1/*- 2 * CAM IO Scheduler Interface 3 * 4 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 5 * 6 * Copyright (c) 2015 Netflix, Inc. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions, and the following disclaimer, 13 * without modification, immediately at the beginning of the file. 14 * 2. The name of the author may not be used to endorse or promote products 15 * derived from this software without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR 21 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 * 29 * $FreeBSD$ 30 */ 31 32#include "opt_cam.h" 33#include "opt_ddb.h" 34 35#include <sys/cdefs.h> 36__FBSDID("$FreeBSD$"); 37 38#include <sys/param.h> 39 40#include <sys/systm.h> 41#include <sys/kernel.h> 42#include <sys/bio.h> 43#include <sys/lock.h> 44#include <sys/malloc.h> 45#include <sys/mutex.h> 46#include <sys/sbuf.h> 47#include <sys/sysctl.h> 48 49#include <cam/cam.h> 50#include <cam/cam_ccb.h> 51#include <cam/cam_periph.h> 52#include <cam/cam_xpt_periph.h> 53#include <cam/cam_xpt_internal.h> 54#include <cam/cam_iosched.h> 55 56#include <ddb/ddb.h> 57 58static MALLOC_DEFINE(M_CAMSCHED, "CAM I/O Scheduler", 59 "CAM I/O Scheduler buffers"); 60 61/* 62 * Default I/O scheduler for FreeBSD. This implementation is just a thin-vineer 63 * over the bioq_* interface, with notions of separate calls for normal I/O and 64 * for trims. 65 * 66 * When CAM_IOSCHED_DYNAMIC is defined, the scheduler is enhanced to dynamically 67 * steer the rate of one type of traffic to help other types of traffic (eg 68 * limit writes when read latency deteriorates on SSDs). 69 */ 70 71#ifdef CAM_IOSCHED_DYNAMIC 72 73static int do_dynamic_iosched = 1; 74TUNABLE_INT("kern.cam.do_dynamic_iosched", &do_dynamic_iosched); 75SYSCTL_INT(_kern_cam, OID_AUTO, do_dynamic_iosched, CTLFLAG_RD, 76 &do_dynamic_iosched, 1, 77 "Enable Dynamic I/O scheduler optimizations."); 78 79/* 80 * For an EMA, with an alpha of alpha, we know 81 * alpha = 2 / (N + 1) 82 * or 83 * N = 1 + (2 / alpha) 84 * where N is the number of samples that 86% of the current 85 * EMA is derived from. 86 * 87 * So we invent[*] alpha_bits: 88 * alpha_bits = -log_2(alpha) 89 * alpha = 2^-alpha_bits 90 * So 91 * N = 1 + 2^(alpha_bits + 1) 92 * 93 * The default 9 gives a 1025 lookback for 86% of the data. 94 * For a brief intro: https://en.wikipedia.org/wiki/Moving_average 95 * 96 * [*] Steal from the load average code and many other places. 97 * Note: See computation of EMA and EMVAR for acceptable ranges of alpha. 98 */ 99static int alpha_bits = 9; 100TUNABLE_INT("kern.cam.iosched_alpha_bits", &alpha_bits); 101SYSCTL_INT(_kern_cam, OID_AUTO, iosched_alpha_bits, CTLFLAG_RW, 102 &alpha_bits, 1, 103 "Bits in EMA's alpha."); 104 105struct iop_stats; 106struct cam_iosched_softc; 107 108int iosched_debug = 0; 109 110typedef enum { 111 none = 0, /* No limits */ 112 queue_depth, /* Limit how many ops we queue to SIM */ 113 iops, /* Limit # of IOPS to the drive */ 114 bandwidth, /* Limit bandwidth to the drive */ 115 limiter_max 116} io_limiter; 117 118static const char *cam_iosched_limiter_names[] = 119 { "none", "queue_depth", "iops", "bandwidth" }; 120 121/* 122 * Called to initialize the bits of the iop_stats structure relevant to the 123 * limiter. Called just after the limiter is set. 124 */ 125typedef int l_init_t(struct iop_stats *); 126 127/* 128 * Called every tick. 129 */ 130typedef int l_tick_t(struct iop_stats *); 131 132/* 133 * Called to see if the limiter thinks this IOP can be allowed to 134 * proceed. If so, the limiter assumes that the IOP proceeded 135 * and makes any accounting of it that's needed. 136 */ 137typedef int l_iop_t(struct iop_stats *, struct bio *); 138 139/* 140 * Called when an I/O completes so the limiter can update its 141 * accounting. Pending I/Os may complete in any order (even when 142 * sent to the hardware at the same time), so the limiter may not 143 * make any assumptions other than this I/O has completed. If it 144 * returns 1, then xpt_schedule() needs to be called again. 145 */ 146typedef int l_iodone_t(struct iop_stats *, struct bio *); 147 148static l_iop_t cam_iosched_qd_iop; 149static l_iop_t cam_iosched_qd_caniop; 150static l_iodone_t cam_iosched_qd_iodone; 151 152static l_init_t cam_iosched_iops_init; 153static l_tick_t cam_iosched_iops_tick; 154static l_iop_t cam_iosched_iops_caniop; 155static l_iop_t cam_iosched_iops_iop; 156 157static l_init_t cam_iosched_bw_init; 158static l_tick_t cam_iosched_bw_tick; 159static l_iop_t cam_iosched_bw_caniop; 160static l_iop_t cam_iosched_bw_iop; 161 162struct limswitch { 163 l_init_t *l_init; 164 l_tick_t *l_tick; 165 l_iop_t *l_iop; 166 l_iop_t *l_caniop; 167 l_iodone_t *l_iodone; 168} limsw[] = 169{ 170 { /* none */ 171 .l_init = NULL, 172 .l_tick = NULL, 173 .l_iop = NULL, 174 .l_iodone= NULL, 175 }, 176 { /* queue_depth */ 177 .l_init = NULL, 178 .l_tick = NULL, 179 .l_caniop = cam_iosched_qd_caniop, 180 .l_iop = cam_iosched_qd_iop, 181 .l_iodone= cam_iosched_qd_iodone, 182 }, 183 { /* iops */ 184 .l_init = cam_iosched_iops_init, 185 .l_tick = cam_iosched_iops_tick, 186 .l_caniop = cam_iosched_iops_caniop, 187 .l_iop = cam_iosched_iops_iop, 188 .l_iodone= NULL, 189 }, 190 { /* bandwidth */ 191 .l_init = cam_iosched_bw_init, 192 .l_tick = cam_iosched_bw_tick, 193 .l_caniop = cam_iosched_bw_caniop, 194 .l_iop = cam_iosched_bw_iop, 195 .l_iodone= NULL, 196 }, 197}; 198 199struct iop_stats { 200 /* 201 * sysctl state for this subnode. 202 */ 203 struct sysctl_ctx_list sysctl_ctx; 204 struct sysctl_oid *sysctl_tree; 205 206 /* 207 * Information about the current rate limiters, if any 208 */ 209 io_limiter limiter; /* How are I/Os being limited */ 210 int min; /* Low range of limit */ 211 int max; /* High range of limit */ 212 int current; /* Current rate limiter */ 213 int l_value1; /* per-limiter scratch value 1. */ 214 int l_value2; /* per-limiter scratch value 2. */ 215 216 /* 217 * Debug information about counts of I/Os that have gone through the 218 * scheduler. 219 */ 220 int pending; /* I/Os pending in the hardware */ 221 int queued; /* number currently in the queue */ 222 int total; /* Total for all time -- wraps */ 223 int in; /* number queued all time -- wraps */ 224 int out; /* number completed all time -- wraps */ 225 int errs; /* Number of I/Os completed with error -- wraps */ 226 227 /* 228 * Statistics on different bits of the process. 229 */ 230 /* Exp Moving Average, see alpha_bits for more details */ 231 sbintime_t ema; 232 sbintime_t emvar; 233 sbintime_t sd; /* Last computed sd */ 234 235 uint32_t state_flags; 236#define IOP_RATE_LIMITED 1u 237 238#define LAT_BUCKETS 15 /* < 1ms < 2ms ... < 2^(n-1)ms >= 2^(n-1)ms*/ 239 uint64_t latencies[LAT_BUCKETS]; 240 241 struct cam_iosched_softc *softc; 242}; 243 244typedef enum { 245 set_max = 0, /* current = max */ 246 read_latency, /* Steer read latency by throttling writes */ 247 cl_max /* Keep last */ 248} control_type; 249 250static const char *cam_iosched_control_type_names[] = 251 { "set_max", "read_latency" }; 252 253struct control_loop { 254 /* 255 * sysctl state for this subnode. 