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3dcf60bc | 1 | // SPDX-License-Identifier: GPL-2.0 |
e34cbd30 JA |
2 | /* |
3 | * buffered writeback throttling. loosely based on CoDel. We can't drop | |
4 | * packets for IO scheduling, so the logic is something like this: | |
5 | * | |
6 | * - Monitor latencies in a defined window of time. | |
7 | * - If the minimum latency in the above window exceeds some target, increment | |
8 | * scaling step and scale down queue depth by a factor of 2x. The monitoring | |
9 | * window is then shrunk to 100 / sqrt(scaling step + 1). | |
10 | * - For any window where we don't have solid data on what the latencies | |
11 | * look like, retain status quo. | |
12 | * - If latencies look good, decrement scaling step. | |
13 | * - If we're only doing writes, allow the scaling step to go negative. This | |
14 | * will temporarily boost write performance, snapping back to a stable | |
15 | * scaling step of 0 if reads show up or the heavy writers finish. Unlike | |
16 | * positive scaling steps where we shrink the monitoring window, a negative | |
17 | * scaling step retains the default step==0 window size. | |
18 | * | |
19 | * Copyright (C) 2016 Jens Axboe | |
20 | * | |
21 | */ | |
22 | #include <linux/kernel.h> | |
23 | #include <linux/blk_types.h> | |
24 | #include <linux/slab.h> | |
25 | #include <linux/backing-dev.h> | |
26 | #include <linux/swap.h> | |
27 | ||
0bc65bd4 | 28 | #include "blk-stat.h" |
e34cbd30 | 29 | #include "blk-wbt.h" |
a7905043 | 30 | #include "blk-rq-qos.h" |
671fae5e | 31 | #include "elevator.h" |
e34cbd30 JA |
32 | |
33 | #define CREATE_TRACE_POINTS | |
34 | #include <trace/events/wbt.h> | |
35 | ||
0bc65bd4 CH |
36 | enum wbt_flags { |
37 | WBT_TRACKED = 1, /* write, tracked for throttling */ | |
38 | WBT_READ = 2, /* read */ | |
39 | WBT_KSWAPD = 4, /* write, from kswapd */ | |
40 | WBT_DISCARD = 8, /* discard */ | |
41 | ||
42 | WBT_NR_BITS = 4, /* number of bits */ | |
43 | }; | |
44 | ||
45 | enum { | |
46 | WBT_RWQ_BG = 0, | |
47 | WBT_RWQ_KSWAPD, | |
48 | WBT_RWQ_DISCARD, | |
49 | WBT_NUM_RWQ, | |
50 | }; | |
51 | ||
52 | /* | |
53 | * If current state is WBT_STATE_ON/OFF_DEFAULT, it can be covered to any other | |
54 | * state, if current state is WBT_STATE_ON/OFF_MANUAL, it can only be covered | |
55 | * to WBT_STATE_OFF/ON_MANUAL. | |
56 | */ | |
57 | enum { | |
58 | WBT_STATE_ON_DEFAULT = 1, /* on by default */ | |
59 | WBT_STATE_ON_MANUAL = 2, /* on manually by sysfs */ | |
60 | WBT_STATE_OFF_DEFAULT = 3, /* off by default */ | |
61 | WBT_STATE_OFF_MANUAL = 4, /* off manually by sysfs */ | |
62 | }; | |
63 | ||
64 | struct rq_wb { | |
65 | /* | |
66 | * Settings that govern how we throttle | |
67 | */ | |
68 | unsigned int wb_background; /* background writeback */ | |
69 | unsigned int wb_normal; /* normal writeback */ | |
70 | ||
71 | short enable_state; /* WBT_STATE_* */ | |
72 | ||
73 | /* | |
74 | * Number of consecutive periods where we don't have enough | |
75 | * information to make a firm scale up/down decision. | |
76 | */ | |
77 | unsigned int unknown_cnt; | |
78 | ||
79 | u64 win_nsec; /* default window size */ | |
80 | u64 cur_win_nsec; /* current window size */ | |
81 | ||
82 | struct blk_stat_callback *cb; | |
83 | ||
84 | u64 sync_issue; | |
85 | void *sync_cookie; | |
86 | ||
87 | unsigned int wc; | |
88 | ||
89 | unsigned long last_issue; /* last non-throttled issue */ | |
90 | unsigned long last_comp; /* last non-throttled comp */ | |
91 | unsigned long min_lat_nsec; | |
92 | struct rq_qos rqos; | |
93 | struct rq_wait rq_wait[WBT_NUM_RWQ]; | |
94 | struct rq_depth rq_depth; | |
95 | }; | |
96 | ||
97 | static inline struct rq_wb *RQWB(struct rq_qos *rqos) | |
98 | { | |
99 | return container_of(rqos, struct rq_wb, rqos); | |
100 | } | |
101 | ||
a8a45941 | 102 | static inline void wbt_clear_state(struct request *rq) |
934031a1 | 103 | { |
544ccc8d | 104 | rq->wbt_flags = 0; |
934031a1 OS |
105 | } |
106 | ||
a8a45941 | 107 | static inline enum wbt_flags wbt_flags(struct request *rq) |
934031a1 | 108 | { |
544ccc8d | 109 | return rq->wbt_flags; |
934031a1 OS |
110 | } |
111 | ||
a8a45941 | 112 | static inline bool wbt_is_tracked(struct request *rq) |
934031a1 | 113 | { |
544ccc8d | 114 | return rq->wbt_flags & WBT_TRACKED; |
