| // SPDX-License-Identifier: GPL-2.0 |
| /* |
| * 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" |
| #include "blk-rq-qos.h" |
| |
| #define CREATE_TRACE_POINTS |
| #include <trace/events/wbt.h> |
| |
| static inline void wbt_clear_state(struct request *rq) |
| { |
| rq->wbt_flags = 0; |
| } |
| |
| static inline enum wbt_flags wbt_flags(struct request *rq) |
| { |
| return rq->wbt_flags; |
| } |
| |
| static inline bool wbt_is_tracked(struct request *rq) |
| { |
| return rq->wbt_flags & WBT_TRACKED; |
| } |
| |
| static inline bool wbt_is_read(struct request *rq) |
| { |
| return rq->wbt_flags & WBT_READ; |
| } |
| |
| 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->enable_state != WBT_STATE_OFF_DEFAULT && |
| rwb->wb_normal != 0; |
| } |
| |
| 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->rqos.q->disk->bdi->wb; |
| |
| return time_before(jiffies, wb->dirty_sleep + HZ); |
| } |
| |
| static inline struct rq_wait *get_rq_wait(struct rq_wb *rwb, |
| enum wbt_flags wb_acct) |
| { |
| if (wb_acct & WBT_KSWAPD) |
| return &rwb->rq_wait[WBT_RWQ_KSWAPD]; |
| else if (wb_acct & WBT_DISCARD) |
| return &rwb->rq_wait[WBT_RWQ_DISCARD]; |
| |
| return &rwb->rq_wait[WBT_RWQ_BG]; |
| } |
| |
| 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 (wq_has_sleeper(&rqw->wait)) |
| wake_up_all(&rqw->wait); |
| } |
| } |
| |
| static void wbt_rqw_done(struct rq_wb *rwb, struct rq_wait *rqw, |
| enum wbt_flags wb_acct) |
| { |
| int inflight, limit; |
| |
| 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; |
| } |
| |
| /* |
| * For discards, our limit is always the background. For writes, if |
| * the device does write back caching, drop further down before we |
| * wake people up. |
| */ |
| if (wb_acct & WBT_DISCARD) |
| limit = rwb->wb_background; |
| else 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 (wq_has_sleeper(&rqw->wait)) { |
| int diff = limit - inflight; |
| |
| if (!inflight || diff >= rwb->wb_background / 2) |
| wake_up_all(&rqw->wait); |
| } |
| } |
| |
| static void __wbt_done(struct rq_qos *rqos, enum wbt_flags wb_acct) |
| { |
| struct rq_wb *rwb = RQWB(rqos); |
| struct rq_wait *rqw; |
| |
| if (!(wb_acct & WBT_TRACKED)) |
| return; |
| |
| rqw = get_rq_wait(rwb, wb_acct); |
| wbt_rqw_done(rwb, rqw, wb_acct); |
| } |
| |
| /* |
| * Called on completion of a request. Note that it's also called when |
| * a request is merged, when the request gets freed. |
| */ |
| static void wbt_done(struct rq_qos *rqos, struct request *rq) |
| { |
| struct rq_wb *rwb = RQWB(rqos); |
| |
| if (!wbt_is_tracked(rq)) { |
| if (rwb->sync_cookie == rq) { |
| rwb->sync_issue = 0; |
| rwb->sync_cookie = NULL; |
| } |
| |
| if (wbt_is_read(rq)) |
| wb_timestamp(rwb, &rwb->last_comp); |
| } else { |
| WARN_ON_ONCE(rq == rwb->sync_cookie); |
| __wbt_done(rqos, wbt_flags(rq)); |
| } |
| wbt_clear_state(rq); |
| } |
| |
| static inline bool 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[READ].nr_samples >= 1 && |
| stat[WRITE].nr_samples >= RWB_MIN_WRITE_SAMPLES); |
| } |
| |
| static u64 rwb_sync_issue_lat(struct rq_wb *rwb) |
| { |
| u64 now, issue = READ_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) |
| { |
| struct backing_dev_info *bdi = rwb->rqos.q->disk->bdi; |
