| // SPDX-License-Identifier: GPL-2.0 |
| /* |
| * Interface for controlling IO bandwidth on a request queue |
| * |
| * Copyright (C) 2010 Vivek Goyal <vgoyal@redhat.com> |
| */ |
| |
| #include <linux/module.h> |
| #include <linux/slab.h> |
| #include <linux/blkdev.h> |
| #include <linux/bio.h> |
| #include <linux/blktrace_api.h> |
| #include <linux/blk-cgroup.h> |
| #include "blk.h" |
| |
| /* Max dispatch from a group in 1 round */ |
| static int throtl_grp_quantum = 8; |
| |
| /* Total max dispatch from all groups in one round */ |
| static int throtl_quantum = 32; |
| |
| /* Throttling is performed over a slice and after that slice is renewed */ |
| #define DFL_THROTL_SLICE_HD (HZ / 10) |
| #define DFL_THROTL_SLICE_SSD (HZ / 50) |
| #define MAX_THROTL_SLICE (HZ) |
| #define MAX_IDLE_TIME (5L * 1000 * 1000) /* 5 s */ |
| #define MIN_THROTL_BPS (320 * 1024) |
| #define MIN_THROTL_IOPS (10) |
| #define DFL_LATENCY_TARGET (-1L) |
| #define DFL_IDLE_THRESHOLD (0) |
| #define DFL_HD_BASELINE_LATENCY (4000L) /* 4ms */ |
| #define LATENCY_FILTERED_SSD (0) |
| /* |
| * For HD, very small latency comes from sequential IO. Such IO is helpless to |
| * help determine if its IO is impacted by others, hence we ignore the IO |
| */ |
| #define LATENCY_FILTERED_HD (1000L) /* 1ms */ |
| |
| static struct blkcg_policy blkcg_policy_throtl; |
| |
| /* A workqueue to queue throttle related work */ |
| static struct workqueue_struct *kthrotld_workqueue; |
| |
| /* |
| * To implement hierarchical throttling, throtl_grps form a tree and bios |
| * are dispatched upwards level by level until they reach the top and get |
| * issued. When dispatching bios from the children and local group at each |
| * level, if the bios are dispatched into a single bio_list, there's a risk |
| * of a local or child group which can queue many bios at once filling up |
| * the list starving others. |
| * |
| * To avoid such starvation, dispatched bios are queued separately |
| * according to where they came from. When they are again dispatched to |
| * the parent, they're popped in round-robin order so that no single source |
| * hogs the dispatch window. |
| * |
| * throtl_qnode is used to keep the queued bios separated by their sources. |
| * Bios are queued to throtl_qnode which in turn is queued to |
| * throtl_service_queue and then dispatched in round-robin order. |
| * |
| * It's also used to track the reference counts on blkg's. A qnode always |
| * belongs to a throtl_grp and gets queued on itself or the parent, so |
| * incrementing the reference of the associated throtl_grp when a qnode is |
| * queued and decrementing when dequeued is enough to keep the whole blkg |
| * tree pinned while bios are in flight. |
| */ |
| struct throtl_qnode { |
| struct list_head node; /* service_queue->queued[] */ |
| struct bio_list bios; /* queued bios */ |
| struct throtl_grp *tg; /* tg this qnode belongs to */ |
| }; |
| |
| struct throtl_service_queue { |
| struct throtl_service_queue *parent_sq; /* the parent service_queue */ |
| |
| /* |
| * Bios queued directly to this service_queue or dispatched from |
| * children throtl_grp's. |
| */ |
| struct list_head queued[2]; /* throtl_qnode [READ/WRITE] */ |
| unsigned int nr_queued[2]; /* number of queued bios */ |
| |
| /* |
| * RB tree of active children throtl_grp's, which are sorted by |
| * their ->disptime. |
| */ |
| struct rb_root_cached pending_tree; /* RB tree of active tgs */ |
| unsigned int nr_pending; /* # queued in the tree */ |
| unsigned long first_pending_disptime; /* disptime of the first tg */ |
| struct timer_list pending_timer; /* fires on first_pending_disptime */ |
| }; |
| |
| enum tg_state_flags { |
| THROTL_TG_PENDING = 1 << 0, /* on parent's pending tree */ |
| THROTL_TG_WAS_EMPTY = 1 << 1, /* bio_lists[] became non-empty */ |
| }; |
| |
| #define rb_entry_tg(node) rb_entry((node), struct throtl_grp, rb_node) |
| |
| enum { |
| LIMIT_LOW, |
| LIMIT_MAX, |
| LIMIT_CNT, |
| }; |
| |
| struct throtl_grp { |
| /* must be the first member */ |
| struct blkg_policy_data pd; |
| |
| /* active throtl group service_queue member */ |
| struct rb_node rb_node; |
| |
| /* throtl_data this group belongs to */ |
| struct throtl_data *td; |
| |
| /* this group's service queue */ |
| struct throtl_service_queue service_queue; |
| |
| /* |
| * qnode_on_self is used when bios are directly queued to this |
| * throtl_grp so that local bios compete fairly with bios |
| * dispatched from children. qnode_on_parent is used when bios are |
| * dispatched from this throtl_grp into its parent and will compete |
| * with the sibling qnode_on_parents and the parent's |
| * qnode_on_self. |
| */ |
| struct throtl_qnode qnode_on_self[2]; |
| struct throtl_qnode qnode_on_parent[2]; |
| |
| /* |
| * Dispatch time in jiffies. This is the estimated time when group |
| * will unthrottle and is ready to dispatch more bio. It is used as |
| * key to sort active groups in service tree. |
| */ |
| unsigned long disptime; |
| |
| unsigned int flags; |
| |
| /* are there any throtl rules between this group and td? */ |
| bool has_rules[2]; |
| |
| /* internally used bytes per second rate limits */ |
| uint64_t bps[2][LIMIT_CNT]; |
| /* user configured bps limits */ |
| uint64_t bps_conf[2][LIMIT_CNT]; |
| |
| /* internally used IOPS limits */ |
| unsigned int iops[2][LIMIT_CNT]; |
| /* user configured IOPS limits */ |
| unsigned int iops_conf[2][LIMIT_CNT]; |
| |
| /* Number of bytes disptached in current slice */ |
| uint64_t bytes_disp[2]; |
| /* Number of bio's dispatched in current slice */ |
| unsigned int io_disp[2]; |
| |
| unsigned long last_low_overflow_time[2]; |
| |
| uint64_t last_bytes_disp[2]; |
| unsigned int last_io_disp[2]; |
| |
| unsigned long last_check_time; |
| |
| unsigned long latency_target; /* us */ |
| unsigned long latency_target_conf; /* us */ |
| /* When did we start a new slice */ |
| unsigned long slice_start[2]; |
| unsigned long slice_end[2]; |
| |
| unsigned long last_finish_time; /* ns / 1024 */ |
| unsigned long checked_last_finish_time; /* ns / 1024 */ |
| unsigned long avg_idletime; /* ns / 1024 */ |
| unsigned long idletime_threshold; /* us */ |
| unsigned long idletime_threshold_conf; /* us */ |
| |
| unsigned int bio_cnt; /* total bios */ |
| unsigned int bad_bio_cnt; /* bios exceeding latency threshold */ |
| unsigned long bio_cnt_reset_time; |
| }; |
| |
| /* We measure latency for request size from <= 4k to >= 1M */ |
| #define LATENCY_BUCKET_SIZE 9 |
| |
| struct latency_bucket { |
| unsigned long total_latency; /* ns / 1024 */ |
| int samples; |
| }; |
| |
| struct avg_latency_bucket { |
| unsigned long latency; /* ns / 1024 */ |
| bool valid; |
| }; |
| |
| struct throtl_data |
| { |
| /* service tree for active throtl groups */ |
| struct throtl_service_queue service_queue; |
| |
| struct request_queue *queue; |
| |
| /* Total Number of queued bios on READ and WRITE lists */ |
| unsigned int nr_queued[2]; |
| |
| unsigned int throtl_slice; |
| |
| /* Work for dispatching throttled bios */ |
| struct work_struct dispatch_work; |
| unsigned int limit_index; |
| bool limit_valid[LIMIT_CNT]; |
| |
| unsigned long low_upgrade_time; |
| unsigned long low_downgrade_time; |
| |
| unsigned int scale; |
| |
| struct latency_bucket tmp_buckets[2][LATENCY_BUCKET_SIZE]; |
| struct avg_latency_bucket avg_buckets[2][LATENCY_BUCKET_SIZE]; |
| struct latency_bucket __percpu *latency_buckets[2]; |
| unsigned long last_calculate_time; |
| unsigned long filtered_latency; |
| |
| bool track_bio_latency; |
| }; |
| |
| static void throtl_pending_timer_fn(struct timer_list *t); |
| |
| static inline struct throtl_grp *pd_to_tg(struct blkg_policy_data *pd) |
| { |
| return pd ? container_of(pd, struct throtl_grp, pd) : NULL; |
| } |
| |
| static inline struct throtl_grp *blkg_to_tg(struct blkcg_gq *blkg) |
| { |
| return pd_to_tg(blkg_to_pd(blkg, &blkcg_policy_throtl)); |
| } |
| |
| static inline struct blkcg_gq *tg_to_blkg(struct throtl_grp *tg) |
| { |
| return pd_to_blkg(&tg->pd); |
| } |
| |
| /** |
| * sq_to_tg - return the throl_grp the specified service queue belongs to |
| * @sq: the throtl_service_queue of interest |
| * |
| * Return the throtl_grp @sq belongs to. If @sq is the top-level one |
| * embedded in throtl_data, %NULL is returned. |
| */ |
| static struct throtl_grp *sq_to_tg(struct throtl_service_queue *sq) |
| { |
| if (sq && sq->parent_sq) |
| return container_of(sq, struct throtl_grp, service_queue); |
| else |
| return NULL; |
| } |
| |
| /** |
| * sq_to_td - return throtl_data the specified service queue belongs to |
| * @sq: the throtl_service_queue of interest |
| * |
| * A service_queue can be embedded in either a throtl_grp or throtl_data. |
| * Determine the associated throtl_data accordingly and return it. |
| */ |
| static struct throtl_data *sq_to_td(struct throtl_service_queue *sq) |
| { |
| struct throtl_grp *tg = sq_to_tg(sq); |
| |
| if (tg) |
| return tg->td; |
| else |
| return container_of(sq, struct throtl_data, service_queue); |
| } |
| |
| /* |
| * cgroup's limit in LIMIT_MAX is scaled if low limit is set. This scale is to |
| * make the IO dispatch more smooth. |
| * Scale up: linearly scale up according to lapsed time since upgrade. For |
| * every throtl_slice, the limit scales up 1/2 .low limit till the |
| * limit hits .max limit |
| * Scale down: exponentially scale down if a cgroup doesn't hit its .low limit |
| */ |
