Christoph Hellwig | 3dcf60bc | 2019-04-30 14:42:43 -0400 | [diff] [blame] | 1 | // SPDX-License-Identifier: GPL-2.0 |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 2 | /* |
| 3 | * Block rq-qos base io controller |
| 4 | * |
| 5 | * This works similar to wbt with a few exceptions |
| 6 | * |
| 7 | * - It's bio based, so the latency covers the whole block layer in addition to |
| 8 | * the actual io. |
| 9 | * - We will throttle all IO that comes in here if we need to. |
| 10 | * - We use the mean latency over the 100ms window. This is because writes can |
| 11 | * be particularly fast, which could give us a false sense of the impact of |
| 12 | * other workloads on our protected workload. |
Josef Bacik | a284390 | 2018-07-11 10:34:42 -0400 | [diff] [blame] | 13 | * - By default there's no throttling, we set the queue_depth to UINT_MAX so |
| 14 | * that we can have as many outstanding bio's as we're allowed to. Only at |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 15 | * throttle time do we pay attention to the actual queue depth. |
| 16 | * |
| 17 | * The hierarchy works like the cpu controller does, we track the latency at |
| 18 | * every configured node, and each configured node has it's own independent |
| 19 | * queue depth. This means that we only care about our latency targets at the |
| 20 | * peer level. Some group at the bottom of the hierarchy isn't going to affect |
| 21 | * a group at the end of some other path if we're only configred at leaf level. |
| 22 | * |
| 23 | * Consider the following |
| 24 | * |
| 25 | * root blkg |
| 26 | * / \ |
| 27 | * fast (target=5ms) slow (target=10ms) |
| 28 | * / \ / \ |
| 29 | * a b normal(15ms) unloved |
| 30 | * |
| 31 | * "a" and "b" have no target, but their combined io under "fast" cannot exceed |
| 32 | * an average latency of 5ms. If it does then we will throttle the "slow" |
| 33 | * group. In the case of "normal", if it exceeds its 15ms target, we will |
| 34 | * throttle "unloved", but nobody else. |
| 35 | * |
| 36 | * In this example "fast", "slow", and "normal" will be the only groups actually |
| 37 | * accounting their io latencies. We have to walk up the heirarchy to the root |
| 38 | * on every submit and complete so we can do the appropriate stat recording and |
| 39 | * adjust the queue depth of ourselves if needed. |
| 40 | * |
| 41 | * There are 2 ways we throttle IO. |
| 42 | * |
| 43 | * 1) Queue depth throttling. As we throttle down we will adjust the maximum |
| 44 | * number of IO's we're allowed to have in flight. This starts at (u64)-1 down |
| 45 | * to 1. If the group is only ever submitting IO for itself then this is the |
| 46 | * only way we throttle. |
| 47 | * |
| 48 | * 2) Induced delay throttling. This is for the case that a group is generating |
| 49 | * IO that has to be issued by the root cg to avoid priority inversion. So think |
| 50 | * REQ_META or REQ_SWAP. If we are already at qd == 1 and we're getting a lot |
| 51 | * of work done for us on behalf of the root cg and are being asked to scale |
| 52 | * down more then we induce a latency at userspace return. We accumulate the |
| 53 | * total amount of time we need to be punished by doing |
| 54 | * |
| 55 | * total_time += min_lat_nsec - actual_io_completion |
| 56 | * |
| 57 | * and then at throttle time will do |
| 58 | * |
| 59 | * throttle_time = min(total_time, NSEC_PER_SEC) |
| 60 | * |
| 61 | * This induced delay will throttle back the activity that is generating the |
| 62 | * root cg issued io's, wethere that's some metadata intensive operation or the |
| 63 | * group is using so much memory that it is pushing us into swap. |
| 64 | * |
| 65 | * Copyright (C) 2018 Josef Bacik |
| 66 | */ |
| 67 | #include <linux/kernel.h> |
| 68 | #include <linux/blk_types.h> |
| 69 | #include <linux/backing-dev.h> |
| 70 | #include <linux/module.h> |
| 71 | #include <linux/timer.h> |
| 72 | #include <linux/memcontrol.h> |
Dennis Zhou (Facebook) | c480bcf | 2018-08-01 23:15:41 -0700 | [diff] [blame] | 73 | #include <linux/sched/loadavg.h> |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 74 | #include <linux/sched/signal.h> |
| 75 | #include <trace/events/block.h> |
Liu Bo | 8c772a9 | 2019-01-25 08:12:47 +0800 | [diff] [blame] | 76 | #include <linux/blk-mq.h> |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 77 | #include "blk-rq-qos.h" |
| 78 | #include "blk-stat.h" |
Ming Lei | 672fdcf | 2022-02-11 18:11:49 +0800 | [diff] [blame] | 79 | #include "blk-cgroup.h" |
Bart Van Assche | 373e915 | 2019-03-20 13:15:01 -0700 | [diff] [blame] | 80 | #include "blk.h" |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 81 | |
| 82 | #define DEFAULT_SCALE_COOKIE 1000000U |
| 83 | |
| 84 | static struct blkcg_policy blkcg_policy_iolatency; |
| 85 | struct iolatency_grp; |
| 86 | |
| 87 | struct blk_iolatency { |
| 88 | struct rq_qos rqos; |
| 89 | struct timer_list timer; |
Tejun Heo | 8a177a3 | 2022-05-13 20:55:45 -1000 | [diff] [blame] | 90 | |
| 91 | /* |
| 92 | * ->enabled is the master enable switch gating the throttling logic and |
| 93 | * inflight tracking. The number of cgroups which have iolat enabled is |
| 94 | * tracked in ->enable_cnt, and ->enable is flipped on/off accordingly |
| 95 | * from ->enable_work with the request_queue frozen. For details, See |
| 96 | * blkiolatency_enable_work_fn(). |
| 97 | */ |
| 98 | bool enabled; |
| 99 | atomic_t enable_cnt; |
| 100 | struct work_struct enable_work; |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 101 | }; |
| 102 | |
| 103 | static inline struct blk_iolatency *BLKIOLATENCY(struct rq_qos *rqos) |
| 104 | { |
| 105 | return container_of(rqos, struct blk_iolatency, rqos); |
| 106 | } |
| 107 | |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 108 | struct child_latency_info { |
| 109 | spinlock_t lock; |
| 110 | |
| 111 | /* Last time we adjusted the scale of everybody. */ |
| 112 | u64 last_scale_event; |
| 113 | |
| 114 | /* The latency that we missed. */ |
| 115 | u64 scale_lat; |
| 116 | |
| 117 | /* Total io's from all of our children for the last summation. */ |
| 118 | u64 nr_samples; |
| 119 | |
| 120 | /* The guy who actually changed the latency numbers. */ |
| 121 | struct iolatency_grp *scale_grp; |
| 122 | |
| 123 | /* Cookie to tell if we need to scale up or down. */ |
| 124 | atomic_t scale_cookie; |
| 125 | }; |
| 126 | |
Josef Bacik | 1fa2840 | 2018-09-28 13:45:42 -0400 | [diff] [blame] | 127 | struct percentile_stats { |
| 128 | u64 total; |
| 129 | u64 missed; |
| 130 | }; |
| 131 | |
| 132 | struct latency_stat { |
| 133 | union { |
| 134 | struct percentile_stats ps; |
| 135 | struct blk_rq_stat rqs; |
| 136 | }; |
| 137 | }; |
| 138 | |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 139 | struct iolatency_grp { |