256 */ 257 struct sysctl_ctx_list sysctl_ctx; 258 struct sysctl_oid *sysctl_tree; 259 260 sbintime_t next_steer; /* Time of next steer */ 261 sbintime_t steer_interval; /* How often do we steer? */ 262 sbintime_t lolat; 263 sbintime_t hilat; 264 int alpha; 265 control_type type; /* What type of control? */ 266 int last_count; /* Last I/O count */ 267 268 struct cam_iosched_softc *softc; 269}; 270 271#endif 272 273struct cam_iosched_softc { 274 struct bio_queue_head bio_queue; 275 struct bio_queue_head trim_queue; 276 /* scheduler flags < 16, user flags >= 16 */ 277 uint32_t flags; 278 int sort_io_queue; 279 int trim_goal; /* # of trims to queue before sending */ 280 int trim_ticks; /* Max ticks to hold trims */ 281 int last_trim_tick; /* Last 'tick' time ld a trim */ 282 int queued_trims; /* Number of trims in the queue */ 283#ifdef CAM_IOSCHED_DYNAMIC 284 int read_bias; /* Read bias setting */ 285 int current_read_bias; /* Current read bias state */ 286 int total_ticks; 287 int load; /* EMA of 'load average' of disk / 2^16 */ 288 289 struct bio_queue_head write_queue; 290 struct iop_stats read_stats, write_stats, trim_stats; 291 struct sysctl_ctx_list sysctl_ctx; 292 struct sysctl_oid *sysctl_tree; 293 294 int quanta; /* Number of quanta per second */ 295 struct callout ticker; /* Callout for our quota system */ 296 struct cam_periph *periph; /* cam periph associated with this device */ 297 uint32_t this_frac; /* Fraction of a second (1024ths) for this tick */ 298 sbintime_t last_time; /* Last time we ticked */ 299 struct control_loop cl; 300 sbintime_t max_lat; /* when != 0, if iop latency > max_lat, call max_lat_fcn */ 301 cam_iosched_latfcn_t latfcn; 302 void *latarg; 303#endif 304}; 305 306#ifdef CAM_IOSCHED_DYNAMIC 307/* 308 * helper functions to call the limsw functions. 309 */ 310static int 311cam_iosched_limiter_init(struct iop_stats *ios) 312{ 313 int lim = ios->limiter; 314 315 /* maybe this should be a kassert */ 316 if (lim < none || lim >= limiter_max) 317 return EINVAL; 318 319 if (limsw[lim].l_init) 320 return limsw[lim].l_init(ios); 321 322 return 0; 323} 324 325static int 326cam_iosched_limiter_tick(struct iop_stats *ios) 327{ 328 int lim = ios->limiter; 329 330 /* maybe this should be a kassert */ 331 if (lim < none || lim >= limiter_max) 332 return EINVAL; 333 334 if (limsw[lim].l_tick) 335 return limsw[lim].l_tick(ios); 336 337 return 0; 338} 339 340static int 341cam_iosched_limiter_iop(struct iop_stats *ios, struct bio *bp) 342{ 343 int lim = ios->limiter; 344 345 /* maybe this should be a kassert */ 346 if (lim < none || lim >= limiter_max) 347 return EINVAL; 348 349 if (limsw[lim].l_iop) 350 return limsw[lim].l_iop(ios, bp); 351 352 return 0; 353} 354 355static int 356cam_iosched_limiter_caniop(struct iop_stats *ios, struct bio *bp) 357{ 358 int lim = ios->limiter; 359 360 /* maybe this should be a kassert */ 361 if (lim < none || lim >= limiter_max) 362 return EINVAL; 363 364 if (limsw[lim].l_caniop) 365 return limsw[lim].l_caniop(ios, bp); 366 367 return 0; 368} 369 370static int 371cam_iosched_limiter_iodone(struct iop_stats *ios, struct bio *bp) 372{ 373 int lim = ios->limiter; 374 375 /* maybe this should be a kassert */ 376 if (lim < none || lim >= limiter_max) 377 return 0; 378 379 if (limsw[lim].l_iodone) 380 return limsw[lim].l_iodone(ios, bp); 381 382 return 0; 383} 384 385/* 386 * Functions to implement the different kinds of limiters 387 */ 388 389static int 390cam_iosched_qd_iop(struct iop_stats *ios, struct bio *bp) 391{ 392 393 if (ios->current <= 0 || ios->pending < ios->current) 394 return 0; 395 396 return EAGAIN; 397} 398 399static int 400cam_iosched_qd_caniop(struct iop_stats *ios, struct bio *bp) 401{ 402 403 if (ios->current <= 0 || ios->pending < ios->current) 404 return 0; 405 406 return EAGAIN; 407} 408 409static int 410cam_iosched_qd_iodone(struct iop_stats *ios, struct bio *bp) 411{ 412 413 if (ios->current <= 0 || ios->pending != ios->current) 414 return 0; 415 416 return 1; 417} 418 419static int 420cam_iosched_iops_init(struct iop_stats *ios) 421{ 422 423 ios->l_value1 = ios->current / ios->softc->quanta; 424 if (ios->l_value1 <= 0) 425 ios->l_value1 = 1; 426 ios->l_value2 = 0; 427 428 return 0; 429} 430 431static int 432cam_iosched_iops_tick(struct iop_stats *ios) 433{ 434 int new_ios; 435 436 /* 437 * Allow at least one IO per tick until all 438 * the IOs for this interval have been spent. 439 */ 440 new_ios = (int)((ios->current * (uint64_t)ios->softc->this_frac) >> 16); 441 if (new_ios < 1 && ios->l_value2 < ios->current) { 442 new_ios = 1; 443 ios->l_value2++; 444 } 445 446 /* 447 * If this a new accounting interval, discard any "unspent" ios 448 * granted in the previous interval. Otherwise add the new ios to 449 * the previously granted ones that haven't been spent yet. 450 */ 451 if ((ios->softc->total_ticks % ios->softc->quanta) == 0) { 452 ios->l_value1 = new_ios; 453 ios->l_value2 = 1; 454 } else { 455 ios->l_value1 += new_ios; 456 } 457 458 return 0; 459} 460 461static int 462cam_iosched_iops_caniop(struct iop_stats *ios, struct bio *bp) 463{ 464 465 /* 466 * So if we have any more IOPs left, allow it, 467 * otherwise wait. If current iops is 0, treat that 468 * as unlimited as a failsafe. 469 */ 470 if (ios->current > 0 && ios->l_value1 <= 0) 471 return EAGAIN; 472 return 0; 473} 474 475static int 476cam_iosched_iops_iop(struct iop_stats *ios, struct bio *bp) 477{ 478 int rv; 479 480 rv = cam_iosched_limiter_caniop(ios, bp); 481 if (rv == 0) 482 ios->l_value1--; 483 484 return rv; 485} 486 487static int 488cam_iosched_bw_init(struct iop_stats *ios) 489{ 490 491 /* ios->current is in kB/s, so scale to bytes */ 492 ios->l_value1 = ios->current * 1000 / ios->softc->quanta; 493 494 return 0; 495} 496 497static int 498cam_iosched_bw_tick(struct iop_stats *ios) 499{ 500 int bw; 501 502 /* 503 * If we're in the hole for available quota from 504 * the last time, then add the quantum for this. 505 * If we have any left over from last quantum, 506 * then too bad, that's lost. Also, ios->current 507 * is in kB/s, so scale. 508 * 509 * We also allow up to 4 quanta of credits to 510 * accumulate to deal with burstiness. 4 is extremely 511 * arbitrary. 512 */ 513 bw = (int)((ios->current * 1000ull * (uint64_t)ios->softc->this_frac) >> 16); 514 if (ios->l_value1 < bw * 4) 515 ios->l_value1 += bw; 516 517 return 0; 518} 519 520static int 521cam_iosched_bw_caniop(struct iop_stats *ios, struct bio *bp) 522{ 523 /* 524 * So if we have any more bw quota left, allow it, 525 * otherwise wait. Note, we'll go negative and that's 526 * OK. We'll just get a little less next quota. 527 * 528 * Note on going negative: that allows us to process 529 * requests in order better, since we won't allow 530 * shorter reads to get around the long one that we 531 * don't have the quota to do just yet. It also prevents 532 * starvation by being a little more permissive about 533 * what we let through this quantum (to prevent the 534 * starvation), at the cost of getting a little less 535 * next quantum. 536 * 537 * Also note that if the current limit is <= 0, 538 * we treat it as unlimited as a failsafe. 539 */ 540 if (ios->current > 0 && ios->l_value1 <= 0) 541 return EAGAIN; 542 543 return 0; 544} 545 546static int 547cam_iosched_bw_iop(struct iop_stats *ios, struct bio *bp) 548{ 549 int rv; 550 551 rv = cam_iosched_limiter_caniop(ios, bp); 552 if (rv == 0) 553 ios->l_value1 -= bp->bio_length; 554 555 return rv; 556} 557 558static void cam_iosched_cl_maybe_steer(struct control_loop *clp); 559 560static void 561cam_iosched_ticker(void *arg) 562{ 563 struct cam_iosched_softc *isc = arg; 564 sbintime_t now, delta; 565 int pending; 566 567 callout_reset(&isc->ticker, hz / isc->quanta, cam_iosched_ticker, isc); 568 569 now = sbinuptime(); 570 delta = now - isc->last_time; 571 isc->this_frac = (uint32_t)delta >> 16; /* Note: discards seconds -- should be 0 harmless if not */ 572 isc->last_time = now; 573 574 cam_iosched_cl_maybe_steer(&isc->cl); 575 576 cam_iosched_limiter_tick(&isc->read_stats); 577 cam_iosched_limiter_tick(&isc->write_stats); 578 cam_iosched_limiter_tick(&isc->trim_stats); 579 580 cam_iosched_schedule(isc, isc->periph); 581 582 /* 583 * isc->load is an EMA of the pending I/Os at each tick. The number of 584 * pending I/Os is the sum of the I/Os queued to the hardware, and those 585 * in the software queue that could be queued to the hardware if there 586 * were slots. 