| static uint64_t throtl_adjusted_limit(uint64_t low, struct throtl_data *td) |
| { |
| /* arbitrary value to avoid too big scale */ |
| if (td->scale < 4096 && time_after_eq(jiffies, |
| td->low_upgrade_time + td->scale * td->throtl_slice)) |
| td->scale = (jiffies - td->low_upgrade_time) / td->throtl_slice; |
| |
| return low + (low >> 1) * td->scale; |
| } |
| |
| static uint64_t tg_bps_limit(struct throtl_grp *tg, int rw) |
| { |
| struct blkcg_gq *blkg = tg_to_blkg(tg); |
| struct throtl_data *td; |
| uint64_t ret; |
| |
| if (cgroup_subsys_on_dfl(io_cgrp_subsys) && !blkg->parent) |
| return U64_MAX; |
| |
| td = tg->td; |
| ret = tg->bps[rw][td->limit_index]; |
| if (ret == 0 && td->limit_index == LIMIT_LOW) { |
| /* intermediate node or iops isn't 0 */ |
| if (!list_empty(&blkg->blkcg->css.children) || |
| tg->iops[rw][td->limit_index]) |
| return U64_MAX; |
| else |
| return MIN_THROTL_BPS; |
| } |
| |
| if (td->limit_index == LIMIT_MAX && tg->bps[rw][LIMIT_LOW] && |
| tg->bps[rw][LIMIT_LOW] != tg->bps[rw][LIMIT_MAX]) { |
| uint64_t adjusted; |
| |
| adjusted = throtl_adjusted_limit(tg->bps[rw][LIMIT_LOW], td); |
| ret = min(tg->bps[rw][LIMIT_MAX], adjusted); |
| } |
| return ret; |
| } |
| |
| static unsigned int tg_iops_limit(struct throtl_grp *tg, int rw) |
| { |
| struct blkcg_gq *blkg = tg_to_blkg(tg); |
| struct throtl_data *td; |
| unsigned int ret; |
| |
| if (cgroup_subsys_on_dfl(io_cgrp_subsys) && !blkg->parent) |
| return UINT_MAX; |
| |
| td = tg->td; |
| ret = tg->iops[rw][td->limit_index]; |
| if (ret == 0 && tg->td->limit_index == LIMIT_LOW) { |
| /* intermediate node or bps isn't 0 */ |
| if (!list_empty(&blkg->blkcg->css.children) || |
| tg->bps[rw][td->limit_index]) |
| return UINT_MAX; |
| else |
| return MIN_THROTL_IOPS; |
| } |
| |
| if (td->limit_index == LIMIT_MAX && tg->iops[rw][LIMIT_LOW] && |
| tg->iops[rw][LIMIT_LOW] != tg->iops[rw][LIMIT_MAX]) { |
| uint64_t adjusted; |
| |
| adjusted = throtl_adjusted_limit(tg->iops[rw][LIMIT_LOW], td); |
| if (adjusted > UINT_MAX) |
| adjusted = UINT_MAX; |
| ret = min_t(unsigned int, tg->iops[rw][LIMIT_MAX], adjusted); |
| } |
| return ret; |
| } |
| |
| #define request_bucket_index(sectors) \ |
| clamp_t(int, order_base_2(sectors) - 3, 0, LATENCY_BUCKET_SIZE - 1) |
| |
| /** |
| * throtl_log - log debug message via blktrace |
| * @sq: the service_queue being reported |
| * @fmt: printf format string |
| * @args: printf args |
| * |
| * The messages are prefixed with "throtl BLKG_NAME" if @sq belongs to a |
| * throtl_grp; otherwise, just "throtl". |
| */ |
| #define throtl_log(sq, fmt, args...) do { \ |
| struct throtl_grp *__tg = sq_to_tg((sq)); \ |
| struct throtl_data *__td = sq_to_td((sq)); \ |
| \ |
| (void)__td; \ |
| if (likely(!blk_trace_note_message_enabled(__td->queue))) \ |
| break; \ |
| if ((__tg)) { \ |
| blk_add_cgroup_trace_msg(__td->queue, \ |
| tg_to_blkg(__tg)->blkcg, "throtl " fmt, ##args);\ |
| } else { \ |
| blk_add_trace_msg(__td->queue, "throtl " fmt, ##args); \ |
| } \ |
| } while (0) |
| |
| static inline unsigned int throtl_bio_data_size(struct bio *bio) |
| { |
| /* assume it's one sector */ |
| if (unlikely(bio_op(bio) == REQ_OP_DISCARD)) |
| return 512; |
| return bio->bi_iter.bi_size; |
| } |
| |
| static void throtl_qnode_init(struct throtl_qnode *qn, struct throtl_grp *tg) |
| { |
| INIT_LIST_HEAD(&qn->node); |
| bio_list_init(&qn->bios); |
| qn->tg = tg; |
| } |
| |
| /** |
| * throtl_qnode_add_bio - add a bio to a throtl_qnode and activate it |
| * @bio: bio being added |
| * @qn: qnode to add bio to |
| * @queued: the service_queue->queued[] list @qn belongs to |
| * |
| * Add @bio to @qn and put @qn on @queued if it's not already on. |
| * @qn->tg's reference count is bumped when @qn is activated. See the |
| * comment on top of throtl_qnode definition for details. |
| */ |
| static void throtl_qnode_add_bio(struct bio *bio, struct throtl_qnode *qn, |
| struct list_head *queued) |
| { |
| bio_list_add(&qn->bios, bio); |
| if (list_empty(&qn->node)) { |
| list_add_tail(&qn->node, queued); |
| blkg_get(tg_to_blkg(qn->tg)); |
| } |
| } |
| |
| /** |
| * throtl_peek_queued - peek the first bio on a qnode list |
| * @queued: the qnode list to peek |
| */ |
| static struct bio *throtl_peek_queued(struct list_head *queued) |
| { |
| struct throtl_qnode *qn = list_first_entry(queued, struct throtl_qnode, node); |
| struct bio *bio; |
| |
| if (list_empty(queued)) |
| return NULL; |
| |
| bio = bio_list_peek(&qn->bios); |
| WARN_ON_ONCE(!bio); |
| return bio; |
| } |
| |
| /** |
| * throtl_pop_queued - pop the first bio form a qnode list |
| * @queued: the qnode list to pop a bio from |
| * @tg_to_put: optional out argument for throtl_grp to put |
| * |
| * Pop the first bio from the qnode list @queued. After popping, the first |
| * qnode is removed from @queued if empty or moved to the end of @queued so |
| * that the popping order is round-robin. |
| * |
| * When the first qnode is removed, its associated throtl_grp should be put |
| * too. If @tg_to_put is NULL, this function automatically puts it; |
| * otherwise, *@tg_to_put is set to the throtl_grp to put and the caller is |
| * responsible for putting it. |
| */ |
| static struct bio *throtl_pop_queued(struct list_head *queued, |
| struct throtl_grp **tg_to_put) |
| { |
| struct throtl_qnode *qn = list_first_entry(queued, struct throtl_qnode, node); |
| struct bio *bio; |
| |
| if (list_empty(queued)) |
| return NULL; |
| |
| bio = bio_list_pop(&qn->bios); |
| WARN_ON_ONCE(!bio); |
| |
| if (bio_list_empty(&qn->bios)) { |
| list_del_init(&qn->node); |
| if (tg_to_put) |
| *tg_to_put = qn->tg; |
| else |
| blkg_put(tg_to_blkg(qn->tg)); |
| } else { |
| list_move_tail(&qn->node, queued); |
| } |
| |
| return bio; |
| } |
| |
| /* init a service_queue, assumes the caller zeroed it */ |
| static void throtl_service_queue_init(struct throtl_service_queue *sq) |
| { |
| INIT_LIST_HEAD(&sq->queued[0]); |
| INIT_LIST_HEAD(&sq->queued[1]); |
| sq->pending_tree = RB_ROOT_CACHED; |
| timer_setup(&sq->pending_timer, throtl_pending_timer_fn, 0); |
| } |
| |
| static struct blkg_policy_data *throtl_pd_alloc(gfp_t gfp, |
| struct request_queue *q, |
| struct blkcg *blkcg) |
| { |
| struct throtl_grp *tg; |
| int rw; |
| |
| tg = kzalloc_node(sizeof(*tg), gfp, q->node); |
| if (!tg) |
| return NULL; |
| |
| throtl_service_queue_init(&tg->service_queue); |
| |
| for (rw = READ; rw <= WRITE; rw++) { |
| throtl_qnode_init(&tg->qnode_on_self[rw], tg); |
| throtl_qnode_init(&tg->qnode_on_parent[rw], tg); |
| } |
| |
| RB_CLEAR_NODE(&tg->rb_node); |
| tg->bps[READ][LIMIT_MAX] = U64_MAX; |
| tg->bps[WRITE][LIMIT_MAX] = U64_MAX; |
| tg->iops[READ][LIMIT_MAX] = UINT_MAX; |
| tg->iops[WRITE][LIMIT_MAX] = UINT_MAX; |
| tg->bps_conf[READ][LIMIT_MAX] = U64_MAX; |
| tg->bps_conf[WRITE][LIMIT_MAX] = U64_MAX; |
| tg->iops_conf[READ][LIMIT_MAX] = UINT_MAX; |
| tg->iops_conf[WRITE][LIMIT_MAX] = UINT_MAX; |
| /* LIMIT_LOW will have default value 0 */ |
| |
| tg->latency_target = DFL_LATENCY_TARGET; |
| tg->latency_target_conf = DFL_LATENCY_TARGET; |
| tg->idletime_threshold = DFL_IDLE_THRESHOLD; |
| tg->idletime_threshold_conf = DFL_IDLE_THRESHOLD; |
| |
| return &tg->pd; |
| } |
| |
| static void throtl_pd_init(struct blkg_policy_data *pd) |
| { |
| struct throtl_grp *tg = pd_to_tg(pd); |
| struct blkcg_gq *blkg = tg_to_blkg(tg); |
| struct throtl_data *td = blkg->q->td; |
| struct throtl_service_queue *sq = &tg->service_queue; |
| |
| /* |
| * If on the default hierarchy, we switch to properly hierarchical |
| * behavior where limits on a given throtl_grp are applied to the |
| * whole subtree rather than just the group itself. e.g. If 16M |
| * read_bps limit is set on the root group, the whole system can't |
| * exceed 16M for the device. |
| * |
| * If not on the default hierarchy, the broken flat hierarchy |
| * behavior is retained where all throtl_grps are treated as if |
| * they're all separate root groups right below throtl_data. |
| * Limits of a group don't interact with limits of other groups |
| * regardless of the position of the group in the hierarchy. |
| */ |
| sq->parent_sq = &td->service_queue; |
| if (cgroup_subsys_on_dfl(io_cgrp_subsys) && blkg->parent) |
| sq->parent_sq = &blkg_to_tg(blkg->parent)->service_queue; |
| tg->td = td; |
| } |
| |
| /* |
| * Set has_rules[] if @tg or any of its parents have limits configured. |
| * This doesn't require walking up to the top of the hierarchy as the |
| * parent's has_rules[] is guaranteed to be correct. |
| */ |
| static void tg_update_has_rules(struct throtl_grp *tg) |
| { |
| struct throtl_grp *parent_tg = sq_to_tg(tg->service_queue.parent_sq); |
| struct throtl_data *td = tg->td; |
| int rw; |
| |
| for (rw = READ; rw <= WRITE; rw++) |
| tg->has_rules[rw] = (parent_tg && parent_tg->has_rules[rw]) || |
| (td->limit_valid[td->limit_index] && |
| (tg_bps_limit(tg, rw) != U64_MAX || |
| tg_iops_limit(tg, rw) != UINT_MAX)); |
| } |
| |
| static void throtl_pd_online(struct blkg_policy_data *pd) |
| { |
| struct throtl_grp *tg = pd_to_tg(pd); |
| /* |
| * We don't want new groups to escape the limits of its ancestors. |
| * Update has_rules[] after a new group is brought online. |
| */ |
| tg_update_has_rules(tg); |
| } |
| |
| static void blk_throtl_update_limit_valid(struct throtl_data *td) |
| { |
| struct cgroup_subsys_state *pos_css; |
| struct blkcg_gq *blkg; |
| bool low_valid = false; |
| |
| rcu_read_lock(); |
| blkg_for_each_descendant_post(blkg, pos_css, td->queue->root_blkg) { |