934031a1 OS |
115 | } |
116 | ||
a8a45941 | 117 | static inline bool wbt_is_read(struct request *rq) |
934031a1 | 118 | { |
544ccc8d | 119 | return rq->wbt_flags & WBT_READ; |
934031a1 OS |
120 | } |
121 | ||
e34cbd30 JA |
122 | enum { |
123 | /* | |
124 | * Default setting, we'll scale up (to 75% of QD max) or down (min 1) | |
125 | * from here depending on device stats | |
126 | */ | |
127 | RWB_DEF_DEPTH = 16, | |
128 | ||
129 | /* | |
130 | * 100msec window | |
131 | */ | |
132 | RWB_WINDOW_NSEC = 100 * 1000 * 1000ULL, | |
133 | ||
134 | /* | |
135 | * Disregard stats, if we don't meet this minimum | |
136 | */ | |
137 | RWB_MIN_WRITE_SAMPLES = 3, | |
138 | ||
139 | /* | |
140 | * If we have this number of consecutive windows with not enough | |
141 | * information to scale up or down, scale up. | |
142 | */ | |
143 | RWB_UNKNOWN_BUMP = 5, | |
144 | }; | |
145 | ||
146 | static inline bool rwb_enabled(struct rq_wb *rwb) | |
147 | { | |
1d0903d6 ZY |
148 | return rwb && rwb->enable_state != WBT_STATE_OFF_DEFAULT && |
149 | rwb->wb_normal != 0; | |
e34cbd30 JA |
150 | } |
151 | ||
e34cbd30 JA |
152 | static void wb_timestamp(struct rq_wb *rwb, unsigned long *var) |
153 | { | |
154 | if (rwb_enabled(rwb)) { | |
155 | const unsigned long cur = jiffies; | |
156 | ||
157 | if (cur != *var) | |
158 | *var = cur; | |
159 | } | |
160 | } | |
161 | ||
162 | /* | |
163 | * If a task was rate throttled in balance_dirty_pages() within the last | |
164 | * second or so, use that to indicate a higher cleaning rate. | |
165 | */ | |
166 | static bool wb_recent_wait(struct rq_wb *rwb) | |
167 | { | |
ba91c849 | 168 | struct bdi_writeback *wb = &rwb->rqos.disk->bdi->wb; |
e34cbd30 JA |
169 | |
170 | return time_before(jiffies, wb->dirty_sleep + HZ); | |
171 | } | |
172 | ||
8bea6090 JA |
173 | static inline struct rq_wait *get_rq_wait(struct rq_wb *rwb, |
174 | enum wbt_flags wb_acct) | |
e34cbd30 | 175 | { |
8bea6090 JA |
176 | if (wb_acct & WBT_KSWAPD) |
177 | return &rwb->rq_wait[WBT_RWQ_KSWAPD]; | |
782f5697 JA |
178 | else if (wb_acct & WBT_DISCARD) |
179 | return &rwb->rq_wait[WBT_RWQ_DISCARD]; | |
8bea6090 JA |
180 | |
181 | return &rwb->rq_wait[WBT_RWQ_BG]; | |
e34cbd30 JA |
182 | } |
183 | ||
184 | static void rwb_wake_all(struct rq_wb *rwb) | |
185 | { | |
186 | int i; | |
187 | ||
188 | for (i = 0; i < WBT_NUM_RWQ; i++) { | |
189 | struct rq_wait *rqw = &rwb->rq_wait[i]; | |
190 | ||
b7882093 | 191 | if (wq_has_sleeper(&rqw->wait)) |
e34cbd30 JA |
192 | wake_up_all(&rqw->wait); |
193 | } | |
194 | } | |
195 | ||
061a5427 JA |
196 | static void wbt_rqw_done(struct rq_wb *rwb, struct rq_wait *rqw, |
197 | enum wbt_flags wb_acct) | |
e34cbd30 | 198 | { |
e34cbd30 JA |
199 | int inflight, limit; |
200 | ||
e34cbd30 JA |
201 | inflight = atomic_dec_return(&rqw->inflight); |
202 | ||
203 | /* | |
204 | * wbt got disabled with IO in flight. Wake up any potential | |
205 | * waiters, we don't have to do more than that. | |
206 | */ | |
207 | if (unlikely(!rwb_enabled(rwb))) { | |
208 | rwb_wake_all(rwb); | |
209 | return; | |
210 | } | |
211 | ||
212 | /* | |
782f5697 JA |
213 | * For discards, our limit is always the background. For writes, if |
214 | * the device does write back caching, drop further down before we | |
215 | * wake people up. | |
e34cbd30 | 216 | */ |
782f5697 JA |
217 | if (wb_acct & WBT_DISCARD) |
218 | limit = rwb->wb_background; | |
219 | else if (rwb->wc && !wb_recent_wait(rwb)) | |
e34cbd30 JA |
220 | limit = 0; |
221 | else | |
222 | limit = rwb->wb_normal; | |
223 | ||
224 | /* | |
225 | * Don't wake anyone up if we are above the normal limit. | |
226 | */ | |
227 | if (inflight && inflight >= limit) | |
228 | return; | |
229 | ||
b7882093 | 230 | if (wq_has_sleeper(&rqw->wait)) { |
e34cbd30 JA |
231 | int diff = limit - inflight; |
232 | ||
233 | if (!inflight || diff >= rwb->wb_background / 2) | |
38cfb5a4 | 234 | wake_up_all(&rqw->wait); |
e34cbd30 JA |
235 | } |
236 | } | |
237 | ||
061a5427 JA |
238 | static void __wbt_done(struct rq_qos *rqos, enum wbt_flags wb_acct) |
239 | { | |
240 | struct rq_wb *rwb = RQWB(rqos); | |
241 | struct rq_wait *rqw; | |
242 | ||
243 | if (!(wb_acct & WBT_TRACKED)) | |
244 | return; | |
245 | ||
246 | rqw = get_rq_wait(rwb, wb_acct); | |