| 140 | struct blkg_policy_data pd; |
Josef Bacik | 1fa2840 | 2018-09-28 13:45:42 -0400 | [diff] [blame] | 141 | struct latency_stat __percpu *stats; |
Josef Bacik | 451bb7c | 2018-09-28 13:45:43 -0400 | [diff] [blame] | 142 | struct latency_stat cur_stat; |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 143 | struct blk_iolatency *blkiolat; |
Kemeng Shi | dc572f4 | 2022-10-18 19:12:40 +0800 | [diff] [blame] | 144 | unsigned int max_depth; |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 145 | struct rq_wait rq_wait; |
| 146 | atomic64_t window_start; |
| 147 | atomic_t scale_cookie; |
| 148 | u64 min_lat_nsec; |
| 149 | u64 cur_win_nsec; |
| 150 | |
| 151 | /* total running average of our io latency. */ |
Dennis Zhou (Facebook) | c480bcf | 2018-08-01 23:15:41 -0700 | [diff] [blame] | 152 | u64 lat_avg; |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 153 | |
| 154 | /* Our current number of IO's for the last summation. */ |
| 155 | u64 nr_samples; |
| 156 | |
Josef Bacik | 1fa2840 | 2018-09-28 13:45:42 -0400 | [diff] [blame] | 157 | bool ssd; |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 158 | struct child_latency_info child_lat; |
| 159 | }; |
| 160 | |
Dennis Zhou (Facebook) | c480bcf | 2018-08-01 23:15:41 -0700 | [diff] [blame] | 161 | #define BLKIOLATENCY_MIN_WIN_SIZE (100 * NSEC_PER_MSEC) |
| 162 | #define BLKIOLATENCY_MAX_WIN_SIZE NSEC_PER_SEC |
| 163 | /* |
| 164 | * These are the constants used to fake the fixed-point moving average |
Johannes Weiner | 8508cf3 | 2018-10-26 15:06:11 -0700 | [diff] [blame] | 165 | * calculation just like load average. The call to calc_load() folds |
Dennis Zhou (Facebook) | c480bcf | 2018-08-01 23:15:41 -0700 | [diff] [blame] | 166 | * (FIXED_1 (2048) - exp_factor) * new_sample into lat_avg. The sampling |
| 167 | * window size is bucketed to try to approximately calculate average |
| 168 | * latency such that 1/exp (decay rate) is [1 min, 2.5 min) when windows |
| 169 | * elapse immediately. Note, windows only elapse with IO activity. Idle |
| 170 | * periods extend the most recent window. |
| 171 | */ |
| 172 | #define BLKIOLATENCY_NR_EXP_FACTORS 5 |
| 173 | #define BLKIOLATENCY_EXP_BUCKET_SIZE (BLKIOLATENCY_MAX_WIN_SIZE / \ |
| 174 | (BLKIOLATENCY_NR_EXP_FACTORS - 1)) |
| 175 | static const u64 iolatency_exp_factors[BLKIOLATENCY_NR_EXP_FACTORS] = { |
| 176 | 2045, // exp(1/600) - 600 samples |
| 177 | 2039, // exp(1/240) - 240 samples |
| 178 | 2031, // exp(1/120) - 120 samples |
| 179 | 2023, // exp(1/80) - 80 samples |
| 180 | 2014, // exp(1/60) - 60 samples |
| 181 | }; |
| 182 | |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 183 | static inline struct iolatency_grp *pd_to_lat(struct blkg_policy_data *pd) |
| 184 | { |
| 185 | return pd ? container_of(pd, struct iolatency_grp, pd) : NULL; |
| 186 | } |
| 187 | |
| 188 | static inline struct iolatency_grp *blkg_to_lat(struct blkcg_gq *blkg) |
| 189 | { |
| 190 | return pd_to_lat(blkg_to_pd(blkg, &blkcg_policy_iolatency)); |
| 191 | } |
| 192 | |
| 193 | static inline struct blkcg_gq *lat_to_blkg(struct iolatency_grp *iolat) |
| 194 | { |
| 195 | return pd_to_blkg(&iolat->pd); |
| 196 | } |
| 197 | |
Josef Bacik | 1fa2840 | 2018-09-28 13:45:42 -0400 | [diff] [blame] | 198 | static inline void latency_stat_init(struct iolatency_grp *iolat, |
| 199 | struct latency_stat *stat) |
| 200 | { |
| 201 | if (iolat->ssd) { |
| 202 | stat->ps.total = 0; |
| 203 | stat->ps.missed = 0; |
| 204 | } else |
| 205 | blk_rq_stat_init(&stat->rqs); |
| 206 | } |
| 207 | |
| 208 | static inline void latency_stat_sum(struct iolatency_grp *iolat, |
| 209 | struct latency_stat *sum, |
| 210 | struct latency_stat *stat) |
| 211 | { |
| 212 | if (iolat->ssd) { |
| 213 | sum->ps.total += stat->ps.total; |
| 214 | sum->ps.missed += stat->ps.missed; |
| 215 | } else |
| 216 | blk_rq_stat_sum(&sum->rqs, &stat->rqs); |
| 217 | } |
| 218 | |
| 219 | static inline void latency_stat_record_time(struct iolatency_grp *iolat, |
| 220 | u64 req_time) |
| 221 | { |
| 222 | struct latency_stat *stat = get_cpu_ptr(iolat->stats); |
| 223 | if (iolat->ssd) { |
| 224 | if (req_time >= iolat->min_lat_nsec) |
| 225 | stat->ps.missed++; |
| 226 | stat->ps.total++; |
| 227 | } else |
| 228 | blk_rq_stat_add(&stat->rqs, req_time); |
| 229 | put_cpu_ptr(stat); |
| 230 | } |
| 231 | |
| 232 | static inline bool latency_sum_ok(struct iolatency_grp *iolat, |
| 233 | struct latency_stat *stat) |
| 234 | { |
| 235 | if (iolat->ssd) { |
| 236 | u64 thresh = div64_u64(stat->ps.total, 10); |
| 237 | thresh = max(thresh, 1ULL); |
| 238 | return stat->ps.missed < thresh; |
| 239 | } |
| 240 | return stat->rqs.mean <= iolat->min_lat_nsec; |
| 241 | } |
| 242 | |
| 243 | static inline u64 latency_stat_samples(struct iolatency_grp *iolat, |
| 244 | struct latency_stat *stat) |
| 245 | { |
| 246 | if (iolat->ssd) |
| 247 | return stat->ps.total; |
| 248 | return stat->rqs.nr_samples; |
| 249 | } |
| 250 | |
| 251 | static inline void iolat_update_total_lat_avg(struct iolatency_grp *iolat, |
| 252 | struct latency_stat *stat) |
| 253 | { |
| 254 | int exp_idx; |
| 255 | |
| 256 | if (iolat->ssd) |
| 257 | return; |
| 258 | |
| 259 | /* |
Johannes Weiner | 8508cf3 | 2018-10-26 15:06:11 -0700 | [diff] [blame] | 260 | * calc_load() takes in a number stored in fixed point representation. |
Josef Bacik | 1fa2840 | 2018-09-28 13:45:42 -0400 | [diff] [blame] | 261 | * Because we are using this for IO time in ns, the values stored |
| 262 | * are significantly larger than the FIXED_1 denominator (2048). |
| 263 | * Therefore, rounding errors in the calculation are negligible and |
| 264 | * can be ignored. |
| 265 | */ |
| 266 | exp_idx = min_t(int, BLKIOLATENCY_NR_EXP_FACTORS - 1, |
| 267 | div64_u64(iolat->cur_win_nsec, |
| 268 | BLKIOLATENCY_EXP_BUCKET_SIZE)); |
Johannes Weiner | 8508cf3 | 2018-10-26 15:06:11 -0700 | [diff] [blame] | 269 | iolat->lat_avg = calc_load(iolat->lat_avg, |
| 270 | iolatency_exp_factors[exp_idx], |
| 271 | stat->rqs.mean); |
Josef Bacik | 1fa2840 | 2018-09-28 13:45:42 -0400 | [diff] [blame] | 272 | } |
| 273 | |
Josef Bacik | d3fcdff | 2018-12-04 12:59:04 -0500 | [diff] [blame] | 274 | static void iolat_cleanup_cb(struct rq_wait *rqw, void *private_data) |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 275 | { |
Josef Bacik | d3fcdff | 2018-12-04 12:59:04 -0500 | [diff] [blame] | 276 | atomic_dec(&rqw->inflight); |
| 277 | wake_up(&rqw->wait); |
| 278 | } |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 279 | |
Josef Bacik | d3fcdff | 2018-12-04 12:59:04 -0500 | [diff] [blame] | 280 | static bool iolat_acquire_inflight(struct rq_wait *rqw, void *private_data) |
| 281 | { |
| 282 | struct iolatency_grp *iolat = private_data; |
