diff options
Diffstat (limited to 'drivers/block/null_blk.c')
| -rw-r--r-- | drivers/block/null_blk.c | 116 |
1 files changed, 114 insertions, 2 deletions
diff --git a/drivers/block/null_blk.c b/drivers/block/null_blk.c index 1f3cf25..7e6332e 100644 --- a/drivers/block/null_blk.c +++ b/drivers/block/null_blk.c @@ -23,6 +23,14 @@ #define FREE_BATCH 16 +#define TICKS_PER_SEC 50ULL +#define TIMER_INTERVAL (NSEC_PER_SEC / TICKS_PER_SEC) + +static inline u64 mb_per_tick(int mbps) +{ + return (1 << 20) / TICKS_PER_SEC * ((u64) mbps); +} + struct nullb_cmd { struct list_head list; struct llist_node ll_list; @@ -49,10 +57,12 @@ struct nullb_queue { * * CONFIGURED: Device has been configured and turned on. Cannot reconfigure. * UP: Device is currently on and visible in userspace. + * THROTTLED: Device is being throttled. */ enum nullb_device_flags { NULLB_DEV_FL_CONFIGURED = 0, NULLB_DEV_FL_UP = 1, + NULLB_DEV_FL_THROTTLED = 2, }; /* @@ -83,6 +93,7 @@ struct nullb_device { unsigned int irqmode; /* IRQ completion handler */ unsigned int hw_queue_depth; /* queue depth */ unsigned int index; /* index of the disk, only valid with a disk */ + unsigned int mbps; /* Bandwidth throttle cap (in MB/s) */ bool use_lightnvm; /* register as a LightNVM device */ bool blocking; /* blocking blk-mq device */ bool use_per_node_hctx; /* use per-node allocation for hardware context */ @@ -100,8 +111,9 @@ struct nullb { struct nvm_dev *ndev; struct blk_mq_tag_set *tag_set; struct blk_mq_tag_set __tag_set; - struct hrtimer timer; unsigned int queue_depth; + atomic_long_t cur_bytes; + struct hrtimer bw_timer; spinlock_t lock; struct nullb_queue *queues; @@ -320,6 +332,7 @@ NULLB_DEVICE_ATTR(blocking, bool); NULLB_DEVICE_ATTR(use_per_node_hctx, bool); NULLB_DEVICE_ATTR(memory_backed, bool); NULLB_DEVICE_ATTR(discard, bool); +NULLB_DEVICE_ATTR(mbps, uint); static ssize_t nullb_device_power_show(struct config_item *item, char *page) { @@ -376,6 +389,7 @@ static struct configfs_attribute *nullb_device_attrs[] = { &nullb_device_attr_power, &nullb_device_attr_memory_backed, &nullb_device_attr_discard, + &nullb_device_attr_mbps, NULL, }; @@ -428,7 +442,7 @@ nullb_group_drop_item(struct config_group *group, struct config_item *item) static ssize_t memb_group_features_show(struct config_item *item, char *page) { - return snprintf(page, PAGE_SIZE, "memory_backed,discard\n"); + return snprintf(page, PAGE_SIZE, "memory_backed,discard,bandwidth\n"); } CONFIGFS_ATTR_RO(memb_group_, features); @@ -914,11 +928,65 @@ static int null_handle_bio(struct nullb_cmd *cmd) return 0; } +static void null_stop_queue(struct nullb *nullb) +{ + struct request_queue *q = nullb->q; + + if (nullb->dev->queue_mode == NULL_Q_MQ) + blk_mq_stop_hw_queues(q); + else { + spin_lock_irq(q->queue_lock); + blk_stop_queue(q); + spin_unlock_irq(q->queue_lock); + } +} + +static void null_restart_queue_async(struct nullb *nullb) +{ + struct request_queue *q = nullb->q; + unsigned long flags; + + if (nullb->dev->queue_mode == NULL_Q_MQ) + blk_mq_start_stopped_hw_queues(q, true); + else { + spin_lock_irqsave(q->queue_lock, flags); + blk_start_queue_async(q); + spin_unlock_irqrestore(q->queue_lock, flags); + } +} + static