247 | wbt_rqw_done(rwb, rqw, wb_acct); | |
248 | } | |
249 | ||
e34cbd30 JA |
250 | /* |
251 | * Called on completion of a request. Note that it's also called when | |
252 | * a request is merged, when the request gets freed. | |
253 | */ | |
a7905043 | 254 | static void wbt_done(struct rq_qos *rqos, struct request *rq) |
e34cbd30 | 255 | { |
a7905043 | 256 | struct rq_wb *rwb = RQWB(rqos); |
e34cbd30 | 257 | |
a8a45941 OS |
258 | if (!wbt_is_tracked(rq)) { |
259 | if (rwb->sync_cookie == rq) { | |
e34cbd30 JA |
260 | rwb->sync_issue = 0; |
261 | rwb->sync_cookie = NULL; | |
262 | } | |
263 | ||
a8a45941 | 264 | if (wbt_is_read(rq)) |
e34cbd30 | 265 | wb_timestamp(rwb, &rwb->last_comp); |
e34cbd30 | 266 | } else { |
a8a45941 | 267 | WARN_ON_ONCE(rq == rwb->sync_cookie); |
a7905043 | 268 | __wbt_done(rqos, wbt_flags(rq)); |
e34cbd30 | 269 | } |
a8a45941 | 270 | wbt_clear_state(rq); |
e34cbd30 JA |
271 | } |
272 | ||
4121d385 | 273 | static inline bool stat_sample_valid(struct blk_rq_stat *stat) |
e34cbd30 JA |
274 | { |
275 | /* | |
276 | * We need at least one read sample, and a minimum of | |
277 | * RWB_MIN_WRITE_SAMPLES. We require some write samples to know | |
278 | * that it's writes impacting us, and not just some sole read on | |
279 | * a device that is in a lower power state. | |
280 | */ | |
fa2e39cb OS |
281 | return (stat[READ].nr_samples >= 1 && |
282 | stat[WRITE].nr_samples >= RWB_MIN_WRITE_SAMPLES); | |
e34cbd30 JA |
283 | } |
284 | ||
285 | static u64 rwb_sync_issue_lat(struct rq_wb *rwb) | |
286 | { | |
6aa7de05 | 287 | u64 now, issue = READ_ONCE(rwb->sync_issue); |
e34cbd30 JA |
288 | |
289 | if (!issue || !rwb->sync_cookie) | |
290 | return 0; | |
291 | ||
292 | now = ktime_to_ns(ktime_get()); | |
293 | return now - issue; | |
294 | } | |
295 | ||
0bc65bd4 CH |
296 | static inline unsigned int wbt_inflight(struct rq_wb *rwb) |
297 | { | |
298 | unsigned int i, ret = 0; | |
299 | ||
300 | for (i = 0; i < WBT_NUM_RWQ; i++) | |
301 | ret += atomic_read(&rwb->rq_wait[i].inflight); | |
302 | ||
303 | return ret; | |
304 | } | |
305 | ||
e34cbd30 JA |
306 | enum { |
307 | LAT_OK = 1, | |
308 | LAT_UNKNOWN, | |
309 | LAT_UNKNOWN_WRITES, | |
310 | LAT_EXCEEDED, | |
311 | }; | |
312 | ||
34dbad5d | 313 | static int latency_exceeded(struct rq_wb *rwb, struct blk_rq_stat *stat) |
e34cbd30 | 314 | { |
ba91c849 | 315 | struct backing_dev_info *bdi = rwb->rqos.disk->bdi; |
a7905043 | 316 | struct rq_depth *rqd = &rwb->rq_depth; |
e34cbd30 JA |
317 | u64 thislat; |
318 | ||
319 | /* | |
320 | * If our stored sync issue exceeds the window size, or it | |
321 | * exceeds our min target AND we haven't logged any entries, | |
322 | * flag the latency as exceeded. wbt works off completion latencies, | |
323 | * but for a flooded device, a single sync IO can take a long time | |
324 | * to complete after being issued. If this time exceeds our | |
325 | * monitoring window AND we didn't see any other completions in that | |
326 | * window, then count that sync IO as a violation of the latency. | |
327 | */ | |
328 | thislat = rwb_sync_issue_lat(rwb); | |
329 | if (thislat > rwb->cur_win_nsec || | |
fa2e39cb | 330 | (thislat > rwb->min_lat_nsec && !stat[READ].nr_samples)) { |
d8a0cbfd | 331 | trace_wbt_lat(bdi, thislat); |
e34cbd30 JA |
332 | return LAT_EXCEEDED; |
333 | } | |
334 | ||
335 | /* | |
336 | * No read/write mix, if stat isn't valid | |
337 | */ | |
338 | if (!stat_sample_valid(stat)) { | |
339 | /* | |
340 | * If we had writes in this stat window and the window is | |
341 | * current, we're only doing writes. If a task recently | |
342 | * waited or still has writes in flights, consider us doing | |
343 | * just writes as well. | |
344 | */ | |
34dbad5d OS |
345 | if (stat[WRITE].nr_samples || wb_recent_wait(rwb) || |
346 | wbt_inflight(rwb)) | |
e34cbd30 JA |
347 | return LAT_UNKNOWN_WRITES; |
348 | return LAT_UNKNOWN; | |
349 | } | |
350 | ||
351 | /* | |
352 | * If the 'min' latency exceeds our target, step down. | |
353 | */ | |
fa2e39cb OS |
354 | if (stat[READ].min > rwb->min_lat_nsec) { |
355 | trace_wbt_lat(bdi, stat[READ].min); | |
d8a0cbfd | 356 | trace_wbt_stat(bdi, stat); |
e34cbd30 JA |
357 | return LAT_EXCEEDED; |
358 | } | |
359 | ||
a7905043 | 360 | if (rqd->scale_step) |
d8a0cbfd | 361 | trace_wbt_stat(bdi, stat); |