Kemeng Shi | dc572f4 | 2022-10-18 19:12:40 +0800 | [diff] [blame] | 283 | return rq_wait_inc_below(rqw, iolat->max_depth); |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 284 | } |
| 285 | |
| 286 | static void __blkcg_iolatency_throttle(struct rq_qos *rqos, |
| 287 | struct iolatency_grp *iolat, |
Christoph Hellwig | d533756 | 2018-11-14 17:02:09 +0100 | [diff] [blame] | 288 | bool issue_as_root, |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 289 | bool use_memdelay) |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 290 | { |
| 291 | struct rq_wait *rqw = &iolat->rq_wait; |
| 292 | unsigned use_delay = atomic_read(&lat_to_blkg(iolat)->use_delay); |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 293 | |
| 294 | if (use_delay) |
Christoph Hellwig | ba91c84 | 2023-02-03 16:03:56 +0100 | [diff] [blame] | 295 | blkcg_schedule_throttle(rqos->disk, use_memdelay); |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 296 | |
| 297 | /* |
| 298 | * To avoid priority inversions we want to just take a slot if we are |
| 299 | * issuing as root. If we're being killed off there's no point in |
| 300 | * delaying things, we may have been killed by OOM so throttling may |
| 301 | * make recovery take even longer, so just let the IO's through so the |
| 302 | * task can go away. |
| 303 | */ |
| 304 | if (issue_as_root || fatal_signal_pending(current)) { |
| 305 | atomic_inc(&rqw->inflight); |
| 306 | return; |
| 307 | } |
| 308 | |
Josef Bacik | d3fcdff | 2018-12-04 12:59:04 -0500 | [diff] [blame] | 309 | rq_qos_wait(rqw, iolat, iolat_acquire_inflight, iolat_cleanup_cb); |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 310 | } |
| 311 | |
| 312 | #define SCALE_DOWN_FACTOR 2 |
| 313 | #define SCALE_UP_FACTOR 4 |
| 314 | |
| 315 | static inline unsigned long scale_amount(unsigned long qd, bool up) |
| 316 | { |
| 317 | return max(up ? qd >> SCALE_UP_FACTOR : qd >> SCALE_DOWN_FACTOR, 1UL); |
| 318 | } |
| 319 | |
| 320 | /* |
| 321 | * We scale the qd down faster than we scale up, so we need to use this helper |
| 322 | * to adjust the scale_cookie accordingly so we don't prematurely get |
| 323 | * scale_cookie at DEFAULT_SCALE_COOKIE and unthrottle too much. |
| 324 | * |
| 325 | * Each group has their own local copy of the last scale cookie they saw, so if |
| 326 | * the global scale cookie goes up or down they know which way they need to go |
| 327 | * based on their last knowledge of it. |
| 328 | */ |
| 329 | static void scale_cookie_change(struct blk_iolatency *blkiolat, |
| 330 | struct child_latency_info *lat_info, |
| 331 | bool up) |
| 332 | { |
Christoph Hellwig | ba91c84 | 2023-02-03 16:03:56 +0100 | [diff] [blame] | 333 | unsigned long qd = blkiolat->rqos.disk->queue->nr_requests; |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 334 | unsigned long scale = scale_amount(qd, up); |
| 335 | unsigned long old = atomic_read(&lat_info->scale_cookie); |
| 336 | unsigned long max_scale = qd << 1; |
| 337 | unsigned long diff = 0; |
| 338 | |
| 339 | if (old < DEFAULT_SCALE_COOKIE) |
| 340 | diff = DEFAULT_SCALE_COOKIE - old; |
| 341 | |
| 342 | if (up) { |
| 343 | if (scale + old > DEFAULT_SCALE_COOKIE) |
| 344 | atomic_set(&lat_info->scale_cookie, |
| 345 | DEFAULT_SCALE_COOKIE); |
| 346 | else if (diff > qd) |
| 347 | atomic_inc(&lat_info->scale_cookie); |
| 348 | else |
| 349 | atomic_add(scale, &lat_info->scale_cookie); |
| 350 | } else { |
| 351 | /* |
| 352 | * We don't want to dig a hole so deep that it takes us hours to |
| 353 | * dig out of it. Just enough that we don't throttle/unthrottle |
| 354 | * with jagged workloads but can still unthrottle once pressure |
| 355 | * has sufficiently dissipated. |
| 356 | */ |
| 357 | if (diff > qd) { |
| 358 | if (diff < max_scale) |
| 359 | atomic_dec(&lat_info->scale_cookie); |
| 360 | } else { |
| 361 | atomic_sub(scale, &lat_info->scale_cookie); |
| 362 | } |
| 363 | } |
| 364 | } |
| 365 | |
| 366 | /* |
Kemeng Shi | 6891f96 | 2022-10-18 19:12:39 +0800 | [diff] [blame] | 367 | * Change the queue depth of the iolatency_grp. We add 1/16th of the |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 368 | * queue depth at a time so we don't get wild swings and hopefully dial in to |
Kemeng Shi | 6891f96 | 2022-10-18 19:12:39 +0800 | [diff] [blame] | 369 | * fairer distribution of the overall queue depth. We halve the queue depth |
| 370 | * at a time so we can scale down queue depth quickly from default unlimited |
| 371 | * to target. |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 372 | */ |
| 373 | static void scale_change(struct iolatency_grp *iolat, bool up) |
| 374 | { |
Christoph Hellwig | ba91c84 | 2023-02-03 16:03:56 +0100 | [diff] [blame] | 375 | unsigned long qd = iolat->blkiolat->rqos.disk->queue->nr_requests; |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 376 | unsigned long scale = scale_amount(qd, up); |
Kemeng Shi | dc572f4 | 2022-10-18 19:12:40 +0800 | [diff] [blame] | 377 | unsigned long old = iolat->max_depth; |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 378 | |
| 379 | if (old > qd) |
| 380 | old = qd; |
| 381 | |
| 382 | if (up) { |
| 383 | if (old == 1 && blkcg_unuse_delay(lat_to_blkg(iolat))) |
| 384 | return; |
| 385 | |
| 386 | if (old < qd) { |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 387 | old += scale; |
| 388 | old = min(old, qd); |
Kemeng Shi | dc572f4 | 2022-10-18 19:12:40 +0800 | [diff] [blame] | 389 | iolat->max_depth = old; |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 390 | wake_up_all(&iolat->rq_wait.wait); |
| 391 | } |
Josef Bacik | 9f60511 | 2018-09-28 13:45:40 -0400 | [diff] [blame] | 392 | } else { |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 393 | old >>= 1; |
Kemeng Shi | dc572f4 | 2022-10-18 19:12:40 +0800 | [diff] [blame] | 394 | iolat->max_depth = max(old, 1UL); |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 395 | } |
| 396 | } |
| 397 | |
| 398 | /* Check our parent and see if the scale cookie has changed. */ |
| 399 | static void check_scale_change(struct iolatency_grp *iolat) |
| 400 | { |
| 401 | struct iolatency_grp *parent; |
| 402 | struct child_latency_info *lat_info; |
| 403 | unsigned int cur_cookie; |
| 404 | unsigned int our_cookie = atomic_read(&iolat->scale_cookie); |
| 405 | u64 scale_lat; |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 406 | int direction = 0; |
| 407 | |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 408 | parent = blkg_to_lat(lat_to_blkg(iolat)->parent); |
| 409 | if (!parent) |
| 410 | return; |
| 411 | |
| 412 | lat_info = &parent->child_lat; |
| 413 | cur_cookie = atomic_read(&lat_info->scale_cookie); |
| 414 | scale_lat = READ_ONCE(lat_info->scale_lat); |
| 415 | |