587 * 588 * ios_stats.pending is a count of requests in the SIM right now for 589 * each of these types of I/O. So the total pending count is the sum of 590 * these I/Os and the sum of the queued I/Os still in the software queue 591 * for those operations that aren't being rate limited at the moment. 592 * 593 * The reason for the rate limiting bit is because those I/Os 594 * aren't part of the software queued load (since we could 595 * give them to hardware, but choose not to). 596 * 597 * Note: due to a bug in counting pending TRIM in the device, we 598 * don't include them in this count. We count each BIO_DELETE in 599 * the pending count, but the periph drivers collapse them down 600 * into one TRIM command. That one trim command gets the completion 601 * so the counts get off. 602 */ 603 pending = isc->read_stats.pending + isc->write_stats.pending /* + isc->trim_stats.pending */; 604 pending += !!(isc->read_stats.state_flags & IOP_RATE_LIMITED) * isc->read_stats.queued + 605 !!(isc->write_stats.state_flags & IOP_RATE_LIMITED) * isc->write_stats.queued /* + 606 !!(isc->trim_stats.state_flags & IOP_RATE_LIMITED) * isc->trim_stats.queued */ ; 607 pending <<= 16; 608 pending /= isc->periph->path->device->ccbq.total_openings; 609 610 isc->load = (pending + (isc->load << 13) - isc->load) >> 13; /* see above: 13 -> 16139 / 200/s = ~81s ~1 minute */ 611 612 isc->total_ticks++; 613} 614 615static void 616cam_iosched_cl_init(struct control_loop *clp, struct cam_iosched_softc *isc) 617{ 618 619 clp->next_steer = sbinuptime(); 620 clp->softc = isc; 621 clp->steer_interval = SBT_1S * 5; /* Let's start out steering every 5s */ 622 clp->lolat = 5 * SBT_1MS; 623 clp->hilat = 15 * SBT_1MS; 624 clp->alpha = 20; /* Alpha == gain. 20 = .2 */ 625 clp->type = set_max; 626} 627 628static void 629cam_iosched_cl_maybe_steer(struct control_loop *clp) 630{ 631 struct cam_iosched_softc *isc; 632 sbintime_t now, lat; 633 int old; 634 635 isc = clp->softc; 636 now = isc->last_time; 637 if (now < clp->next_steer) 638 return; 639 640 clp->next_steer = now + clp->steer_interval; 641 switch (clp->type) { 642 case set_max: 643 if (isc->write_stats.current != isc->write_stats.max) 644 printf("Steering write from %d kBps to %d kBps\n", 645 isc->write_stats.current, isc->write_stats.max); 646 isc->read_stats.current = isc->read_stats.max; 647 isc->write_stats.current = isc->write_stats.max; 648 isc->trim_stats.current = isc->trim_stats.max; 649 break; 650 case read_latency: 651 old = isc->write_stats.current; 652 lat = isc->read_stats.ema; 653 /* 654 * Simple PLL-like engine. Since we're steering to a range for 655 * the SP (set point) that makes things a little more 656 * complicated. In addition, we're not directly controlling our 657 * PV (process variable), the read latency, but instead are 658 * manipulating the write bandwidth limit for our MV 659 * (manipulation variable), analysis of this code gets a bit 660 * messy. Also, the MV is a very noisy control surface for read 661 * latency since it is affected by many hidden processes inside 662 * the device which change how responsive read latency will be 663 * in reaction to changes in write bandwidth. Unlike the classic 664 * boiler control PLL. this may result in over-steering while 665 * the SSD takes its time to react to the new, lower load. This 666 * is why we use a relatively low alpha of between .1 and .25 to 667 * compensate for this effect. At .1, it takes ~22 steering 668 * intervals to back off by a factor of 10. At .2 it only takes 669 * ~10. At .25 it only takes ~8. However some preliminary data 670 * from the SSD drives suggests a reasponse time in 10's of 671 * seconds before latency drops regardless of the new write 672 * rate. Careful observation will be required to tune this 673 * effectively. 674 * 675 * Also, when there's no read traffic, we jack up the write 676 * limit too regardless of the last read latency. 10 is 677 * somewhat arbitrary. 678 */ 679 if (lat < clp->lolat || isc->read_stats.total - clp->last_count < 10) 680 isc->write_stats.current = isc->write_stats.current * 681 (100 + clp->alpha) / 100; /* Scale up */ 682 else if (lat > clp->hilat) 683 isc->write_stats.current = isc->write_stats.current * 684 (100 - clp->alpha) / 100; /* Scale down */ 685 clp->last_count = isc->read_stats.total; 686 687 /* 688 * Even if we don't steer, per se, enforce the min/max limits as 689 * those may have changed. 690 */ 691 if (isc->write_stats.current < isc->write_stats.min) 692 isc->write_stats.current = isc->write_stats.min; 693 if (isc->write_stats.current > isc->write_stats.max) 694 isc->write_stats.current = isc->write_stats.max; 695 if (old != isc->write_stats.current && iosched_debug) 696 printf("Steering write from %d kBps to %d kBps due to latency of %jdus\n", 697 old, isc->write_stats.current, 698 (uintmax_t)((uint64_t)1000000 * (uint32_t)lat) >> 32); 699 break; 700 case cl_max: 701 break; 702 } 703} 704#endif 705 706/* 707 * Trim or similar currently pending completion. Should only be set for 708 * those drivers wishing only one Trim active at a time. 709 */ 710#define CAM_IOSCHED_FLAG_TRIM_ACTIVE (1ul << 0) 711 /* Callout active, and needs to be torn down */ 712#define CAM_IOSCHED_FLAG_CALLOUT_ACTIVE (1ul << 1) 713 714 /* Periph drivers set these flags to indicate work */ 715#define CAM_IOSCHED_FLAG_WORK_FLAGS ((0xffffu) << 16) 716 717#ifdef CAM_IOSCHED_DYNAMIC 718static void 719cam_iosched_io_metric_update(struct cam_iosched_softc *isc, 720 sbintime_t sim_latency, int cmd, size_t size); 721#endif 722 723static inline bool 724cam_iosched_has_flagged_work(struct cam_iosched_softc *isc) 725{ 726 return !!(isc->flags & CAM_IOSCHED_FLAG_WORK_FLAGS); 727} 728 729static inline bool 730cam_iosched_has_io(struct cam_iosched_softc *isc) 731{ 732#ifdef CAM_IOSCHED_DYNAMIC 733 if (do_dynamic_iosched) { 734 struct bio *rbp = bioq_first(&isc->bio_queue); 735 struct bio *wbp = bioq_first(&isc->write_queue); 736 bool can_write = wbp != NULL && 737 cam_iosched_limiter_caniop(&isc->write_stats, wbp) == 0; 738 bool can_read = rbp != NULL && 739 cam_iosched_limiter_caniop(&isc->read_stats, rbp) == 0; 740 if (iosched_debug > 2) { 741 printf("can write %d: pending_writes %d max_writes %d\n", can_write, isc->write_stats.pending, isc->write_stats.max); 742 printf("can read %d: read_stats.pending %d max_reads %d\n", can_read, isc->read_stats.pending, isc->read_stats.max); 743 printf("Queued reads %d writes %d\n", isc->read_stats.queued, isc->write_stats.queued); 744 } 745 return can_read || can_write; 746 } 747#endif 748 return bioq_first(&isc->bio_queue) != NULL; 749} 750 751static inline bool 752cam_iosched_has_more_trim(struct cam_iosched_softc *isc) 753{ 754 struct bio *bp; 755 756 bp = bioq_first(&isc->trim_queue); 757#ifdef CAM_IOSCHED_DYNAMIC 758 if (do_dynamic_iosched) { 759 /* 760 * If we're limiting trims, then defer action on trims 761 * for a bit. 762 */ 763 if (bp == NULL || cam_iosched_limiter_caniop(&isc->trim_stats, bp) != 0) 764 return false; 765 } 766#endif 767 768 /* 769 * If we've set a trim_goal, then if we exceed that allow trims 770 * to be passed back to the driver. If we've also set a tick timeout 771 * allow trims back to the driver. Otherwise, don't allow trims yet. 772 */ 773 if (isc->trim_goal > 0) { 774 if (isc->queued_trims >= isc->trim_goal) 775 return true; 776 if (isc->queued_trims > 0 && 777 isc->trim_ticks > 0 && 778 ticks - isc->last_trim_tick > isc->trim_ticks) 779 return true; 780 return false; 781 } 782 783 /* NB: Should perhaps have a max trim active independent of I/O limiters */ 784 return !