blk_status_t null_handle_cmd(struct nullb_cmd *cmd) { struct nullb_device *dev = cmd->nq->dev; + struct nullb *nullb = dev->nullb; int err = 0; + if (test_bit(NULLB_DEV_FL_THROTTLED, &dev->flags)) { + struct request *rq = cmd->rq; + + if (!hrtimer_active(&nullb->bw_timer)) + hrtimer_restart(&nullb->bw_timer); + + if (atomic_long_sub_return(blk_rq_bytes(rq), + &nullb->cur_bytes) < 0) { + null_stop_queue(nullb); + /* race with timer */ + if (atomic_long_read(&nullb->cur_bytes) > 0) + null_restart_queue_async(nullb); + if (dev->queue_mode == NULL_Q_RQ) { + struct request_queue *q = nullb->q; + + spin_lock_irq(q->queue_lock); + rq->rq_flags |= RQF_DONTPREP; + blk_requeue_request(q, rq); + spin_unlock_irq(q->queue_lock); + return BLK_STS_OK; + } else + /* requeue request */ + return BLK_STS_RESOURCE; + } + } + if (dev->memory_backed) { if (dev->queue_mode == NULL_Q_BIO) err = null_handle_bio(cmd); @@ -954,6 +1022,33 @@ static blk_status_t null_handle_cmd(struct nullb_cmd *cmd) return BLK_STS_OK; } +static enum hrtimer_restart nullb_bwtimer_fn(struct hrtimer *timer) +{ + struct nullb *nullb = container_of(timer, struct nullb, bw_timer); + ktime_t timer_interval = ktime_set(0, TIMER_INTERVAL); + unsigned int mbps = nullb->dev->mbps; + + if (atomic_long_read(&nullb->cur_bytes) == mb_per_tick(mbps)) + return HRTIMER_NORESTART; + + atomic_long_set(&nullb->cur_bytes, mb_per_tick(mbps)); + null_restart_queue_async(nullb); + + hrtimer_forward_now(&nullb->bw_timer, timer_interval); + + return HRTIMER_RESTART; +} + +static void nullb_setup_bwtimer(struct nullb *nullb) +{ + ktime_t timer_interval = ktime_set(0, TIMER_INTERVAL); + + hrtimer_init(&nullb->bw_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); + nullb->bw_timer.function = nullb_bwtimer_fn; + atomic_long_set(&nullb->cur_bytes, mb_per_tick(nullb->dev->mbps)); + hrtimer_start(&nullb->bw_timer, timer_interval, HRTIMER_MODE_REL); +} + static struct nullb_queue *nullb_to_queue(struct nullb *nullb) { int index = 0; @@ -1224,6 +1319,13 @@ static void null_del_dev(struct nullb *nullb) null_nvm_unregister(nullb); else del_gendisk(nullb->disk); + + if (test_bit(NULLB_DEV_FL_THROTTLED, &nullb->dev->flags)) { + hrtimer_cancel(&nullb->bw_timer); + atomic_long_set(&nullb->cur_bytes, LONG_MAX); + null_restart_queue_async(nullb); + } + blk_cleanup_queue(nullb->q); if (dev->queue_mode == NULL_Q_MQ && nullb->tag_set == &nullb->__tag_set) @@ -1409,6 +1511,11 @@ static void null_validate_conf(struct nullb_device *dev) /* Do memory allocation, so set blocking */ if (dev->memory_backed) dev->blocking = true; + + dev->mbps = min_t(unsigned int, 1024 * 40, dev->mbps); + /* can not stop a queue */ + if (dev->queue_mode == NULL_Q_BIO) + dev->mbps = 0; } static int null_add_dev(struct nullb_device *dev) @@ -1474,6 +1581,11 @@ static int null_add_dev(struct nullb_device *dev) goto out_cleanup_blk_queue; } + if (dev->mbps) { + set_bit(NULLB_DEV_FL_THROTTLED, &dev->flags); + nullb_setup_bwtimer(nullb); + } + nullb->q->queuedata = nullb; queue_flag_set_unlocked(QUEUE_FLAG_NONROT, nullb->q); queue_flag_clear_unlocked(QUEUE_FLAG_ADD_RANDOM, nullb->q); |