| 416 | if (cur_cookie < our_cookie) |
| 417 | direction = -1; |
| 418 | else if (cur_cookie > our_cookie) |
| 419 | direction = 1; |
| 420 | else |
| 421 | return; |
| 422 | |
Uros Bizjak | aee8960 | 2022-07-12 17:19:47 +0200 | [diff] [blame] | 423 | if (!atomic_try_cmpxchg(&iolat->scale_cookie, &our_cookie, cur_cookie)) { |
| 424 | /* Somebody beat us to the punch, just bail. */ |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 425 | return; |
Uros Bizjak | aee8960 | 2022-07-12 17:19:47 +0200 | [diff] [blame] | 426 | } |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 427 | |
| 428 | if (direction < 0 && iolat->min_lat_nsec) { |
| 429 | u64 samples_thresh; |
| 430 | |
| 431 | if (!scale_lat || iolat->min_lat_nsec <= scale_lat) |
| 432 | return; |
| 433 | |
| 434 | /* |
| 435 | * Sometimes high priority groups are their own worst enemy, so |
| 436 | * instead of taking it out on some poor other group that did 5% |
| 437 | * or less of the IO's for the last summation just skip this |
| 438 | * scale down event. |
| 439 | */ |
| 440 | samples_thresh = lat_info->nr_samples * 5; |
Josef Bacik | 22ed8a9 | 2018-09-28 13:45:41 -0400 | [diff] [blame] | 441 | samples_thresh = max(1ULL, div64_u64(samples_thresh, 100)); |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 442 | if (iolat->nr_samples <= samples_thresh) |
| 443 | return; |
| 444 | } |
| 445 | |
| 446 | /* We're as low as we can go. */ |
Kemeng Shi | dc572f4 | 2022-10-18 19:12:40 +0800 | [diff] [blame] | 447 | if (iolat->max_depth == 1 && direction < 0) { |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 448 | blkcg_use_delay(lat_to_blkg(iolat)); |
| 449 | return; |
| 450 | } |
| 451 | |
| 452 | /* We're back to the default cookie, unthrottle all the things. */ |
| 453 | if (cur_cookie == DEFAULT_SCALE_COOKIE) { |
| 454 | blkcg_clear_delay(lat_to_blkg(iolat)); |
Kemeng Shi | dc572f4 | 2022-10-18 19:12:40 +0800 | [diff] [blame] | 455 | iolat->max_depth = UINT_MAX; |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 456 | wake_up_all(&iolat->rq_wait.wait); |
| 457 | return; |
| 458 | } |
| 459 | |
| 460 | scale_change(iolat, direction > 0); |
| 461 | } |
| 462 | |
Christoph Hellwig | d533756 | 2018-11-14 17:02:09 +0100 | [diff] [blame] | 463 | static void blkcg_iolatency_throttle(struct rq_qos *rqos, struct bio *bio) |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 464 | { |
| 465 | struct blk_iolatency *blkiolat = BLKIOLATENCY(rqos); |
Dennis Zhou | 5cdf2e3 | 2018-12-05 12:10:31 -0500 | [diff] [blame] | 466 | struct blkcg_gq *blkg = bio->bi_blkg; |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 467 | bool issue_as_root = bio_issue_as_root_blkg(bio); |
| 468 | |
Tejun Heo | 8a177a3 | 2022-05-13 20:55:45 -1000 | [diff] [blame] | 469 | if (!blkiolat->enabled) |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 470 | return; |
| 471 | |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 472 | while (blkg && blkg->parent) { |
| 473 | struct iolatency_grp *iolat = blkg_to_lat(blkg); |
| 474 | if (!iolat) { |
| 475 | blkg = blkg->parent; |
| 476 | continue; |
| 477 | } |
| 478 | |
| 479 | check_scale_change(iolat); |
Christoph Hellwig | d533756 | 2018-11-14 17:02:09 +0100 | [diff] [blame] | 480 | __blkcg_iolatency_throttle(rqos, iolat, issue_as_root, |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 481 | (bio->bi_opf & REQ_SWAP) == REQ_SWAP); |
| 482 | blkg = blkg->parent; |
| 483 | } |
| 484 | if (!timer_pending(&blkiolat->timer)) |
| 485 | mod_timer(&blkiolat->timer, jiffies + HZ); |
| 486 | } |
| 487 | |
| 488 | static void iolatency_record_time(struct iolatency_grp *iolat, |
| 489 | struct bio_issue *issue, u64 now, |
| 490 | bool issue_as_root) |
| 491 | { |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 492 | u64 start = bio_issue_time(issue); |
| 493 | u64 req_time; |
| 494 | |
Josef Bacik | 71e9690 | 2018-07-16 12:12:23 -0400 | [diff] [blame] | 495 | /* |
| 496 | * Have to do this so we are truncated to the correct time that our |
| 497 | * issue is truncated to. |
| 498 | */ |
| 499 | now = __bio_issue_time(now); |
| 500 | |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 501 | if (now <= start) |
| 502 | return; |
| 503 | |
| 504 | req_time = now - start; |
| 505 | |
| 506 | /* |
| 507 | * We don't want to count issue_as_root bio's in the cgroups latency |
| 508 | * statistics as it could skew the numbers downwards. |
| 509 | */ |
Kemeng Shi | dc572f4 | 2022-10-18 19:12:40 +0800 | [diff] [blame] | 510 | if (unlikely(issue_as_root && iolat->max_depth != UINT_MAX)) { |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 511 | u64 sub = iolat->min_lat_nsec; |
| 512 | if (req_time < sub) |
| 513 | blkcg_add_delay(lat_to_blkg(iolat), now, sub - req_time); |
| 514 | return; |
| 515 | } |
| 516 | |
Josef Bacik | 1fa2840 | 2018-09-28 13:45:42 -0400 | [diff] [blame] | 517 | latency_stat_record_time(iolat, req_time); |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 518 | } |
| 519 | |
| 520 | #define BLKIOLATENCY_MIN_ADJUST_TIME (500 * NSEC_PER_MSEC) |
| 521 | #define BLKIOLATENCY_MIN_GOOD_SAMPLES 5 |
| 522 | |
| 523 | static void iolatency_check_latencies(struct iolatency_grp *iolat, u64 now) |
| 524 | { |
| 525 | struct blkcg_gq *blkg = lat_to_blkg(iolat); |
| 526 | struct iolatency_grp *parent; |
| 527 | struct child_latency_info *lat_info; |
Josef Bacik | 1fa2840 | 2018-09-28 13:45:42 -0400 | [diff] [blame] | 528 | struct latency_stat stat; |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 529 | unsigned long flags; |
Josef Bacik | 1fa2840 | 2018-09-28 13:45:42 -0400 | [diff] [blame] | 530 | int cpu; |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 531 | |
Josef Bacik | 1fa2840 | 2018-09-28 13:45:42 -0400 | [diff] [blame] | 532 | latency_stat_init(iolat, &stat); |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 533 | preempt_disable(); |
| 534 | for_each_online_cpu(cpu) { |
Josef Bacik | 1fa2840 | 2018-09-28 13:45:42 -0400 | [diff] [blame] | 535 | struct latency_stat *s; |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 536 | s = per_cpu_ptr(iolat->stats, cpu); |
Josef Bacik | 1fa2840 | 2018-09-28 13:45:42 -0400 | [diff] [blame] | 537 | latency_stat_sum(iolat, &stat, s); |
| 538 | latency_stat_init(iolat, s); |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 539 | } |
| 540 | preempt_enable(); |
| 541 | |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 542 | parent = blkg_to_lat(blkg->parent); |
| 543 | if (!parent) |
| 544 | return; |
| 545 | |
| 546 | lat_info = &parent->child_lat; |
| 547 | |
Josef Bacik | 1fa2840 | 2018-09-28 13:45:42 -0400 | [diff] [blame] | 548 | iolat_update_total_lat_avg(iolat, &stat); |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 549 | |
| 550 | /* Everything is ok and we don't need to adjust the scale. */ |
