
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static void null_ipi_cmd_end_io(void *data)
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{
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struct completion_queue *cq;
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struct llist_node *entry, *next;
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struct nullb_cmd *cmd;
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cq = &per_cpu(completion_queues, smp_processor_id());
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entry = llist_del_all(&cq->list);
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while (entry) {
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next = entry->next;
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cmd = llist_entry(entry, struct nullb_cmd, ll_list);
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end_cmd(cmd);
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entry = next;
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}
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}
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static void null_cmd_end_ipi(struct nullb_cmd *cmd)
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{
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struct call_single_data *data = &cmd->csd;
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int cpu = get_cpu();
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struct completion_queue *cq = &per_cpu(completion_queues, cpu);
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cmd->ll_list.next = NULL;
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if (llist_add(&cmd->ll_list, &cq->list)) {
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data->func = null_ipi_cmd_end_io;
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data->flags = 0;
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__smp_call_function_single(cpu, data, 0);
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}
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put_cpu();
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}
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#endif /* CONFIG_SMP && CONFIG_USE_GENERIC_SMP_HELPERS */
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static inline void null_handle_cmd(struct nullb_cmd *cmd)
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{
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/* Complete IO by inline, softirq or timer */
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switch (irqmode) {
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case NULL_IRQ_NONE:
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end_cmd(cmd);
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break;
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case NULL_IRQ_SOFTIRQ:
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#if defined(CONFIG_SMP) && defined(CONFIG_USE_GENERIC_SMP_HELPERS)
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null_cmd_end_ipi(cmd);
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#else
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end_cmd(cmd);
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#endif
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break;
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case NULL_IRQ_TIMER:
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null_cmd_end_timer(cmd);
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break;
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}
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}
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static struct nullb_queue *nullb_to_queue(struct nullb *nullb)
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{
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int index = 0;
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if (nullb->nr_queues != 1)
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index = raw_smp_processor_id() / ((nr_cpu_ids + nullb->nr_queues - 1) / nullb->nr_queues);
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return &nullb->queues[index];
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}
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static void null_queue_bio(struct request_queue *q, struct bio *bio)
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{
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struct nullb *nullb = q->queuedata;
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struct nullb_queue *nq = nullb_to_queue(nullb);
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struct nullb_cmd *cmd;
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cmd = alloc_cmd(nq, 1);
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cmd->bio = bio;
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null_handle_cmd(cmd);
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}
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static int null_rq_prep_fn(struct request_queue *q, struct request *req)
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{
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struct nullb *nullb = q->queuedata;
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struct nullb_queue *nq = nullb_to_queue(nullb);
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struct nullb_cmd *cmd;
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cmd = alloc_cmd(nq, 0);
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if (cmd) {
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cmd->rq = req;
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req->special = cmd;
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return BLKPREP_OK;
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}
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return BLKPREP_DEFER;
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}
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static void null_request_fn(struct request_queue *q)
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{
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struct request *rq;
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while ((rq = blk_fetch_request(q)) != NULL) {
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struct nullb_cmd *cmd = rq->special;
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spin_unlock_irq(q->queue_lock);
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null_handle_cmd(cmd);
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spin_lock_irq(q->queue_lock);
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}
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}