(isc->flags & CAM_IOSCHED_FLAG_TRIM_ACTIVE) && bp != NULL; 785} 786 787#define cam_iosched_sort_queue(isc) ((isc)->sort_io_queue >= 0 ? \ 788 (isc)->sort_io_queue : cam_sort_io_queues) 789 790static inline bool 791cam_iosched_has_work(struct cam_iosched_softc *isc) 792{ 793#ifdef CAM_IOSCHED_DYNAMIC 794 if (iosched_debug > 2) 795 printf("has work: %d %d %d\n", cam_iosched_has_io(isc), 796 cam_iosched_has_more_trim(isc), 797 cam_iosched_has_flagged_work(isc)); 798#endif 799 800 return cam_iosched_has_io(isc) || 801 cam_iosched_has_more_trim(isc) || 802 cam_iosched_has_flagged_work(isc); 803} 804 805#ifdef CAM_IOSCHED_DYNAMIC 806static void 807cam_iosched_iop_stats_init(struct cam_iosched_softc *isc, struct iop_stats *ios) 808{ 809 810 ios->limiter = none; 811 ios->in = 0; 812 ios->max = ios->current = 300000; 813 ios->min = 1; 814 ios->out = 0; 815 ios->errs = 0; 816 ios->pending = 0; 817 ios->queued = 0; 818 ios->total = 0; 819 ios->ema = 0; 820 ios->emvar = 0; 821 ios->softc = isc; 822 cam_iosched_limiter_init(ios); 823} 824 825static int 826cam_iosched_limiter_sysctl(SYSCTL_HANDLER_ARGS) 827{ 828 char buf[16]; 829 struct iop_stats *ios; 830 struct cam_iosched_softc *isc; 831 int value, i, error; 832 const char *p; 833 834 ios = arg1; 835 isc = ios->softc; 836 value = ios->limiter; 837 if (value < none || value >= limiter_max) 838 p = "UNKNOWN"; 839 else 840 p = cam_iosched_limiter_names[value]; 841 842 strlcpy(buf, p, sizeof(buf)); 843 error = sysctl_handle_string(oidp, buf, sizeof(buf), req); 844 if (error != 0 || req->newptr == NULL) 845 return error; 846 847 cam_periph_lock(isc->periph); 848 849 for (i = none; i < limiter_max; i++) { 850 if (strcmp(buf, cam_iosched_limiter_names[i]) != 0) 851 continue; 852 ios->limiter = i; 853 error = cam_iosched_limiter_init(ios); 854 if (error != 0) { 855 ios->limiter = value; 856 cam_periph_unlock(isc->periph); 857 return error; 858 } 859 /* Note: disk load averate requires ticker to be always running */ 860 callout_reset(&isc->ticker, hz / isc->quanta, cam_iosched_ticker, isc); 861 isc->flags |= CAM_IOSCHED_FLAG_CALLOUT_ACTIVE; 862 863 cam_periph_unlock(isc->periph); 864 return 0; 865 } 866 867 cam_periph_unlock(isc->periph); 868 return EINVAL; 869} 870 871static int 872cam_iosched_control_type_sysctl(SYSCTL_HANDLER_ARGS) 873{ 874 char buf[16]; 875 struct control_loop *clp; 876 struct cam_iosched_softc *isc; 877 int value, i, error; 878 const char *p; 879 880 clp = arg1; 881 isc = clp->softc; 882 value = clp->type; 883 if (value < none || value >= cl_max) 884 p = "UNKNOWN"; 885 else 886 p = cam_iosched_control_type_names[value]; 887 888 strlcpy(buf, p, sizeof(buf)); 889 error = sysctl_handle_string(oidp, buf, sizeof(buf), req); 890 if (error != 0 || req->newptr == NULL) 891 return error; 892 893 for (i = set_max; i < cl_max; i++) { 894 if (strcmp(buf, cam_iosched_control_type_names[i]) != 0) 895 continue; 896 cam_periph_lock(isc->periph); 897 clp->type = i; 898 cam_periph_unlock(isc->periph); 899 return 0; 900 } 901 902 return EINVAL; 903} 904 905static int 906cam_iosched_sbintime_sysctl(SYSCTL_HANDLER_ARGS) 907{ 908 char buf[16]; 909 sbintime_t value; 910 int error; 911 uint64_t us; 912 913 value = *(sbintime_t *)arg1; 914 us = (uint64_t)value / SBT_1US; 915 snprintf(buf, sizeof(buf), "%ju", (intmax_t)us); 916 error = sysctl_handle_string(oidp, buf, sizeof(buf), req); 917 if (error != 0 || req->newptr == NULL) 918 return error; 919 us = strtoul(buf, NULL, 10); 920 if (us == 0) 921 return EINVAL; 922 *(sbintime_t *)arg1 = us * SBT_1US; 923 return 0; 924} 925 926static int 927cam_iosched_sysctl_latencies(SYSCTL_HANDLER_ARGS) 928{ 929 int i, error; 930 struct sbuf sb; 931 uint64_t *latencies; 932 933 latencies = arg1; 934 sbuf_new_for_sysctl(&sb, NULL, LAT_BUCKETS * 16, req); 935 936 for (i = 0; i < LAT_BUCKETS - 1; i++) 937 sbuf_printf(&sb, "%jd,", (intmax_t)latencies[i]); 938 sbuf_printf(&sb, "%jd", (intmax_t)latencies[LAT_BUCKETS - 1]); 939 error = sbuf_finish(&sb); 940 sbuf_delete(&sb); 941 942 return (error); 943} 944 945static int 946cam_iosched_quanta_sysctl(SYSCTL_HANDLER_ARGS) 947{ 948 int *quanta; 949 int error, value; 950 951 quanta = (unsigned *)arg1; 952 value = *quanta; 953 954 error = sysctl_handle_int(oidp, (int *)&value, 0, req); 955 if ((error != 0) || (req->newptr == NULL)) 956 return (error); 957 958 if (value < 1 || value > hz) 959 return (EINVAL); 960 961 *quanta = value; 962 963 return (0); 964} 965 966static void 967cam_iosched_iop_stats_sysctl_init(struct cam_iosched_softc *isc, struct iop_stats *ios, char *name) 968{ 969 struct sysctl_oid_list *n; 970 struct sysctl_ctx_list *ctx; 971 972 ios->sysctl_tree = SYSCTL_ADD_NODE(&isc->sysctl_ctx, 973 SYSCTL_CHILDREN(isc->sysctl_tree), OID_AUTO, name, 974 CTLFLAG_RD | CTLFLAG_MPSAFE, 0, name); 975 n = SYSCTL_CHILDREN(ios->sysctl_tree); 976 ctx = &ios->sysctl_ctx; 977 978 SYSCTL_ADD_UQUAD(ctx, n, 979 OID_AUTO, "ema", CTLFLAG_RD, 980 &ios->ema, 981 "Fast Exponentially Weighted Moving Average"); 982 SYSCTL_ADD_UQUAD(ctx, n, 983 OID_AUTO, "emvar", CTLFLAG_RD, 984 &ios->emvar, 985 "Fast Exponentially Weighted Moving Variance"); 986 987 SYSCTL_ADD_INT(ctx, n, 988 OID_AUTO, "pending", CTLFLAG_RD, 989 &ios->pending, 0, 990 "Instantaneous # of pending transactions"); 991 SYSCTL_ADD_INT(ctx, n, 992 OID_AUTO, "count", CTLFLAG_RD, 993 &ios->total, 0, 994 "# of transactions submitted to hardware"); 995 SYSCTL_ADD_INT(ctx, n, 996 OID_AUTO, "queued", CTLFLAG_RD, 997 &ios->queued, 0, 998 "# of transactions in the queue"); 999 SYSCTL_ADD_INT(ctx, n, 1000 OID_AUTO, "in", CTLFLAG_RD, 1001 &ios->in, 0, 1002 "# of transactions queued to driver"); 1003 SYSCTL_ADD_INT(ctx, n, 1004 OID_AUTO, "out", CTLFLAG_RD, 1005 &ios->out, 0, 1006 "# of transactions completed (including with error)"); 1007 SYSCTL_ADD_INT(ctx, n, 1008 OID_AUTO, "errs", CTLFLAG_RD, 1009 &ios->errs, 0, 1010 "# of transactions completed with an error"); 1011 1012 SYSCTL_ADD_PROC(ctx, n, 1013 OID_AUTO, "limiter", 1014 CTLTYPE_STRING | CTLFLAG_RW | CTLFLAG_NEEDGIANT, 1015 ios, 0, cam_iosched_limiter_sysctl, "A", 1016 "Current limiting type."); 1017 SYSCTL_ADD_INT(ctx, n, 1018 OID_AUTO, "min", CTLFLAG_RW, 1019 &ios->min, 0, 1020 "min resource"); 1021 SYSCTL_ADD_INT(ctx, n, 1022 OID_AUTO, "max", CTLFLAG_RW, 1023 &ios->max, 0, 1024 "max resource"); 1025 SYSCTL_ADD_INT(ctx, n, 1026 OID_AUTO, "current", CTLFLAG_RW, 1027 &ios->current, 0, 1028 "current resource"); 1029 1030 SYSCTL_ADD_PROC(ctx, n, 1031 OID_AUTO, "latencies", 1032 CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_NEEDGIANT, 1033 &ios->latencies, 0, 1034 cam_iosched_sysctl_latencies, "A", 1035 "Array of power of 2 latency from 1ms to 1.024s"); 1036} 1037 1038static void 1039cam_iosched_iop_stats_fini(struct iop_stats *ios) 1040{ 1041 if (ios->sysctl_tree) 1042 if (sysctl_ctx_free(&ios->sysctl_ctx) != 0) 1043 printf("can't remove iosched sysctl stats context\n"); 1044} 1045 1046static void 1047cam_iosched_cl_sysctl_init(struct cam_iosched_softc *isc) 1048{ 1049 struct sysctl_oid_list *n; 1050 struct sysctl_ctx_list *ctx; 1051 struct control_loop *clp; 1052 1053 clp = &isc->cl; 1054 clp->sysctl_tree = SYSCTL_ADD_NODE(&isc->sysctl_ctx, 1055 SYSCTL_CHILDREN(isc->sysctl_tree), OID_AUTO, "control", 1056 CTLFLAG_RD | CTLFLAG_MPSAFE, 0, "Control loop info"); 1057 n = SYSCTL_CHILDREN(clp->sysctl_tree); 1058 ctx = &clp->sysctl_ctx; 1059 1060 SYSCTL_ADD_PROC(ctx, n, 1061 OID_AUTO, "type", 1062 CTLTYPE_STRING | CTLFLAG_RW | CTLFLAG_NEEDGIANT, 1063 clp, 0, cam_iosched_control_type_sysctl, "A", 