| struct throtl_grp *tg = blkg_to_tg(blkg); |
| |
| if (tg->bps[READ][LIMIT_LOW] || tg->bps[WRITE][LIMIT_LOW] || |
| tg->iops[READ][LIMIT_LOW] || tg->iops[WRITE][LIMIT_LOW]) { |
| low_valid = true; |
| break; |
| } |
| } |
| rcu_read_unlock(); |
| |
| td->limit_valid[LIMIT_LOW] = low_valid; |
| } |
| |
| static void throtl_upgrade_state(struct throtl_data *td); |
| static void throtl_pd_offline(struct blkg_policy_data *pd) |
| { |
| struct throtl_grp *tg = pd_to_tg(pd); |
| |
| tg->bps[READ][LIMIT_LOW] = 0; |
| tg->bps[WRITE][LIMIT_LOW] = 0; |
| tg->iops[READ][LIMIT_LOW] = 0; |
| tg->iops[WRITE][LIMIT_LOW] = 0; |
| |
| blk_throtl_update_limit_valid(tg->td); |
| |
| if (!tg->td->limit_valid[tg->td->limit_index]) |
| throtl_upgrade_state(tg->td); |
| } |
| |
| static void throtl_pd_free(struct blkg_policy_data *pd) |
| { |
| struct throtl_grp *tg = pd_to_tg(pd); |
| |
| del_timer_sync(&tg->service_queue.pending_timer); |
| kfree(tg); |
| } |
| |
| static struct throtl_grp * |
| throtl_rb_first(struct throtl_service_queue *parent_sq) |
| { |
| struct rb_node *n; |
| /* Service tree is empty */ |
| if (!parent_sq->nr_pending) |
| return NULL; |
| |
| n = rb_first_cached(&parent_sq->pending_tree); |
| WARN_ON_ONCE(!n); |
| if (!n) |
| return NULL; |
| return rb_entry_tg(n); |
| } |
| |
| static void throtl_rb_erase(struct rb_node *n, |
| struct throtl_service_queue *parent_sq) |
| { |
| rb_erase_cached(n, &parent_sq->pending_tree); |
| RB_CLEAR_NODE(n); |
| --parent_sq->nr_pending; |
| } |
| |
| static void update_min_dispatch_time(struct throtl_service_queue *parent_sq) |
| { |
| struct throtl_grp *tg; |
| |
| tg = throtl_rb_first(parent_sq); |
| if (!tg) |
| return; |
| |
| parent_sq->first_pending_disptime = tg->disptime; |
| } |
| |
| static void tg_service_queue_add(struct throtl_grp *tg) |
| { |
| struct throtl_service_queue *parent_sq = tg->service_queue.parent_sq; |
| struct rb_node **node = &parent_sq->pending_tree.rb_root.rb_node; |
| struct rb_node *parent = NULL; |
| struct throtl_grp *__tg; |
| unsigned long key = tg->disptime; |
| bool leftmost = true; |
| |
| while (*node != NULL) { |
| parent = *node; |
| __tg = rb_entry_tg(parent); |
| |
| if (time_before(key, __tg->disptime)) |
| node = &parent->rb_left; |
| else { |
| node = &parent->rb_right; |
| leftmost = false; |
| } |
| } |
| |
| rb_link_node(&tg->rb_node, parent, node); |
| rb_insert_color_cached(&tg->rb_node, &parent_sq->pending_tree, |
| leftmost); |
| } |
| |
| static void __throtl_enqueue_tg(struct throtl_grp *tg) |
| { |
| tg_service_queue_add(tg); |
| tg->flags |= THROTL_TG_PENDING; |
| tg->service_queue.parent_sq->nr_pending++; |
| } |
| |
| static void throtl_enqueue_tg(struct throtl_grp *tg) |
| { |
| if (!(tg->flags & THROTL_TG_PENDING)) |
| __throtl_enqueue_tg(tg); |
| } |
| |
| static void __throtl_dequeue_tg(struct throtl_grp *tg) |
| { |
| throtl_rb_erase(&tg->rb_node, tg->service_queue.parent_sq); |
| tg->flags &= ~THROTL_TG_PENDING; |
| } |
| |
| static void throtl_dequeue_tg(struct throtl_grp *tg) |
| { |
| if (tg->flags & THROTL_TG_PENDING) |
| __throtl_dequeue_tg(tg); |
| } |
| |
| /* Call with queue lock held */ |
| static void throtl_schedule_pending_timer(struct throtl_service_queue *sq, |
| unsigned long expires) |
| { |
| unsigned long max_expire = jiffies + 8 * sq_to_td(sq)->throtl_slice; |
| |
| /* |
| * Since we are adjusting the throttle limit dynamically, the sleep |
| * time calculated according to previous limit might be invalid. It's |
| * possible the cgroup sleep time is very long and no other cgroups |
| * have IO running so notify the limit changes. Make sure the cgroup |
| * doesn't sleep too long to avoid the missed notification. |
| */ |
| if (time_after(expires, max_expire)) |
| expires = max_expire; |
| mod_timer(&sq->pending_timer, expires); |
| throtl_log(sq, "schedule timer. delay=%lu jiffies=%lu", |
| expires - jiffies, jiffies); |
| } |
| |
| /** |
| * throtl_schedule_next_dispatch - schedule the next dispatch cycle |
| * @sq: the service_queue to schedule dispatch for |
| * @force: force scheduling |
| * |
| * Arm @sq->pending_timer so that the next dispatch cycle starts on the |
| * dispatch time of the first pending child. Returns %true if either timer |
| * is armed or there's no pending child left. %false if the current |
| * dispatch window is still open and the caller should continue |
| * dispatching. |
| * |
| * If @force is %true, the dispatch timer is always scheduled and this |
| * function is guaranteed to return %true. This is to be used when the |
| * caller can't dispatch itself and needs to invoke pending_timer |
| * unconditionally. Note that forced scheduling is likely to induce short |
| * delay before dispatch starts even if @sq->first_pending_disptime is not |
| * in the future and thus shouldn't be used in hot paths. |
| */ |
| static bool throtl_schedule_next_dispatch(struct throtl_service_queue *sq, |
| bool force) |
| { |
| /* any pending children left? */ |
| if (!sq->nr_pending) |
| return true; |
| |
| update_min_dispatch_time(sq); |
| |
| /* is the next dispatch time in the future? */ |
| if (force || time_after(sq->first_pending_disptime, jiffies)) { |
| throtl_schedule_pending_timer(sq, sq->first_pending_disptime); |
| return true; |
| } |
| |
| /* tell the caller to continue dispatching */ |
| return false; |
| } |
| |
| static inline void throtl_start_new_slice_with_credit(struct throtl_grp *tg, |
| bool rw, unsigned long start) |
| { |
| tg->bytes_disp[rw] = 0; |
| tg->io_disp[rw] = 0; |
| |
| /* |
| * Previous slice has expired. We must have trimmed it after last |
| * bio dispatch. That means since start of last slice, we never used |
| * that bandwidth. Do try to make use of that bandwidth while giving |
| * credit. |
| */ |
| if (time_after_eq(start, tg->slice_start[rw])) |
| tg->slice_start[rw] = start; |
| |
| tg->slice_end[rw] = jiffies + tg->td->throtl_slice; |
| throtl_log(&tg->service_queue, |
| "[%c] new slice with credit start=%lu end=%lu jiffies=%lu", |
| rw == READ ? 'R' : 'W', tg->slice_start[rw], |
| tg->slice_end[rw], jiffies); |
| } |
| |
| static inline void throtl_start_new_slice(struct throtl_grp *tg, bool rw) |
| { |
| tg->bytes_disp[rw] = 0; |
| tg->io_disp[rw] = 0; |
| tg->slice_start[rw] = jiffies; |
| tg->slice_end[rw] = jiffies + tg->td->throtl_slice; |
| throtl_log(&tg->service_queue, |
| "[%c] new slice start=%lu end=%lu jiffies=%lu", |
| rw == READ ? 'R' : 'W', tg->slice_start[rw], |
| tg->slice_end[rw], jiffies); |
| } |
| |
| static inline void throtl_set_slice_end(struct throtl_grp *tg, bool rw, |
| unsigned long jiffy_end) |
| { |
| tg->slice_end[rw] = roundup(jiffy_end, tg->td->throtl_slice); |
| } |
| |
| static inline void throtl_extend_slice(struct throtl_grp *tg, bool rw, |
| unsigned long jiffy_end) |
| { |
| tg->slice_end[rw] = roundup(jiffy_end, tg->td->throtl_slice); |
| throtl_log(&tg->service_queue, |
| "[%c] extend slice start=%lu end=%lu jiffies=%lu", |
| rw == READ ? 'R' : 'W', tg->slice_start[rw], |
| tg->slice_end[rw], jiffies); |
| } |
| |
| /* Determine if previously allocated or extended slice is complete or not */ |
| static bool throtl_slice_used(struct throtl_grp *tg, bool rw) |
| { |
| if (time_in_range(jiffies, tg->slice_start[rw], tg->slice_end[rw])) |
| return false; |
| |
| return true; |
| } |
| |
| /* Trim the used slices and adjust slice start accordingly */ |
| static inline void throtl_trim_slice(struct throtl_grp *tg, bool rw) |
| { |
| unsigned long nr_slices, time_elapsed, io_trim; |
| u64 bytes_trim, tmp; |
| |
| BUG_ON(time_before(tg->slice_end[rw], tg->slice_start[rw])); |
| |
| /* |
| * If bps are unlimited (-1), then time slice don't get |
| * renewed. Don't try to trim the slice if slice is used. A new |
| * slice will start when appropriate. |
| */ |
| if (throtl_slice_used(tg, rw)) |
| return; |
| |
| /* |
| * A bio has been dispatched. Also adjust slice_end. It might happen |
| * that initially cgroup limit was very low resulting in high |
| * slice_end, but later limit was bumped up and bio was dispached |
| * sooner, then we need to reduce slice_end. A high bogus slice_end |
| * is bad because it does not allow new slice to start. |
| */ |
| |
| throtl_set_slice_end(tg, rw, jiffies + tg->td->throtl_slice); |
| |
| time_elapsed = jiffies - tg->slice_start[rw]; |
| |
| nr_slices = time_elapsed / tg->td->throtl_slice; |
| |
| if (!nr_slices) |
| return; |
| tmp = tg_bps_limit(tg, rw) * tg->td->throtl_slice * nr_slices; |
| do_div(tmp, HZ); |
| bytes_trim = tmp; |
| |
| io_trim = (tg_iops_limit(tg, rw) * tg->td->throtl_slice * nr_slices) / |
| HZ; |
| |
| if (!bytes_trim && !io_trim) |
| return; |
| |
| if (tg->bytes_disp[rw] >= bytes_trim) |
| tg->bytes_disp[rw] -= bytes_trim; |
| else |
| tg->bytes_disp[rw] = 0; |
| |
| if (tg->io_disp[rw] >= io_trim) |
| tg->io_disp[rw] -= io_trim; |
| else |
| tg->io_disp[rw] = 0; |
| |
| tg->slice_start[rw] += nr_slices * tg->td->throtl_slice; |
| |
| throtl_log(&tg->service_queue, |
| "[%c] trim slice nr=%lu bytes=%llu io=%lu start=%lu end=%lu jiffies=%lu", |
| rw == READ ? 'R' : 'W', nr_slices, bytes_trim, io_trim, |
| tg->slice_start[rw], tg->slice_end[rw], jiffies); |
| } |
| |
| static bool tg_with_in_iops_limit(struct throtl_grp *tg, struct bio *bio, |
| unsigned long *wait) |
| { |
| bool rw = bio_data_dir(bio); |
| unsigned int io_allowed; |
| unsigned long jiffy_elapsed, jiffy_wait, jiffy_elapsed_rnd; |
| u64 tmp; |