e34cbd30 JA |
362 | |
363 | return LAT_OK; | |
364 | } | |
365 | ||
e34cbd30 JA |
366 | static void rwb_trace_step(struct rq_wb *rwb, const char *msg) |
367 | { | |
ba91c849 | 368 | struct backing_dev_info *bdi = rwb->rqos.disk->bdi; |
a7905043 | 369 | struct rq_depth *rqd = &rwb->rq_depth; |
d8a0cbfd | 370 | |
a7905043 JB |
371 | trace_wbt_step(bdi, msg, rqd->scale_step, rwb->cur_win_nsec, |
372 | rwb->wb_background, rwb->wb_normal, rqd->max_depth); | |
e34cbd30 JA |
373 | } |
374 | ||
a7905043 | 375 | static void calc_wb_limits(struct rq_wb *rwb) |
e34cbd30 | 376 | { |
a7905043 JB |
377 | if (rwb->min_lat_nsec == 0) { |
378 | rwb->wb_normal = rwb->wb_background = 0; | |
379 | } else if (rwb->rq_depth.max_depth <= 2) { | |
380 | rwb->wb_normal = rwb->rq_depth.max_depth; | |
381 | rwb->wb_background = 1; | |
382 | } else { | |
383 | rwb->wb_normal = (rwb->rq_depth.max_depth + 1) / 2; | |
384 | rwb->wb_background = (rwb->rq_depth.max_depth + 3) / 4; | |
385 | } | |
386 | } | |
e34cbd30 | 387 | |
a7905043 JB |
388 | static void scale_up(struct rq_wb *rwb) |
389 | { | |
b84477d3 HS |
390 | if (!rq_depth_scale_up(&rwb->rq_depth)) |
391 | return; | |
a7905043 | 392 | calc_wb_limits(rwb); |
e34cbd30 | 393 | rwb->unknown_cnt = 0; |
5e65a203 | 394 | rwb_wake_all(rwb); |
3a89c25d | 395 | rwb_trace_step(rwb, tracepoint_string("scale up")); |
e34cbd30 JA |
396 | } |
397 | ||
e34cbd30 JA |
398 | static void scale_down(struct rq_wb *rwb, bool hard_throttle) |
399 | { | |
b84477d3 HS |
400 | if (!rq_depth_scale_down(&rwb->rq_depth, hard_throttle)) |
401 | return; | |
e34cbd30 | 402 | calc_wb_limits(rwb); |
a7905043 | 403 | rwb->unknown_cnt = 0; |
3a89c25d | 404 | rwb_trace_step(rwb, tracepoint_string("scale down")); |
e34cbd30 JA |
405 | } |
406 | ||
407 | static void rwb_arm_timer(struct rq_wb *rwb) | |
408 | { | |
a7905043 JB |
409 | struct rq_depth *rqd = &rwb->rq_depth; |
410 | ||
411 | if (rqd->scale_step > 0) { | |
e34cbd30 JA |
412 | /* |
413 | * We should speed this up, using some variant of a fast | |
414 | * integer inverse square root calculation. Since we only do | |
415 | * this for every window expiration, it's not a huge deal, | |
416 | * though. | |
417 | */ | |
418 | rwb->cur_win_nsec = div_u64(rwb->win_nsec << 4, | |
a7905043 | 419 | int_sqrt((rqd->scale_step + 1) << 8)); |
e34cbd30 JA |
420 | } else { |
421 | /* | |
422 | * For step < 0, we don't want to increase/decrease the | |
423 | * window size. | |
424 | */ | |
425 | rwb->cur_win_nsec = rwb->win_nsec; | |
426 | } | |
427 | ||
34dbad5d | 428 | blk_stat_activate_nsecs(rwb->cb, rwb->cur_win_nsec); |
e34cbd30 JA |
429 | } |
430 | ||
34dbad5d | 431 | static void wb_timer_fn(struct blk_stat_callback *cb) |
e34cbd30 | 432 | { |
34dbad5d | 433 | struct rq_wb *rwb = cb->data; |
a7905043 | 434 | struct rq_depth *rqd = &rwb->rq_depth; |
e34cbd30 JA |
435 | unsigned int inflight = wbt_inflight(rwb); |
436 | int status; | |
437 | ||
ba91c849 | 438 | if (!rwb->rqos.disk) |
480d42dc AR |
439 | return; |
440 | ||
34dbad5d | 441 | status = latency_exceeded(rwb, cb->stat); |
e34cbd30 | 442 | |
ba91c849 | 443 | trace_wbt_timer(rwb->rqos.disk->bdi, status, rqd->scale_step, inflight); |
e34cbd30 JA |
444 | |
445 | /* | |
446 | * If we exceeded the latency target, step down. If we did not, | |
447 | * step one level up. If we don't know enough to say either exceeded | |
448 | * or ok, then don't do anything. | |
449 | */ | |
450 | switch (status) { | |
451 | case LAT_EXCEEDED: | |
452 | scale_down(rwb, true); | |
453 | break; | |
454 | case LAT_OK: | |
455 | scale_up(rwb); | |
456 | break; | |
457 | case LAT_UNKNOWN_WRITES: | |
458 | /* | |
459 | * We started a the center step, but don't have a valid | |
460 | * read/write sample, but we do have writes going on. | |
461 | * Allow step to go negative, to increase write perf. | |
462 | */ | |
463 | scale_up(rwb); | |
464 | break; | |
465 | case LAT_UNKNOWN: | |
466 | if (++rwb->unknown_cnt < RWB_UNKNOWN_BUMP) | |
467 | break; | |
468 | /* | |
469 | * We get here when previously scaled reduced depth, and we | |
470 | * currently don't have a valid read/write sample. For that | |
471 | * case, slowly return to center state (step == 0). | |
472 | */ | |
a7905043 | 473 | if (rqd->scale_step > 0) |
e34cbd30 | 474 | scale_up(rwb); |
