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-rw-r--r--block/blk-wbt.c866
1 files changed, 866 insertions, 0 deletions
diff --git a/block/blk-wbt.c b/block/blk-wbt.c
new file mode 100644
index 000000000..c293e08b3
--- /dev/null
+++ b/block/blk-wbt.c
@@ -0,0 +1,866 @@
+// 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, blk_opf_t opf)
+{
+ 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 ((opf & 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 ((opf & REQ_HIPRIO) || wb_recent_wait(rwb) || current_is_kswapd())
+ limit = rwb->rq_depth.max_depth;
+ else if ((opf & 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;
+ blk_opf_t opf;
+};
+
+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->opf));
+}
+
+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,
+ blk_opf_t opf)
+{
+ struct rq_wait *rqw = get_rq_wait(rwb, wb_acct);
+ struct wbt_wait_data data = {
+ .rwb = rwb,
+ .wb_acct = wb_acct,
+ .opf = opf,
+ };
+
+ 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 enum req_op 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;
+
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-25 12:55:41 +0000