| struct rq_depth *rqd = &rwb->rq_depth; |
| 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[READ].nr_samples)) { |
| trace_wbt_lat(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[WRITE].nr_samples || 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[READ].min > rwb->min_lat_nsec) { |
| trace_wbt_lat(bdi, stat[READ].min); |
| trace_wbt_stat(bdi, stat); |
| return LAT_EXCEEDED; |
| } |
| |
| if (rqd->scale_step) |
| trace_wbt_stat(bdi, stat); |
| |
| return LAT_OK; |
| } |
| |
| static void rwb_trace_step(struct rq_wb *rwb, const char *msg) |
| { |
| struct backing_dev_info *bdi = rwb->rqos.q->disk->bdi; |
| struct rq_depth *rqd = &rwb->rq_depth; |
| |
| trace_wbt_step(bdi, msg, rqd->scale_step, rwb->cur_win_nsec, |
| rwb->wb_background, rwb->wb_normal, rqd->max_depth); |
| } |
| |
| static void calc_wb_limits(struct rq_wb *rwb) |
| { |
| if (rwb->min_lat_nsec == 0) { |
| rwb->wb_normal = rwb->wb_background = 0; |
| } else if (rwb->rq_depth.max_depth <= 2) { |
| rwb->wb_normal = rwb->rq_depth.max_depth; |
| rwb->wb_background = 1; |
| } else { |
| rwb->wb_normal = (rwb->rq_depth.max_depth + 1) / 2; |
| rwb->wb_background = (rwb->rq_depth.max_depth + 3) / 4; |
| } |
| } |
| |
| static void scale_up(struct rq_wb *rwb) |
| { |
| if (!rq_depth_scale_up(&rwb->rq_depth)) |
| return; |
| calc_wb_limits(rwb); |
| rwb->unknown_cnt = 0; |
| rwb_wake_all(rwb); |
| rwb_trace_step(rwb, tracepoint_string("scale up")); |
| } |
| |
| static void scale_down(struct rq_wb *rwb, bool hard_throttle) |
| { |
| if (!rq_depth_scale_down(&rwb->rq_depth, hard_throttle)) |
| return; |
| calc_wb_limits(rwb); |
| rwb->unknown_cnt = 0; |
| rwb_trace_step(rwb, tracepoint_string("scale down")); |
| } |
| |
| static void rwb_arm_timer(struct rq_wb *rwb) |
| { |
| struct rq_depth *rqd = &rwb->rq_depth; |
| |
| if (rqd->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((rqd->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; |
| } |
| |
| blk_stat_activate_nsecs(rwb->cb, rwb->cur_win_nsec); |
| } |
| |
| static void wb_timer_fn(struct blk_stat_callback *cb) |
| { |
| struct rq_wb *rwb = cb->data; |
| struct rq_depth *rqd = &rwb->rq_depth; |
| unsigned int inflight = wbt_inflight(rwb); |
| int status; |
| |
| if (!rwb->rqos.q->disk) |
| return; |
| |
| status = latency_exceeded(rwb, cb->stat); |
| |
| trace_wbt_timer(rwb->rqos.q->disk->bdi, status, rqd->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 (rqd->scale_step > 0) |
| scale_up(rwb); |
| else if (rqd->scale_step < 0) |
| scale_down(rwb, false); |
| break; |
| default: |
| break; |
| } |
| |
| /* |
| * Re-arm timer, if we have IO in flight |
| */ |
| if (rqd->scale_step || inflight) |
| rwb_arm_timer(rwb); |
| } |
| |
| static void wbt_update_limits(struct rq_wb *rwb) |
| { |
| struct rq_depth *rqd = &rwb->rq_depth; |
| |
| rqd->scale_step = 0; |
| rqd->scaled_max = false; |
| |
| rq_depth_calc_max_depth(rqd); |
| calc_wb_limits(rwb); |
| |
| rwb_wake_all(rwb); |
| } |
| |
| u64 wbt_get_min_lat(struct request_queue *q) |
| { |
| struct rq_qos *rqos = wbt_rq_qos(q); |
| if (!rqos) |
| return 0; |
| return RQWB(rqos)->min_lat_nsec; |
| } |
| |
| void wbt_set_min_lat(struct request_queue *q, u64 val) |
| { |
| struct rq_qos *rqos = wbt_rq_qos(q); |