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static int null_queue_rq(struct blk_mq_hw_ctx *hctx, struct request *rq)
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{
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struct nullb_cmd *cmd = rq->special;
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cmd->rq = rq;
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cmd->nq = hctx->driver_data;
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null_handle_cmd(cmd);
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return BLK_MQ_RQ_QUEUE_OK;
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}
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static struct blk_mq_hw_ctx *null_alloc_hctx(struct blk_mq_reg *reg, unsigned int hctx_index)
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{
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return kzalloc_node(sizeof(struct blk_mq_hw_ctx), GFP_KERNEL,
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hctx_index);
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}
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static void null_free_hctx(struct blk_mq_hw_ctx *hctx, unsigned int hctx_index)
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{
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kfree(hctx);
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}
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static int null_init_hctx(struct blk_mq_hw_ctx *hctx, void *data,
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unsigned int index)
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{
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struct nullb *nullb = data;
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struct nullb_queue *nq = &nullb->queues[index];
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init_waitqueue_head(&nq->wait);
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nq->queue_depth = nullb->queue_depth;
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nullb->nr_queues++;
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hctx->driver_data = nq;
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return 0;
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}
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static struct blk_mq_ops null_mq_ops = {
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.queue_rq = null_queue_rq,
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.map_queue = blk_mq_map_queue,
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.init_hctx = null_init_hctx,
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};
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static struct blk_mq_reg null_mq_reg = {
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.ops = &null_mq_ops,
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.queue_depth = 64,
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.cmd_size = sizeof(struct nullb_cmd),
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.flags = BLK_MQ_F_SHOULD_MERGE,
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};
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static void null_del_dev(struct nullb *nullb)
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{
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list_del_init(&nullb->list);
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del_gendisk(nullb->disk);
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if (queue_mode == NULL_Q_MQ)
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blk_mq_free_queue(nullb->q);
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else
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blk_cleanup_queue(nullb->q);
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put_disk(nullb->disk);
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kfree(nullb);
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}
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static int null_open(struct block_device *bdev, fmode_t mode)
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{
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return 0;
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}
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static void null_release(struct gendisk *disk, fmode_t mode)
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{
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}
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static const struct block_device_operations null_fops = {
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.owner = THIS_MODULE,
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.open = null_open,
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.release = null_release,
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};
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static int setup_commands(struct nullb_queue *nq)
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{
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struct nullb_cmd *cmd;
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int i, tag_size;
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nq->cmds = kzalloc(nq->queue_depth * sizeof(*cmd), GFP_KERNEL);
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if (!nq->cmds)
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return 1;
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tag_size = ALIGN(nq->queue_depth, BITS_PER_LONG) / BITS_PER_LONG;
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nq->tag_map = kzalloc(tag_size * sizeof(unsigned long), GFP_KERNEL);
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if (!nq->tag_map) {
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kfree(nq->cmds);
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return 1;
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}
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for (i = 0; i < nq->queue_depth; i++) {
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cmd = &nq->cmds[i];
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INIT_LIST_HEAD(&cmd->list);
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cmd->ll_list.next = NULL;
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cmd->tag = -1U;
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}
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return 0;
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}
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static void cleanup_queue(struct nullb_queue *nq)
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{
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kfree(nq->tag_map);