Josef Bacik | 1fa2840 | 2018-09-28 13:45:42 -0400 | [diff] [blame] | 551 | if (latency_sum_ok(iolat, &stat) && |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 552 | atomic_read(&lat_info->scale_cookie) == DEFAULT_SCALE_COOKIE) |
| 553 | return; |
| 554 | |
| 555 | /* Somebody beat us to the punch, just bail. */ |
| 556 | spin_lock_irqsave(&lat_info->lock, flags); |
Josef Bacik | 451bb7c | 2018-09-28 13:45:43 -0400 | [diff] [blame] | 557 | |
| 558 | latency_stat_sum(iolat, &iolat->cur_stat, &stat); |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 559 | lat_info->nr_samples -= iolat->nr_samples; |
Josef Bacik | 451bb7c | 2018-09-28 13:45:43 -0400 | [diff] [blame] | 560 | lat_info->nr_samples += latency_stat_samples(iolat, &iolat->cur_stat); |
| 561 | iolat->nr_samples = latency_stat_samples(iolat, &iolat->cur_stat); |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 562 | |
| 563 | if ((lat_info->last_scale_event >= now || |
Josef Bacik | 451bb7c | 2018-09-28 13:45:43 -0400 | [diff] [blame] | 564 | now - lat_info->last_scale_event < BLKIOLATENCY_MIN_ADJUST_TIME)) |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 565 | goto out; |
| 566 | |
Josef Bacik | 451bb7c | 2018-09-28 13:45:43 -0400 | [diff] [blame] | 567 | if (latency_sum_ok(iolat, &iolat->cur_stat) && |
| 568 | latency_sum_ok(iolat, &stat)) { |
| 569 | if (latency_stat_samples(iolat, &iolat->cur_stat) < |
Josef Bacik | 1fa2840 | 2018-09-28 13:45:42 -0400 | [diff] [blame] | 570 | BLKIOLATENCY_MIN_GOOD_SAMPLES) |
| 571 | goto out; |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 572 | if (lat_info->scale_grp == iolat) { |
| 573 | lat_info->last_scale_event = now; |
| 574 | scale_cookie_change(iolat->blkiolat, lat_info, true); |
| 575 | } |
Josef Bacik | 451bb7c | 2018-09-28 13:45:43 -0400 | [diff] [blame] | 576 | } else if (lat_info->scale_lat == 0 || |
| 577 | lat_info->scale_lat >= iolat->min_lat_nsec) { |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 578 | lat_info->last_scale_event = now; |
| 579 | if (!lat_info->scale_grp || |
| 580 | lat_info->scale_lat > iolat->min_lat_nsec) { |
| 581 | WRITE_ONCE(lat_info->scale_lat, iolat->min_lat_nsec); |
| 582 | lat_info->scale_grp = iolat; |
| 583 | } |
| 584 | scale_cookie_change(iolat->blkiolat, lat_info, false); |
| 585 | } |
Josef Bacik | 451bb7c | 2018-09-28 13:45:43 -0400 | [diff] [blame] | 586 | latency_stat_init(iolat, &iolat->cur_stat); |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 587 | out: |
| 588 | spin_unlock_irqrestore(&lat_info->lock, flags); |
| 589 | } |
| 590 | |
| 591 | static void blkcg_iolatency_done_bio(struct rq_qos *rqos, struct bio *bio) |
| 592 | { |
| 593 | struct blkcg_gq *blkg; |
| 594 | struct rq_wait *rqw; |
| 595 | struct iolatency_grp *iolat; |
| 596 | u64 window_start; |
Hongnan Li | 6e2fa4d | 2020-07-01 16:09:38 +0800 | [diff] [blame] | 597 | u64 now; |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 598 | bool issue_as_root = bio_issue_as_root_blkg(bio); |
Liu Bo | 391f552 | 2019-01-25 08:12:48 +0800 | [diff] [blame] | 599 | int inflight = 0; |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 600 | |
| 601 | blkg = bio->bi_blkg; |
Tejun Heo | aa1b46d | 2022-03-13 21:15:02 -1000 | [diff] [blame] | 602 | if (!blkg || !bio_flagged(bio, BIO_QOS_THROTTLED)) |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 603 | return; |
| 604 | |
| 605 | iolat = blkg_to_lat(bio->bi_blkg); |
| 606 | if (!iolat) |
| 607 | return; |
| 608 | |
Tejun Heo | 8a177a3 | 2022-05-13 20:55:45 -1000 | [diff] [blame] | 609 | if (!iolat->blkiolat->enabled) |
Liu Bo | 8c772a9 | 2019-01-25 08:12:47 +0800 | [diff] [blame] | 610 | return; |
| 611 | |
Jens Axboe | 08420cf | 2024-01-15 14:45:07 -0700 | [diff] [blame] | 612 | now = blk_time_get_ns(); |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 613 | while (blkg && blkg->parent) { |
| 614 | iolat = blkg_to_lat(blkg); |
| 615 | if (!iolat) { |
| 616 | blkg = blkg->parent; |
| 617 | continue; |
| 618 | } |
| 619 | rqw = &iolat->rq_wait; |
| 620 | |
Liu Bo | 391f552 | 2019-01-25 08:12:48 +0800 | [diff] [blame] | 621 | inflight = atomic_dec_return(&rqw->inflight); |
| 622 | WARN_ON_ONCE(inflight < 0); |
Dennis Zhou | c9b3007 | 2019-07-05 17:09:09 -0400 | [diff] [blame] | 623 | /* |
| 624 | * If bi_status is BLK_STS_AGAIN, the bio wasn't actually |
| 625 | * submitted, so do not account for it. |
| 626 | */ |
| 627 | if (iolat->min_lat_nsec && bio->bi_status != BLK_STS_AGAIN) { |
| 628 | iolatency_record_time(iolat, &bio->bi_issue, now, |
| 629 | issue_as_root); |
| 630 | window_start = atomic64_read(&iolat->window_start); |
| 631 | if (now > window_start && |
| 632 | (now - window_start) >= iolat->cur_win_nsec) { |
Uros Bizjak | aee8960 | 2022-07-12 17:19:47 +0200 | [diff] [blame] | 633 | if (atomic64_try_cmpxchg(&iolat->window_start, |
| 634 | &window_start, now)) |
Dennis Zhou | c9b3007 | 2019-07-05 17:09:09 -0400 | [diff] [blame] | 635 | iolatency_check_latencies(iolat, now); |
| 636 | } |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 637 | } |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 638 | wake_up(&rqw->wait); |
| 639 | blkg = blkg->parent; |
| 640 | } |
| 641 | } |
| 642 | |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 643 | static void blkcg_iolatency_exit(struct rq_qos *rqos) |
| 644 | { |
| 645 | struct blk_iolatency *blkiolat = BLKIOLATENCY(rqos); |
| 646 | |
Steven Rostedt (Google) | 292a089 | 2022-12-20 13:45:19 -0500 | [diff] [blame] | 647 | timer_shutdown_sync(&blkiolat->timer); |
Tejun Heo | 8a177a3 | 2022-05-13 20:55:45 -1000 | [diff] [blame] | 648 | flush_work(&blkiolat->enable_work); |
Christoph Hellwig | 40e4996 | 2023-02-03 16:03:57 +0100 | [diff] [blame] | 649 | blkcg_deactivate_policy(rqos->disk, &blkcg_policy_iolatency); |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 650 | kfree(blkiolat); |
| 651 | } |
| 652 | |
Christoph Hellwig | 3963d84d | 2023-02-03 16:03:55 +0100 | [diff] [blame] | 653 | static const struct rq_qos_ops blkcg_iolatency_ops = { |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 654 | .throttle = blkcg_iolatency_throttle, |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 655 | .done_bio = blkcg_iolatency_done_bio, |
| 656 | .exit = blkcg_iolatency_exit, |
| 657 | }; |
| 658 | |
| 659 | static void blkiolatency_timer_fn(struct timer_list *t) |
| 660 | { |
| 661 | struct blk_iolatency *blkiolat = from_timer(blkiolat, t, timer); |
| 662 | struct blkcg_gq *blkg; |
| 663 | struct cgroup_subsys_state *pos_css; |
Jens Axboe | 08420cf | 2024-01-15 14:45:07 -0700 | [diff] [blame] | 664 | u64 now = blk_time_get_ns(); |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 665 | |
| 666 | rcu_read_lock(); |