a7905043 | 475 | else if (rqd->scale_step < 0) |
e34cbd30 JA |
476 | scale_down(rwb, false); |
477 | break; | |
478 | default: | |
479 | break; | |
480 | } | |
481 | ||
482 | /* | |
483 | * Re-arm timer, if we have IO in flight | |
484 | */ | |
a7905043 | 485 | if (rqd->scale_step || inflight) |
e34cbd30 JA |
486 | rwb_arm_timer(rwb); |
487 | } | |
488 | ||
4d89e1d1 | 489 | static void wbt_update_limits(struct rq_wb *rwb) |
e34cbd30 | 490 | { |
a7905043 JB |
491 | struct rq_depth *rqd = &rwb->rq_depth; |
492 | ||
493 | rqd->scale_step = 0; | |
494 | rqd->scaled_max = false; | |
495 | ||
496 | rq_depth_calc_max_depth(rqd); | |
e34cbd30 JA |
497 | calc_wb_limits(rwb); |
498 | ||
499 | rwb_wake_all(rwb); | |
500 | } | |
501 | ||
3642ef4d YK |
502 | bool wbt_disabled(struct request_queue *q) |
503 | { | |
504 | struct rq_qos *rqos = wbt_rq_qos(q); | |
505 | ||
506 | return !rqos || RQWB(rqos)->enable_state == WBT_STATE_OFF_DEFAULT || | |
507 | RQWB(rqos)->enable_state == WBT_STATE_OFF_MANUAL; | |
508 | } | |
509 | ||
a7905043 JB |
510 | u64 wbt_get_min_lat(struct request_queue *q) |
511 | { | |
512 | struct rq_qos *rqos = wbt_rq_qos(q); | |
513 | if (!rqos) | |
514 | return 0; | |
515 | return RQWB(rqos)->min_lat_nsec; | |
516 | } | |
517 | ||
518 | void wbt_set_min_lat(struct request_queue *q, u64 val) | |
519 | { | |
520 | struct rq_qos *rqos = wbt_rq_qos(q); | |
521 | if (!rqos) | |
522 | return; | |
a9a236d2 | 523 | |
a7905043 | 524 | RQWB(rqos)->min_lat_nsec = val; |
a9a236d2 YK |
525 | if (val) |
526 | RQWB(rqos)->enable_state = WBT_STATE_ON_MANUAL; | |
527 | else | |
528 | RQWB(rqos)->enable_state = WBT_STATE_OFF_MANUAL; | |
529 | ||
4d89e1d1 | 530 | wbt_update_limits(RQWB(rqos)); |
a7905043 JB |
531 | } |
532 | ||
533 | ||
e34cbd30 JA |
534 | static bool close_io(struct rq_wb *rwb) |
535 | { | |
536 | const unsigned long now = jiffies; | |
537 | ||
538 | return time_before(now, rwb->last_issue + HZ / 10) || | |
539 | time_before(now, rwb->last_comp + HZ / 10); | |
540 | } | |
541 | ||
542 | #define REQ_HIPRIO (REQ_SYNC | REQ_META | REQ_PRIO) | |
543 | ||
16458cf3 | 544 | static inline unsigned int get_limit(struct rq_wb *rwb, blk_opf_t opf) |
e34cbd30 JA |
545 | { |
546 | unsigned int limit; | |
547 | ||
ffa358dc JA |
548 | /* |
549 | * If we got disabled, just return UINT_MAX. This ensures that | |
550 | * we'll properly inc a new IO, and dec+wakeup at the end. | |
551 | */ | |
552 | if (!rwb_enabled(rwb)) | |
553 | return UINT_MAX; | |
554 | ||
16458cf3 | 555 | if ((opf & REQ_OP_MASK) == REQ_OP_DISCARD) |
782f5697 JA |
556 | return rwb->wb_background; |
557 | ||
e34cbd30 JA |
558 | /* |
559 | * At this point we know it's a buffered write. If this is | |
3dfbdc44 | 560 | * kswapd trying to free memory, or REQ_SYNC is set, then |
e34cbd30 JA |
561 | * it's WB_SYNC_ALL writeback, and we'll use the max limit for |
562 | * that. If the write is marked as a background write, then use | |
563 | * the idle limit, or go to normal if we haven't had competing | |
564 | * IO for a bit. | |
565 | */ | |
16458cf3 | 566 | if ((opf & REQ_HIPRIO) || wb_recent_wait(rwb) || current_is_kswapd()) |
a7905043 | 567 | limit = rwb->rq_depth.max_depth; |
16458cf3 | 568 | else if ((opf & REQ_BACKGROUND) || close_io(rwb)) { |
e34cbd30 JA |
569 | /* |
570 | * If less than 100ms since we completed unrelated IO, | |
571 | * limit us to half the depth for background writeback. | |
572 | */ | |
573 | limit = rwb->wb_background; | |
574 | } else | |
575 | limit = rwb->wb_normal; | |
576 | ||
577 | return limit; | |
578 | } | |
579 | ||
38cfb5a4 | 580 | struct wbt_wait_data { |
38cfb5a4 | 581 | struct rq_wb *rwb; |
b6c7b58f | 582 | enum wbt_flags wb_acct; |
16458cf3 | 583 | blk_opf_t opf; |
38cfb5a4 JA |
584 | }; |
585 | ||
b6c7b58f | 586 | static bool wbt_inflight_cb(struct rq_wait *rqw, void *private_data) |
38cfb5a4 | 587 | { |
b6c7b58f | 588 | struct wbt_wait_data *data = private_data; |
16458cf3 | 589 | return rq_wait_inc_below(rqw, get_limit(data->rwb, data->opf)); |
b6c7b58f | 590 | } |
38cfb5a4 | 591 | |
b6c7b58f JB |
592 | static void wbt_cleanup_cb(struct rq_wait *rqw, void *private_data) |
593 | { | |
594 | struct wbt_wait_data *data = private_data; | |
595 | wbt_rqw_done(data->rwb, rqw, data->wb_acct); | |
38cfb5a4 JA |