1064 "Control loop algorithm"); 1065 SYSCTL_ADD_PROC(ctx, n, 1066 OID_AUTO, "steer_interval", 1067 CTLTYPE_STRING | CTLFLAG_RW | CTLFLAG_NEEDGIANT, 1068 &clp->steer_interval, 0, cam_iosched_sbintime_sysctl, "A", 1069 "How often to steer (in us)"); 1070 SYSCTL_ADD_PROC(ctx, n, 1071 OID_AUTO, "lolat", 1072 CTLTYPE_STRING | CTLFLAG_RW | CTLFLAG_NEEDGIANT, 1073 &clp->lolat, 0, cam_iosched_sbintime_sysctl, "A", 1074 "Low water mark for Latency (in us)"); 1075 SYSCTL_ADD_PROC(ctx, n, 1076 OID_AUTO, "hilat", 1077 CTLTYPE_STRING | CTLFLAG_RW | CTLFLAG_NEEDGIANT, 1078 &clp->hilat, 0, cam_iosched_sbintime_sysctl, "A", 1079 "Hi water mark for Latency (in us)"); 1080 SYSCTL_ADD_INT(ctx, n, 1081 OID_AUTO, "alpha", CTLFLAG_RW, 1082 &clp->alpha, 0, 1083 "Alpha for PLL (x100) aka gain"); 1084} 1085 1086static void 1087cam_iosched_cl_sysctl_fini(struct control_loop *clp) 1088{ 1089 if (clp->sysctl_tree) 1090 if (sysctl_ctx_free(&clp->sysctl_ctx) != 0) 1091 printf("can't remove iosched sysctl control loop context\n"); 1092} 1093#endif 1094 1095/* 1096 * Allocate the iosched structure. This also insulates callers from knowing 1097 * sizeof struct cam_iosched_softc. 1098 */ 1099int 1100cam_iosched_init(struct cam_iosched_softc **iscp, struct cam_periph *periph) 1101{ 1102 1103 *iscp = malloc(sizeof(**iscp), M_CAMSCHED, M_NOWAIT | M_ZERO); 1104 if (*iscp == NULL) 1105 return ENOMEM; 1106#ifdef CAM_IOSCHED_DYNAMIC 1107 if (iosched_debug) 1108 printf("CAM IOSCHEDULER Allocating entry at %p\n", *iscp); 1109#endif 1110 (*iscp)->sort_io_queue = -1; 1111 bioq_init(&(*iscp)->bio_queue); 1112 bioq_init(&(*iscp)->trim_queue); 1113#ifdef CAM_IOSCHED_DYNAMIC 1114 if (do_dynamic_iosched) { 1115 bioq_init(&(*iscp)->write_queue); 1116 (*iscp)->read_bias = 100; 1117 (*iscp)->current_read_bias = 100; 1118 (*iscp)->quanta = min(hz, 200); 1119 cam_iosched_iop_stats_init(*iscp, &(*iscp)->read_stats); 1120 cam_iosched_iop_stats_init(*iscp, &(*iscp)->write_stats); 1121 cam_iosched_iop_stats_init(*iscp, &(*iscp)->trim_stats); 1122 (*iscp)->trim_stats.max = 1; /* Trims are special: one at a time for now */ 1123 (*iscp)->last_time = sbinuptime(); 1124 callout_init_mtx(&(*iscp)->ticker, cam_periph_mtx(periph), 0); 1125 (*iscp)->periph = periph; 1126 cam_iosched_cl_init(&(*iscp)->cl, *iscp); 1127 callout_reset(&(*iscp)->ticker, hz / (*iscp)->quanta, cam_iosched_ticker, *iscp); 1128 (*iscp)->flags |= CAM_IOSCHED_FLAG_CALLOUT_ACTIVE; 1129 } 1130#endif 1131 1132 return 0; 1133} 1134 1135/* 1136 * Reclaim all used resources. This assumes that other folks have 1137 * drained the requests in the hardware. Maybe an unwise assumption. 1138 */ 1139void 1140cam_iosched_fini(struct cam_iosched_softc *isc) 1141{ 1142 if (isc) { 1143 cam_iosched_flush(isc, NULL, ENXIO); 1144#ifdef CAM_IOSCHED_DYNAMIC 1145 cam_iosched_iop_stats_fini(&isc->read_stats); 1146 cam_iosched_iop_stats_fini(&isc->write_stats); 1147 cam_iosched_iop_stats_fini(&isc->trim_stats); 1148 cam_iosched_cl_sysctl_fini(&isc->cl); 1149 if (isc->sysctl_tree) 1150 if (sysctl_ctx_free(&isc->sysctl_ctx) != 0) 1151 printf("can't remove iosched sysctl stats context\n"); 1152 if (isc->flags & CAM_IOSCHED_FLAG_CALLOUT_ACTIVE) { 1153 callout_drain(&isc->ticker); 1154 isc->flags &= ~ CAM_IOSCHED_FLAG_CALLOUT_ACTIVE; 1155 } 1156#endif 1157 free(isc, M_CAMSCHED); 1158 } 1159} 1160 1161/* 1162 * After we're sure we're attaching a device, go ahead and add 1163 * hooks for any sysctl we may wish to honor. 1164 */ 1165void cam_iosched_sysctl_init(struct cam_iosched_softc *isc, 1166 struct sysctl_ctx_list *ctx, struct sysctl_oid *node) 1167{ 1168 struct sysctl_oid_list *n; 1169 1170 n = SYSCTL_CHILDREN(node); 1171 SYSCTL_ADD_INT(ctx, n, 1172 OID_AUTO, "sort_io_queue", CTLFLAG_RW | CTLFLAG_MPSAFE, 1173 &isc->sort_io_queue, 0, 1174 "Sort IO queue to try and optimise disk access patterns"); 1175 SYSCTL_ADD_INT(ctx, n, 1176 OID_AUTO, "trim_goal", CTLFLAG_RW, 1177 &isc->trim_goal, 0, 1178 "Number of trims to try to accumulate before sending to hardware"); 1179 SYSCTL_ADD_INT(ctx, n, 1180 OID_AUTO, "trim_ticks", CTLFLAG_RW, 1181 &isc->trim_goal, 0, 1182 "IO Schedul qaunta to hold back trims for when accumulating"); 1183 1184#ifdef CAM_IOSCHED_DYNAMIC 1185 if (!do_dynamic_iosched) 1186 return; 1187 1188 isc->sysctl_tree = SYSCTL_ADD_NODE(&isc->sysctl_ctx, 1189 SYSCTL_CHILDREN(node), OID_AUTO, "iosched", 1190 CTLFLAG_RD | CTLFLAG_MPSAFE, 0, "I/O scheduler statistics"); 1191 n = SYSCTL_CHILDREN(isc->sysctl_tree); 1192 ctx = &isc->sysctl_ctx; 1193 1194 cam_iosched_iop_stats_sysctl_init(isc, &isc->read_stats, "read"); 1195 cam_iosched_iop_stats_sysctl_init(isc, &isc->write_stats, "write"); 1196 cam_iosched_iop_stats_sysctl_init(isc, &isc->trim_stats, "trim"); 1197 cam_iosched_cl_sysctl_init(isc); 1198 1199 SYSCTL_ADD_INT(ctx, n, 1200 OID_AUTO, "read_bias", CTLFLAG_RW, 1201 &isc->read_bias, 100, 1202 "How biased towards read should we be independent of limits"); 1203 1204 SYSCTL_ADD_PROC(ctx, n, 1205 OID_AUTO, "quanta", CTLTYPE_UINT | CTLFLAG_RW | CTLFLAG_NEEDGIANT, 1206 &isc->quanta, 0, cam_iosched_quanta_sysctl, "I", 1207 "How many quanta per second do we slice the I/O up into"); 1208 1209 SYSCTL_ADD_INT(ctx, n, 1210 OID_AUTO, "total_ticks", CTLFLAG_RD, 1211 &isc->total_ticks, 0, 1212 "Total number of ticks we've done"); 1213 1214 SYSCTL_ADD_INT(ctx, n, 1215 OID_AUTO, "load", CTLFLAG_RD, 1216 &isc->load, 0, 1217 "scaled load average / 100"); 1218 1219 SYSCTL_ADD_U64(ctx, n, 1220 OID_AUTO, "latency_trigger", CTLFLAG_RW, 1221 &isc->max_lat, 0, 1222 "Latency treshold to trigger callbacks"); 1223#endif 1224} 1225 1226void 1227cam_iosched_set_latfcn(struct cam_iosched_softc *isc, 1228 cam_iosched_latfcn_t fnp, void *argp) 1229{ 1230#ifdef CAM_IOSCHED_DYNAMIC 1231 isc->latfcn = fnp; 1232 isc->latarg = argp; 1233#endif 1234} 1235 1236/* 1237 * Client drivers can set two parameters. "goal" is the number of BIO_DELETEs 1238 * that will be queued up before iosched will "release" the trims to the client 1239 * driver to wo with what they will (usually combine as many as possible). If we 1240 * don't get this many, after trim_ticks we'll submit the I/O anyway with 1241 * whatever we have. We do need an I/O of some kind of to clock the deferred 1242 * trims out to disk. Since we will eventually get a write for the super block 1243 * or something before we shutdown, the trims will complete. To be safe, when a 1244 * BIO_FLUSH is presented to the iosched work queue, we set the ticks time far 1245 * enough in the past so we'll present the BIO_DELETEs to the client driver. 1246 * There might be a race if no BIO_DELETESs were queued, a BIO_FLUSH comes in 1247 * and then a BIO_DELETE is sent down. No know client does this, and there's 1248 * already a race between an ordered BIO_FLUSH and any BIO_DELETEs in flight, 1249 * but no client depends on the ordering being honored. 1250 * 1251 * XXX I'm not sure what the interaction between UFS direct BIOs and the BUF 1252 * flushing on shutdown. I think there's bufs that would be dependent on the BIO 1253 * finishing to write out at least metadata, so we'll be fine. To be safe, keep 1254 * the number of ticks low (less than maybe 10s) to avoid shutdown races. 