diff options
| -rw-r--r-- | block/Makefile | 1 | ||||
| -rw-r--r-- | block/blk-wbt.c | 735 | ||||
| -rw-r--r-- | block/blk-wbt.h | 165 | ||||
| -rw-r--r-- | include/trace/events/wbt.h | 153 |
4 files changed, 1054 insertions, 0 deletions
diff --git a/block/Makefile b/block/Makefile index 2528c596f7ec..a827f988c4e6 100644 --- a/block/Makefile +++ b/block/Makefile @@ -24,3 +24,4 @@ obj-$(CONFIG_BLK_CMDLINE_PARSER) += cmdline-parser.o obj-$(CONFIG_BLK_DEV_INTEGRITY) += bio-integrity.o blk-integrity.o t10-pi.o obj-$(CONFIG_BLK_MQ_PCI) += blk-mq-pci.o obj-$(CONFIG_BLK_DEV_ZONED) += blk-zoned.o +obj-$(CONFIG_BLK_WBT) += blk-wbt.o diff --git a/block/blk-wbt.c b/block/blk-wbt.c new file mode 100644 index 000000000000..889c17ff8503 --- /dev/null +++ b/block/blk-wbt.c @@ -0,0 +1,735 @@ +/* + * buffered writeback throttling. loosely based on CoDel. We can't drop + * packets for IO scheduling, so the logic is something like this: + * + * - Monitor latencies in a defined window of time. + * - If the minimum latency in the above window exceeds some target, increment + * scaling step and scale down queue depth by a factor of 2x. The monitoring + * window is then shrunk to 100 / sqrt(scaling step + 1). + * - For any window where we don't have solid data on what the latencies + * look like, retain status quo. + * - If latencies look good, decrement scaling step. + * - If we're only doing writes, allow the scaling step to go negative. This + * will temporarily boost write performance, snapping back to a stable + * scaling step of 0 if reads show up or the heavy writers finish. Unlike + * positive scaling steps where we shrink the monitoring window, a negative + * scaling step retains the default step==0 window size. + * + * Copyright (C) 2016 Jens Axboe + * + */ +#include <linux/kernel.h> +#include <linux/blk_types.h> +#include <linux/slab.h> +#include <linux/backing-dev.h> +#include <linux/swap.h> + +#include "blk-wbt.h" + +#define CREATE_TRACE_POINTS +#include <trace/events/wbt.h> + +enum { + /* + * Default setting, we'll scale up (to 75% of QD max) or down (min 1) + * from here depending on device stats + */ + RWB_DEF_DEPTH = 16, + + /* + * 100msec window + */ + RWB_WINDOW_NSEC = 100 * 1000 * 1000ULL, + + /* + * Disregard stats, if we don't meet this minimum + */ + RWB_MIN_WRITE_SAMPLES = 3, + + /* + * If we have this number of consecutive windows with not enough + * information to scale up or down, scale up. + */ + RWB_UNKNOWN_BUMP = 5, +}; + +static inline bool rwb_enabled(struct rq_wb *rwb) +{ + return rwb && rwb->wb_normal != 0; +} + +/* + * Increment 'v', if 'v' is below 'below'. Returns true if we succeeded, + * false if 'v' + 1 would be bigger than 'below'. + */ +static bool atomic_inc_below(atomic_t *v, int below) +{ + int cur = atomic_read(v); + + for (;;) { + int old; + + if (cur >= below) + return false; + old = atomic_cmpxchg(v, cur, cur + 1); + if (old == cur) + break; + cur = old; + } + + return true; +} + +static void wb_timestamp(struct rq_wb *rwb, unsigned long *var) +{ + if (rwb_enabled(rwb)) { + const unsigned long cur = jiffies; + + if (cur != *var) + *var = cur; + } +} + +/* + * If a task was rate throttled in balance_dirty_pages() within the last + * second or so, use that to indicate a higher cleaning rate. + */ +static bool wb_recent_wait(struct rq_wb *rwb) +{ + struct bdi_writeback *wb = &rwb->bdi->wb; + + return time_before(jiffies, wb->dirty_sleep + HZ); +} + +static inline struct rq_wait *get_rq_wait(struct rq_wb *rwb, bool is_kswapd) +{ + return &rwb->rq_wait[is_kswapd]; +} + +static void rwb_wake_all(struct rq_wb *rwb) +{ + int i; + + for (i = 0; i < WBT_NUM_RWQ; i++) { + struct rq_wait *rqw = &rwb->rq_wait[i]; + + if (waitqueue_active(&rqw->wait)) + wake_up_all(&rqw->wait); + } +} + +void __wbt_done(struct rq_wb *rwb, enum wbt_flags wb_acct) +{ + struct rq_wait *rqw; + int inflight, limit; + + if (!(wb_acct & WBT_TRACKED)) + return; + + rqw = get_rq_wait(rwb, wb_acct & WBT_KSWAPD); + inflight = atomic_dec_return(&rqw->inflight); + + /* + * wbt got disabled with IO in flight. Wake up any potential + * waiters, we don't have to do more than that. + */ + if (unlikely(!rwb_enabled(rwb))) { + rwb_wake_all(rwb); + return; + } + + /* + * If the device does write back caching, drop further down + * before we wake people up. + */ + if (rwb->wc && !wb_recent_wait(rwb)) + limit = 0; + else + limit = rwb->wb_normal; + + /* + * Don't wake anyone up if we are above the normal limit. + */ + if (inflight && inflight >= limit) + return; + + if (waitqueue_active(&rqw->wait)) { + int diff = limit - inflight; + + if (!inflight || diff >= rwb->wb_background / 2) + wake_up_all(&rqw->wait); + } +} + +/* + * Called on completion of a request. Note that it's also called when + * a request is merged, when the request gets freed. + */ +void wbt_done(struct rq_wb *rwb, struct blk_issue_stat *stat) +{ + if (!rwb) + return; + + if (!wbt_is_tracked(stat)) { + if (rwb->sync_cookie == stat) { + rwb->sync_issue = 0; + rwb->sync_cookie = NULL; + } + + if (wbt_is_read(stat)) + wb_timestamp(rwb, &rwb->last_comp); + wbt_clear_state(stat); + } else { + WARN_ON_ONCE(stat == rwb->sync_cookie); + __wbt_done(rwb, wbt_stat_to_mask(stat)); + wbt_clear_state(stat); + } +} + +/* + * Return true, if we can't increase the depth further by scaling + */ +static bool calc_wb_limits(struct rq_wb *rwb) +{ + unsigned int depth; + bool ret = false; + + if (!rwb->min_lat_nsec) { + rwb->wb_max = rwb->wb_normal = rwb->wb_background = 0; + return false; + } + + /* + * For QD=1 devices, this is a special case. It's important for those + * to have one request ready when one completes, so force a depth of + * 2 for those devices. On the backend, it'll be a depth of 1 anyway, + * since the device can't have more than that in flight. If we're + * scaling down, then keep a setting of 1/1/1. + */ + if (rwb->queue_depth == 1) { + if (rwb->scale_step > 0) + rwb->wb_max = rwb->wb_normal = 1; + else { + rwb->wb_max = rwb->wb_normal = 2; + ret = true; + } + rwb->wb_background = 1; + } else { + /* + * scale_step == 0 is our default state. If we have suffered + * latency spikes, step will be > 0, and we shrink the + * allowed write depths. If step is < 0, we're only doing + * writes, and we allow a temporarily higher depth to + * increase performance. + */ + depth = min_t(unsigned int, RWB_DEF_DEPTH, rwb->queue_depth); + if (rwb->scale_step > 0) + depth = 1 + ((depth - 1) >> min(31, rwb->scale_step)); + else if (rwb->scale_step < 0) { + unsigned int maxd = 3 * rwb->queue_depth / 4; + + depth = 1 + ((depth - 1) << -rwb->scale_step); + if (depth > maxd) { + depth = maxd; + ret = true; + } + } + + /* + * Set our max/normal/bg queue depths based on how