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kfree(nq->cmds);
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}
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static void cleanup_queues(struct nullb *nullb)
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{
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int i;
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for (i = 0; i < nullb->nr_queues; i++)
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cleanup_queue(&nullb->queues[i]);
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kfree(nullb->queues);
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}
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static int setup_queues(struct nullb *nullb)
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{
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struct nullb_queue *nq;
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int i;
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nullb->queues = kzalloc(submit_queues * sizeof(*nq), GFP_KERNEL);
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if (!nullb->queues)
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return 1;
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nullb->nr_queues = 0;
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nullb->queue_depth = hw_queue_depth;
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if (queue_mode == NULL_Q_MQ)
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return 0;
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for (i = 0; i < submit_queues; i++) {
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nq = &nullb->queues[i];
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init_waitqueue_head(&nq->wait);
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nq->queue_depth = hw_queue_depth;
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if (setup_commands(nq))
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break;
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nullb->nr_queues++;
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}
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|
||||
if (i == submit_queues)
|
||||
return 0;
|
||||
|
||||
cleanup_queues(nullb);
|
||||
return 1;
|
||||
}
|
||||
|
||||
static int null_add_dev(void)
|
||||
{
|
||||
struct gendisk *disk;
|
||||
struct nullb *nullb;
|
||||
sector_t size;
|
||||
|
||||
nullb = kzalloc_node(sizeof(*nullb), GFP_KERNEL, home_node);
|
||||
if (!nullb)
|
||||
return -ENOMEM;
|
||||
|
||||
spin_lock_init(&nullb->lock);
|
||||
|
||||
if (setup_queues(nullb))
|
||||
goto err;
|
||||
|
||||
if (queue_mode == NULL_Q_MQ) {
|
||||
null_mq_reg.numa_node = home_node;
|
||||
null_mq_reg.queue_depth = hw_queue_depth;
|
||||
|
||||
if (use_per_node_hctx) {
|
||||
null_mq_reg.ops->alloc_hctx = null_alloc_hctx;
|
||||
null_mq_reg.ops->free_hctx = null_free_hctx;
|
||||
|
||||
null_mq_reg.nr_hw_queues = nr_online_nodes;
|
||||
} else {
|
||||
null_mq_reg.ops->alloc_hctx = blk_mq_alloc_single_hw_queue;
|
||||
null_mq_reg.ops->free_hctx = blk_mq_free_single_hw_queue;
|
||||
|
||||
null_mq_reg.nr_hw_queues = submit_queues;
|
||||
}
|
||||
|
||||
nullb->q = blk_mq_init_queue(&null_mq_reg, nullb);
|
||||
} else if (queue_mode == NULL_Q_BIO) {
|
||||
nullb->q = blk_alloc_queue_node(GFP_KERNEL, home_node);
|
||||
blk_queue_make_request(nullb->q, null_queue_bio);
|
||||
} else {
|
||||
nullb->q = blk_init_queue_node(null_request_fn, &nullb->lock, home_node);
|
||||
blk_queue_prep_rq(nullb->q, null_rq_prep_fn);
|
||||
if (nullb->q)
|
||||
blk_queue_softirq_done(nullb->q, null_softirq_done_fn);
|
||||
}
|
||||
|
||||
if (!nullb->q)
|
||||
goto queue_fail;
|
||||
|
||||
nullb->q->queuedata = nullb;
|
||||
queue_flag_set_unlocked(QUEUE_FLAG_NONROT, nullb->q);
|
||||
|
||||
disk = nullb->disk = alloc_disk_node(1, home_node);
|
||||
if (!disk) {
|
||||
queue_fail:
|
||||
if (queue_mode == NULL_Q_MQ)
|
||||
blk_mq_free_queue(nullb->q);
|
||||
else
|
||||
blk_cleanup_queue(nullb->q);
|
||||
cleanup_queues(nullb);
|
||||
err:
|
||||
kfree(nullb);
|
||||
return -ENOMEM;
|
||||
}
|
||||
|
||||
mutex_lock(&lock);
|
||||
list_add_tail(&nullb->list, &nullb_list);
|
||||
nullb->index = nullb_indexes++;
|
||||
mutex_unlock(&lock);
|
||||
|
||||
blk_queue_logical_block_size(nullb->q, bs);
|
||||
blk_queue_physical_block_size(nullb->q, bs);
|
||||
|
||||
size = gb * 1024 * 1024 * 1024ULL;
|
||||
sector_div(size, bs);
|
||||
set_capacity(disk, size);
|
||||
|
||||
disk->flags |= GENHD_FL_EXT_DEVT;
|
||||
disk->major = null_major;
|
||||
disk->first_minor = nullb->index;
|
||||
disk->fops = &null_fops;
|
||||
disk->private_data = nullb;
|
||||
disk->queue = nullb->q;
|
||||
sprintf(disk->disk_name, "nullb%d", nullb->index);
|
||||
add_disk(disk);
|
||||
return 0;
|
||||
}
|
||||
|
||||
static int __init null_init(void)
|
||||
{
|
||||
unsigned int i;
|
||||
|
||||
#if !defined(CONFIG_SMP) || !defined(CONFIG_USE_GENERIC_SMP_HELPERS)
|
||||
if (irqmode == NULL_IRQ_SOFTIRQ) {
|
||||
pr_warn("null_blk: softirq completions not available.\n");
|
||||
pr_warn("null_blk: using direct completions.\n");
|
||||
irqmode = NULL_IRQ_NONE;
|
||||
}
|
||||
#endif
|
||||
|
||||
if (submit_queues > nr_cpu_ids)
|
||||
submit_queues = nr_cpu_ids;
|
||||
else if (!submit_queues)
|
||||
submit_queues = 1;
|
||||
|
||||
mutex_init(&lock);
|
||||
|
||||
/* Initialize a separate list for each CPU for issuing softirqs */
|
||||
for_each_possible_cpu(i) {
|
||||
struct completion_queue *cq = &per_cpu(completion_queues, i);
|
||||
|
||||
init_llist_head(&cq->list);
|
||||
|
||||
if (irqmode != NULL_IRQ_TIMER)
|
||||
continue;
|
||||
|
||||
hrtimer_init(&cq->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
|
||||
cq->timer.function = null_cmd_timer_expired;
|
||||
}
|
||||
|
||||
null_major = register_blkdev(0, "nullb");
|
||||
if (null_major < 0)
|
||||
return null_major;
|
||||
|
||||
for (i = 0; i < nr_devices; i++) {
|
||||
if (null_add_dev()) {
|
||||
unregister_blkdev(null_major, "nullb");
|
||||
return -EINVAL;
|
||||
}
|
||||
}
|
||||
|
||||
pr_info("null: module loaded\n");
|
||||
return 0;
|
||||
}
|
||||
|
||||
static void __exit null_exit(void)
|
||||
{
|
||||
struct nullb *nullb;
|
||||
|
||||
unregister_blkdev(null_major, "nullb");
|
||||
|
||||
mutex_lock(&lock);
|
||||
while (!list_empty(&nullb_list)) {
|
||||
nullb = list_entry(nullb_list.next, struct nullb, list);
|
||||
null_del_dev(nullb);
|
||||
}
|
||||
mutex_unlock(&lock);
|
||||
}
|
||||
|
||||
module_init(null_init);
|
||||
module_exit(null_exit);
|
||||
|
||||
MODULE_AUTHOR("Jens Axboe <jaxboe@fusionio.com>");
|
||||
MODULE_LICENSE("GPL");
|
||||
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