1255 */ 1256 1257void 1258cam_iosched_set_trim_goal(struct cam_iosched_softc *isc, int goal) 1259{ 1260 1261 isc->trim_goal = goal; 1262} 1263 1264void 1265cam_iosched_set_trim_ticks(struct cam_iosched_softc *isc, int trim_ticks) 1266{ 1267 1268 isc->trim_ticks = trim_ticks; 1269} 1270 1271/* 1272 * Flush outstanding I/O. Consumers of this library don't know all the 1273 * queues we may keep, so this allows all I/O to be flushed in one 1274 * convenient call. 1275 */ 1276void 1277cam_iosched_flush(struct cam_iosched_softc *isc, struct devstat *stp, int err) 1278{ 1279 bioq_flush(&isc->bio_queue, stp, err); 1280 bioq_flush(&isc->trim_queue, stp, err); 1281#ifdef CAM_IOSCHED_DYNAMIC 1282 if (do_dynamic_iosched) 1283 bioq_flush(&isc->write_queue, stp, err); 1284#endif 1285} 1286 1287#ifdef CAM_IOSCHED_DYNAMIC 1288static struct bio * 1289cam_iosched_get_write(struct cam_iosched_softc *isc) 1290{ 1291 struct bio *bp; 1292 1293 /* 1294 * We control the write rate by controlling how many requests we send 1295 * down to the drive at any one time. Fewer requests limits the 1296 * effects of both starvation when the requests take a while and write 1297 * amplification when each request is causing more than one write to 1298 * the NAND media. Limiting the queue depth like this will also limit 1299 * the write throughput and give and reads that want to compete to 1300 * compete unfairly. 1301 */ 1302 bp = bioq_first(&isc->write_queue); 1303 if (bp == NULL) { 1304 if (iosched_debug > 3) 1305 printf("No writes present in write_queue\n"); 1306 return NULL; 1307 } 1308 1309 /* 1310 * If pending read, prefer that based on current read bias 1311 * setting. 1312 */ 1313 if (bioq_first(&isc->bio_queue) && isc->current_read_bias) { 1314 if (iosched_debug) 1315 printf( 1316 "Reads present and current_read_bias is %d queued " 1317 "writes %d queued reads %d\n", 1318 isc->current_read_bias, isc->write_stats.queued, 1319 isc->read_stats.queued); 1320 isc->current_read_bias--; 1321 /* We're not limiting writes, per se, just doing reads first */ 1322 return NULL; 1323 } 1324 1325 /* 1326 * See if our current limiter allows this I/O. 1327 */ 1328 if (cam_iosched_limiter_iop(&isc->write_stats, bp) != 0) { 1329 if (iosched_debug) 1330 printf("Can't write because limiter says no.\n"); 1331 isc->write_stats.state_flags |= IOP_RATE_LIMITED; 1332 return NULL; 1333 } 1334 1335 /* 1336 * Let's do this: We've passed all the gates and we're a go 1337 * to schedule the I/O in the SIM. 1338 */ 1339 isc->current_read_bias = isc->read_bias; 1340 bioq_remove(&isc->write_queue, bp); 1341 if (bp->bio_cmd == BIO_WRITE) { 1342 isc->write_stats.queued--; 1343 isc->write_stats.total++; 1344 isc->write_stats.pending++; 1345 } 1346 if (iosched_debug > 9) 1347 printf("HWQ : %p %#x\n", bp, bp->bio_cmd); 1348 isc->write_stats.state_flags &= ~IOP_RATE_LIMITED; 1349 return bp; 1350} 1351#endif 1352 1353/* 1354 * Put back a trim that you weren't able to actually schedule this time. 1355 */ 1356void 1357cam_iosched_put_back_trim(struct cam_iosched_softc *isc, struct bio *bp) 1358{ 1359 bioq_insert_head(&isc->trim_queue, bp); 1360 if (isc->queued_trims == 0) 1361 isc->last_trim_tick = ticks; 1362 isc->queued_trims++; 1363#ifdef CAM_IOSCHED_DYNAMIC 1364 isc->trim_stats.queued++; 1365 isc->trim_stats.total--; /* since we put it back, don't double count */ 1366 isc->trim_stats.pending--; 1367#endif 1368} 1369 1370/* 1371 * gets the next trim from the trim queue. 1372 * 1373 * Assumes we're called with the periph lock held. It removes this 1374 * trim from the queue and the device must explicitly reinsert it 1375 * should the need arise. 1376 */ 1377struct bio * 1378cam_iosched_next_trim(struct cam_iosched_softc *isc) 1379{ 1380 struct bio *bp; 1381 1382 bp = bioq_first(&isc->trim_queue); 1383 if (bp == NULL) 1384 return NULL; 1385 bioq_remove(&isc->trim_queue, bp); 1386 isc->queued_trims--; 1387 isc->last_trim_tick = ticks; /* Reset the tick timer when we take trims */ 1388#ifdef CAM_IOSCHED_DYNAMIC 1389 isc->trim_stats.queued--; 1390 isc->trim_stats.total++; 1391 isc->trim_stats.pending++; 1392#endif 1393 return bp; 1394} 1395 1396/* 1397 * gets an available trim from the trim queue, if there's no trim 1398 * already pending. It removes this trim from the queue and the device 1399 * must explicitly reinsert it should the need arise. 1400 * 1401 * Assumes we're called with the periph lock held. 1402 */ 1403struct bio * 1404cam_iosched_get_trim(struct cam_iosched_softc *isc) 1405{ 1406#ifdef CAM_IOSCHED_DYNAMIC 1407 struct bio *bp; 1408#endif 1409 1410 if (!cam_iosched_has_more_trim(isc)) 1411 return NULL; 1412#ifdef CAM_IOSCHED_DYNAMIC 1413 bp = bioq_first(&isc->trim_queue); 1414 if (bp == NULL) 1415 return NULL; 1416 1417 /* 1418 * If pending read, prefer that based on current read bias setting. The 1419 * read bias is shared for both writes and TRIMs, but on TRIMs the bias 1420 * is for a combined TRIM not a single TRIM request that's come in. 1421 */ 1422 if (do_dynamic_iosched) { 1423 if (bioq_first(&isc->bio_queue) && isc->current_read_bias) { 1424 if (iosched_debug) 1425 printf("Reads present and current_read_bias is %d" 1426 " queued trims %d queued reads %d\n", 1427 isc->current_read_bias, isc->trim_stats.queued, 1428 isc->read_stats.queued); 1429 isc->current_read_bias--; 1430 /* We're not limiting TRIMS, per se, just doing reads first */ 1431 return NULL; 1432 } 1433 /* 1434 * We're going to do a trim, so reset the bias. 1435 */ 1436 isc->current_read_bias = isc->read_bias; 1437 } 1438 1439 /* 1440 * See if our current limiter allows this I/O. Because we only call this 1441 * here, and not in next_trim, the 'bandwidth' limits for trims won't 1442 * work, while the iops or max queued limits will work. It's tricky 1443 * because we want the limits to be from the perspective of the 1444 * "commands sent to the device." To make iops work, we need to check 1445 * only here (since we want all the ops we combine to count as one). To 1446 * make bw limits work, we'd need to check in next_trim, but that would 1447 * have the effect of limiting the iops as seen from the upper layers. 1448 */ 1449 if (cam_iosched_limiter_iop(&isc->trim_stats, bp) != 0) { 1450 if (iosched_debug) 1451 printf("Can't trim because limiter says no.\n"); 1452 isc->trim_stats.state_flags |= IOP_RATE_LIMITED; 1453 return NULL; 1454 } 1455 isc->current_read_bias = isc->read_bias; 1456 isc->trim_stats.state_flags &= ~IOP_RATE_LIMITED; 1457 /* cam_iosched_next_trim below keeps proper book */ 1458#endif 1459 return cam_iosched_next_trim(isc); 1460} 1461 1462/* 1463 * Determine what the next bit of work to do is for the periph. The 1464 * default implementation looks to see if we have trims to do, but no 1465 * trims outstanding. If so, we do that. Otherwise we see if we have 1466 * other work. If we do, then we do that. Otherwise why were we called? 1467 */ 1468struct bio * 1469cam_iosched_next_bio(struct cam_iosched_softc *isc) 1470{ 1471 struct bio *bp; 1472 1473 /* 1474 * See if we have a trim that can be scheduled. We can only send one 1475 * at a time down, so this takes that into account. 1476 * 1477 * XXX newer TRIM commands are queueable. Revisit this when we 1478 * implement them. 1479 */ 1480 if ((bp = cam_iosched_get_trim(isc)) != NULL) 1481 return bp; 1482 1483#ifdef CAM_IOSCHED_DYNAMIC 1484 /* 1485 * See if we have any pending writes, and room in the queue for them, 1486 * and if so, those are next. 1487 */ 1488 if (do_dynamic_iosched) { 1489 if ((bp = cam_iosched_get_write(isc)) != NULL) 1490 return bp; 1491 } 1492#endif 1493 1494 /* 1495 * next, see if there's other, normal I/O waiting. If so return that. 1496 */ 1497 if ((bp = bioq_first(&isc->bio_queue)) == NULL) 1498 return NULL; 1499 1500#ifdef CAM_IOSCHED_DYNAMIC 1501 /* 1502 * For the dynamic scheduler, bio_queue is only for reads, so enforce 1503 * the limits here. Enforce only for reads. 