far + * we have scaled down (->scale_step). + */ + rwb->wb_max = depth; + rwb->wb_normal = (rwb->wb_max + 1) / 2; + rwb->wb_background = (rwb->wb_max + 3) / 4; + } + + return ret; +} + +static bool inline stat_sample_valid(struct blk_rq_stat *stat) +{ + /* + * We need at least one read sample, and a minimum of + * RWB_MIN_WRITE_SAMPLES. We require some write samples to know + * that it's writes impacting us, and not just some sole read on + * a device that is in a lower power state. + */ + return stat[0].nr_samples >= 1 && + stat[1].nr_samples >= RWB_MIN_WRITE_SAMPLES; +} + +static u64 rwb_sync_issue_lat(struct rq_wb *rwb) +{ + u64 now, issue = ACCESS_ONCE(rwb->sync_issue); + + if (!issue || !rwb->sync_cookie) + return 0; + + now = ktime_to_ns(ktime_get()); + return now - issue; +} + +enum { + LAT_OK = 1, + LAT_UNKNOWN, + LAT_UNKNOWN_WRITES, + LAT_EXCEEDED, +}; + +static int __latency_exceeded(struct rq_wb *rwb, struct blk_rq_stat *stat) +{ + u64 thislat; + + /* + * If our stored sync issue exceeds the window size, or it + * exceeds our min target AND we haven't logged any entries, + * flag the latency as exceeded. wbt works off completion latencies, + * but for a flooded device, a single sync IO can take a long time + * to complete after being issued. If this time exceeds our + * monitoring window AND we didn't see any other completions in that + * window, then count that sync IO as a violation of the latency. + */ + thislat = rwb_sync_issue_lat(rwb); + if (thislat > rwb->cur_win_nsec || + (thislat > rwb->min_lat_nsec && !stat[0].nr_samples)) { + trace_wbt_lat(rwb->bdi, thislat); + return LAT_EXCEEDED; + } + + /* + * No read/write mix, if stat isn't valid + */ + if (!stat_sample_valid(stat)) { + /* + * If we had writes in this stat window and the window is + * current, we're only doing writes. If a task recently + * waited or still has writes in flights, consider us doing + * just writes as well. + */ + if ((stat[1].nr_samples && rwb->stat_ops->is_current(stat)) || + wb_recent_wait(rwb) || wbt_inflight(rwb)) + return LAT_UNKNOWN_WRITES; + return LAT_UNKNOWN; + } + + /* + * If the 'min' latency exceeds our target, step down. + */ + if (stat[0].min > rwb->min_lat_nsec) { + trace_wbt_lat(rwb->bdi, stat[0].min); + trace_wbt_stat(rwb->bdi, stat); + return LAT_EXCEEDED; + } + + if (rwb->scale_step) + trace_wbt_stat(rwb->bdi, stat); + + return LAT_OK; +} + +static int latency_exceeded(struct rq_wb *rwb) +{ + struct blk_rq_stat stat[2]; + + rwb->stat_ops->get(rwb->ops_data, stat); + return __latency_exceeded(rwb, stat); +} + +static void rwb_trace_step(struct rq_wb *rwb, const char *msg) +{ + trace_wbt_step(rwb->bdi, msg, rwb->scale_step, rwb->cur_win_nsec, + rwb->wb_background, rwb->wb_normal, rwb->wb_max); +} + +static void scale_up(struct rq_wb *rwb) +{ + /* + * Hit max in previous round, stop here + */ + if (rwb->scaled_max) + return; + + rwb->scale_step--; + rwb->unknown_cnt = 0; + rwb->stat_ops->clear(rwb->ops_data); + + rwb->scaled_max = calc_wb_limits(rwb); + + rwb_wake_all(rwb); + + rwb_trace_step(rwb, "step up"); +} + +/* + * Scale rwb down. If 'hard_throttle' is set, do it quicker, since we + * had a latency violation. + */ +static void scale_down(struct rq_wb *rwb, bool hard_throttle) +{ + /* + * Stop scaling down when we've hit the limit. This also prevents + * ->scale_step from going to crazy