| if (!rqos) |
| return; |
| RQWB(rqos)->min_lat_nsec = val; |
| RQWB(rqos)->enable_state = WBT_STATE_ON_MANUAL; |
| wbt_update_limits(RQWB(rqos)); |
| } |
| |
| |
| 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; |
| |
| /* |
| * If we got disabled, just return UINT_MAX. This ensures that |
| * we'll properly inc a new IO, and dec+wakeup at the end. |
| */ |
| if (!rwb_enabled(rwb)) |
| return UINT_MAX; |
| |
| if ((rw & REQ_OP_MASK) == REQ_OP_DISCARD) |
| return rwb->wb_background; |
| |
| /* |
| * At this point we know it's a buffered write. If this is |
| * kswapd trying to free memory, or REQ_SYNC is 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->rq_depth.max_depth; |
| 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; |
| } |
| |
| struct wbt_wait_data { |
| struct rq_wb *rwb; |
| enum wbt_flags wb_acct; |
| unsigned long rw; |
| }; |
| |
| static bool wbt_inflight_cb(struct rq_wait *rqw, void *private_data) |
| { |
| struct wbt_wait_data *data = private_data; |
| return rq_wait_inc_below(rqw, get_limit(data->rwb, data->rw)); |
| } |
| |
| static void wbt_cleanup_cb(struct rq_wait *rqw, void *private_data) |
| { |
| struct wbt_wait_data *data = private_data; |
| wbt_rqw_done(data->rwb, rqw, data->wb_acct); |
| } |
| |
| /* |
| * 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, enum wbt_flags wb_acct, |
| unsigned long rw) |
| { |
| struct rq_wait *rqw = get_rq_wait(rwb, wb_acct); |
| struct wbt_wait_data data = { |
| .rwb = rwb, |
| .wb_acct = wb_acct, |
| .rw = rw, |
| }; |
| |
| rq_qos_wait(rqw, &data, wbt_inflight_cb, wbt_cleanup_cb); |
| } |
| |
| static inline bool wbt_should_throttle(struct bio *bio) |
| { |
| switch (bio_op(bio)) { |
| case REQ_OP_WRITE: |
| /* |
| * Don't throttle WRITE_ODIRECT |
| */ |
| if ((bio->bi_opf & (REQ_SYNC | REQ_IDLE)) == |
| (REQ_SYNC | REQ_IDLE)) |
| return false; |
| fallthrough; |
| case REQ_OP_DISCARD: |
| return true; |
| default: |
| return false; |
| } |
| } |
| |
| static enum wbt_flags bio_to_wbt_flags(struct rq_wb *rwb, struct bio *bio) |
| { |
| enum wbt_flags flags = 0; |
| |
| if (!rwb_enabled(rwb)) |
| return 0; |
| |
| if (bio_op(bio) == REQ_OP_READ) { |
| flags = WBT_READ; |
| } else if (wbt_should_throttle(bio)) { |
| if (current_is_kswapd()) |
| flags |= WBT_KSWAPD; |
| if (bio_op(bio) == REQ_OP_DISCARD) |
| flags |= WBT_DISCARD; |
| flags |= WBT_TRACKED; |
| } |
| return flags; |
| } |
| |
| static void wbt_cleanup(struct rq_qos *rqos, struct bio *bio) |
| { |
| struct rq_wb *rwb = RQWB(rqos); |
| enum wbt_flags flags = bio_to_wbt_flags(rwb, bio); |
| __wbt_done(rqos, flags); |
| } |
| |
| /* |
| * 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. |
| */ |
| static void wbt_wait(struct rq_qos *rqos, struct bio *bio) |
| { |
| struct rq_wb *rwb = RQWB(rqos); |
| enum wbt_flags flags; |
| |
| flags = bio_to_wbt_flags(rwb, bio); |
| if (!(flags & WBT_TRACKED)) { |
| if (flags & WBT_READ) |
| wb_timestamp(rwb, &rwb->last_issue); |
| return; |
| } |
| |
| __wbt_wait(rwb, flags, bio->bi_opf); |
| |
| if (!blk_stat_is_active(rwb->cb)) |
| rwb_arm_timer(rwb); |
| } |
| |
| static void wbt_track(struct rq_qos *rqos, struct request *rq, struct bio *bio) |
| { |
| struct rq_wb *rwb = RQWB(rqos); |