1504 */ 1505 if (do_dynamic_iosched) { 1506 if (bp->bio_cmd == BIO_READ && 1507 cam_iosched_limiter_iop(&isc->read_stats, bp) != 0) { 1508 isc->read_stats.state_flags |= IOP_RATE_LIMITED; 1509 return NULL; 1510 } 1511 } 1512 isc->read_stats.state_flags &= ~IOP_RATE_LIMITED; 1513#endif 1514 bioq_remove(&isc->bio_queue, bp); 1515#ifdef CAM_IOSCHED_DYNAMIC 1516 if (do_dynamic_iosched) { 1517 if (bp->bio_cmd == BIO_READ) { 1518 isc->read_stats.queued--; 1519 isc->read_stats.total++; 1520 isc->read_stats.pending++; 1521 } else 1522 printf("Found bio_cmd = %#x\n", bp->bio_cmd); 1523 } 1524 if (iosched_debug > 9) 1525 printf("HWQ : %p %#x\n", bp, bp->bio_cmd); 1526#endif 1527 return bp; 1528} 1529 1530/* 1531 * Driver has been given some work to do by the block layer. Tell the 1532 * scheduler about it and have it queue the work up. The scheduler module 1533 * will then return the currently most useful bit of work later, possibly 1534 * deferring work for various reasons. 1535 */ 1536void 1537cam_iosched_queue_work(struct cam_iosched_softc *isc, struct bio *bp) 1538{ 1539 1540 /* 1541 * A BIO_SPEEDUP from the uppper layers means that they have a block 1542 * shortage. At the present, this is only sent when we're trying to 1543 * allocate blocks, but have a shortage before giving up. bio_length is 1544 * the size of their shortage. We will complete just enough BIO_DELETEs 1545 * in the queue to satisfy the need. If bio_length is 0, we'll complete 1546 * them all. This allows the scheduler to delay BIO_DELETEs to improve 1547 * read/write performance without worrying about the upper layers. When 1548 * it's possibly a problem, we respond by pretending the BIO_DELETEs 1549 * just worked. We can't do anything about the BIO_DELETEs in the 1550 * hardware, though. We have to wait for them to complete. 1551 */ 1552 if (bp->bio_cmd == BIO_SPEEDUP) { 1553 off_t len; 1554 struct bio *nbp; 1555 1556 len = 0; 1557 while (bioq_first(&isc->trim_queue) && 1558 (bp->bio_length == 0 || len < bp->bio_length)) { 1559 nbp = bioq_takefirst(&isc->trim_queue); 1560 len += nbp->bio_length; 1561 nbp->bio_error = 0; 1562 biodone(nbp); 1563 } 1564 if (bp->bio_length > 0) { 1565 if (bp->bio_length > len) 1566 bp->bio_resid = bp->bio_length - len; 1567 else 1568 bp->bio_resid = 0; 1569 } 1570 bp->bio_error = 0; 1571 biodone(bp); 1572 return; 1573 } 1574 1575 /* 1576 * If we get a BIO_FLUSH, and we're doing delayed BIO_DELETEs then we 1577 * set the last tick time to one less than the current ticks minus the 1578 * delay to force the BIO_DELETEs to be presented to the client driver. 1579 */ 1580 if (bp->bio_cmd == BIO_FLUSH && isc->trim_ticks > 0) 1581 isc->last_trim_tick = ticks - isc->trim_ticks - 1; 1582 1583 /* 1584 * Put all trims on the trim queue. Otherwise put the work on the bio 1585 * queue. 1586 */ 1587 if (bp->bio_cmd == BIO_DELETE) { 1588 bioq_insert_tail(&isc->trim_queue, bp); 1589 if (isc->queued_trims == 0) 1590 isc->last_trim_tick = ticks; 1591 isc->queued_trims++; 1592#ifdef CAM_IOSCHED_DYNAMIC 1593 isc->trim_stats.in++; 1594 isc->trim_stats.queued++; 1595#endif 1596 } 1597#ifdef CAM_IOSCHED_DYNAMIC 1598 else if (do_dynamic_iosched && (bp->bio_cmd != BIO_READ)) { 1599 if (cam_iosched_sort_queue(isc)) 1600 bioq_disksort(&isc->write_queue, bp); 1601 else 1602 bioq_insert_tail(&isc->write_queue, bp); 1603 if (iosched_debug > 9) 1604 printf("Qw : %p %#x\n", bp, bp->bio_cmd); 1605 if (bp->bio_cmd == BIO_WRITE) { 1606 isc->write_stats.in++; 1607 isc->write_stats.queued++; 1608 } 1609 } 1610#endif 1611 else { 1612 if (cam_iosched_sort_queue(isc)) 1613 bioq_disksort(&isc->bio_queue, bp); 1614 else 1615 bioq_insert_tail(&isc->bio_queue, bp); 1616#ifdef CAM_IOSCHED_DYNAMIC 1617 if (iosched_debug > 9) 1618 printf("Qr : %p %#x\n", bp, bp->bio_cmd); 1619 if (bp->bio_cmd == BIO_READ) { 1620 isc->read_stats.in++; 1621 isc->read_stats.queued++; 1622 } else if (bp->bio_cmd == BIO_WRITE) { 1623 isc->write_stats.in++; 1624 isc->write_stats.queued++; 1625 } 1626#endif 1627 } 1628} 1629 1630/* 1631 * If we have work, get it scheduled. Called with the periph lock held. 1632 */ 1633void 1634cam_iosched_schedule(struct cam_iosched_softc *isc, struct cam_periph *periph) 1635{ 1636 1637 if (cam_iosched_has_work(isc)) 1638 xpt_schedule(periph, CAM_PRIORITY_NORMAL); 1639} 1640 1641/* 1642 * Complete a trim request. Mark that we no longer have one in flight. 1643 */ 1644void 1645cam_iosched_trim_done(struct cam_iosched_softc *isc) 1646{ 1647 1648 isc->flags &= ~CAM_IOSCHED_FLAG_TRIM_ACTIVE; 1649} 1650 1651/* 1652 * Complete a bio. Called before we release the ccb with xpt_release_ccb so we 1653 * might use notes in the ccb for statistics. 1654 */ 1655int 1656cam_iosched_bio_complete(struct cam_iosched_softc *isc, struct bio *bp, 1657 union ccb *done_ccb) 1658{ 1659 int retval = 0; 1660#ifdef CAM_IOSCHED_DYNAMIC 1661 if (!do_dynamic_iosched) 1662 return retval; 1663 1664 if (iosched_debug > 10) 1665 printf("done: %p %#x\n", bp, bp->bio_cmd); 1666 if (bp->bio_cmd == BIO_WRITE) { 1667 retval = cam_iosched_limiter_iodone(&isc->write_stats, bp); 1668 if ((bp->bio_flags & BIO_ERROR) != 0) 1669 isc->write_stats.errs++; 1670 isc->write_stats.out++; 1671 isc->write_stats.pending--; 1672 } else if (bp->bio_cmd == BIO_READ) { 1673 retval = cam_iosched_limiter_iodone(&isc->read_stats, bp); 1674 if ((bp->bio_flags & BIO_ERROR) != 0) 1675 isc->read_stats.errs++; 1676 isc->read_stats.out++; 1677 isc->read_stats.pending--; 1678 } else if (bp->bio_cmd == BIO_DELETE) { 1679 if ((bp->bio_flags & BIO_ERROR) != 0) 1680 isc->trim_stats.errs++; 1681 isc->trim_stats.out++; 1682 isc->trim_stats.pending--; 1683 } else if (bp->bio_cmd != BIO_FLUSH) { 1684 if (iosched_debug) 1685 printf("Completing command with bio_cmd == %#x\n", bp->bio_cmd); 1686 } 1687 1688 if (!(bp->bio_flags & BIO_ERROR) && done_ccb != NULL) { 1689 sbintime_t sim_latency; 1690 1691 sim_latency = cam_iosched_sbintime_t(done_ccb->ccb_h.qos.periph_data); 1692 1693 cam_iosched_io_metric_update(isc, sim_latency, 1694 bp->bio_cmd, bp->bio_bcount); 1695 /* 1696 * Debugging code: allow callbacks to the periph driver when latency max 1697 * is exceeded. This can be useful for triggering external debugging actions. 1698 */ 1699 if (isc->latfcn && isc->max_lat != 0 && sim_latency > isc->max_lat) 1700 isc->latfcn(isc->latarg, sim_latency, bp); 1701 } 1702 1703#endif 1704 return retval; 1705} 1706 1707/* 1708 * Tell the io scheduler that you've pushed a trim down into the sim. 1709 * This also tells the I/O scheduler not to push any more trims down, so 1710 * some periphs do not call it if they can cope with multiple trims in flight. 1711 */ 1712void 1713cam_iosched_submit_trim(struct cam_iosched_softc *isc) 1714{ 1715 1716 isc->flags |= CAM_IOSCHED_FLAG_TRIM_ACTIVE; 1717} 1718 1719/* 1720 * Change the sorting policy hint for I/O transactions for this device. 1721 */ 1722void 1723cam_iosched_set_sort_queue(struct cam_iosched_softc *isc, int val) 1724{ 1725 1726 isc->sort_io_queue = val; 1727} 1728 1729int 1730cam_iosched_has_work_flags(struct cam_iosched_softc *isc, uint32_t flags) 1731{ 1732 return isc->flags & flags; 1733} 1734 1735void 1736cam_iosched_set_work_flags(struct cam_iosched_softc *isc, uint32_t flags) 1737{ 1738 isc->flags |= flags; 1739} 1740 1741void 1742cam_iosched_clr_work_flags(struct cam_iosched_softc *isc, uint32_t flags) 1743{ 1744 isc->flags &= ~flags; 1745} 1746 1747#ifdef CAM_IOSCHED_DYNAMIC 1748/* 1749 * After the method presented in Jack Crenshaw's 1998 article "Integer 1750 * Square Roots," reprinted at 1751 * http://www.embedded.com/electronics-blogs/programmer-s-toolbox/4219659/Integer-Square-Roots 1752 * and well worth the read. Briefly, we find the power of 4 that's the 1753 * largest smaller than val. We then check each smaller power of 4 to 1754 * see if val is still bigger. The right shifts at each step divide 1755 * the result by 2 which after successive application winds up 1756 * accumulating the right answer. It could also have been accumulated 1757 * using a separate root counter, but this code is smaller and faster 1758 * than that method. This method is also integer size invariant. 