| |
| jiffy_elapsed = jiffies - tg->slice_start[rw]; |
| |
| /* Round up to the next throttle slice, wait time must be nonzero */ |
| jiffy_elapsed_rnd = roundup(jiffy_elapsed + 1, tg->td->throtl_slice); |
| |
| /* |
| * jiffy_elapsed_rnd should not be a big value as minimum iops can be |
| * 1 then at max jiffy elapsed should be equivalent of 1 second as we |
| * will allow dispatch after 1 second and after that slice should |
| * have been trimmed. |
| */ |
| |
| tmp = (u64)tg_iops_limit(tg, rw) * jiffy_elapsed_rnd; |
| do_div(tmp, HZ); |
| |
| if (tmp > UINT_MAX) |
| io_allowed = UINT_MAX; |
| else |
| io_allowed = tmp; |
| |
| if (tg->io_disp[rw] + 1 <= io_allowed) { |
| if (wait) |
| *wait = 0; |
| return true; |
| } |
| |
| /* Calc approx time to dispatch */ |
| jiffy_wait = jiffy_elapsed_rnd - jiffy_elapsed; |
| |
| if (wait) |
| *wait = jiffy_wait; |
| return false; |
| } |
| |
| static bool tg_with_in_bps_limit(struct throtl_grp *tg, struct bio *bio, |
| unsigned long *wait) |
| { |
| bool rw = bio_data_dir(bio); |
| u64 bytes_allowed, extra_bytes, tmp; |
| unsigned long jiffy_elapsed, jiffy_wait, jiffy_elapsed_rnd; |
| unsigned int bio_size = throtl_bio_data_size(bio); |
| |
| jiffy_elapsed = jiffy_elapsed_rnd = jiffies - tg->slice_start[rw]; |
| |
| /* Slice has just started. Consider one slice interval */ |
| if (!jiffy_elapsed) |
| jiffy_elapsed_rnd = tg->td->throtl_slice; |
| |
| jiffy_elapsed_rnd = roundup(jiffy_elapsed_rnd, tg->td->throtl_slice); |
| |
| tmp = tg_bps_limit(tg, rw) * jiffy_elapsed_rnd; |
| do_div(tmp, HZ); |
| bytes_allowed = tmp; |
| |
| if (tg->bytes_disp[rw] + bio_size <= bytes_allowed) { |
| if (wait) |
| *wait = 0; |
| return true; |
| } |
| |
| /* Calc approx time to dispatch */ |
| extra_bytes = tg->bytes_disp[rw] + bio_size - bytes_allowed; |
| jiffy_wait = div64_u64(extra_bytes * HZ, tg_bps_limit(tg, rw)); |
| |
| if (!jiffy_wait) |
| jiffy_wait = 1; |
| |
| /* |
| * This wait time is without taking into consideration the rounding |
| * up we did. Add that time also. |
| */ |
| jiffy_wait = jiffy_wait + (jiffy_elapsed_rnd - jiffy_elapsed); |
| if (wait) |
| *wait = jiffy_wait; |
| return false; |
| } |
| |
| /* |
| * Returns whether one can dispatch a bio or not. Also returns approx number |
| * of jiffies to wait before this bio is with-in IO rate and can be dispatched |
| */ |
| static bool tg_may_dispatch(struct throtl_grp *tg, struct bio *bio, |
| unsigned long *wait) |
| { |
| bool rw = bio_data_dir(bio); |
| unsigned long bps_wait = 0, iops_wait = 0, max_wait = 0; |
| |
| /* |
| * Currently whole state machine of group depends on first bio |
| * queued in the group bio list. So one should not be calling |
| * this function with a different bio if there are other bios |
| * queued. |
| */ |
| BUG_ON(tg->service_queue.nr_queued[rw] && |
| bio != throtl_peek_queued(&tg->service_queue.queued[rw])); |
| |
| /* If tg->bps = -1, then BW is unlimited */ |
| if (tg_bps_limit(tg, rw) == U64_MAX && |
| tg_iops_limit(tg, rw) == UINT_MAX) { |
| if (wait) |
| *wait = 0; |
| return true; |
| } |
| |
| /* |
| * If previous slice expired, start a new one otherwise renew/extend |
| * existing slice to make sure it is at least throtl_slice interval |
| * long since now. New slice is started only for empty throttle group. |
| * If there is queued bio, that means there should be an active |
| * slice and it should be extended instead. |
| */ |
| if (throtl_slice_used(tg, rw) && !(tg->service_queue.nr_queued[rw])) |
| throtl_start_new_slice(tg, rw); |
| else { |
| if (time_before(tg->slice_end[rw], |
| jiffies + tg->td->throtl_slice)) |
| throtl_extend_slice(tg, rw, |
| jiffies + tg->td->throtl_slice); |
| } |
| |
| if (tg_with_in_bps_limit(tg, bio, &bps_wait) && |
| tg_with_in_iops_limit(tg, bio, &iops_wait)) { |
| if (wait) |
| *wait = 0; |
| return true; |
| } |
| |
| max_wait = max(bps_wait, iops_wait); |
| |
| if (wait) |
| *wait = max_wait; |
| |
| if (time_before(tg->slice_end[rw], jiffies + max_wait)) |
| throtl_extend_slice(tg, rw, jiffies + max_wait); |
| |
| return false; |
| } |
| |
| static void throtl_charge_bio(struct throtl_grp *tg, struct bio *bio) |
| { |
| bool rw = bio_data_dir(bio); |
| unsigned int bio_size = throtl_bio_data_size(bio); |
| |
| /* Charge the bio to the group */ |
| tg->bytes_disp[rw] += bio_size; |
| tg->io_disp[rw]++; |
| tg->last_bytes_disp[rw] += bio_size; |
| tg->last_io_disp[rw]++; |
| |
| /* |
| * BIO_THROTTLED is used to prevent the same bio to be throttled |
| * more than once as a throttled bio will go through blk-throtl the |
| * second time when it eventually gets issued. Set it when a bio |
| * is being charged to a tg. |
| */ |
| if (!bio_flagged(bio, BIO_THROTTLED)) |
| bio_set_flag(bio, BIO_THROTTLED); |
| } |
| |
| /** |
| * throtl_add_bio_tg - add a bio to the specified throtl_grp |
| * @bio: bio to add |
| * @qn: qnode to use |
| * @tg: the target throtl_grp |
| * |
| * Add @bio to @tg's service_queue using @qn. If @qn is not specified, |
| * tg->qnode_on_self[] is used. |
| */ |
| static void throtl_add_bio_tg(struct bio *bio, struct throtl_qnode *qn, |
| struct throtl_grp *tg) |
| { |
| struct throtl_service_queue *sq = &tg->service_queue; |
| bool rw = bio_data_dir(bio); |
| |
| if (!qn) |
| qn = &tg->qnode_on_self[rw]; |
| |
| /* |
| * If @tg doesn't currently have any bios queued in the same |
| * direction, queueing @bio can change when @tg should be |
| * dispatched. Mark that @tg was empty. This is automatically |
| * cleaered on the next tg_update_disptime(). |
| */ |
| if (!sq->nr_queued[rw]) |
| tg->flags |= THROTL_TG_WAS_EMPTY; |
| |
| throtl_qnode_add_bio(bio, qn, &sq->queued[rw]); |
| |
| sq->nr_queued[rw]++; |
| throtl_enqueue_tg(tg); |
| } |
| |
| static void tg_update_disptime(struct throtl_grp *tg) |
| { |
| struct throtl_service_queue *sq = &tg->service_queue; |
| unsigned long read_wait = -1, write_wait = -1, min_wait = -1, disptime; |
| struct bio *bio; |
| |
| bio = throtl_peek_queued(&sq->queued[READ]); |
| if (bio) |
| tg_may_dispatch(tg, bio, &read_wait); |
| |
| bio = throtl_peek_queued(&sq->queued[WRITE]); |
| if (bio) |
| tg_may_dispatch(tg, bio, &write_wait); |
| |
| min_wait = min(read_wait, write_wait); |
| disptime = jiffies + min_wait; |
| |
| /* Update dispatch time */ |
| throtl_dequeue_tg(tg); |
| tg->disptime = disptime; |
| throtl_enqueue_tg(tg); |
| |
| /* see throtl_add_bio_tg() */ |
| tg->flags &= ~THROTL_TG_WAS_EMPTY; |
| } |
| |
| static void start_parent_slice_with_credit(struct throtl_grp *child_tg, |
| struct throtl_grp *parent_tg, bool rw) |
| { |
| if (throtl_slice_used(parent_tg, rw)) { |
| throtl_start_new_slice_with_credit(parent_tg, rw, |
| child_tg->slice_start[rw]); |
| } |
| |
| } |
| |
| static void tg_dispatch_one_bio(struct throtl_grp *tg, bool rw) |
| { |
| struct throtl_service_queue *sq = &tg->service_queue; |
| struct throtl_service_queue *parent_sq = sq->parent_sq; |
| struct throtl_grp *parent_tg = sq_to_tg(parent_sq); |
| struct throtl_grp *tg_to_put = NULL; |
| struct bio *bio; |
| |
| /* |
| * @bio is being transferred from @tg to @parent_sq. Popping a bio |
| * from @tg may put its reference and @parent_sq might end up |
| * getting released prematurely. Remember the tg to put and put it |
| * after @bio is transferred to @parent_sq. |
| */ |
| bio = throtl_pop_queued(&sq->queued[rw], &tg_to_put); |
| sq->nr_queued[rw]--; |
| |
| throtl_charge_bio(tg, bio); |
| |
| /* |
| * If our parent is another tg, we just need to transfer @bio to |
| * the parent using throtl_add_bio_tg(). If our parent is |
| * @td->service_queue, @bio is ready to be issued. Put it on its |
| * bio_lists[] and decrease total number queued. The caller is |
| * responsible for issuing these bios. |
| */ |
| if (parent_tg) { |
| throtl_add_bio_tg(bio, &tg->qnode_on_parent[rw], parent_tg); |
| start_parent_slice_with_credit(tg, parent_tg, rw); |
| } else { |
| throtl_qnode_add_bio(bio, &tg->qnode_on_parent[rw], |
| &parent_sq->queued[rw]); |
| BUG_ON(tg->td->nr_queued[rw] <= 0); |
| tg->td->nr_queued[rw]--; |
| } |
| |
| throtl_trim_slice(tg, rw); |
| |
| if (tg_to_put) |
| blkg_put(tg_to_blkg(tg_to_put)); |
| } |
| |
| static int throtl_dispatch_tg(struct throtl_grp *tg) |
| { |
| struct throtl_service_queue *sq = &tg->service_queue; |
| unsigned int nr_reads = 0, nr_writes = 0; |
| unsigned int max_nr_reads = throtl_grp_quantum*3/4; |
| unsigned int max_nr_writes = throtl_grp_quantum - max_nr_reads; |
| struct bio *bio; |
| |
| /* Try to dispatch 75% READS and 25% WRITES */ |
| |
| while ((bio = throtl_peek_queued(&sq->queued[READ])) && |
| tg_may_dispatch(tg, bio, NULL)) { |
| |
| tg_dispatch_one_bio(tg, bio_data_dir(bio)); |
| nr_reads++; |
| |
| if (nr_reads >= max_nr_reads) |
| break; |
| } |
| |
| while ((bio = throtl_peek_queued(&sq->queued[WRITE])) && |
| tg_may_dispatch(tg, bio, NULL)) { |
| |
| tg_dispatch_one_bio(tg, bio_data_dir(bio)); |
| nr_writes++; |
| |
| if (nr_writes >= max_nr_writes) |
| break; |
| } |
| |
| return nr_reads + nr_writes; |
| } |
| |
| static int throtl_select_dispatch(struct throtl_service_queue *parent_sq) |
| { |
| unsigned int nr_disp = 0; |
| |
| while (1) { |
| struct throtl_grp *tg = throtl_rb_first(parent_sq); |
| struct throtl_service_queue *sq; |
| |
| if (!tg) |
| break; |
| |
| if (time_before(jiffies, tg->disptime)) |
| break; |
| |
| throtl_dequeue_tg(tg); |
| |
| nr_disp += throtl_dispatch_tg(tg); |
| |
| sq = &tg->service_queue; |
