kernel/rcu/rcuperf.c

   1 /*
   2  * Read-Copy Update module-based performance-test facility
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, you can access it online at
  16  * http://www.gnu.org/licenses/gpl-2.0.html.
  17  *
  18  * Copyright (C) IBM Corporation, 2015
  19  *
  20  * Authors: Paul E. McKenney <paulmck@us.ibm.com>
  21  */
  22 #include <linux/types.h>
  23 #include <linux/kernel.h>
  24 #include <linux/init.h>
  25 #include <linux/module.h>
  26 #include <linux/kthread.h>
  27 #include <linux/err.h>
  28 #include <linux/spinlock.h>
  29 #include <linux/smp.h>
  30 #include <linux/rcupdate.h>
  31 #include <linux/interrupt.h>
  32 #include <linux/sched.h>
  33 #include <uapi/linux/sched/types.h>
  34 #include <linux/atomic.h>
  35 #include <linux/bitops.h>
  36 #include <linux/completion.h>
  37 #include <linux/moduleparam.h>
  38 #include <linux/percpu.h>
  39 #include <linux/notifier.h>
  40 #include <linux/reboot.h>
  41 #include <linux/freezer.h>
  42 #include <linux/cpu.h>
  43 #include <linux/delay.h>
  44 #include <linux/stat.h>
  45 #include <linux/srcu.h>
  46 #include <linux/slab.h>
  47 #include <asm/byteorder.h>
  48 #include <linux/torture.h>
  49 #include <linux/vmalloc.h>
  50
  51 #include "rcu.h"
  52
  53 MODULE_LICENSE("GPL");
  54 MODULE_AUTHOR("Paul E. McKenney <paulmck@linux.vnet.ibm.com>");
  55
  56 #define PERF_FLAG "-perf:"
  57 #define PERFOUT_STRING(s) \
  58         pr_alert("%s" PERF_FLAG " %s\n", perf_type, s)
  59 #define VERBOSE_PERFOUT_STRING(s) \
  60         do { if (verbose) pr_alert("%s" PERF_FLAG " %s\n", perf_type, s); } while (0)
  61 #define VERBOSE_PERFOUT_ERRSTRING(s) \
  62         do { if (verbose) pr_alert("%s" PERF_FLAG "!!! %s\n", perf_type, s); } while (0)
  63
  64 torture_param(bool, gp_async, false, "Use asynchronous GP wait primitives");
  65 torture_param(int, gp_async_max, 1000, "Max # outstanding waits per reader");
  66 torture_param(bool, gp_exp, false, "Use expedited GP wait primitives");
  67 torture_param(int, holdoff, 10, "Holdoff time before test start (s)");
  68 torture_param(int, nreaders, 0, "Number of RCU reader threads");
  69 torture_param(int, nwriters, -1, "Number of RCU updater threads");
  70 torture_param(bool, shutdown, !IS_ENABLED(MODULE),
  71               "Shutdown at end of performance tests.");
  72 torture_param(bool, verbose, true, "Enable verbose debugging printk()s");
  73 torture_param(int, writer_holdoff, 0, "Holdoff (us) between GPs, zero to disable");
  74
  75 static char *perf_type = "rcu";
  76 module_param(perf_type, charp, 0444);
  77 MODULE_PARM_DESC(perf_type, "Type of RCU to performance-test (rcu, rcu_bh, ...)");
  78
  79 static int nrealreaders;
  80 static int nrealwriters;
  81 static struct task_struct **writer_tasks;
  82 static struct task_struct **reader_tasks;
  83 static struct task_struct *shutdown_task;
  84
  85 static u64 **writer_durations;
  86 static int *writer_n_durations;
  87 static atomic_t n_rcu_perf_reader_started;
  88 static atomic_t n_rcu_perf_writer_started;
  89 static atomic_t n_rcu_perf_writer_finished;
  90 static wait_queue_head_t shutdown_wq;
  91 static u64 t_rcu_perf_writer_started;
  92 static u64 t_rcu_perf_writer_finished;
  93 static unsigned long b_rcu_perf_writer_started;
  94 static unsigned long b_rcu_perf_writer_finished;
  95 static DEFINE_PER_CPU(atomic_t, n_async_inflight);
  96
  97 static int rcu_perf_writer_state;
  98 #define RTWS_INIT               0
  99 #define RTWS_ASYNC              1
 100 #define RTWS_BARRIER            2
 101 #define RTWS_EXP_SYNC           3
 102 #define RTWS_SYNC               4
 103 #define RTWS_IDLE               5
 104 #define RTWS_STOPPING           6
 105
 106 #define MAX_MEAS 10000
 107 #define MIN_MEAS 100
 108
 109 /*
 110  * Operations vector for selecting different types of tests.
 111  */
 112
 113 struct rcu_perf_ops {
 114         int ptype;
 115         void (*init)(void);
 116         void (*cleanup)(void);
 117         int (*readlock)(void);
 118         void (*readunlock)(int idx);
 119         unsigned long (*started)(void);
 120         unsigned long (*completed)(void);
 121         unsigned long (*exp_completed)(void);
 122         void (*async)(struct rcu_head *head, rcu_callback_t func);
 123         void (*gp_barrier)(void);
 124         void (*sync)(void);
 125         void (*exp_sync)(void);
 126         const char *name;
 127 };
 128
 129 static struct rcu_perf_ops *cur_ops;
 130
 131 /*
 132  * Definitions for rcu perf testing.