| rq->wbt_flags |= bio_to_wbt_flags(rwb, bio); |
| } |
| |
| static void wbt_issue(struct rq_qos *rqos, struct request *rq) |
| { |
| struct rq_wb *rwb = RQWB(rqos); |
| |
| 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. The request can go away when it 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(rq) && !rwb->sync_issue) { |
| rwb->sync_cookie = rq; |
| rwb->sync_issue = rq->io_start_time_ns; |
| } |
| } |
| |
| static void wbt_requeue(struct rq_qos *rqos, struct request *rq) |
| { |
| struct rq_wb *rwb = RQWB(rqos); |
| if (!rwb_enabled(rwb)) |
| return; |
| if (rq == rwb->sync_cookie) { |
| rwb->sync_issue = 0; |
| rwb->sync_cookie = NULL; |
| } |
| } |
| |
| void wbt_set_write_cache(struct request_queue *q, bool write_cache_on) |
| { |
| struct rq_qos *rqos = wbt_rq_qos(q); |
| if (rqos) |
| RQWB(rqos)->wc = write_cache_on; |
| } |
| |
| /* |
| * Enable wbt if defaults are configured that way |
| */ |
| void wbt_enable_default(struct request_queue *q) |
| { |
| struct rq_qos *rqos = wbt_rq_qos(q); |
| |
| /* Throttling already enabled? */ |
| if (rqos) { |
| if (RQWB(rqos)->enable_state == WBT_STATE_OFF_DEFAULT) |
| RQWB(rqos)->enable_state = WBT_STATE_ON_DEFAULT; |
| return; |
| } |
| |
| /* Queue not registered? Maybe shutting down... */ |
| if (!blk_queue_registered(q)) |
| return; |
| |
| if (queue_is_mq(q) && IS_ENABLED(CONFIG_BLK_WBT_MQ)) |
| wbt_init(q); |
| } |
| EXPORT_SYMBOL_GPL(wbt_enable_default); |
| |
| u64 wbt_default_latency_nsec(struct request_queue *q) |
| { |
| /* |
| * We default to 2msec for non-rotational storage, and 75msec |
| * for rotational storage. |
| */ |
| if (blk_queue_nonrot(q)) |
| return 2000000ULL; |
| else |
| return 75000000ULL; |
| } |
| |
| static int wbt_data_dir(const struct request *rq) |
| { |
| const int op = req_op(rq); |
| |
| if (op == REQ_OP_READ) |
| return READ; |
| else if (op_is_write(op)) |
| return WRITE; |
| |
| /* don't account */ |
| return -1; |
| } |
| |
| static void wbt_queue_depth_changed(struct rq_qos *rqos) |
| { |
| RQWB(rqos)->rq_depth.queue_depth = blk_queue_depth(rqos->q); |
| wbt_update_limits(RQWB(rqos)); |
| } |
| |
| static void wbt_exit(struct rq_qos *rqos) |
| { |
| struct rq_wb *rwb = RQWB(rqos); |
| struct request_queue *q = rqos->q; |
| |
| blk_stat_remove_callback(q, rwb->cb); |
| blk_stat_free_callback(rwb->cb); |
| kfree(rwb); |
| } |
| |
| /* |
| * Disable wbt, if enabled by default. |
| */ |
| void wbt_disable_default(struct request_queue *q) |
| { |
| struct rq_qos *rqos = wbt_rq_qos(q); |
| struct rq_wb *rwb; |
| if (!rqos) |
| return; |
| rwb = RQWB(rqos); |
| if (rwb->enable_state == WBT_STATE_ON_DEFAULT) { |
| blk_stat_deactivate(rwb->cb); |
| rwb->enable_state = WBT_STATE_OFF_DEFAULT; |
| } |
| } |
| EXPORT_SYMBOL_GPL(wbt_disable_default); |
| |
| #ifdef CONFIG_BLK_DEBUG_FS |
| static int wbt_curr_win_nsec_show(void *data, struct seq_file *m) |
| { |
| struct rq_qos *rqos = data; |
| struct rq_wb *rwb = RQWB(rqos); |
| |
| seq_printf(m, "%llu\n", rwb->cur_win_nsec); |
| return 0; |
| } |
| |
| static int wbt_enabled_show(void *data, struct seq_file *m) |
| { |
| struct rq_qos *rqos = data; |
| struct rq_wb *rwb = RQWB(rqos); |
| |
| seq_printf(m, "%d\n", rwb->enable_state); |
| return 0; |
| } |
| |