1759 * It returns floor(sqrt((float)val)), or the largest integer less than 1760 * or equal to the square root. 1761 */ 1762static uint64_t 1763isqrt64(uint64_t val) 1764{ 1765 uint64_t res = 0; 1766 uint64_t bit = 1ULL << (sizeof(uint64_t) * NBBY - 2); 1767 1768 /* 1769 * Find the largest power of 4 smaller than val. 1770 */ 1771 while (bit > val) 1772 bit >>= 2; 1773 1774 /* 1775 * Accumulate the answer, one bit at a time (we keep moving 1776 * them over since 2 is the square root of 4 and we test 1777 * powers of 4). We accumulate where we find the bit, but 1778 * the successive shifts land the bit in the right place 1779 * by the end. 1780 */ 1781 while (bit != 0) { 1782 if (val >= res + bit) { 1783 val -= res + bit; 1784 res = (res >> 1) + bit; 1785 } else 1786 res >>= 1; 1787 bit >>= 2; 1788 } 1789 1790 return res; 1791} 1792 1793static sbintime_t latencies[LAT_BUCKETS - 1] = { 1794 SBT_1MS << 0, 1795 SBT_1MS << 1, 1796 SBT_1MS << 2, 1797 SBT_1MS << 3, 1798 SBT_1MS << 4, 1799 SBT_1MS << 5, 1800 SBT_1MS << 6, 1801 SBT_1MS << 7, 1802 SBT_1MS << 8, 1803 SBT_1MS << 9, 1804 SBT_1MS << 10, 1805 SBT_1MS << 11, 1806 SBT_1MS << 12, 1807 SBT_1MS << 13 /* 8.192s */ 1808}; 1809 1810static void 1811cam_iosched_update(struct iop_stats *iop, sbintime_t sim_latency) 1812{ 1813 sbintime_t y, deltasq, delta; 1814 int i; 1815 1816 /* 1817 * Keep counts for latency. We do it by power of two buckets. 1818 * This helps us spot outlier behavior obscured by averages. 1819 */ 1820 for (i = 0; i < LAT_BUCKETS - 1; i++) { 1821 if (sim_latency < latencies[i]) { 1822 iop->latencies[i]++; 1823 break; 1824 } 1825 } 1826 if (i == LAT_BUCKETS - 1) 1827 iop->latencies[i]++; /* Put all > 1024ms values into the last bucket. */ 1828 1829 /* 1830 * Classic exponentially decaying average with a tiny alpha 1831 * (2 ^ -alpha_bits). For more info see the NIST statistical 1832 * handbook. 1833 * 1834 * ema_t = y_t * alpha + ema_t-1 * (1 - alpha) [nist] 1835 * ema_t = y_t * alpha + ema_t-1 - alpha * ema_t-1 1836 * ema_t = alpha * y_t - alpha * ema_t-1 + ema_t-1 1837 * alpha = 1 / (1 << alpha_bits) 1838 * sub e == ema_t-1, b == 1/alpha (== 1 << alpha_bits), d == y_t - ema_t-1 1839 * = y_t/b - e/b + be/b 1840 * = (y_t - e + be) / b 1841 * = (e + d) / b 1842 * 1843 * Since alpha is a power of two, we can compute this w/o any mult or 1844 * division. 1845 * 1846 * Variance can also be computed. Usually, it would be expressed as follows: 1847 * diff_t = y_t - ema_t-1 1848 * emvar_t = (1 - alpha) * (emavar_t-1 + diff_t^2 * alpha) 1849 * = emavar_t-1 - alpha * emavar_t-1 + delta_t^2 * alpha - (delta_t * alpha)^2 1850 * sub b == 1/alpha (== 1 << alpha_bits), e == emavar_t-1, d = delta_t^2 1851 * = e - e/b + dd/b + dd/bb 1852 * = (bbe - be + bdd + dd) / bb 1853 * = (bbe + b(dd-e) + dd) / bb (which is expanded below bb = 1<<(2*alpha_bits)) 1854 */ 1855 /* 1856 * XXX possible numeric issues 1857 * o We assume right shifted integers do the right thing, since that's 1858 * implementation defined. You can change the right shifts to / (1LL << alpha). 1859 * o alpha_bits = 9 gives ema ceiling of 23 bits of seconds for ema and 14 bits 1860 * for emvar. This puts a ceiling of 13 bits on alpha since we need a 1861 * few tens of seconds of representation. 1862 * o We mitigate alpha issues by never setting it too high. 1863 */ 1864 y = sim_latency; 1865 delta = (y - iop->ema); /* d */ 1866 iop->ema = ((iop->ema << alpha_bits) + delta) >> alpha_bits; 1867 1868 /* 1869 * Were we to naively plow ahead at this point, we wind up with many numerical 1870 * issues making any SD > ~3ms unreliable. So, we shift right by 12. This leaves 1871 * us with microsecond level precision in the input, so the same in the 1872 * output. It means we can't overflow deltasq unless delta > 4k seconds. It 1873 * also means that emvar can be up 46 bits 40 of which are fraction, which 1874 * gives us a way to measure up to ~8s in the SD before the computation goes 1875 * unstable. Even the worst hard disk rarely has > 1s service time in the 1876 * drive. It does mean we have to shift left 12 bits after taking the 1877 * square root to compute the actual standard deviation estimate. This loss of 1878 * precision is preferable to needing int128 types to work. The above numbers 1879 * assume alpha=9. 10 or 11 are ok, but we start to run into issues at 12, 1880 * so 12 or 13 is OK for EMA, EMVAR and SD will be wrong in those cases. 1881 */ 1882 delta >>= 12; 1883 deltasq = delta * delta; /* dd */ 1884 iop->emvar = ((iop->emvar << (2 * alpha_bits)) + /* bbe */ 1885 ((deltasq - iop->emvar) << alpha_bits) + /* b(dd-e) */ 1886 deltasq) /* dd */ 1887 >> (2 * alpha_bits); /* div bb */ 1888 iop->sd = (sbintime_t)isqrt64((uint64_t)iop->emvar) << 12; 1889} 1890 1891static void 1892cam_iosched_io_metric_update(struct cam_iosched_softc *isc, 1893 sbintime_t sim_latency, int cmd, size_t size) 1894{ 1895 /* xxx Do we need to scale based on the size of the I/O ? */ 1896 switch (cmd) { 1897 case BIO_READ: 1898 cam_iosched_update(&isc->read_stats, sim_latency); 1899 break; 1900 case BIO_WRITE: 1901 cam_iosched_update(&isc->write_stats, sim_latency); 1902 break; 1903 case BIO_DELETE: 1904 cam_iosched_update(&isc->trim_stats, sim_latency); 1905 break; 1906 default: 1907 break; 1908 } 1909} 1910 1911#ifdef DDB 1912static int biolen(struct bio_queue_head *bq) 1913{ 1914 int i = 0; 1915 struct bio *bp; 1916 1917 TAILQ_FOREACH(bp, &bq->queue, bio_queue) { 1918 i++; 1919 } 1920 return i; 1921} 1922 1923/* 1924 * Show the internal state of the I/O scheduler. 1925 */ 1926DB_SHOW_COMMAND(iosched, cam_iosched_db_show) 1927{ 1928 struct cam_iosched_softc *isc; 1929 1930 if (!have_addr) { 1931 db_printf("Need addr\n"); 1932 return; 1933 } 1934 isc = (struct cam_iosched_softc *)addr; 1935 db_printf("pending_reads: %d\n", isc->read_stats.pending); 1936 db_printf("min_reads: %d\n", isc->read_stats.min); 1937 db_printf("max_reads: %d\n", isc->read_stats.max); 1938 db_printf("reads: %d\n", isc->read_stats.total); 1939 db_printf("in_reads: %d\n", isc->read_stats.in); 1940 db_printf("out_reads: %d\n", isc->read_stats.out); 1941 db_printf("queued_reads: %d\n", isc->read_stats.queued); 1942 db_printf("Read Q len %d\n", biolen(&isc->bio_queue)); 1943 db_printf("pending_writes: %d\n", isc->write_stats.pending); 1944 db_printf("min_writes: %d\n", isc->write_stats.min); 1945 db_printf("max_writes: %d\n", isc->write_stats.max); 1946 db_printf("writes: %d\n", isc->write_stats.total); 1947 db_printf("in_writes: %d\n", isc->write_stats.in); 1948 db_printf("out_writes: %d\n", isc->write_stats.out); 1949 db_printf("queued_writes: %d\n", isc->write_stats.queued); 1950 db_printf("Write Q len %d\n", biolen(&isc->write_queue)); 1951 db_printf("pending_trims: %d\n", isc->trim_stats.pending); 1952 db_printf("min_trims: %d\n", isc->trim_stats.min); 1953 db_printf("max_trims: %d\n", isc->trim_stats.max); 1954 db_printf("trims: %d\n", isc->trim_stats.total); 1955 db_printf("in_trims: %d\n", isc->trim_stats.in); 1956 db_printf("out_trims: %d\n", isc->trim_stats.out); 1957 db_printf("queued_trims: %d\n", isc->trim_stats.queued); 1958 db_printf("Trim Q len %d\n", biolen(&isc->trim_queue)); 1959 db_printf("read_bias: %d\n", isc->read_bias); 1960 db_printf("current_read_bias: %d\n", isc->current_read_bias); 1961 db_printf("Trim active? %s\n", 1962 (isc->flags & CAM_IOSCHED_FLAG_TRIM_ACTIVE) ? "yes" : "no"); 1963} 1964#endif 1965#endif 1966