values, if the device can't + * keep up. + */ + if (rwb->wb_max == 1) + return; + + if (rwb->scale_step < 0 && hard_throttle) + rwb->scale_step = 0; + else + rwb->scale_step++; + + rwb->scaled_max = false; + rwb->unknown_cnt = 0; + rwb->stat_ops->clear(rwb->ops_data); + calc_wb_limits(rwb); + rwb_trace_step(rwb, "step down"); +} + +static void rwb_arm_timer(struct rq_wb *rwb) +{ + unsigned long expires; + + if (rwb->scale_step > 0) { + /* + * We should speed this up, using some variant of a fast + * integer inverse square root calculation. Since we only do + * this for every window expiration, it's not a huge deal, + * though. + */ + rwb->cur_win_nsec = div_u64(rwb->win_nsec << 4, + int_sqrt((rwb->scale_step + 1) << 8)); + } else { + /* + * For step < 0, we don't want to increase/decrease the + * window size. + */ + rwb->cur_win_nsec = rwb->win_nsec; + } + + expires = jiffies + nsecs_to_jiffies(rwb->cur_win_nsec); + mod_timer(&rwb->window_timer, expires); +} + +static void wb_timer_fn(unsigned long data) +{ + struct rq_wb *rwb = (struct rq_wb *) data; + unsigned int inflight = wbt_inflight(rwb); + int status; + + status = latency_exceeded(rwb); + + trace_wbt_timer(rwb->bdi, status, rwb->scale_step, inflight); + + /* + * If we exceeded the latency target, step down. If we did not, + * step one level up. If we don't know enough to say either exceeded + * or ok, then don't do anything. + */ + switch (status) { + case LAT_EXCEEDED: + scale_down(rwb, true); + break; + case LAT_OK: + scale_up(rwb); + break; + case LAT_UNKNOWN_WRITES: + /* + * We started a the center step, but don't have a valid + * read/write sample, but we do have writes going on. + * Allow step to go negative, to increase write perf. + */ + scale_up(rwb); + break; + case LAT_UNKNOWN: + if (++rwb->unknown_cnt < RWB_UNKNOWN_BUMP) + break; + /* + * We get here when previously scaled reduced depth, and we + * currently don't have a valid read/write sample. For that + * case, slowly return to center state (step == 0). + */ + if (rwb->scale_step > 0) + scale_up(rwb); + else if (rwb->scale_step < 0) + scale_down(rwb, false); + break; + default: + break; + } + + /* + * Re-arm timer, if we have IO in flight + */ + if (rwb->scale_step || inflight) + rwb_arm_timer(rwb); +} + +void wbt_update_limits(struct rq_wb *rwb) +{ + rwb->scale_step = 0; + rwb->scaled_max = false; + calc_wb_limits(rwb); + + rwb_wake_all(rwb); +} + +static bool close_io(struct rq_wb *rwb) +{ + const unsigned long now = jiffies; + + return time_before(now, rwb->last_issue + HZ / 10) || + time_before(now, rwb->last_comp + HZ / 10); +} + +#define REQ_HIPRIO (REQ_SYNC | REQ_META | REQ_PRIO) + +static inline unsigned int get_limit(struct rq_wb *rwb, unsigned long rw) +{ + unsigned int limit; + + /* + * At this point we know it's a buffered write. If this is + * kswapd trying to free memory, or REQ_SYNC is set, set, then + * it's WB_SYNC_ALL writeback, and we'll use the max limit for + * that. If the write is marked as a background write, then use + * the idle limit, or go to normal if we haven't had competing + * IO for a bit. + */ + if ((rw & REQ_HIPRIO) || wb_recent_wait(rwb) || current_is_kswapd()) + limit = rwb->wb_max; + else if ((rw & REQ_BACKGROUND) || close_io(rwb)) { + /* + * If less than 100ms since we completed unrelated IO, + * limit us to half the depth for background