596 | } |
597 | ||
e34cbd30 JA |
598 | /* |
599 | * Block if we will exceed our limit, or if we are currently waiting for | |
600 | * the timer to kick off queuing again. | |
601 | */ | |
8bea6090 | 602 | static void __wbt_wait(struct rq_wb *rwb, enum wbt_flags wb_acct, |
16458cf3 | 603 | blk_opf_t opf) |
e34cbd30 | 604 | { |
8bea6090 | 605 | struct rq_wait *rqw = get_rq_wait(rwb, wb_acct); |
38cfb5a4 | 606 | struct wbt_wait_data data = { |
38cfb5a4 | 607 | .rwb = rwb, |
b6c7b58f | 608 | .wb_acct = wb_acct, |
16458cf3 | 609 | .opf = opf, |
38cfb5a4 | 610 | }; |
e34cbd30 | 611 | |
b6c7b58f | 612 | rq_qos_wait(rqw, &data, wbt_inflight_cb, wbt_cleanup_cb); |
e34cbd30 JA |
613 | } |
614 | ||
482e302a | 615 | static inline bool wbt_should_throttle(struct bio *bio) |
e34cbd30 | 616 | { |
782f5697 JA |
617 | switch (bio_op(bio)) { |
618 | case REQ_OP_WRITE: | |
619 | /* | |
620 | * Don't throttle WRITE_ODIRECT | |
621 | */ | |
622 | if ((bio->bi_opf & (REQ_SYNC | REQ_IDLE)) == | |
623 | (REQ_SYNC | REQ_IDLE)) | |
624 | return false; | |
df561f66 | 625 | fallthrough; |
782f5697 JA |
626 | case REQ_OP_DISCARD: |
627 | return true; | |
628 | default: | |
e34cbd30 | 629 | return false; |
782f5697 | 630 | } |
e34cbd30 JA |
631 | } |
632 | ||
c1c80384 JB |
633 | static enum wbt_flags bio_to_wbt_flags(struct rq_wb *rwb, struct bio *bio) |
634 | { | |
635 | enum wbt_flags flags = 0; | |
636 | ||
c125311d JA |
637 | if (!rwb_enabled(rwb)) |
638 | return 0; | |
639 | ||
c1c80384 JB |
640 | if (bio_op(bio) == REQ_OP_READ) { |
641 | flags = WBT_READ; | |
482e302a | 642 | } else if (wbt_should_throttle(bio)) { |
c1c80384 JB |
643 | if (current_is_kswapd()) |
644 | flags |= WBT_KSWAPD; | |
645 | if (bio_op(bio) == REQ_OP_DISCARD) | |
646 | flags |= WBT_DISCARD; | |
647 | flags |= WBT_TRACKED; | |
648 | } | |
649 | return flags; | |
650 | } | |
651 | ||
652 | static void wbt_cleanup(struct rq_qos *rqos, struct bio *bio) | |
653 | { | |
654 | struct rq_wb *rwb = RQWB(rqos); | |
655 | enum wbt_flags flags = bio_to_wbt_flags(rwb, bio); | |
656 | __wbt_done(rqos, flags); | |
657 | } | |
658 | ||
e34cbd30 | 659 | /* |
e34cbd30 JA |
660 | * May sleep, if we have exceeded the writeback limits. Caller can pass |
661 | * in an irq held spinlock, if it holds one when calling this function. | |
662 | * If we do sleep, we'll release and re-grab it. | |
663 | */ | |
d5337560 | 664 | static void wbt_wait(struct rq_qos *rqos, struct bio *bio) |
e34cbd30 | 665 | { |
a7905043 | 666 | struct rq_wb *rwb = RQWB(rqos); |
c1c80384 | 667 | enum wbt_flags flags; |
e34cbd30 | 668 | |
c1c80384 | 669 | flags = bio_to_wbt_flags(rwb, bio); |
df60f6e8 | 670 | if (!(flags & WBT_TRACKED)) { |
c1c80384 | 671 | if (flags & WBT_READ) |
e34cbd30 | 672 | wb_timestamp(rwb, &rwb->last_issue); |
c1c80384 | 673 | return; |
e34cbd30 JA |
674 | } |
675 | ||
d5337560 | 676 | __wbt_wait(rwb, flags, bio->bi_opf); |
e34cbd30 | 677 | |
34dbad5d | 678 | if (!blk_stat_is_active(rwb->cb)) |
e34cbd30 | 679 | rwb_arm_timer(rwb); |
c1c80384 | 680 | } |
e34cbd30 | 681 | |
c1c80384 JB |
682 | static void wbt_track(struct rq_qos *rqos, struct request *rq, struct bio *bio) |
683 | { | |
684 | struct rq_wb *rwb = RQWB(rqos); | |
685 | rq->wbt_flags |= bio_to_wbt_flags(rwb, bio); | |
e34cbd30 JA |
686 | } |
687 | ||
c83f536a | 688 | static void wbt_issue(struct rq_qos *rqos, struct request *rq) |
e34cbd30 | 689 | { |
a7905043 JB |
690 | struct rq_wb *rwb = RQWB(rqos); |
691 | ||
e34cbd30 JA |
692 | if (!rwb_enabled(rwb)) |
693 | return; | |
694 | ||
695 | /* | |
a8a45941 OS |
696 | * Track sync issue, in case it takes a long time to complete. Allows us |
697 | * to react quicker, if a sync IO takes a long time to complete. Note | |
698 | * that this is just a hint. The request can go away when it completes, | |
699 | * so it's important we never dereference it. We only use the address to | |
700 | * compare with, which is why we store the sync_issue time locally. | |
e34cbd30 | 701 | */ |
a8a45941 OS |
702 | if (wbt_is_read(rq) && !rwb->sync_issue) { |
703 | rwb->sync_cookie = rq; | |
544ccc8d | 704 | rwb->sync_issue = rq->io_start_time_ns; |
e34cbd30 JA |
705 | } |
706 | } | |
707 | ||
c83f536a | 708 | static void wbt_requeue(struct rq_qos *rqos, struct request *rq) |
e34cbd30 | 709 | { |