| if (sq->nr_queued[0] || sq->nr_queued[1]) |
| tg_update_disptime(tg); |
| |
| if (nr_disp >= throtl_quantum) |
| break; |
| } |
| |
| return nr_disp; |
| } |
| |
| static bool throtl_can_upgrade(struct throtl_data *td, |
| struct throtl_grp *this_tg); |
| /** |
| * throtl_pending_timer_fn - timer function for service_queue->pending_timer |
| * @t: the pending_timer member of the throtl_service_queue being serviced |
| * |
| * This timer is armed when a child throtl_grp with active bio's become |
| * pending and queued on the service_queue's pending_tree and expires when |
| * the first child throtl_grp should be dispatched. This function |
| * dispatches bio's from the children throtl_grps to the parent |
| * service_queue. |
| * |
| * If the parent's parent is another throtl_grp, dispatching is propagated |
| * by either arming its pending_timer or repeating dispatch directly. If |
| * the top-level service_tree is reached, throtl_data->dispatch_work is |
| * kicked so that the ready bio's are issued. |
| */ |
| static void throtl_pending_timer_fn(struct timer_list *t) |
| { |
| struct throtl_service_queue *sq = from_timer(sq, t, pending_timer); |
| struct throtl_grp *tg = sq_to_tg(sq); |
| struct throtl_data *td = sq_to_td(sq); |
| struct request_queue *q = td->queue; |
| struct throtl_service_queue *parent_sq; |
| bool dispatched; |
| int ret; |
| |
| spin_lock_irq(&q->queue_lock); |
| if (throtl_can_upgrade(td, NULL)) |
| throtl_upgrade_state(td); |
| |
| again: |
| parent_sq = sq->parent_sq; |
| dispatched = false; |
| |
| while (true) { |
| throtl_log(sq, "dispatch nr_queued=%u read=%u write=%u", |
| sq->nr_queued[READ] + sq->nr_queued[WRITE], |
| sq->nr_queued[READ], sq->nr_queued[WRITE]); |
| |
| ret = throtl_select_dispatch(sq); |
| if (ret) { |
| throtl_log(sq, "bios disp=%u", ret); |
| dispatched = true; |
| } |
| |
| if (throtl_schedule_next_dispatch(sq, false)) |
| break; |
| |
| /* this dispatch windows is still open, relax and repeat */ |
| spin_unlock_irq(&q->queue_lock); |
| cpu_relax(); |
| spin_lock_irq(&q->queue_lock); |
| } |
| |
| if (!dispatched) |
| goto out_unlock; |
| |
| if (parent_sq) { |
| /* @parent_sq is another throl_grp, propagate dispatch */ |
| if (tg->flags & THROTL_TG_WAS_EMPTY) { |
| tg_update_disptime(tg); |
| if (!throtl_schedule_next_dispatch(parent_sq, false)) { |
| /* window is already open, repeat dispatching */ |
| sq = parent_sq; |
| tg = sq_to_tg(sq); |
| goto again; |
| } |
| } |
| } else { |
| /* reached the top-level, queue issueing */ |
| queue_work(kthrotld_workqueue, &td->dispatch_work); |
| } |
| out_unlock: |
| spin_unlock_irq(&q->queue_lock); |
| } |
| |
| /** |
| * blk_throtl_dispatch_work_fn - work function for throtl_data->dispatch_work |
| * @work: work item being executed |
| * |
| * This function is queued for execution when bio's reach the bio_lists[] |
| * of throtl_data->service_queue. Those bio's are ready and issued by this |
| * function. |
| */ |
| static void blk_throtl_dispatch_work_fn(struct work_struct *work) |
| { |
| struct throtl_data *td = container_of(work, struct throtl_data, |
| dispatch_work); |
| struct throtl_service_queue *td_sq = &td->service_queue; |
| struct request_queue *q = td->queue; |
| struct bio_list bio_list_on_stack; |
| struct bio *bio; |
| struct blk_plug plug; |
| int rw; |
| |
| bio_list_init(&bio_list_on_stack); |
| |
| spin_lock_irq(&q->queue_lock); |
| for (rw = READ; rw <= WRITE; rw++) |
| while ((bio = throtl_pop_queued(&td_sq->queued[rw], NULL))) |
| bio_list_add(&bio_list_on_stack, bio); |
| spin_unlock_irq(&q->queue_lock); |
| |
| if (!bio_list_empty(&bio_list_on_stack)) { |
| blk_start_plug(&plug); |
| while((bio = bio_list_pop(&bio_list_on_stack))) |
| generic_make_request(bio); |
| blk_finish_plug(&plug); |
| } |
| } |
| |
| static u64 tg_prfill_conf_u64(struct seq_file *sf, struct blkg_policy_data *pd, |
| int off) |
| { |
| struct throtl_grp *tg = pd_to_tg(pd); |
| u64 v = *(u64 *)((void *)tg + off); |
| |
| if (v == U64_MAX) |
| return 0; |
| return __blkg_prfill_u64(sf, pd, v); |
| } |
| |
| static u64 tg_prfill_conf_uint(struct seq_file *sf, struct blkg_policy_data *pd, |
| int off) |
| { |
| struct throtl_grp *tg = pd_to_tg(pd); |
| unsigned int v = *(unsigned int *)((void *)tg + off); |
| |
| if (v == UINT_MAX) |
| return 0; |
| return __blkg_prfill_u64(sf, pd, v); |
| } |
| |
| static int tg_print_conf_u64(struct seq_file *sf, void *v) |
| { |
| blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), tg_prfill_conf_u64, |
| &blkcg_policy_throtl, seq_cft(sf)->private, false); |
| return 0; |
| } |
| |
| static int tg_print_conf_uint(struct seq_file *sf, void *v) |
| { |
| blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), tg_prfill_conf_uint, |
| &blkcg_policy_throtl, seq_cft(sf)->private, false); |
| return 0; |
| } |
| |
| static void tg_conf_updated(struct throtl_grp *tg, bool global) |
| { |
| struct throtl_service_queue *sq = &tg->service_queue; |
| struct cgroup_subsys_state *pos_css; |
| struct blkcg_gq *blkg; |
| |
| throtl_log(&tg->service_queue, |
| "limit change rbps=%llu wbps=%llu riops=%u wiops=%u", |
| tg_bps_limit(tg, READ), tg_bps_limit(tg, WRITE), |
| tg_iops_limit(tg, READ), tg_iops_limit(tg, WRITE)); |
| |
| /* |
| * Update has_rules[] flags for the updated tg's subtree. A tg is |
| * considered to have rules if either the tg itself or any of its |
| * ancestors has rules. This identifies groups without any |
| * restrictions in the whole hierarchy and allows them to bypass |
| * blk-throttle. |
| */ |
| blkg_for_each_descendant_pre(blkg, pos_css, |
| global ? tg->td->queue->root_blkg : tg_to_blkg(tg)) { |
| struct throtl_grp *this_tg = blkg_to_tg(blkg); |
| struct throtl_grp *parent_tg; |
| |
| tg_update_has_rules(this_tg); |
| /* ignore root/second level */ |
| if (!cgroup_subsys_on_dfl(io_cgrp_subsys) || !blkg->parent || |
| !blkg->parent->parent) |
| continue; |
| parent_tg = blkg_to_tg(blkg->parent); |
| /* |
| * make sure all children has lower idle time threshold and |
| * higher latency target |
| */ |
| this_tg->idletime_threshold = min(this_tg->idletime_threshold, |
| parent_tg->idletime_threshold); |
| this_tg->latency_target = max(this_tg->latency_target, |
| parent_tg->latency_target); |
| } |
| |
| /* |
| * We're already holding queue_lock and know @tg is valid. Let's |
| * apply the new config directly. |
| * |
| * Restart the slices for both READ and WRITES. It might happen |
| * that a group's limit are dropped suddenly and we don't want to |
| * account recently dispatched IO with new low rate. |
| */ |
| throtl_start_new_slice(tg, 0); |
| throtl_start_new_slice(tg, 1); |
| |
| if (tg->flags & THROTL_TG_PENDING) { |
| tg_update_disptime(tg); |
| throtl_schedule_next_dispatch(sq->parent_sq, true); |
| } |
| } |
| |
| static ssize_t tg_set_conf(struct kernfs_open_file *of, |
| char *buf, size_t nbytes, loff_t off, bool is_u64) |
| { |
| struct blkcg *blkcg = css_to_blkcg(of_css(of)); |
| struct blkg_conf_ctx ctx; |
| struct throtl_grp *tg; |
| int ret; |
| u64 v; |
| |
| ret = blkg_conf_prep(blkcg, &blkcg_policy_throtl, buf, &ctx); |
| if (ret) |
| return ret; |
| |
| ret = -EINVAL; |
| if (sscanf(ctx.body, "%llu", &v) != 1) |
| goto out_finish; |
| if (!v) |
| v = U64_MAX; |
| |
| tg = blkg_to_tg(ctx.blkg); |
| |
| if (is_u64) |
| *(u64 *)((void *)tg + of_cft(of)->private) = v; |
| else |
| *(unsigned int *)((void *)tg + of_cft(of)->private) = v; |
| |
| tg_conf_updated(tg, false); |
| ret = 0; |
| out_finish: |
| blkg_conf_finish(&ctx); |
| return ret ?: nbytes; |
| } |
| |
| static ssize_t tg_set_conf_u64(struct kernfs_open_file *of, |
| char *buf, size_t nbytes, loff_t off) |
| { |
| return tg_set_conf(of, buf, nbytes, off, true); |
| } |
| |
| static ssize_t tg_set_conf_uint(struct kernfs_open_file *of, |
| char *buf, size_t nbytes, loff_t off) |
| { |
| return tg_set_conf(of, buf, nbytes, off, false); |
| } |
| |
| static struct cftype throtl_legacy_files[] = { |
| { |
| .name = "throttle.read_bps_device", |
| .private = offsetof(struct throtl_grp, bps[READ][LIMIT_MAX]), |
| .seq_show = tg_print_conf_u64, |
| .write = tg_set_conf_u64, |
| }, |
| { |
| .name = "throttle.write_bps_device", |
| .private = offsetof(struct throtl_grp, bps[WRITE][LIMIT_MAX]), |
| .seq_show = tg_print_conf_u64, |
| .write = tg_set_conf_u64, |
| }, |
| { |
| .name = "throttle.read_iops_device", |
| .private = offsetof(struct throtl_grp, iops[READ][LIMIT_MAX]), |
| .seq_show = tg_print_conf_uint, |
| .write = tg_set_conf_uint, |
| }, |
| { |
| .name = "throttle.write_iops_device", |
| .private = offsetof(struct throtl_grp, iops[WRITE][LIMIT_MAX]), |
| .seq_show = tg_print_conf_uint, |
| .write = tg_set_conf_uint, |
| }, |
| { |
| .name = "throttle.io_service_bytes", |
| .private = (unsigned long)&blkcg_policy_throtl, |
| .seq_show = blkg_print_stat_bytes, |
| }, |
| { |
| .name = "throttle.io_service_bytes_recursive", |
| .private = (unsigned long)&blkcg_policy_throtl, |
| .seq_show = blkg_print_stat_bytes_recursive, |
| }, |
| { |
| .name = "throttle.io_serviced", |
| .private = (unsigned long)&blkcg_policy_throtl, |
| .seq_show = blkg_print_stat_ios, |
| }, |
| { |
| .name = "throttle.io_serviced_recursive", |
| .private = (unsigned long)&blkcg_policy_throtl, |
| .seq_show = blkg_print_stat_ios_recursive, |
| }, |
| { } /* terminate */ |
| }; |
| |
| static u64 tg_prfill_limit(struct seq_file *sf, struct blkg_policy_data *pd, |
| int off) |
| { |
| struct throtl_grp *tg = pd_to_tg(pd); |