writeback. + */ + limit = rwb->wb_background; + } else + limit = rwb->wb_normal; + + return limit; +} + +static inline bool may_queue(struct rq_wb *rwb, struct rq_wait *rqw, + wait_queue_t *wait, unsigned long rw) +{ + /* + * inc it here even if disabled, since we'll dec it at completion. + * this only happens if the task was sleeping in __wbt_wait(), + * and someone turned it off at the same time. + */ + if (!rwb_enabled(rwb)) { + atomic_inc(&rqw->inflight); + return true; + } + + /* + * If the waitqueue is already active and we are not the next + * in line to be woken up, wait for our turn. + */ + if (waitqueue_active(&rqw->wait) && + rqw->wait.task_list.next != &wait->task_list) + return false; + + return atomic_inc_below(&rqw->inflight, get_limit(rwb, rw)); +} + +/* + * Block if we will exceed our limit, or if we are currently waiting for + * the timer to kick off queuing again. + */ +static void __wbt_wait(struct rq_wb *rwb, unsigned long rw, spinlock_t *lock) +{ + struct rq_wait *rqw = get_rq_wait(rwb, current_is_kswapd()); + DEFINE_WAIT(wait); + + if (may_queue(rwb, rqw, &wait, rw)) + return; + + do { + prepare_to_wait_exclusive(&rqw->wait, &wait, + TASK_UNINTERRUPTIBLE); + + if (may_queue(rwb, rqw, &wait, rw)) + break; + + if (lock) + spin_unlock_irq(lock); + + io_schedule(); + + if (lock) + spin_lock_irq(lock); + } while (1); + + finish_wait(&rqw->wait, &wait); +} + +static inline bool wbt_should_throttle(struct rq_wb *rwb, struct bio *bio) +{ + const int op = bio_op(bio); + + /* + * If not a WRITE (or a discard), do nothing + */ + if (!(op == REQ_OP_WRITE || op == REQ_OP_DISCARD)) + return false; + + /* + * Don't throttle WRITE_ODIRECT + */ + if ((bio->bi_opf & (REQ_SYNC | REQ_IDLE)) == (REQ_SYNC | REQ_IDLE)) + return false; + + return true; +} + +/* + * Returns true if the IO request should be accounted, false if not. + * May sleep, if we have exceeded the writeback limits. Caller can pass + * in an irq held spinlock, if it holds one when calling this function. + * If we do sleep, we'll release and re-grab it. + */ +unsigned int wbt_wait(struct rq_wb *rwb, struct bio *bio, spinlock_t *lock) +{ + unsigned int ret = 0; + + if (!rwb_enabled(rwb)) + return 0; + + if (bio_op(bio) == REQ_OP_READ) + ret = WBT_READ; + + if (!wbt_should_throttle(rwb, bio)) { + if (ret & WBT_READ) + wb_timestamp(rwb, &rwb->last_issue); + return ret; + } + + __wbt_wait(rwb, bio->bi_opf, lock); + + if (!timer_pending(&rwb->window_timer)) + rwb_arm_timer(rwb); + + if (current_is_kswapd()) + ret |= WBT_KSWAPD; + + return ret | WBT_TRACKED; +} + +void wbt_issue(struct rq_wb *rwb, struct blk_issue_stat *stat) +{ + if (!rwb_enabled(rwb)) + return; + + /* + * Track sync issue, in case it takes a long time to complete. Allows + * us to react quicker, if a sync IO takes a long time to complete. + * Note that this is just a hint. 'stat' can go away when the + * request completes, so it's important we never dereference it. We + * only use the address to compare with, which is why we store the + * sync_issue time locally. + */ + if (wbt_is_read(stat) && !rwb->sync_issue) { + rwb->sync_cookie = stat; + rwb->sync_issue = blk_stat_time(stat); + } +} + +void wbt_requeue(struct rq_wb *rwb, struct blk_issue_stat *stat) +{ + if (!rwb_enabled(rwb)) + return; + if (stat == rwb->sync_cookie) { + rwb->sync_issue = 0; + rwb->sync_cookie = NULL; + } +} + +void wbt_set_queue_depth(struct rq_wb *rwb, unsigned int depth) +{ + if (rwb) { + rwb->queue_depth = depth; + wbt_update_limits(rwb); + } +} + +void wbt_set_write_cache(struct rq_wb *rwb, bool write_cache_on) +{ + if (rwb) + rwb->wc = write_cache_on; +} + +void wbt_disable(struct rq_wb *rwb) +{ + if (rwb) { + del_timer_sync(&rwb->window_timer); + rwb->win_nsec = rwb->min_lat_nsec = 0; + wbt_update_limits(rwb); + } +} +EXPORT_SYMBOL_GPL(wbt_disable); + +int wbt_init(struct request_queue *q, struct wb_stat_ops *ops) +{ + struct rq_wb *rwb; + int i; + + /* + * For now, we depend on the stats window being larger than + * our monitoring window. Ensure that this isn't inadvertently + * violated. + */ + BUILD_BUG_ON(RWB_WINDOW_NSEC > BLK_STAT_NSEC); + BUILD_BUG_ON(WBT_NR_BITS > BLK_STAT_RES_BITS); + + if (!ops->get || !ops->is_current || !ops->clear) + return -EINVAL; + + rwb = kzalloc(sizeof(*rwb), GFP_KERNEL); + if (!rwb) + return -ENOMEM; + + for (i = 0; i < WBT_NUM_RWQ; i++) { + atomic_set(&rwb->rq_wait[i].inflight, 0); + init_waitqueue_head(&rwb->rq_wait[i].wait); + } + + setup_timer(&rwb->window_timer, wb_timer_fn, (unsigned long) rwb); + rwb->wc = 1; + rwb->queue_depth = RWB_DEF_DEPTH; + rwb->last_comp = rwb->last_issue = jiffies; + rwb->bdi = &q->backing_dev_info; + rwb->win_nsec = RWB_WINDOW_NSEC; + rwb->stat_ops = ops; + rwb->ops_data = q; + wbt_update_limits(rwb); + + /* + * Assign rwb, and turn on stats tracking for this queue + */ + q->rq_wb = rwb; + blk_stat_enable(q); + + if (blk_queue_nonrot(q)) + rwb->min_lat_nsec = 2000000ULL; + else + rwb->min_lat_nsec = 75000000ULL; + + wbt_set_queue_depth(rwb, blk_queue_depth(q)); + wbt_set_write_cache(rwb, test_bit(QUEUE_FLAG_WC, &q->queue_flags)); + + return 0; +} + +void wbt_exit(struct request_queue *q) +{ + struct rq_wb *rwb = q->rq_wb; + + if (rwb) { + del_timer_sync(&rwb->window_timer); + q->rq_wb = NULL; + kfree(rwb); + } +} diff --git a/block/blk-wbt.h b/block/blk-wbt.h new file mode 100644 index 000000000000..e57700337c26 --- /dev/null +++ b/block/blk-wbt.h @@ -0,0 +1,165 @@ +#ifndef WB_THROTTLE_H +#define WB_THROTTLE_H + +#include <linux/kernel.h> +#include <linux/atomic.h> +#include <linux/wait.h> +#include <linux/timer.h> +#include <linux/ktime.h> + +#include "blk-stat.h" + +enum wbt_flags { + WBT_TRACKED = 1, /* write, tracked for throttling */ + WBT_READ = 2, /* read */ + WBT_KSWAPD = 4, /* write, from kswapd */ + + WBT_NR_BITS = 3, /* number of bits */ +}; + +enum { + WBT_NUM_RWQ = 2, +}; + +static inline void wbt_clear_state(struct blk_issue_stat *stat) +{ + stat->time &= BLK_STAT_TIME_MASK; +} + +static inline enum wbt_flags wbt_stat_to_mask(struct blk_issue_stat *stat) +{ + return (stat->time & BLK_STAT_MASK) >> BLK_STAT_SHIFT; +} + +static inline void wbt_track(struct blk_issue_stat *stat, enum wbt_flags wb_acct) +{ + stat->time |= ((u64) wb_acct) << BLK_STAT_SHIFT; +} + +static inline bool wbt_is_tracked(struct blk_issue_stat *stat) +{ + return (stat->time >> BLK_STAT_SHIFT) & WBT_TRACKED; +} + +static inline bool wbt_is_read(struct blk_issue_stat *stat) +{ + return (stat->time >> BLK_STAT_SHIFT) & WBT_READ; +} + +struct wb_stat_ops { + void (*get)(void *, struct blk_rq_stat *); + bool (*is_current)(struct blk_rq_stat *); + void (*clear)(void *); +}; + +struct rq_wait { + wait_queue_head_t wait; + atomic_t