a7905043 | 710 | struct rq_wb *rwb = RQWB(rqos); |
e34cbd30 JA |
711 | if (!rwb_enabled(rwb)) |
712 | return; | |
a8a45941 | 713 | if (rq == rwb->sync_cookie) { |
e34cbd30 JA |
714 | rwb->sync_issue = 0; |
715 | rwb->sync_cookie = NULL; | |
716 | } | |
717 | } | |
718 | ||
a7905043 | 719 | void wbt_set_write_cache(struct request_queue *q, bool write_cache_on) |
e34cbd30 | 720 | { |
a7905043 JB |
721 | struct rq_qos *rqos = wbt_rq_qos(q); |
722 | if (rqos) | |
723 | RQWB(rqos)->wc = write_cache_on; | |
e34cbd30 | 724 | } |
e34cbd30 | 725 | |
8330cdb0 JK |
726 | /* |
727 | * Enable wbt if defaults are configured that way | |
728 | */ | |
04aad37b | 729 | void wbt_enable_default(struct gendisk *disk) |
8330cdb0 | 730 | { |
04aad37b | 731 | struct request_queue *q = disk->queue; |
671fae5e YK |
732 | struct rq_qos *rqos; |
733 | bool disable_flag = q->elevator && | |
734 | test_bit(ELEVATOR_FLAG_DISABLE_WBT, &q->elevator->flags); | |
76a80408 | 735 | |
8330cdb0 | 736 | /* Throttling already enabled? */ |
671fae5e | 737 | rqos = wbt_rq_qos(q); |
76a80408 | 738 | if (rqos) { |
671fae5e YK |
739 | if (!disable_flag && |
740 | RQWB(rqos)->enable_state == WBT_STATE_OFF_DEFAULT) | |
76a80408 | 741 | RQWB(rqos)->enable_state = WBT_STATE_ON_DEFAULT; |
8330cdb0 | 742 | return; |
76a80408 | 743 | } |
8330cdb0 JK |
744 | |
745 | /* Queue not registered? Maybe shutting down... */ | |
58c898ba | 746 | if (!blk_queue_registered(q)) |
8330cdb0 JK |
747 | return; |
748 | ||
671fae5e | 749 | if (queue_is_mq(q) && !disable_flag) |
958f2965 | 750 | wbt_init(disk); |
8330cdb0 JK |
751 | } |
752 | EXPORT_SYMBOL_GPL(wbt_enable_default); | |
753 | ||
80e091d1 JA |
754 | u64 wbt_default_latency_nsec(struct request_queue *q) |
755 | { | |
756 | /* | |
757 | * We default to 2msec for non-rotational storage, and 75msec | |
758 | * for rotational storage. | |
759 | */ | |
760 | if (blk_queue_nonrot(q)) | |
761 | return 2000000ULL; | |
762 | else | |
763 | return 75000000ULL; | |
764 | } | |
765 | ||
99c749a4 JA |
766 | static int wbt_data_dir(const struct request *rq) |
767 | { | |
77e7ffd7 | 768 | const enum req_op op = req_op(rq); |
5235553d JA |
769 | |
770 | if (op == REQ_OP_READ) | |
771 | return READ; | |
825843b0 | 772 | else if (op_is_write(op)) |
5235553d JA |
773 | return WRITE; |
774 | ||
775 | /* don't account */ | |
776 | return -1; | |
99c749a4 JA |
777 | } |
778 | ||
9677a3e0 TH |
779 | static void wbt_queue_depth_changed(struct rq_qos *rqos) |
780 | { | |
ba91c849 | 781 | RQWB(rqos)->rq_depth.queue_depth = blk_queue_depth(rqos->disk->queue); |
4d89e1d1 | 782 | wbt_update_limits(RQWB(rqos)); |
9677a3e0 TH |
783 | } |
784 | ||
a7905043 JB |
785 | static void wbt_exit(struct rq_qos *rqos) |
786 | { | |
787 | struct rq_wb *rwb = RQWB(rqos); | |
a7905043 | 788 | |
ba91c849 | 789 | blk_stat_remove_callback(rqos->disk->queue, rwb->cb); |
a7905043 JB |
790 | blk_stat_free_callback(rwb->cb); |
791 | kfree(rwb); | |
792 | } | |
793 | ||
794 | /* | |
795 | * Disable wbt, if enabled by default. | |
796 | */ | |
04aad37b | 797 | void wbt_disable_default(struct gendisk *disk) |
a7905043 | 798 | { |
04aad37b | 799 | struct rq_qos *rqos = wbt_rq_qos(disk->queue); |
a7905043 JB |
800 | struct rq_wb *rwb; |
801 | if (!rqos) | |
802 | return; | |
803 | rwb = RQWB(rqos); | |
544fbd16 ML |
804 | if (rwb->enable_state == WBT_STATE_ON_DEFAULT) { |
805 | blk_stat_deactivate(rwb->cb); | |
1d0903d6 | 806 | rwb->enable_state = WBT_STATE_OFF_DEFAULT; |
544fbd16 | 807 | } |
a7905043 | 808 | } |
e815f404 | 809 | EXPORT_SYMBOL_GPL(wbt_disable_default); |
a7905043 | 810 | |
d19afebc ML |
811 | #ifdef CONFIG_BLK_DEBUG_FS |
812 | static int wbt_curr_win_nsec_show(void *data, struct seq_file *m) | |
813 | { | |
814 | struct rq_qos *rqos = data; | |
815 | struct rq_wb *rwb = RQWB(rqos); | |
816 | ||
817 | seq_printf(m, "%llu\n", rwb->cur_win_nsec); | |
818 | return 0; | |
819 | } | |
820 | ||
821 | static int wbt_enabled_show(void *data, struct seq_file *m) | |
822 | { | |
823 | struct rq_qos *rqos = data; | |
824 | struct rq_wb *rwb = RQWB(rqos); | |
825 | ||
826 | seq_printf(m, "%d\n", rwb->enable_state); | |
827 | return 0; | |
828 | } | |
829 | ||
830 | static int wbt_id_show(void *data, struct seq_file *m) | |
831 | { | |
832 | struct rq_qos *rqos = data; | |