| const char *dname = blkg_dev_name(pd->blkg); |
| char bufs[4][21] = { "max", "max", "max", "max" }; |
| u64 bps_dft; |
| unsigned int iops_dft; |
| char idle_time[26] = ""; |
| char latency_time[26] = ""; |
| |
| if (!dname) |
| return 0; |
| |
| if (off == LIMIT_LOW) { |
| bps_dft = 0; |
| iops_dft = 0; |
| } else { |
| bps_dft = U64_MAX; |
| iops_dft = UINT_MAX; |
| } |
| |
| if (tg->bps_conf[READ][off] == bps_dft && |
| tg->bps_conf[WRITE][off] == bps_dft && |
| tg->iops_conf[READ][off] == iops_dft && |
| tg->iops_conf[WRITE][off] == iops_dft && |
| (off != LIMIT_LOW || |
| (tg->idletime_threshold_conf == DFL_IDLE_THRESHOLD && |
| tg->latency_target_conf == DFL_LATENCY_TARGET))) |
| return 0; |
| |
| if (tg->bps_conf[READ][off] != U64_MAX) |
| snprintf(bufs[0], sizeof(bufs[0]), "%llu", |
| tg->bps_conf[READ][off]); |
| if (tg->bps_conf[WRITE][off] != U64_MAX) |
| snprintf(bufs[1], sizeof(bufs[1]), "%llu", |
| tg->bps_conf[WRITE][off]); |
| if (tg->iops_conf[READ][off] != UINT_MAX) |
| snprintf(bufs[2], sizeof(bufs[2]), "%u", |
| tg->iops_conf[READ][off]); |
| if (tg->iops_conf[WRITE][off] != UINT_MAX) |
| snprintf(bufs[3], sizeof(bufs[3]), "%u", |
| tg->iops_conf[WRITE][off]); |
| if (off == LIMIT_LOW) { |
| if (tg->idletime_threshold_conf == ULONG_MAX) |
| strcpy(idle_time, " idle=max"); |
| else |
| snprintf(idle_time, sizeof(idle_time), " idle=%lu", |
| tg->idletime_threshold_conf); |
| |
| if (tg->latency_target_conf == ULONG_MAX) |
| strcpy(latency_time, " latency=max"); |
| else |
| snprintf(latency_time, sizeof(latency_time), |
| " latency=%lu", tg->latency_target_conf); |
| } |
| |
| seq_printf(sf, "%s rbps=%s wbps=%s riops=%s wiops=%s%s%s\n", |
| dname, bufs[0], bufs[1], bufs[2], bufs[3], idle_time, |
| latency_time); |
| return 0; |
| } |
| |
| static int tg_print_limit(struct seq_file *sf, void *v) |
| { |
| blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), tg_prfill_limit, |
| &blkcg_policy_throtl, seq_cft(sf)->private, false); |
| return 0; |
| } |
| |
| static ssize_t tg_set_limit(struct kernfs_open_file *of, |
| char *buf, size_t nbytes, loff_t off) |
| { |
| struct blkcg *blkcg = css_to_blkcg(of_css(of)); |
| struct blkg_conf_ctx ctx; |
| struct throtl_grp *tg; |
| u64 v[4]; |
| unsigned long idle_time; |
| unsigned long latency_time; |
| int ret; |
| int index = of_cft(of)->private; |
| |
| ret = blkg_conf_prep(blkcg, &blkcg_policy_throtl, buf, &ctx); |
| if (ret) |
| return ret; |
| |
| tg = blkg_to_tg(ctx.blkg); |
| |
| v[0] = tg->bps_conf[READ][index]; |
| v[1] = tg->bps_conf[WRITE][index]; |
| v[2] = tg->iops_conf[READ][index]; |
| v[3] = tg->iops_conf[WRITE][index]; |
| |
| idle_time = tg->idletime_threshold_conf; |
| latency_time = tg->latency_target_conf; |
| while (true) { |
| char tok[27]; /* wiops=18446744073709551616 */ |
| char *p; |
| u64 val = U64_MAX; |
| int len; |
| |
| if (sscanf(ctx.body, "%26s%n", tok, &len) != 1) |
| break; |
| if (tok[0] == '\0') |
| break; |
| ctx.body += len; |
| |
| ret = -EINVAL; |
| p = tok; |
| strsep(&p, "="); |
| if (!p || (sscanf(p, "%llu", &val) != 1 && strcmp(p, "max"))) |
| goto out_finish; |
| |
| ret = -ERANGE; |
| if (!val) |
| goto out_finish; |
| |
| ret = -EINVAL; |
| if (!strcmp(tok, "rbps")) |
| v[0] = val; |
| else if (!strcmp(tok, "wbps")) |
| v[1] = val; |
| else if (!strcmp(tok, "riops")) |
| v[2] = min_t(u64, val, UINT_MAX); |
| else if (!strcmp(tok, "wiops")) |
| v[3] = min_t(u64, val, UINT_MAX); |
| else if (off == LIMIT_LOW && !strcmp(tok, "idle")) |
| idle_time = val; |
| else if (off == LIMIT_LOW && !strcmp(tok, "latency")) |
| latency_time = val; |
| else |
| goto out_finish; |
| } |
| |
| tg->bps_conf[READ][index] = v[0]; |
| tg->bps_conf[WRITE][index] = v[1]; |
| tg->iops_conf[READ][index] = v[2]; |
| tg->iops_conf[WRITE][index] = v[3]; |
| |
| if (index == LIMIT_MAX) { |
| tg->bps[READ][index] = v[0]; |
| tg->bps[WRITE][index] = v[1]; |
| tg->iops[READ][index] = v[2]; |
| tg->iops[WRITE][index] = v[3]; |
| } |
| tg->bps[READ][LIMIT_LOW] = min(tg->bps_conf[READ][LIMIT_LOW], |
| tg->bps_conf[READ][LIMIT_MAX]); |
| tg->bps[WRITE][LIMIT_LOW] = min(tg->bps_conf[WRITE][LIMIT_LOW], |
| tg->bps_conf[WRITE][LIMIT_MAX]); |
| tg->iops[READ][LIMIT_LOW] = min(tg->iops_conf[READ][LIMIT_LOW], |
| tg->iops_conf[READ][LIMIT_MAX]); |
| tg->iops[WRITE][LIMIT_LOW] = min(tg->iops_conf[WRITE][LIMIT_LOW], |
| tg->iops_conf[WRITE][LIMIT_MAX]); |
| tg->idletime_threshold_conf = idle_time; |
| tg->latency_target_conf = latency_time; |
| |
| /* force user to configure all settings for low limit */ |
| if (!(tg->bps[READ][LIMIT_LOW] || tg->iops[READ][LIMIT_LOW] || |
| tg->bps[WRITE][LIMIT_LOW] || tg->iops[WRITE][LIMIT_LOW]) || |
| tg->idletime_threshold_conf == DFL_IDLE_THRESHOLD || |
| tg->latency_target_conf == DFL_LATENCY_TARGET) { |
| tg->bps[READ][LIMIT_LOW] = 0; |
| tg->bps[WRITE][LIMIT_LOW] = 0; |
| tg->iops[READ][LIMIT_LOW] = 0; |
| tg->iops[WRITE][LIMIT_LOW] = 0; |
| tg->idletime_threshold = DFL_IDLE_THRESHOLD; |
| tg->latency_target = DFL_LATENCY_TARGET; |
| } else if (index == LIMIT_LOW) { |
| tg->idletime_threshold = tg->idletime_threshold_conf; |
| tg->latency_target = tg->latency_target_conf; |
| } |
| |
| blk_throtl_update_limit_valid(tg->td); |
| if (tg->td->limit_valid[LIMIT_LOW]) { |
| if (index == LIMIT_LOW) |
| tg->td->limit_index = LIMIT_LOW; |
| } else |
| tg->td->limit_index = LIMIT_MAX; |
| tg_conf_updated(tg, index == LIMIT_LOW && |
| tg->td->limit_valid[LIMIT_LOW]); |
| ret = 0; |
| out_finish: |
| blkg_conf_finish(&ctx); |
| return ret ?: nbytes; |
| } |
| |
| static struct cftype throtl_files[] = { |
| #ifdef CONFIG_BLK_DEV_THROTTLING_LOW |
| { |
| .name = "low", |
| .flags = CFTYPE_NOT_ON_ROOT, |
| .seq_show = tg_print_limit, |
| .write = tg_set_limit, |
| .private = LIMIT_LOW, |
| }, |
| #endif |
| { |
| .name = "max", |
| .flags = CFTYPE_NOT_ON_ROOT, |
| .seq_show = tg_print_limit, |
| .write = tg_set_limit, |
| .private = LIMIT_MAX, |
| }, |
| { } /* terminate */ |
| }; |
| |
| static void throtl_shutdown_wq(struct request_queue *q) |
| { |
| struct throtl_data *td = q->td; |
| |
| cancel_work_sync(&td->dispatch_work); |
| } |
| |
| static struct blkcg_policy blkcg_policy_throtl = { |
| .dfl_cftypes = throtl_files, |
| .legacy_cftypes = throtl_legacy_files, |
| |
| .pd_alloc_fn = throtl_pd_alloc, |
| .pd_init_fn = throtl_pd_init, |
| .pd_online_fn = throtl_pd_online, |
| .pd_offline_fn = throtl_pd_offline, |
| .pd_free_fn = throtl_pd_free, |
| }; |
| |
| static unsigned long __tg_last_low_overflow_time(struct throtl_grp *tg) |
| { |
| unsigned long rtime = jiffies, wtime = jiffies; |
| |
| if (tg->bps[READ][LIMIT_LOW] || tg->iops[READ][LIMIT_LOW]) |
| rtime = tg->last_low_overflow_time[READ]; |
| if (tg->bps[WRITE][LIMIT_LOW] || tg->iops[WRITE][LIMIT_LOW]) |
| wtime = tg->last_low_overflow_time[WRITE]; |
| return min(rtime, wtime); |
| } |
| |
| /* tg should not be an intermediate node */ |
| static unsigned long tg_last_low_overflow_time(struct throtl_grp *tg) |
| { |
| struct throtl_service_queue *parent_sq; |
| struct throtl_grp *parent = tg; |
| unsigned long ret = __tg_last_low_overflow_time(tg); |
| |
| while (true) { |
| parent_sq = parent->service_queue.parent_sq; |
| parent = sq_to_tg(parent_sq); |
| if (!parent) |
| break; |
| |
| /* |
| * The parent doesn't have low limit, it always reaches low |
| * limit. Its overflow time is useless for children |
| */ |
| if (!parent->bps[READ][LIMIT_LOW] && |
| !parent->iops[READ][LIMIT_LOW] && |
| !parent->bps[WRITE][LIMIT_LOW] && |
| !parent->iops[WRITE][LIMIT_LOW]) |
| continue; |
| if (time_after(__tg_last_low_overflow_time(parent), ret)) |
| ret = __tg_last_low_overflow_time(parent); |
| } |
| return ret; |
| } |
| |
| static bool throtl_tg_is_idle(struct throtl_grp *tg) |
| { |
| /* |
| * cgroup is idle if: |
| * - single idle is too long, longer than a fixed value (in case user |
| * configure a too big threshold) or 4 times of idletime threshold |
| * - average think time is more than threshold |
| * - IO latency is largely below threshold |
| */ |
| unsigned long time; |
| bool ret; |
| |
| time = min_t(unsigned long, MAX_IDLE_TIME, 4 * tg->idletime_threshold); |
| ret = tg->latency_target == DFL_LATENCY_TARGET || |
| tg->idletime_threshold == DFL_IDLE_THRESHOLD || |
| (ktime_get_ns() >> 10) - tg->last_finish_time > time || |
| tg->avg_idletime > tg->idletime_threshold || |
| (tg->latency_target && tg->bio_cnt && |
| tg->bad_bio_cnt * 5 < tg->bio_cnt); |
| throtl_log(&tg->service_queue, |
| "avg_idle=%ld, idle_threshold=%ld, bad_bio=%d, total_bio=%d, is_idle=%d, scale=%d", |
| tg->avg_idletime, tg->idletime_threshold, tg->bad_bio_cnt, |
| tg->bio_cnt, ret, tg->td->scale); |
| return ret; |
| } |
| |
| static bool throtl_tg_can_upgrade(struct throtl_grp *tg) |
| { |
| struct throtl_service_queue *sq = &tg->service_queue; |
| bool read_limit, write_limit; |
| |
| /* |
| * if cgroup reaches low limit (if low limit is 0, the cgroup always |
| * reaches), it's ok to upgrade to next limit |
| */ |
| read_limit = tg->bps[READ][LIMIT_LOW] || tg->iops[READ][LIMIT_LOW]; |
| write_limit = tg->bps[WRITE][LIMIT_LOW] || tg->iops[WRITE][LIMIT_LOW]; |
| if (!read_limit && !write_limit) |
| return true; |
| if (read_limit && sq->nr_queued[READ] && |
| (!write_limit || sq->nr_queued[WRITE])) |
| return true; |
| if (write_limit && sq->nr_queued[WRITE] && |
| (!read_limit || sq->nr_queued[READ])) |
| return true; |
| |
| if (time_after_eq(jiffies, |
| tg_last_low_overflow_time(tg) + tg->td->throtl_slice) && |