| static int wbt_id_show(void *data, struct seq_file *m) |
| { |
| struct rq_qos *rqos = data; |
| |
| seq_printf(m, "%u\n", rqos->id); |
| return 0; |
| } |
| |
| static int wbt_inflight_show(void *data, struct seq_file *m) |
| { |
| struct rq_qos *rqos = data; |
| struct rq_wb *rwb = RQWB(rqos); |
| int i; |
| |
| for (i = 0; i < WBT_NUM_RWQ; i++) |
| seq_printf(m, "%d: inflight %d\n", i, |
| atomic_read(&rwb->rq_wait[i].inflight)); |
| return 0; |
| } |
| |
| static int wbt_min_lat_nsec_show(void *data, struct seq_file *m) |
| { |
| struct rq_qos *rqos = data; |
| struct rq_wb *rwb = RQWB(rqos); |
| |
| seq_printf(m, "%lu\n", rwb->min_lat_nsec); |
| return 0; |
| } |
| |
| static int wbt_unknown_cnt_show(void *data, struct seq_file *m) |
| { |
| struct rq_qos *rqos = data; |
| struct rq_wb *rwb = RQWB(rqos); |
| |
| seq_printf(m, "%u\n", rwb->unknown_cnt); |
| return 0; |
| } |
| |
| static int wbt_normal_show(void *data, struct seq_file *m) |
| { |
| struct rq_qos *rqos = data; |
| struct rq_wb *rwb = RQWB(rqos); |
| |
| seq_printf(m, "%u\n", rwb->wb_normal); |
| return 0; |
| } |
| |
| static int wbt_background_show(void *data, struct seq_file *m) |
| { |
| struct rq_qos *rqos = data; |
| struct rq_wb *rwb = RQWB(rqos); |
| |
| seq_printf(m, "%u\n", rwb->wb_background); |
| return 0; |
| } |
| |
| static const struct blk_mq_debugfs_attr wbt_debugfs_attrs[] = { |
| {"curr_win_nsec", 0400, wbt_curr_win_nsec_show}, |
| {"enabled", 0400, wbt_enabled_show}, |
| {"id", 0400, wbt_id_show}, |
| {"inflight", 0400, wbt_inflight_show}, |
| {"min_lat_nsec", 0400, wbt_min_lat_nsec_show}, |
| {"unknown_cnt", 0400, wbt_unknown_cnt_show}, |
| {"wb_normal", 0400, wbt_normal_show}, |
| {"wb_background", 0400, wbt_background_show}, |
| {}, |
| }; |
| #endif |
| |
| static struct rq_qos_ops wbt_rqos_ops = { |
| .throttle = wbt_wait, |
| .issue = wbt_issue, |
| .track = wbt_track, |
| .requeue = wbt_requeue, |
| .done = wbt_done, |
| .cleanup = wbt_cleanup, |
| .queue_depth_changed = wbt_queue_depth_changed, |
| .exit = wbt_exit, |
| #ifdef CONFIG_BLK_DEBUG_FS |
| .debugfs_attrs = wbt_debugfs_attrs, |
| #endif |
| }; |
| |
| int wbt_init(struct request_queue *q) |
| { |
| struct rq_wb *rwb; |
| int i; |
| int ret; |
| |
| rwb = kzalloc(sizeof(*rwb), GFP_KERNEL); |
| if (!rwb) |
| return -ENOMEM; |
| |
| rwb->cb = blk_stat_alloc_callback(wb_timer_fn, wbt_data_dir, 2, rwb); |
| if (!rwb->cb) { |
| kfree(rwb); |
| return -ENOMEM; |
| } |
| |
| for (i = 0; i < WBT_NUM_RWQ; i++) |
| rq_wait_init(&rwb->rq_wait[i]); |
| |
| rwb->rqos.id = RQ_QOS_WBT; |
| rwb->rqos.ops = &wbt_rqos_ops; |
| rwb->rqos.q = q; |
| rwb->last_comp = rwb->last_issue = jiffies; |
| rwb->win_nsec = RWB_WINDOW_NSEC; |
| rwb->enable_state = WBT_STATE_ON_DEFAULT; |
| rwb->wc = test_bit(QUEUE_FLAG_WC, &q->queue_flags); |
| rwb->rq_depth.default_depth = RWB_DEF_DEPTH; |
| rwb->min_lat_nsec = wbt_default_latency_nsec(q); |
| |
| wbt_queue_depth_changed(&rwb->rqos); |
| |
| /* |
| * Assign rwb and add the stats callback. |
| */ |
| ret = rq_qos_add(q, &rwb->rqos); |
| if (ret) |
| goto err_free; |
| |
| blk_stat_add_callback(q, rwb->cb); |
| |
| return 0; |
| |
| err_free: |
| blk_stat_free_callback(rwb->cb); |
| kfree(rwb); |
| return ret; |
| |
| } |