| 667 | blkg_for_each_descendant_pre(blkg, pos_css, |
Christoph Hellwig | 1231039 | 2023-02-14 19:33:04 +0100 | [diff] [blame] | 668 | blkiolat->rqos.disk->queue->root_blkg) { |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 669 | struct iolatency_grp *iolat; |
| 670 | struct child_latency_info *lat_info; |
| 671 | unsigned long flags; |
| 672 | u64 cookie; |
| 673 | |
| 674 | /* |
| 675 | * We could be exiting, don't access the pd unless we have a |
| 676 | * ref on the blkg. |
| 677 | */ |
Dennis Zhou | 7754f66 | 2018-12-05 12:10:39 -0500 | [diff] [blame] | 678 | if (!blkg_tryget(blkg)) |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 679 | continue; |
| 680 | |
| 681 | iolat = blkg_to_lat(blkg); |
| 682 | if (!iolat) |
Josef Bacik | 52a1199 | 2018-07-31 12:39:02 -0400 | [diff] [blame] | 683 | goto next; |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 684 | |
| 685 | lat_info = &iolat->child_lat; |
| 686 | cookie = atomic_read(&lat_info->scale_cookie); |
| 687 | |
| 688 | if (cookie >= DEFAULT_SCALE_COOKIE) |
| 689 | goto next; |
| 690 | |
| 691 | spin_lock_irqsave(&lat_info->lock, flags); |
| 692 | if (lat_info->last_scale_event >= now) |
| 693 | goto next_lock; |
| 694 | |
| 695 | /* |
| 696 | * We scaled down but don't have a scale_grp, scale up and carry |
| 697 | * on. |
| 698 | */ |
| 699 | if (lat_info->scale_grp == NULL) { |
| 700 | scale_cookie_change(iolat->blkiolat, lat_info, true); |
| 701 | goto next_lock; |
| 702 | } |
| 703 | |
| 704 | /* |
| 705 | * It's been 5 seconds since our last scale event, clear the |
| 706 | * scale grp in case the group that needed the scale down isn't |
| 707 | * doing any IO currently. |
| 708 | */ |
| 709 | if (now - lat_info->last_scale_event >= |
| 710 | ((u64)NSEC_PER_SEC * 5)) |
| 711 | lat_info->scale_grp = NULL; |
| 712 | next_lock: |
| 713 | spin_unlock_irqrestore(&lat_info->lock, flags); |
| 714 | next: |
| 715 | blkg_put(blkg); |
| 716 | } |
| 717 | rcu_read_unlock(); |
| 718 | } |
| 719 | |
Tejun Heo | 8a177a3 | 2022-05-13 20:55:45 -1000 | [diff] [blame] | 720 | /** |
| 721 | * blkiolatency_enable_work_fn - Enable or disable iolatency on the device |
| 722 | * @work: enable_work of the blk_iolatency of interest |
| 723 | * |
| 724 | * iolatency needs to keep track of the number of in-flight IOs per cgroup. This |
| 725 | * is relatively expensive as it involves walking up the hierarchy twice for |
| 726 | * every IO. Thus, if iolatency is not enabled in any cgroup for the device, we |
| 727 | * want to disable the in-flight tracking. |
| 728 | * |
| 729 | * We have to make sure that the counting is balanced - we don't want to leak |
| 730 | * the in-flight counts by disabling accounting in the completion path while IOs |
| 731 | * are in flight. This is achieved by ensuring that no IO is in flight by |
| 732 | * freezing the queue while flipping ->enabled. As this requires a sleepable |
| 733 | * context, ->enabled flipping is punted to this work function. |
| 734 | */ |
| 735 | static void blkiolatency_enable_work_fn(struct work_struct *work) |
| 736 | { |
| 737 | struct blk_iolatency *blkiolat = container_of(work, struct blk_iolatency, |
| 738 | enable_work); |
| 739 | bool enabled; |
| 740 | |
| 741 | /* |
| 742 | * There can only be one instance of this function running for @blkiolat |
| 743 | * and it's guaranteed to be executed at least once after the latest |
| 744 | * ->enabled_cnt modification. Acting on the latest ->enable_cnt is |
| 745 | * sufficient. |
| 746 | * |
| 747 | * Also, we know @blkiolat is safe to access as ->enable_work is flushed |
| 748 | * in blkcg_iolatency_exit(). |
| 749 | */ |
| 750 | enabled = atomic_read(&blkiolat->enable_cnt); |
| 751 | if (enabled != blkiolat->enabled) { |
Christoph Hellwig | ba91c84 | 2023-02-03 16:03:56 +0100 | [diff] [blame] | 752 | blk_mq_freeze_queue(blkiolat->rqos.disk->queue); |
Tejun Heo | 8a177a3 | 2022-05-13 20:55:45 -1000 | [diff] [blame] | 753 | blkiolat->enabled = enabled; |
Christoph Hellwig | ba91c84 | 2023-02-03 16:03:56 +0100 | [diff] [blame] | 754 | blk_mq_unfreeze_queue(blkiolat->rqos.disk->queue); |
Tejun Heo | 8a177a3 | 2022-05-13 20:55:45 -1000 | [diff] [blame] | 755 | } |
| 756 | } |
| 757 | |
Tejun Heo | a13696b | 2023-04-12 14:06:49 -1000 | [diff] [blame] | 758 | static int blk_iolatency_init(struct gendisk *disk) |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 759 | { |
| 760 | struct blk_iolatency *blkiolat; |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 761 | int ret; |
| 762 | |
| 763 | blkiolat = kzalloc(sizeof(*blkiolat), GFP_KERNEL); |
| 764 | if (!blkiolat) |
| 765 | return -ENOMEM; |
| 766 | |
Christoph Hellwig | ce57b55 | 2023-02-03 16:03:54 +0100 | [diff] [blame] | 767 | ret = rq_qos_add(&blkiolat->rqos, disk, RQ_QOS_LATENCY, |
| 768 | &blkcg_iolatency_ops); |
Jinke Han | 14a6e2e | 2022-07-20 17:36:16 +0800 | [diff] [blame] | 769 | if (ret) |
| 770 | goto err_free; |
Christoph Hellwig | 40e4996 | 2023-02-03 16:03:57 +0100 | [diff] [blame] | 771 | ret = blkcg_activate_policy(disk, &blkcg_policy_iolatency); |
Jinke Han | 14a6e2e | 2022-07-20 17:36:16 +0800 | [diff] [blame] | 772 | if (ret) |
| 773 | goto err_qos_del; |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 774 | |
| 775 | timer_setup(&blkiolat->timer, blkiolatency_timer_fn, 0); |
Tejun Heo | 8a177a3 | 2022-05-13 20:55:45 -1000 | [diff] [blame] | 776 | INIT_WORK(&blkiolat->enable_work, blkiolatency_enable_work_fn); |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 777 | |
| 778 | return 0; |
Jinke Han | 14a6e2e | 2022-07-20 17:36:16 +0800 | [diff] [blame] | 779 | |
| 780 | err_qos_del: |
Christoph Hellwig | ce57b55 | 2023-02-03 16:03:54 +0100 | [diff] [blame] | 781 | rq_qos_del(&blkiolat->rqos); |
Jinke Han | 14a6e2e | 2022-07-20 17:36:16 +0800 | [diff] [blame] | 782 | err_free: |
| 783 | kfree(blkiolat); |
| 784 | return ret; |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 785 | } |
| 786 | |
Tejun Heo | 8a177a3 | 2022-05-13 20:55:45 -1000 | [diff] [blame] | 787 | static void iolatency_set_min_lat_nsec(struct blkcg_gq *blkg, u64 val) |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 788 | { |
| 789 | struct iolatency_grp *iolat = blkg_to_lat(blkg); |
Tejun Heo | 8a177a3 | 2022-05-13 20:55:45 -1000 | [diff] [blame] | 790 | struct blk_iolatency *blkiolat = iolat->blkiolat; |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 791 | u64 oldval = iolat->min_lat_nsec; |
| 792 | |
| 793 | iolat->min_lat_nsec = val; |
Dennis Zhou (Facebook) | c480bcf | 2018-08-01 23:15:41 -0700 | [diff] [blame] | 794 | iolat->cur_win_nsec = max_t(u64, val << 4, BLKIOLATENCY_MIN_WIN_SIZE); |
| 795 | iolat->cur_win_nsec = min_t(u64, iolat->cur_win_nsec, |
| 796 | BLKIOLATENCY_MAX_WIN_SIZE); |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 797 | |
