![Akinobu Mita](/assets/img/avatar_default.png)
When irqmode=2 (IRQ completion handler is timer) and queue_mode=1 (Block interface to use is rq), the completion handler should restart request handling for any pending requests on a queue because request processing stops when the number of commands are queued more than hw_queue_depth (null_rq_prep_fn returns BLKPREP_DEFER). Without this change, the following command cannot finish. # modprobe null_blk irqmode=2 queue_mode=1 hw_queue_depth=1 # fio --name=t --rw=read --size=1g --direct=1 \ --ioengine=libaio --iodepth=64 --filename=/dev/nullb0 Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com> Cc: Jens Axboe <axboe@fb.com> Signed-off-by: Jens Axboe <axboe@fb.com>
687 lines
14 KiB
C
687 lines
14 KiB
C
#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 blk_mq_tag_set tag_set;
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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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};
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enum {
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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;
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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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static int null_param_store_val(const char *str, int *val, int min, int max)
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{
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int ret, new_val;
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ret = kstrtoint(str, 10, &new_val);
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if (ret)
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return -EINVAL;
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if (new_val < min || new_val > max)
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return -EINVAL;
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*val = new_val;
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return 0;
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}
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static int null_set_queue_mode(const char *str, const struct kernel_param *kp)
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{
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return null_param_store_val(str, &queue_mode, NULL_Q_BIO, NULL_Q_MQ);
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}
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static struct kernel_param_ops null_queue_mode_param_ops = {
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.set = null_set_queue_mode,
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.get = param_get_int,
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};
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device_param_cb(queue_mode, &null_queue_mode_param_ops, &queue_mode, S_IRUGO);
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MODULE_PARM_DESC(queue_mode, "Block interface to use (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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static int null_set_irqmode(const char *str, const struct kernel_param *kp)
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{
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return null_param_store_val(str, &irqmode, NULL_IRQ_NONE,
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NULL_IRQ_TIMER);
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}
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static struct kernel_param_ops null_irqmode_param_ops = {
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.set = null_set_irqmode,
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.get = param_get_int,
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};
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device_param_cb(irqmode, &null_irqmode_param_ops, &irqmode, 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 = false;
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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: false");
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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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switch (queue_mode) {
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case NULL_Q_MQ:
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blk_mq_end_request(cmd->rq, 0);
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return;
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case NULL_Q_RQ:
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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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break;
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case NULL_Q_BIO:
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bio_endio(cmd->bio, 0);
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break;
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}
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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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entry = llist_reverse_order(entry);
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do {
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cmd = container_of(entry, struct nullb_cmd, ll_list);
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entry = entry->next;
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end_cmd(cmd);
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if (cmd->rq) {
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struct request_queue *q = cmd->rq->q;
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if (!q->mq_ops && blk_queue_stopped(q)) {
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spin_lock(q->queue_lock);
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if (blk_queue_stopped(q))
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blk_start_queue(q);
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spin_unlock(q->queue_lock);
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}
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}
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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_PINNED);
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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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if (queue_mode == NULL_Q_MQ)
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end_cmd(blk_mq_rq_to_pdu(rq));
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else
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end_cmd(rq->special);
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}
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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_SOFTIRQ:
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switch (queue_mode) {
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case NULL_Q_MQ:
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blk_mq_complete_request(cmd->rq);
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break;
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case NULL_Q_RQ:
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blk_complete_request(cmd->rq);
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break;
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case NULL_Q_BIO:
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/*
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* XXX: no proper submitting cpu information available.