| throtl_tg_is_idle(tg)) |
| return true; |
| return false; |
| } |
| |
| static bool throtl_hierarchy_can_upgrade(struct throtl_grp *tg) |
| { |
| while (true) { |
| if (throtl_tg_can_upgrade(tg)) |
| return true; |
| tg = sq_to_tg(tg->service_queue.parent_sq); |
| if (!tg || !tg_to_blkg(tg)->parent) |
| return false; |
| } |
| return false; |
| } |
| |
| static bool throtl_can_upgrade(struct throtl_data *td, |
| struct throtl_grp *this_tg) |
| { |
| struct cgroup_subsys_state *pos_css; |
| struct blkcg_gq *blkg; |
| |
| if (td->limit_index != LIMIT_LOW) |
| return false; |
| |
| if (time_before(jiffies, td->low_downgrade_time + td->throtl_slice)) |
| return false; |
| |
| rcu_read_lock(); |
| blkg_for_each_descendant_post(blkg, pos_css, td->queue->root_blkg) { |
| struct throtl_grp *tg = blkg_to_tg(blkg); |
| |
| if (tg == this_tg) |
| continue; |
| if (!list_empty(&tg_to_blkg(tg)->blkcg->css.children)) |
| continue; |
| if (!throtl_hierarchy_can_upgrade(tg)) { |
| rcu_read_unlock(); |
| return false; |
| } |
| } |
| rcu_read_unlock(); |
| return true; |
| } |
| |
| static void throtl_upgrade_check(struct throtl_grp *tg) |
| { |
| unsigned long now = jiffies; |
| |
| if (tg->td->limit_index != LIMIT_LOW) |
| return; |
| |
| if (time_after(tg->last_check_time + tg->td->throtl_slice, now)) |
| return; |
| |
| tg->last_check_time = now; |
| |
| if (!time_after_eq(now, |
| __tg_last_low_overflow_time(tg) + tg->td->throtl_slice)) |
| return; |
| |
| if (throtl_can_upgrade(tg->td, NULL)) |
| throtl_upgrade_state(tg->td); |
| } |
| |
| static void throtl_upgrade_state(struct throtl_data *td) |
| { |
| struct cgroup_subsys_state *pos_css; |
| struct blkcg_gq *blkg; |
| |
| throtl_log(&td->service_queue, "upgrade to max"); |
| td->limit_index = LIMIT_MAX; |
| td->low_upgrade_time = jiffies; |
| td->scale = 0; |
| rcu_read_lock(); |
| blkg_for_each_descendant_post(blkg, pos_css, td->queue->root_blkg) { |
| struct throtl_grp *tg = blkg_to_tg(blkg); |
| struct throtl_service_queue *sq = &tg->service_queue; |
| |
| tg->disptime = jiffies - 1; |
| throtl_select_dispatch(sq); |
| throtl_schedule_next_dispatch(sq, true); |
| } |
| rcu_read_unlock(); |
| throtl_select_dispatch(&td->service_queue); |
| throtl_schedule_next_dispatch(&td->service_queue, true); |
| queue_work(kthrotld_workqueue, &td->dispatch_work); |
| } |
| |
| static void throtl_downgrade_state(struct throtl_data *td, int new) |
| { |
| td->scale /= 2; |
| |
| throtl_log(&td->service_queue, "downgrade, scale %d", td->scale); |
| if (td->scale) { |
| td->low_upgrade_time = jiffies - td->scale * td->throtl_slice; |
| return; |
| } |
| |
| td->limit_index = new; |
| td->low_downgrade_time = jiffies; |
| } |
| |
| static bool throtl_tg_can_downgrade(struct throtl_grp *tg) |
| { |
| struct throtl_data *td = tg->td; |
| unsigned long now = jiffies; |
| |
| /* |
| * If cgroup is below low limit, consider downgrade and throttle other |
| * cgroups |
| */ |
| if (time_after_eq(now, td->low_upgrade_time + td->throtl_slice) && |
| time_after_eq(now, tg_last_low_overflow_time(tg) + |
| td->throtl_slice) && |
| (!throtl_tg_is_idle(tg) || |
| !list_empty(&tg_to_blkg(tg)->blkcg->css.children))) |
| return true; |
| return false; |
| } |
| |
| static bool throtl_hierarchy_can_downgrade(struct throtl_grp *tg) |
| { |
| while (true) { |
| if (!throtl_tg_can_downgrade(tg)) |
| return false; |
| tg = sq_to_tg(tg->service_queue.parent_sq); |
| if (!tg || !tg_to_blkg(tg)->parent) |
| break; |
| } |
| return true; |
| } |
| |
| static void throtl_downgrade_check(struct throtl_grp *tg) |
| { |
| uint64_t bps; |
| unsigned int iops; |
| unsigned long elapsed_time; |
| unsigned long now = jiffies; |
| |
| if (tg->td->limit_index != LIMIT_MAX || |
| !tg->td->limit_valid[LIMIT_LOW]) |
| return; |
| if (!list_empty(&tg_to_blkg(tg)->blkcg->css.children)) |
| return; |
| if (time_after(tg->last_check_time + tg->td->throtl_slice, now)) |
| return; |
| |
| elapsed_time = now - tg->last_check_time; |
| tg->last_check_time = now; |
| |
| if (time_before(now, tg_last_low_overflow_time(tg) + |
| tg->td->throtl_slice)) |
| return; |
| |
| if (tg->bps[READ][LIMIT_LOW]) { |
| bps = tg->last_bytes_disp[READ] * HZ; |
| do_div(bps, elapsed_time); |
| if (bps >= tg->bps[READ][LIMIT_LOW]) |
| tg->last_low_overflow_time[READ] = now; |
| } |
| |
| if (tg->bps[WRITE][LIMIT_LOW]) { |
| bps = tg->last_bytes_disp[WRITE] * HZ; |
| do_div(bps, elapsed_time); |
| if (bps >= tg->bps[WRITE][LIMIT_LOW]) |
| tg->last_low_overflow_time[WRITE] = now; |
| } |
| |
| if (tg->iops[READ][LIMIT_LOW]) { |
| iops = tg->last_io_disp[READ] * HZ / elapsed_time; |
| if (iops >= tg->iops[READ][LIMIT_LOW]) |
| tg->last_low_overflow_time[READ] = now; |
| } |
| |
| if (tg->iops[WRITE][LIMIT_LOW]) { |
| iops = tg->last_io_disp[WRITE] * HZ / elapsed_time; |
| if (iops >= tg->iops[WRITE][LIMIT_LOW]) |
| tg->last_low_overflow_time[WRITE] = now; |
| } |
| |
| /* |
| * If cgroup is below low limit, consider downgrade and throttle other |
| * cgroups |
| */ |
| if (throtl_hierarchy_can_downgrade(tg)) |
| throtl_downgrade_state(tg->td, LIMIT_LOW); |
| |
| tg->last_bytes_disp[READ] = 0; |
| tg->last_bytes_disp[WRITE] = 0; |
| tg->last_io_disp[READ] = 0; |
| tg->last_io_disp[WRITE] = 0; |
| } |
| |
| static void blk_throtl_update_idletime(struct throtl_grp *tg) |
| { |
| unsigned long now = ktime_get_ns() >> 10; |
| unsigned long last_finish_time = tg->last_finish_time; |
| |
| if (now <= last_finish_time || last_finish_time == 0 || |
| last_finish_time == tg->checked_last_finish_time) |
| return; |
| |
| tg->avg_idletime = (tg->avg_idletime * 7 + now - last_finish_time) >> 3; |
| tg->checked_last_finish_time = last_finish_time; |
| } |
| |
| #ifdef CONFIG_BLK_DEV_THROTTLING_LOW |
| static void throtl_update_latency_buckets(struct throtl_data *td) |
| { |
| struct avg_latency_bucket avg_latency[2][LATENCY_BUCKET_SIZE]; |
| int i, cpu, rw; |
| unsigned long last_latency[2] = { 0 }; |
| unsigned long latency[2]; |
| |
| if (!blk_queue_nonrot(td->queue)) |
| return; |
| if (time_before(jiffies, td->last_calculate_time + HZ)) |
| return; |
| td->last_calculate_time = jiffies; |
| |
| memset(avg_latency, 0, sizeof(avg_latency)); |
| for (rw = READ; rw <= WRITE; rw++) { |
| for (i = 0; i < LATENCY_BUCKET_SIZE; i++) { |
| struct latency_bucket *tmp = &td->tmp_buckets[rw][i]; |
| |
| for_each_possible_cpu(cpu) { |
| struct latency_bucket *bucket; |
| |
| /* this isn't race free, but ok in practice */ |
| bucket = per_cpu_ptr(td->latency_buckets[rw], |
| cpu); |
| tmp->total_latency += bucket[i].total_latency; |
| tmp->samples += bucket[i].samples; |
| bucket[i].total_latency = 0; |
| bucket[i].samples = 0; |
| } |
| |
| if (tmp->samples >= 32) { |
| int samples = tmp->samples; |
| |
| latency[rw] = tmp->total_latency; |
| |
| tmp->total_latency = 0; |
| tmp->samples = 0; |
| latency[rw] /= samples; |
| if (latency[rw] == 0) |
| continue; |
| avg_latency[rw][i].latency = latency[rw]; |
| } |
| } |
| } |
| |
| for (rw = READ; rw <= WRITE; rw++) { |
| for (i = 0; i < LATENCY_BUCKET_SIZE; i++) { |
| if (!avg_latency[rw][i].latency) { |
| if (td->avg_buckets[rw][i].latency < last_latency[rw]) |
| td->avg_buckets[rw][i].latency = |
| last_latency[rw]; |
| continue; |
| } |
| |
| if (!td->avg_buckets[rw][i].valid) |
| latency[rw] = avg_latency[rw][i].latency; |
| else |
| latency[rw] = (td->avg_buckets[rw][i].latency * 7 + |
| avg_latency[rw][i].latency) >> 3; |
| |
| td->avg_buckets[rw][i].latency = max(latency[rw], |
| last_latency[rw]); |
| td->avg_buckets[rw][i].valid = true; |
| last_latency[rw] = td->avg_buckets[rw][i].latency; |
| } |
| } |
| |
| for (i = 0; i < LATENCY_BUCKET_SIZE; i++) |
| throtl_log(&td->service_queue, |
| "Latency bucket %d: read latency=%ld, read valid=%d, " |
| "write latency=%ld, write valid=%d", i, |
| td->avg_buckets[READ][i].latency, |
| td->avg_buckets[READ][i].valid, |
| td->avg_buckets[WRITE][i].latency, |
| td->avg_buckets[WRITE][i].valid); |
| } |
| #else |
| static inline void throtl_update_latency_buckets(struct throtl_data *td) |
| { |
| } |
| #endif |
| |
| bool blk_throtl_bio(struct request_queue *q, struct blkcg_gq *blkg, |
| struct bio *bio) |
| { |
| struct throtl_qnode *qn = NULL; |
| struct throtl_grp *tg = blkg_to_tg(blkg ?: q->root_blkg); |
| struct throtl_service_queue *sq; |
| bool rw = bio_data_dir(bio); |
| bool throttled = false; |
| struct throtl_data *td = tg->td; |
| |
| WARN_ON_ONCE(!rcu_read_lock_held()); |
| |
| /* see throtl_charge_bio() */ |
| if (bio_flagged(bio, BIO_THROTTLED) || !tg->has_rules[rw]) |
| goto out; |
| |
| spin_lock_irq(&q->queue_lock); |
| |
| throtl_update_latency_buckets(td); |
| |
| blk_throtl_update_idletime(tg); |
| |
| sq = &tg->service_queue; |
| |
| again: |
| while (true) { |
| if (tg->last_low_overflow_time[rw] == 0) |
| tg->last_low_overflow_time[rw] = jiffies; |
| throtl_downgrade_check(tg); |
| throtl_upgrade_check(tg); |
| /* throtl is FIFO - if bios are already queued, should queue */ |
| if (sq->nr_queued[rw]) |
| break; |
| |
| /* if above limits, break to queue */ |
| if (!tg_may_dispatch(tg, bio, NULL)) { |
| tg->last_low_overflow_time[rw] = jiffies; |
| if (throtl_can_upgrade(td, tg)) { |
| throtl_upgrade_state(td); |
| goto again; |
| } |
| break; |
| } |
| |
| /* within limits, let's charge and dispatch directly */ |
| throtl_charge_bio(tg, bio); |
| |
| /* |
| * We need to trim slice even when bios are not being queued |