Tejun Heo | 8a177a3 | 2022-05-13 20:55:45 -1000 | [diff] [blame] | 798 | if (!oldval && val) { |
| 799 | if (atomic_inc_return(&blkiolat->enable_cnt) == 1) |
| 800 | schedule_work(&blkiolat->enable_work); |
| 801 | } |
Tejun Heo | 5de0073 | 2019-06-13 15:30:37 -0700 | [diff] [blame] | 802 | if (oldval && !val) { |
| 803 | blkcg_clear_delay(blkg); |
Tejun Heo | 8a177a3 | 2022-05-13 20:55:45 -1000 | [diff] [blame] | 804 | if (atomic_dec_return(&blkiolat->enable_cnt) == 0) |
| 805 | schedule_work(&blkiolat->enable_work); |
Tejun Heo | 5de0073 | 2019-06-13 15:30:37 -0700 | [diff] [blame] | 806 | } |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 807 | } |
| 808 | |
| 809 | static void iolatency_clear_scaling(struct blkcg_gq *blkg) |
| 810 | { |
| 811 | if (blkg->parent) { |
| 812 | struct iolatency_grp *iolat = blkg_to_lat(blkg->parent); |
| 813 | struct child_latency_info *lat_info; |
| 814 | if (!iolat) |
| 815 | return; |
| 816 | |
| 817 | lat_info = &iolat->child_lat; |
| 818 | spin_lock(&lat_info->lock); |
| 819 | atomic_set(&lat_info->scale_cookie, DEFAULT_SCALE_COOKIE); |
| 820 | lat_info->last_scale_event = 0; |
| 821 | lat_info->scale_grp = NULL; |
| 822 | lat_info->scale_lat = 0; |
| 823 | spin_unlock(&lat_info->lock); |
| 824 | } |
| 825 | } |
| 826 | |
| 827 | static ssize_t iolatency_set_limit(struct kernfs_open_file *of, char *buf, |
| 828 | size_t nbytes, loff_t off) |
| 829 | { |
| 830 | struct blkcg *blkcg = css_to_blkcg(of_css(of)); |
| 831 | struct blkcg_gq *blkg; |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 832 | struct blkg_conf_ctx ctx; |
| 833 | struct iolatency_grp *iolat; |
| 834 | char *p, *tok; |
| 835 | u64 lat_val = 0; |
| 836 | u64 oldval; |
| 837 | int ret; |
| 838 | |
Tejun Heo | faffaab | 2023-04-12 14:06:47 -1000 | [diff] [blame] | 839 | blkg_conf_init(&ctx, buf); |
| 840 | |
Li Lingfeng | 4eb44d1 | 2023-08-10 11:51:11 +0800 | [diff] [blame] | 841 | ret = blkg_conf_open_bdev(&ctx); |
| 842 | if (ret) |
| 843 | goto out; |
| 844 | |
| 845 | /* |
| 846 | * blk_iolatency_init() may fail after rq_qos_add() succeeds which can |
| 847 | * confuse iolat_rq_qos() test. Make the test and init atomic. |
| 848 | */ |
Jens Axboe | 18267a03 | 2023-08-10 17:24:53 -0600 | [diff] [blame] | 849 | lockdep_assert_held(&ctx.bdev->bd_queue->rq_qos_mutex); |
Li Lingfeng | 4eb44d1 | 2023-08-10 11:51:11 +0800 | [diff] [blame] | 850 | if (!iolat_rq_qos(ctx.bdev->bd_queue)) |
| 851 | ret = blk_iolatency_init(ctx.bdev->bd_disk); |
Tejun Heo | a13696b | 2023-04-12 14:06:49 -1000 | [diff] [blame] | 852 | if (ret) |
| 853 | goto out; |
| 854 | |
Tejun Heo | faffaab | 2023-04-12 14:06:47 -1000 | [diff] [blame] | 855 | ret = blkg_conf_prep(blkcg, &blkcg_policy_iolatency, &ctx); |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 856 | if (ret) |
Tejun Heo | faffaab | 2023-04-12 14:06:47 -1000 | [diff] [blame] | 857 | goto out; |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 858 | |
| 859 | iolat = blkg_to_lat(ctx.blkg); |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 860 | p = ctx.body; |
| 861 | |
| 862 | ret = -EINVAL; |
| 863 | while ((tok = strsep(&p, " "))) { |
| 864 | char key[16]; |
| 865 | char val[21]; /* 18446744073709551616 */ |
| 866 | |
| 867 | if (sscanf(tok, "%15[^=]=%20s", key, val) != 2) |
| 868 | goto out; |
| 869 | |
| 870 | if (!strcmp(key, "target")) { |
| 871 | u64 v; |
| 872 | |
| 873 | if (!strcmp(val, "max")) |
| 874 | lat_val = 0; |
| 875 | else if (sscanf(val, "%llu", &v) == 1) |
| 876 | lat_val = v * NSEC_PER_USEC; |
| 877 | else |
| 878 | goto out; |
| 879 | } else { |
| 880 | goto out; |
| 881 | } |
| 882 | } |
| 883 | |
| 884 | /* Walk up the tree to see if our new val is lower than it should be. */ |
| 885 | blkg = ctx.blkg; |
| 886 | oldval = iolat->min_lat_nsec; |
| 887 | |
Tejun Heo | 8a177a3 | 2022-05-13 20:55:45 -1000 | [diff] [blame] | 888 | iolatency_set_min_lat_nsec(blkg, lat_val); |
| 889 | if (oldval != iolat->min_lat_nsec) |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 890 | iolatency_clear_scaling(blkg); |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 891 | ret = 0; |
| 892 | out: |
Tejun Heo | faffaab | 2023-04-12 14:06:47 -1000 | [diff] [blame] | 893 | blkg_conf_exit(&ctx); |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 894 | return ret ?: nbytes; |
| 895 | } |
| 896 | |
| 897 | static u64 iolatency_prfill_limit(struct seq_file *sf, |
| 898 | struct blkg_policy_data *pd, int off) |
| 899 | { |
| 900 | struct iolatency_grp *iolat = pd_to_lat(pd); |
| 901 | const char *dname = blkg_dev_name(pd->blkg); |
| 902 | |
| 903 | if (!dname || !iolat->min_lat_nsec) |
| 904 | return 0; |
| 905 | seq_printf(sf, "%s target=%llu\n", |
Arnd Bergmann | 88b7210 | 2018-07-10 17:21:34 +0200 | [diff] [blame] | 906 | dname, div_u64(iolat->min_lat_nsec, NSEC_PER_USEC)); |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 907 | return 0; |
| 908 | } |
| 909 | |
| 910 | static int iolatency_print_limit(struct seq_file *sf, void *v) |
| 911 | { |
| 912 | blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), |
| 913 | iolatency_prfill_limit, |
| 914 | &blkcg_policy_iolatency, seq_cft(sf)->private, false); |
| 915 | return 0; |
| 916 | } |
| 917 | |
Wolfgang Bumiller | 3607849 | 2022-01-11 09:31:59 +0100 | [diff] [blame] | 918 | static void iolatency_ssd_stat(struct iolatency_grp *iolat, struct seq_file *s) |
Josef Bacik | 1fa2840 | 2018-09-28 13:45:42 -0400 | [diff] [blame] | 919 | { |
| 920 | struct latency_stat stat; |
| 921 | int cpu; |
| 922 | |
| 923 | latency_stat_init(iolat, &stat); |
| 924 | preempt_disable(); |
| 925 | for_each_online_cpu(cpu) { |
| 926 | struct latency_stat *s; |
| 927 | s = per_cpu_ptr(iolat->stats, cpu); |
| 928 | latency_stat_sum(iolat, &stat, s); |
| 929 | } |
| 930 | preempt_enable(); |
| 931 | |
Kemeng Shi | dc572f4 | 2022-10-18 19:12:40 +0800 | [diff] [blame] | 932 | if (iolat->max_depth == UINT_MAX) |
Christoph Hellwig | 252c651 | 2021-08-10 17:26:23 +0200 | [diff] [blame] | 933 | seq_printf(s, " missed=%llu total=%llu depth=max", |
| 934 | (unsigned long long)stat.ps.missed, |
| 935 | (unsigned long long)stat.ps.total); |
| 936 | else |
| 937 | seq_printf(s, " missed=%llu total=%llu depth=%u", |
| 938 | (unsigned long long)stat.ps.missed, |
| 939 | (unsigned long long)stat.ps.total, |
Kemeng Shi | dc572f4 | 2022-10-18 19:12:40 +0800 | [diff] [blame] | 940 | iolat->max_depth); |
Josef Bacik | 1fa2840 | 2018-09-28 13:45:42 -0400 | [diff] [blame] | 941 | } |
| 942 | |
Wolfgang Bumiller | 3607849 | 2022-01-11 09:31:59 +0100 | [diff] [blame] | 943 | static void iolatency_pd_stat(struct blkg_policy_data *pd, struct seq_file *s) |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 944 | { |