833 | ||
834 | seq_printf(m, "%u\n", rqos->id); | |
835 | return 0; | |
836 | } | |
837 | ||
838 | static int wbt_inflight_show(void *data, struct seq_file *m) | |
839 | { | |
840 | struct rq_qos *rqos = data; | |
841 | struct rq_wb *rwb = RQWB(rqos); | |
842 | int i; | |
843 | ||
844 | for (i = 0; i < WBT_NUM_RWQ; i++) | |
845 | seq_printf(m, "%d: inflight %d\n", i, | |
846 | atomic_read(&rwb->rq_wait[i].inflight)); | |
847 | return 0; | |
848 | } | |
849 | ||
850 | static int wbt_min_lat_nsec_show(void *data, struct seq_file *m) | |
851 | { | |
852 | struct rq_qos *rqos = data; | |
853 | struct rq_wb *rwb = RQWB(rqos); | |
854 | ||
855 | seq_printf(m, "%lu\n", rwb->min_lat_nsec); | |
856 | return 0; | |
857 | } | |
858 | ||
859 | static int wbt_unknown_cnt_show(void *data, struct seq_file *m) | |
860 | { | |
861 | struct rq_qos *rqos = data; | |
862 | struct rq_wb *rwb = RQWB(rqos); | |
863 | ||
864 | seq_printf(m, "%u\n", rwb->unknown_cnt); | |
865 | return 0; | |
866 | } | |
867 | ||
868 | static int wbt_normal_show(void *data, struct seq_file *m) | |
869 | { | |
870 | struct rq_qos *rqos = data; | |
871 | struct rq_wb *rwb = RQWB(rqos); | |
872 | ||
873 | seq_printf(m, "%u\n", rwb->wb_normal); | |
874 | return 0; | |
875 | } | |
876 | ||
877 | static int wbt_background_show(void *data, struct seq_file *m) | |
878 | { | |
879 | struct rq_qos *rqos = data; | |
880 | struct rq_wb *rwb = RQWB(rqos); | |
881 | ||
882 | seq_printf(m, "%u\n", rwb->wb_background); | |
883 | return 0; | |
884 | } | |
885 | ||
886 | static const struct blk_mq_debugfs_attr wbt_debugfs_attrs[] = { | |
887 | {"curr_win_nsec", 0400, wbt_curr_win_nsec_show}, | |
888 | {"enabled", 0400, wbt_enabled_show}, | |
889 | {"id", 0400, wbt_id_show}, | |
890 | {"inflight", 0400, wbt_inflight_show}, | |
891 | {"min_lat_nsec", 0400, wbt_min_lat_nsec_show}, | |
892 | {"unknown_cnt", 0400, wbt_unknown_cnt_show}, | |
893 | {"wb_normal", 0400, wbt_normal_show}, | |
894 | {"wb_background", 0400, wbt_background_show}, | |
895 | {}, | |
896 | }; | |
897 | #endif | |
898 | ||
3963d84d | 899 | static const struct rq_qos_ops wbt_rqos_ops = { |
a7905043 JB |
900 | .throttle = wbt_wait, |
901 | .issue = wbt_issue, | |
c1c80384 | 902 | .track = wbt_track, |
a7905043 JB |
903 | .requeue = wbt_requeue, |
904 | .done = wbt_done, | |
c1c80384 | 905 | .cleanup = wbt_cleanup, |
9677a3e0 | 906 | .queue_depth_changed = wbt_queue_depth_changed, |
a7905043 | 907 | .exit = wbt_exit, |
d19afebc ML |
908 | #ifdef CONFIG_BLK_DEBUG_FS |
909 | .debugfs_attrs = wbt_debugfs_attrs, | |
910 | #endif | |
a7905043 JB |
911 | }; |
912 | ||
958f2965 | 913 | int wbt_init(struct gendisk *disk) |
e34cbd30 | 914 | { |
958f2965 | 915 | struct request_queue *q = disk->queue; |
e34cbd30 JA |
916 | struct rq_wb *rwb; |
917 | int i; | |
14a6e2eb | 918 | int ret; |
e34cbd30 | 919 | |
e34cbd30 JA |
920 | rwb = kzalloc(sizeof(*rwb), GFP_KERNEL); |
921 | if (!rwb) | |
922 | return -ENOMEM; | |
923 | ||
99c749a4 | 924 | rwb->cb = blk_stat_alloc_callback(wb_timer_fn, wbt_data_dir, 2, rwb); |
34dbad5d OS |
925 | if (!rwb->cb) { |
926 | kfree(rwb); | |
927 | return -ENOMEM; | |
928 | } | |
929 | ||
a7905043 JB |
930 | for (i = 0; i < WBT_NUM_RWQ; i++) |
931 | rq_wait_init(&rwb->rq_wait[i]); | |
e34cbd30 | 932 | |
e34cbd30 | 933 | rwb->last_comp = rwb->last_issue = jiffies; |
e34cbd30 | 934 | rwb->win_nsec = RWB_WINDOW_NSEC; |
d62118b6 | 935 | rwb->enable_state = WBT_STATE_ON_DEFAULT; |
285febab | 936 | rwb->wc = test_bit(QUEUE_FLAG_WC, &q->queue_flags); |
a7905043 | 937 | rwb->rq_depth.default_depth = RWB_DEF_DEPTH; |
8c5035df | 938 | rwb->min_lat_nsec = wbt_default_latency_nsec(q); |
4e1d91ae CH |
939 | rwb->rq_depth.queue_depth = blk_queue_depth(q); |
940 | wbt_update_limits(rwb); | |
e34cbd30 JA |
941 | |
942 | /* | |
34dbad5d | 943 | * Assign rwb and add the stats callback. |
e34cbd30 | 944 | */ |
ce57b558 | 945 | ret = rq_qos_add(&rwb->rqos, disk, RQ_QOS_WBT, &wbt_rqos_ops); |
14a6e2eb JH |
946 | if (ret) |
947 | goto err_free; | |
948 | ||
34dbad5d | 949 | blk_stat_add_callback(q, rwb->cb); |
e34cbd30 | 950 | |
e34cbd30 | 951 | return 0; |
14a6e2eb JH |
952 | |
953 | err_free: | |
954 | blk_stat_free_callback(rwb->cb); | |
955 | kfree(rwb); | |
956 | return ret; | |
957 | ||
e34cbd30 | 958 | } |