inflight; +}; + +struct rq_wb { + /* + * Settings that govern how we throttle + */ + unsigned int wb_background; /* background writeback */ + unsigned int wb_normal; /* normal writeback */ + unsigned int wb_max; /* max throughput writeback */ + int scale_step; + bool scaled_max; + + /* + * Number of consecutive periods where we don't have enough + * information to make a firm scale up/down decision. + */ + unsigned int unknown_cnt; + + u64 win_nsec; /* default window size */ + u64 cur_win_nsec; /* current window size */ + + struct timer_list window_timer; + + s64 sync_issue; + void *sync_cookie; + + unsigned int wc; + unsigned int queue_depth; + + unsigned long last_issue; /* last non-throttled issue */ + unsigned long last_comp; /* last non-throttled comp */ + unsigned long min_lat_nsec; + struct backing_dev_info *bdi; + struct rq_wait rq_wait[WBT_NUM_RWQ]; + + struct wb_stat_ops *stat_ops; + void *ops_data; +}; + +static inline unsigned int wbt_inflight(struct rq_wb *rwb) +{ + unsigned int i, ret = 0; + + for (i = 0; i < WBT_NUM_RWQ; i++) + ret += atomic_read(&rwb->rq_wait[i].inflight); + + return ret; +} + +struct backing_dev_info; + +#ifdef CONFIG_BLK_WBT + +void __wbt_done(struct rq_wb *, enum wbt_flags); +void wbt_done(struct rq_wb *, struct blk_issue_stat *); +enum wbt_flags wbt_wait(struct rq_wb *, struct bio *, spinlock_t *); +int wbt_init(struct request_queue *, struct wb_stat_ops *); +void wbt_exit(struct request_queue *); +void wbt_update_limits(struct rq_wb *); +void wbt_requeue(struct rq_wb *, struct blk_issue_stat *); +void wbt_issue(struct rq_wb *, struct blk_issue_stat *); +void wbt_disable(struct rq_wb *); + +void wbt_set_queue_depth(struct rq_wb *, unsigned int); +void wbt_set_write_cache(struct rq_wb *, bool); + +#else + +static inline void __wbt_done(struct rq_wb *rwb, enum wbt_flags flags) +{ +} +static inline void wbt_done(struct rq_wb *rwb, struct blk_issue_stat *stat) +{ +} +static inline enum wbt_flags wbt_wait(struct rq_wb *rwb, struct bio *bio, + spinlock_t *lock) +{ + return 0; +} +static inline int wbt_init(struct request_queue *q, struct wb_stat_ops *ops) +{ + return -EINVAL; +} +static inline void wbt_exit(struct request_queue *q) +{ +} +static inline void wbt_update_limits(struct rq_wb *rwb) +{ +} +static inline void wbt_requeue(struct rq_wb *rwb, struct blk_issue_stat *stat) +{ +} +static inline void wbt_issue(struct rq_wb *rwb, struct blk_issue_stat *stat) +{ +} +static inline void wbt_disable(struct rq_wb *rwb) +{ +} +static inline void wbt_set_queue_depth(struct rq_wb *rwb, unsigned int depth) +{ +} +static inline void wbt_set_write_cache(struct rq_wb *rwb, bool wc) +{ +} + +#endif /* CONFIG_BLK_WBT */ + +#endif diff --git a/include/trace/events/wbt.h b/include/trace/events/wbt.h new file mode 100644 index 000000000000..3c518e455680 --- /dev/null +++ b/include/trace/events/wbt.h @@ -0,0 +1,153 @@ +#undef TRACE_SYSTEM +#define TRACE_SYSTEM wbt + +#if !defined(_TRACE_WBT_H) || defined(TRACE_HEADER_MULTI_READ) +#define _TRACE_WBT_H + +#include <linux/tracepoint.h> +#include "../../../block/blk-wbt.h" + +/** + * wbt_stat - trace stats for blk_wb + * @stat: array of read/write stats + */ +TRACE_EVENT(wbt_stat, + + TP_PROTO(struct backing_dev_info *bdi, struct blk_rq_stat *stat), + + TP_ARGS(bdi, stat), + + TP_STRUCT__entry( + __array(char, name, 