| 945 | struct iolatency_grp *iolat = pd_to_lat(pd); |
Josef Bacik | 1fa2840 | 2018-09-28 13:45:42 -0400 | [diff] [blame] | 946 | unsigned long long avg_lat; |
| 947 | unsigned long long cur_win; |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 948 | |
Tejun Heo | 07b0fde | 2019-07-16 07:58:31 -0700 | [diff] [blame] | 949 | if (!blkcg_debug_stats) |
Wolfgang Bumiller | 3607849 | 2022-01-11 09:31:59 +0100 | [diff] [blame] | 950 | return; |
Tejun Heo | 07b0fde | 2019-07-16 07:58:31 -0700 | [diff] [blame] | 951 | |
Josef Bacik | 1fa2840 | 2018-09-28 13:45:42 -0400 | [diff] [blame] | 952 | if (iolat->ssd) |
Christoph Hellwig | 252c651 | 2021-08-10 17:26:23 +0200 | [diff] [blame] | 953 | return iolatency_ssd_stat(iolat, s); |
Josef Bacik | 1fa2840 | 2018-09-28 13:45:42 -0400 | [diff] [blame] | 954 | |
| 955 | avg_lat = div64_u64(iolat->lat_avg, NSEC_PER_USEC); |
| 956 | cur_win = div64_u64(iolat->cur_win_nsec, NSEC_PER_MSEC); |
Kemeng Shi | dc572f4 | 2022-10-18 19:12:40 +0800 | [diff] [blame] | 957 | if (iolat->max_depth == UINT_MAX) |
Christoph Hellwig | 252c651 | 2021-08-10 17:26:23 +0200 | [diff] [blame] | 958 | seq_printf(s, " depth=max avg_lat=%llu win=%llu", |
| 959 | avg_lat, cur_win); |
| 960 | else |
| 961 | seq_printf(s, " depth=%u avg_lat=%llu win=%llu", |
Kemeng Shi | dc572f4 | 2022-10-18 19:12:40 +0800 | [diff] [blame] | 962 | iolat->max_depth, avg_lat, cur_win); |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 963 | } |
| 964 | |
Christoph Hellwig | 0a0b4f7 | 2023-02-03 16:03:58 +0100 | [diff] [blame] | 965 | static struct blkg_policy_data *iolatency_pd_alloc(struct gendisk *disk, |
| 966 | struct blkcg *blkcg, gfp_t gfp) |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 967 | { |
| 968 | struct iolatency_grp *iolat; |
| 969 | |
Christoph Hellwig | 0a0b4f7 | 2023-02-03 16:03:58 +0100 | [diff] [blame] | 970 | iolat = kzalloc_node(sizeof(*iolat), gfp, disk->node_id); |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 971 | if (!iolat) |
| 972 | return NULL; |
Josef Bacik | 1fa2840 | 2018-09-28 13:45:42 -0400 | [diff] [blame] | 973 | iolat->stats = __alloc_percpu_gfp(sizeof(struct latency_stat), |
| 974 | __alignof__(struct latency_stat), gfp); |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 975 | if (!iolat->stats) { |
| 976 | kfree(iolat); |
| 977 | return NULL; |
| 978 | } |
| 979 | return &iolat->pd; |
| 980 | } |
| 981 | |
| 982 | static void iolatency_pd_init(struct blkg_policy_data *pd) |
| 983 | { |
| 984 | struct iolatency_grp *iolat = pd_to_lat(pd); |
| 985 | struct blkcg_gq *blkg = lat_to_blkg(iolat); |
Tejun Heo | 3304918 | 2023-04-12 14:06:48 -1000 | [diff] [blame] | 986 | struct rq_qos *rqos = iolat_rq_qos(blkg->q); |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 987 | struct blk_iolatency *blkiolat = BLKIOLATENCY(rqos); |
Jens Axboe | 08420cf | 2024-01-15 14:45:07 -0700 | [diff] [blame] | 988 | u64 now = blk_time_get_ns(); |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 989 | int cpu; |
| 990 | |
Christoph Hellwig | a06377c | 2023-02-14 19:33:08 +0100 | [diff] [blame] | 991 | if (blk_queue_nonrot(blkg->q)) |
Josef Bacik | 1fa2840 | 2018-09-28 13:45:42 -0400 | [diff] [blame] | 992 | iolat->ssd = true; |
| 993 | else |
| 994 | iolat->ssd = false; |
| 995 | |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 996 | for_each_possible_cpu(cpu) { |
Josef Bacik | 1fa2840 | 2018-09-28 13:45:42 -0400 | [diff] [blame] | 997 | struct latency_stat *stat; |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 998 | stat = per_cpu_ptr(iolat->stats, cpu); |
Josef Bacik | 1fa2840 | 2018-09-28 13:45:42 -0400 | [diff] [blame] | 999 | latency_stat_init(iolat, stat); |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 1000 | } |
| 1001 | |
Josef Bacik | 451bb7c | 2018-09-28 13:45:43 -0400 | [diff] [blame] | 1002 | latency_stat_init(iolat, &iolat->cur_stat); |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 1003 | rq_wait_init(&iolat->rq_wait); |
| 1004 | spin_lock_init(&iolat->child_lat.lock); |
Kemeng Shi | dc572f4 | 2022-10-18 19:12:40 +0800 | [diff] [blame] | 1005 | iolat->max_depth = UINT_MAX; |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 1006 | iolat->blkiolat = blkiolat; |
| 1007 | iolat->cur_win_nsec = 100 * NSEC_PER_MSEC; |
| 1008 | atomic64_set(&iolat->window_start, now); |
| 1009 | |
| 1010 | /* |
| 1011 | * We init things in list order, so the pd for the parent may not be |
| 1012 | * init'ed yet for whatever reason. |
| 1013 | */ |
| 1014 | if (blkg->parent && blkg_to_pd(blkg->parent, &blkcg_policy_iolatency)) { |
| 1015 | struct iolatency_grp *parent = blkg_to_lat(blkg->parent); |
| 1016 | atomic_set(&iolat->scale_cookie, |
| 1017 | atomic_read(&parent->child_lat.scale_cookie)); |
| 1018 | } else { |
| 1019 | atomic_set(&iolat->scale_cookie, DEFAULT_SCALE_COOKIE); |
| 1020 | } |
| 1021 | |
| 1022 | atomic_set(&iolat->child_lat.scale_cookie, DEFAULT_SCALE_COOKIE); |
| 1023 | } |
| 1024 | |
| 1025 | static void iolatency_pd_offline(struct blkg_policy_data *pd) |
| 1026 | { |
| 1027 | struct iolatency_grp *iolat = pd_to_lat(pd); |
| 1028 | struct blkcg_gq *blkg = lat_to_blkg(iolat); |
| 1029 | |
Tejun Heo | 8a177a3 | 2022-05-13 20:55:45 -1000 | [diff] [blame] | 1030 | iolatency_set_min_lat_nsec(blkg, 0); |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 1031 | iolatency_clear_scaling(blkg); |
| 1032 | } |
| 1033 | |
| 1034 | static void iolatency_pd_free(struct blkg_policy_data *pd) |
| 1035 | { |
| 1036 | struct iolatency_grp *iolat = pd_to_lat(pd); |
| 1037 | free_percpu(iolat->stats); |
| 1038 | kfree(iolat); |
| 1039 | } |
| 1040 | |
| 1041 | static struct cftype iolatency_files[] = { |
| 1042 | { |
| 1043 | .name = "latency", |
| 1044 | .flags = CFTYPE_NOT_ON_ROOT, |
| 1045 | .seq_show = iolatency_print_limit, |
| 1046 | .write = iolatency_set_limit, |
| 1047 | }, |
| 1048 | {} |
| 1049 | }; |
| 1050 | |
| 1051 | static struct blkcg_policy blkcg_policy_iolatency = { |
| 1052 | .dfl_cftypes = iolatency_files, |
| 1053 | .pd_alloc_fn = iolatency_pd_alloc, |
| 1054 | .pd_init_fn = iolatency_pd_init, |
| 1055 | .pd_offline_fn = iolatency_pd_offline, |
| 1056 | .pd_free_fn = iolatency_pd_free, |
| 1057 | .pd_stat_fn = iolatency_pd_stat, |
| 1058 | }; |
| 1059 | |
| 1060 | static int __init iolatency_init(void) |
| 1061 | { |
| 1062 | return blkcg_policy_register(&blkcg_policy_iolatency); |
| 1063 | } |
| 1064 | |
| 1065 | static void __exit iolatency_exit(void) |
| 1066 | { |
Baolin Wang | fa1c3ea | 2020-09-28 08:42:26 +0800 | [diff] [blame] | 1067 | blkcg_policy_unregister(&blkcg_policy_iolatency); |
Josef Bacik | d706751 | 2018-07-03 11:15:01 -0400 | [diff] [blame] | 1068 | } |
| 1069 | |
| 1070 | module_init(iolatency_init); |
| 1071 | module_exit(iolatency_exit); |