| * otherwise it might happen that a bio is not queued for |
| * a long time and slice keeps on extending and trim is not |
| * called for a long time. Now if limits are reduced suddenly |
| * we take into account all the IO dispatched so far at new |
| * low rate and * newly queued IO gets a really long dispatch |
| * time. |
| * |
| * So keep on trimming slice even if bio is not queued. |
| */ |
| throtl_trim_slice(tg, rw); |
| |
| /* |
| * @bio passed through this layer without being throttled. |
| * Climb up the ladder. If we''re already at the top, it |
| * can be executed directly. |
| */ |
| qn = &tg->qnode_on_parent[rw]; |
| sq = sq->parent_sq; |
| tg = sq_to_tg(sq); |
| if (!tg) |
| goto out_unlock; |
| } |
| |
| /* out-of-limit, queue to @tg */ |
| throtl_log(sq, "[%c] bio. bdisp=%llu sz=%u bps=%llu iodisp=%u iops=%u queued=%d/%d", |
| rw == READ ? 'R' : 'W', |
| tg->bytes_disp[rw], bio->bi_iter.bi_size, |
| tg_bps_limit(tg, rw), |
| tg->io_disp[rw], tg_iops_limit(tg, rw), |
| sq->nr_queued[READ], sq->nr_queued[WRITE]); |
| |
| tg->last_low_overflow_time[rw] = jiffies; |
| |
| td->nr_queued[rw]++; |
| throtl_add_bio_tg(bio, qn, tg); |
| throttled = true; |
| |
| /* |
| * Update @tg's dispatch time and force schedule dispatch if @tg |
| * was empty before @bio. The forced scheduling isn't likely to |
| * cause undue delay as @bio is likely to be dispatched directly if |
| * its @tg's disptime is not in the future. |
| */ |
| if (tg->flags & THROTL_TG_WAS_EMPTY) { |
| tg_update_disptime(tg); |
| throtl_schedule_next_dispatch(tg->service_queue.parent_sq, true); |
| } |
| |
| out_unlock: |
| spin_unlock_irq(&q->queue_lock); |
| out: |
| bio_set_flag(bio, BIO_THROTTLED); |
| |
| #ifdef CONFIG_BLK_DEV_THROTTLING_LOW |
| if (throttled || !td->track_bio_latency) |
| bio->bi_issue.value |= BIO_ISSUE_THROTL_SKIP_LATENCY; |
| #endif |
| return throttled; |
| } |
| |
| #ifdef CONFIG_BLK_DEV_THROTTLING_LOW |
| static void throtl_track_latency(struct throtl_data *td, sector_t size, |
| int op, unsigned long time) |
| { |
| struct latency_bucket *latency; |
| int index; |
| |
| if (!td || td->limit_index != LIMIT_LOW || |
| !(op == REQ_OP_READ || op == REQ_OP_WRITE) || |
| !blk_queue_nonrot(td->queue)) |
| return; |
| |
| index = request_bucket_index(size); |
| |
| latency = get_cpu_ptr(td->latency_buckets[op]); |
| latency[index].total_latency += time; |
| latency[index].samples++; |
| put_cpu_ptr(td->latency_buckets[op]); |
| } |
| |
| void blk_throtl_stat_add(struct request *rq, u64 time_ns) |
| { |
| struct request_queue *q = rq->q; |
| struct throtl_data *td = q->td; |
| |
| throtl_track_latency(td, blk_rq_stats_sectors(rq), req_op(rq), |
| time_ns >> 10); |
| } |
| |
| void blk_throtl_bio_endio(struct bio *bio) |
| { |
| struct blkcg_gq *blkg; |
| struct throtl_grp *tg; |
| u64 finish_time_ns; |
| unsigned long finish_time; |
| unsigned long start_time; |
| unsigned long lat; |
| int rw = bio_data_dir(bio); |
| |
| blkg = bio->bi_blkg; |
| if (!blkg) |
| return; |
| tg = blkg_to_tg(blkg); |
| |
| finish_time_ns = ktime_get_ns(); |
| tg->last_finish_time = finish_time_ns >> 10; |
| |
| start_time = bio_issue_time(&bio->bi_issue) >> 10; |
| finish_time = __bio_issue_time(finish_time_ns) >> 10; |
| if (!start_time || finish_time <= start_time) |
| return; |
| |
| lat = finish_time - start_time; |
| /* this is only for bio based driver */ |
| if (!(bio->bi_issue.value & BIO_ISSUE_THROTL_SKIP_LATENCY)) |
| throtl_track_latency(tg->td, bio_issue_size(&bio->bi_issue), |
| bio_op(bio), lat); |
| |
| if (tg->latency_target && lat >= tg->td->filtered_latency) { |
| int bucket; |
| unsigned int threshold; |
| |
| bucket = request_bucket_index(bio_issue_size(&bio->bi_issue)); |
| threshold = tg->td->avg_buckets[rw][bucket].latency + |
| tg->latency_target; |
| if (lat > threshold) |
| tg->bad_bio_cnt++; |
| /* |
| * Not race free, could get wrong count, which means cgroups |
| * will be throttled |
| */ |
| tg->bio_cnt++; |
| } |
| |
| if (time_after(jiffies, tg->bio_cnt_reset_time) || tg->bio_cnt > 1024) { |
| tg->bio_cnt_reset_time = tg->td->throtl_slice + jiffies; |
| tg->bio_cnt /= 2; |
| tg->bad_bio_cnt /= 2; |
| } |
| } |
| #endif |
| |
| /* |
| * Dispatch all bios from all children tg's queued on @parent_sq. On |
| * return, @parent_sq is guaranteed to not have any active children tg's |
| * and all bios from previously active tg's are on @parent_sq->bio_lists[]. |
| */ |
| static void tg_drain_bios(struct throtl_service_queue *parent_sq) |
| { |
| struct throtl_grp *tg; |
| |
| while ((tg = throtl_rb_first(parent_sq))) { |
| struct throtl_service_queue *sq = &tg->service_queue; |
| struct bio *bio; |
| |
| throtl_dequeue_tg(tg); |
| |
| while ((bio = throtl_peek_queued(&sq->queued[READ]))) |
| tg_dispatch_one_bio(tg, bio_data_dir(bio)); |
| while ((bio = throtl_peek_queued(&sq->queued[WRITE]))) |
| tg_dispatch_one_bio(tg, bio_data_dir(bio)); |
| } |
| } |
| |
| /** |
| * blk_throtl_drain - drain throttled bios |
| * @q: request_queue to drain throttled bios for |
| * |
| * Dispatch all currently throttled bios on @q through ->make_request_fn(). |
| */ |
| void blk_throtl_drain(struct request_queue *q) |
| __releases(&q->queue_lock) __acquires(&q->queue_lock) |
| { |
| struct throtl_data *td = q->td; |
| struct blkcg_gq *blkg; |
| struct cgroup_subsys_state *pos_css; |
| struct bio *bio; |
| int rw; |
| |
| rcu_read_lock(); |
| |
| /* |
| * Drain each tg while doing post-order walk on the blkg tree, so |
| * that all bios are propagated to td->service_queue. It'd be |
| * better to walk service_queue tree directly but blkg walk is |
| * easier. |
| */ |
| blkg_for_each_descendant_post(blkg, pos_css, td->queue->root_blkg) |
| tg_drain_bios(&blkg_to_tg(blkg)->service_queue); |
| |
| /* finally, transfer bios from top-level tg's into the td */ |
| tg_drain_bios(&td->service_queue); |
| |
| rcu_read_unlock(); |
| spin_unlock_irq(&q->queue_lock); |
| |
| /* all bios now should be in td->service_queue, issue them */ |
| for (rw = READ; rw <= WRITE; rw++) |
| while ((bio = throtl_pop_queued(&td->service_queue.queued[rw], |
| NULL))) |
| generic_make_request(bio); |
| |
| spin_lock_irq(&q->queue_lock); |
| } |
| |
| int blk_throtl_init(struct request_queue *q) |
| { |
| struct throtl_data *td; |
| int ret; |
| |
| td = kzalloc_node(sizeof(*td), GFP_KERNEL, q->node); |
| if (!td) |
| return -ENOMEM; |
| td->latency_buckets[READ] = __alloc_percpu(sizeof(struct latency_bucket) * |
| LATENCY_BUCKET_SIZE, __alignof__(u64)); |
| if (!td->latency_buckets[READ]) { |
| kfree(td); |
| return -ENOMEM; |
| } |
| td->latency_buckets[WRITE] = __alloc_percpu(sizeof(struct latency_bucket) * |
| LATENCY_BUCKET_SIZE, __alignof__(u64)); |
| if (!td->latency_buckets[WRITE]) { |
| free_percpu(td->latency_buckets[READ]); |
| kfree(td); |
| return -ENOMEM; |
| } |
| |
| INIT_WORK(&td->dispatch_work, blk_throtl_dispatch_work_fn); |
| throtl_service_queue_init(&td->service_queue); |
| |
| q->td = td; |
| td->queue = q; |
| |
| td->limit_valid[LIMIT_MAX] = true; |
| td->limit_index = LIMIT_MAX; |
| td->low_upgrade_time = jiffies; |
| td->low_downgrade_time = jiffies; |
| |
| /* activate policy */ |
| ret = blkcg_activate_policy(q, &blkcg_policy_throtl); |
| if (ret) { |
| free_percpu(td->latency_buckets[READ]); |
| free_percpu(td->latency_buckets[WRITE]); |
| kfree(td); |
| } |
| return ret; |
| } |
| |
| void blk_throtl_exit(struct request_queue *q) |
| { |
| BUG_ON(!q->td); |
| del_timer_sync(&q->td->service_queue.pending_timer); |
| throtl_shutdown_wq(q); |
| blkcg_deactivate_policy(q, &blkcg_policy_throtl); |
| free_percpu(q->td->latency_buckets[READ]); |
| free_percpu(q->td->latency_buckets[WRITE]); |
| kfree(q->td); |
| } |
| |
| void blk_throtl_register_queue(struct request_queue *q) |
| { |
| struct throtl_data *td; |
| int i; |
| |
| td = q->td; |
| BUG_ON(!td); |
| |
| if (blk_queue_nonrot(q)) { |
| td->throtl_slice = DFL_THROTL_SLICE_SSD; |
| td->filtered_latency = LATENCY_FILTERED_SSD; |
| } else { |
| td->throtl_slice = DFL_THROTL_SLICE_HD; |
| td->filtered_latency = LATENCY_FILTERED_HD; |
| for (i = 0; i < LATENCY_BUCKET_SIZE; i++) { |
| td->avg_buckets[READ][i].latency = DFL_HD_BASELINE_LATENCY; |
| td->avg_buckets[WRITE][i].latency = DFL_HD_BASELINE_LATENCY; |
| } |
| } |
| #ifndef CONFIG_BLK_DEV_THROTTLING_LOW |
| /* if no low limit, use previous default */ |
| td->throtl_slice = DFL_THROTL_SLICE_HD; |
| #endif |
| |
| td->track_bio_latency = !queue_is_mq(q); |
| if (!td->track_bio_latency) |
| blk_stat_enable_accounting(q); |
| } |
| |
| #ifdef CONFIG_BLK_DEV_THROTTLING_LOW |
| ssize_t blk_throtl_sample_time_show(struct request_queue *q, char *page) |
| { |
| if (!q->td) |
| return -EINVAL; |
| return sprintf(page, "%u\n", jiffies_to_msecs(q->td->throtl_slice)); |
| } |
| |
| ssize_t blk_throtl_sample_time_store(struct request_queue *q, |
| const char *page, size_t count) |
| { |
| unsigned long v; |
| unsigned long t; |
| |
| if (!q->td) |
| return -EINVAL; |
| if (kstrtoul(page, 10, &v)) |
| return -EINVAL; |
| t = msecs_to_jiffies(v); |
| if (t == 0 || t > MAX_THROTL_SLICE) |
| return -EINVAL; |
| q->td->throtl_slice = t; |
| return count; |
| } |
| #endif |
| |
| static int __init throtl_init(void) |
| { |
| kthrotld_workqueue = alloc_workqueue("kthrotld", WQ_MEM_RECLAIM, 0); |
| if (!kthrotld_workqueue) |
| panic("Failed to create kthrotld\n"); |
| |
| return blkcg_policy_register(&blkcg_policy_throtl); |
| } |
| |
| module_init(throtl_init); |