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