32) + __field(s64, rmean) + __field(u64, rmin) + __field(u64, rmax) + __field(s64, rnr_samples) + __field(s64, rtime) + __field(s64, wmean) + __field(u64, wmin) + __field(u64, wmax) + __field(s64, wnr_samples) + __field(s64, wtime) + ), + + TP_fast_assign( + strncpy(__entry->name, dev_name(bdi->dev), 32); + __entry->rmean = stat[0].mean; + __entry->rmin = stat[0].min; + __entry->rmax = stat[0].max; + __entry->rnr_samples = stat[0].nr_samples; + __entry->wmean = stat[1].mean; + __entry->wmin = stat[1].min; + __entry->wmax = stat[1].max; + __entry->wnr_samples = stat[1].nr_samples; + ), + + TP_printk("%s: rmean=%llu, rmin=%llu, rmax=%llu, rsamples=%llu, " + "wmean=%llu, wmin=%llu, wmax=%llu, wsamples=%llu\n", + __entry->name, __entry->rmean, __entry->rmin, __entry->rmax, + __entry->rnr_samples, __entry->wmean, __entry->wmin, + __entry->wmax, __entry->wnr_samples) +); + +/** + * wbt_lat - trace latency event + * @lat: latency trigger + */ +TRACE_EVENT(wbt_lat, + + TP_PROTO(struct backing_dev_info *bdi, unsigned long lat), + + TP_ARGS(bdi, lat), + + TP_STRUCT__entry( + __array(char, name, 32) + __field(unsigned long, lat) + ), + + TP_fast_assign( + strncpy(__entry->name, dev_name(bdi->dev), 32); + __entry->lat = div_u64(lat, 1000); + ), + + TP_printk("%s: latency %lluus\n", __entry->name, + (unsigned long long) __entry->lat) +); + +/** + * wbt_step - trace wb event step + * @msg: context message + * @step: the current scale step count + * @window: the current monitoring window + * @bg: the current background queue limit + * @normal: the current normal writeback limit + * @max: the current max throughput writeback limit + */ +TRACE_EVENT(wbt_step, + + TP_PROTO(struct backing_dev_info *bdi, const char *msg, + int step, unsigned long window, unsigned int bg, + unsigned int normal, unsigned int max), + + TP_ARGS(bdi, msg, step, window, bg, normal, max), + + TP_STRUCT__entry( + __array(char, name, 32) + __field(const char *, msg) + __field(int, step) + __field(unsigned long, window) + __field(unsigned int, bg) + __field(unsigned int, normal) + __field(unsigned int, max) + ), + + TP_fast_assign( + strncpy(__entry->name, dev_name(bdi->dev), 32); + __entry->msg = msg; + __entry->step = step; + __entry->window = div_u64(window, 1000); + __entry->bg = bg; + __entry->normal = normal; + __entry->max = max; + ), + + TP_printk("%s: %s: step=%d, window=%luus, background=%u, normal=%u, max=%u\n", + __entry->name, __entry->msg, __entry->step, __entry->window, + __entry->bg, __entry->normal, __entry->max) +); + +/** + * wbt_timer - trace wb timer event + * @status: timer state status + * @step: the current scale step count + * @inflight: tracked writes inflight + */ +TRACE_EVENT(wbt_timer, + + TP_PROTO(struct backing_dev_info *bdi, unsigned int status, + int step, unsigned int inflight), + + TP_ARGS(bdi, status, step, inflight), + + TP_STRUCT__entry( + __array(char, name, 32) + __field(unsigned int, status) + __field(int, step) + __field(unsigned int, inflight) + ), + + TP_fast_assign( + strncpy(__entry->name, dev_name(bdi->dev), 32); + __entry->status = status; + __entry->step = step; + __entry->inflight = inflight; + ), + + TP_printk("%s: status=%u, step=%d, inflight=%u\n", __entry->name, + __entry->status, __entry->step, __entry->inflight) +); + +#endif /* _TRACE_WBT_H */ + +/* This part must be outside protection */ +#include <trace/define_trace.h> |