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*/
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end_cmd(cmd);
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break;
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}
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break;
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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_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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blk_stop_queue(q);
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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,
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const struct blk_mq_queue_data *bd)
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{
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struct nullb_cmd *cmd = blk_mq_rq_to_pdu(bd->rq);
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cmd->rq = bd->rq;
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cmd->nq = hctx->driver_data;
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blk_mq_start_request(bd->rq);
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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 void null_init_queue(struct nullb *nullb, struct nullb_queue *nq)
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{
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BUG_ON(!nullb);
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BUG_ON(!nq);
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init_waitqueue_head(&nq->wait);
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nq->queue_depth = nullb->queue_depth;
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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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hctx->driver_data = nq;
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null_init_queue(nullb, nq);
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nullb->nr_queues++;
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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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.complete = null_softirq_done_fn,
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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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blk_cleanup_queue(nullb->q);
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if (queue_mode == NULL_Q_MQ)
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blk_mq_free_tag_set(&nullb->tag_set);
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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 -ENOMEM;
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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 -ENOMEM;
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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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nullb->queues = kzalloc(submit_queues * sizeof(struct nullb_queue),
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GFP_KERNEL);
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if (!nullb->queues)
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return -ENOMEM;
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nullb->nr_queues = 0;
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nullb->queue_depth = hw_queue_depth;
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return 0;
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}
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static int init_driver_queues(struct nullb *nullb)
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{
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struct nullb_queue *nq;
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int i, ret = 0;
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for (i = 0; i < submit_queues; i++) {
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nq = &nullb->queues[i];
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null_init_queue(nullb, nq);
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ret = setup_commands(nq);
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if (ret)
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return ret;
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nullb->nr_queues++;
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}
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return 0;
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}
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static int null_add_dev(void)
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{
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struct gendisk *disk;
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struct nullb *nullb;
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sector_t size;
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int rv;
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nullb = kzalloc_node(sizeof(*nullb), GFP_KERNEL, home_node);
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if (!nullb) {
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rv = -ENOMEM;
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goto out;
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}
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spin_lock_init(&nullb->lock);
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if (queue_mode == NULL_Q_MQ && use_per_node_hctx)
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submit_queues = nr_online_nodes;
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rv = setup_queues(nullb);
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if (rv)
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goto out_free_nullb;
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if (queue_mode == NULL_Q_MQ) {
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nullb->tag_set.ops = &null_mq_ops;
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nullb->tag_set.nr_hw_queues = submit_queues;
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nullb->tag_set.queue_depth = hw_queue_depth;
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nullb->tag_set.numa_node = home_node;
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nullb->tag_set.cmd_size = sizeof(struct nullb_cmd);
|
|
nullb->tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
|
|
nullb->tag_set.driver_data = nullb;
|
|
|
|
rv = blk_mq_alloc_tag_set(&nullb->tag_set);
|
|
if (rv)
|
|
goto out_cleanup_queues;
|
|
|
|
nullb->q = blk_mq_init_queue(&nullb->tag_set);
|
|
if (IS_ERR(nullb->q)) {
|
|
rv = -ENOMEM;
|
|
goto out_cleanup_tags;
|
|
}
|
|
} else if (queue_mode == NULL_Q_BIO) {
|
|
nullb->q = blk_alloc_queue_node(GFP_KERNEL, home_node);
|
|
if (!nullb->q) {
|
|
rv = -ENOMEM;
|
|
goto out_cleanup_queues;
|
|
}
|
|
blk_queue_make_request(nullb->q, null_queue_bio);
|
|
rv = init_driver_queues(nullb);
|
|
if (rv)
|
|
goto out_cleanup_blk_queue;
|
|
} else {
|
|
nullb->q = blk_init_queue_node(null_request_fn, &nullb->lock, home_node);
|
|
if (!nullb->q) {
|
|
rv = -ENOMEM;
|
|
goto out_cleanup_queues;
|
|
}
|
|
blk_queue_prep_rq(nullb->q, null_rq_prep_fn);
|
|
blk_queue_softirq_done(nullb->q, null_softirq_done_fn);
|
|
rv = init_driver_queues(nullb);
|
|
if (rv)
|
|
goto out_cleanup_blk_queue;
|
|
}
|
|
|
|
nullb->q->queuedata = nullb;
|
|
queue_flag_set_unlocked(QUEUE_FLAG_NONROT, nullb->q);
|
|
queue_flag_clear_unlocked(QUEUE_FLAG_ADD_RANDOM, nullb->q);
|
|
|
|
disk = nullb->disk = alloc_disk_node(1, home_node);
|
|
if (!disk) {
|
|
rv = -ENOMEM;
|
|
goto out_cleanup_blk_queue;
|
|
}
|
|
|
|
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 | GENHD_FL_SUPPRESS_PARTITION_INFO;
|
|
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;
|
|
|
|
out_cleanup_blk_queue:
|
|
blk_cleanup_queue(nullb->q);
|
|
out_cleanup_tags:
|
|
if (queue_mode == NULL_Q_MQ)
|
|
blk_mq_free_tag_set(&nullb->tag_set);
|
|
out_cleanup_queues:
|
|
cleanup_queues(nullb);
|
|
out_free_nullb:
|
|
kfree(nullb);
|
|
out:
|
|
return rv;
|
|
}
|
|
|
|
static int __init null_init(void)
|
|
{
|
|
unsigned int i;
|
|
|
|
if (bs > PAGE_SIZE) {
|
|
pr_warn("null_blk: invalid block size\n");
|
|
pr_warn("null_blk: defaults block size to %lu\n", PAGE_SIZE);
|
|
bs = PAGE_SIZE;
|
|
}
|
|
|
|
if (queue_mode == NULL_Q_MQ && use_per_node_hctx) {
|
|
if (submit_queues < nr_online_nodes) {
|
|
pr_warn("null_blk: submit_queues param is set to %u.",
|
|
nr_online_nodes);
|
|
submit_queues = nr_online_nodes;
|
|
}
|
|
} else 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");
|