 133  */
 134
 135 static int rcu_perf_read_lock(void) __acquires(RCU)
 136 {
 137         rcu_read_lock();
 138         return 0;
 139 }
 140
 141 static void rcu_perf_read_unlock(int idx) __releases(RCU)
 142 {
 143         rcu_read_unlock();
 144 }
 145
 146 static unsigned long __maybe_unused rcu_no_completed(void)
 147 {
 148         return 0;
 149 }
 150
 151 static void rcu_sync_perf_init(void)
 152 {
 153 }
 154
 155 static struct rcu_perf_ops rcu_ops = {
 156         .ptype          = RCU_FLAVOR,
 157         .init           = rcu_sync_perf_init,
 158         .readlock       = rcu_perf_read_lock,
 159         .readunlock     = rcu_perf_read_unlock,
 160         .started        = rcu_batches_started,
 161         .completed      = rcu_batches_completed,
 162         .exp_completed  = rcu_exp_batches_completed,
 163         .async          = call_rcu,
 164         .gp_barrier     = rcu_barrier,
 165         .sync           = synchronize_rcu,
 166         .exp_sync       = synchronize_rcu_expedited,
 167         .name           = "rcu"
 168 };
 169
 170 /*
 171  * Definitions for rcu_bh perf testing.
 172  */
 173
 174 static int rcu_bh_perf_read_lock(void) __acquires(RCU_BH)
 175 {
 176         rcu_read_lock_bh();
 177         return 0;
 178 }
 179
 180 static void rcu_bh_perf_read_unlock(int idx) __releases(RCU_BH)
 181 {
 182         rcu_read_unlock_bh();
 183 }
 184
 185 static struct rcu_perf_ops rcu_bh_ops = {
 186         .ptype          = RCU_BH_FLAVOR,
 187         .init           = rcu_sync_perf_init,
 188         .readlock       = rcu_bh_perf_read_lock,
 189         .readunlock     = rcu_bh_perf_read_unlock,
 190         .started        = rcu_batches_started_bh,
 191         .completed      = rcu_batches_completed_bh,
 192         .exp_completed  = rcu_exp_batches_completed_sched,
 193         .async          = call_rcu_bh,
 194         .gp_barrier     = rcu_barrier_bh,
 195         .sync           = synchronize_rcu_bh,
 196         .exp_sync       = synchronize_rcu_bh_expedited,
 197         .name           = "rcu_bh"
 198 };
 199
 200 /*
 201  * Definitions for srcu perf testing.
 202  */
 203
 204 DEFINE_STATIC_SRCU(srcu_ctl_perf);
 205 static struct srcu_struct *srcu_ctlp = &srcu_ctl_perf;
 206
 207 static int srcu_perf_read_lock(void) __acquires(srcu_ctlp)
 208 {
 209         return srcu_read_lock(srcu_ctlp);
 210 }
 211
 212 static void srcu_perf_read_unlock(int idx) __releases(srcu_ctlp)
 213 {
 214         srcu_read_unlock(srcu_ctlp, idx);
 215 }
 216
 217 static unsigned long srcu_perf_completed(void)
 218 {
 219         return srcu_batches_completed(srcu_ctlp);
 220 }
 221
 222 static void srcu_call_rcu(struct rcu_head *head, rcu_callback_t func)
 223 {
 224         call_srcu(srcu_ctlp, head, func);
 225 }
 226
 227 static void srcu_rcu_barrier(void)
 228 {
 229         srcu_barrier(srcu_ctlp);
 230 }
 231
 232 static void srcu_perf_synchronize(void)
 233 {
 234         synchronize_srcu(srcu_ctlp);
 235 }
 236
 237 static void srcu_perf_synchronize_expedited(void)
 238 {
 239         synchronize_srcu_expedited(srcu_ctlp);
 240 }
 241
 242 static struct rcu_perf_ops srcu_ops = {
 243         .ptype          = SRCU_FLAVOR,
 244         .init           = rcu_sync_perf_init,
 245         .readlock       = srcu_perf_read_lock,
 246         .readunlock     = srcu_perf_read_unlock,
 247         .started        = NULL,
 248         .completed      = srcu_perf_completed,
 249         .exp_completed  = srcu_perf_completed,
 250         .async          = srcu_call_rcu,
 251         .gp_barrier     = srcu_rcu_barrier,
 252         .sync           = srcu_perf_synchronize,
 253         .exp_sync       = srcu_perf_synchronize_expedited,
 254         .name           = "srcu"
 255 };
 256
 257 static struct srcu_struct srcud;
 258
 259 static void srcu_sync_perf_init(void)
 260 {
 261         srcu_ctlp = &srcud;
 262         init_srcu_struct(srcu_ctlp);
 263 }
 264
 265 static void srcu_sync_perf_cleanup(void)
 266 {
 267         cleanup_srcu_struct(srcu_ctlp);
 268 }
 269
 270 static struct rcu_perf_ops srcud_ops = {
 271         .ptype          = SRCU_FLAVOR,
 272         .init           = srcu_sync_perf_init,
 273         .cleanup        = srcu_sync_perf_cleanup,
 274         .readlock       = srcu_perf_read_lock,
 275         .readunlock     = srcu_perf_read_unlock,
 276         .started        = NULL,
 277         .completed      = srcu_perf_completed,
 278         .exp_completed  = srcu_perf_completed,
 279         .async          = srcu_call_rcu,
 280         .gp_barrier     = srcu_rcu_barrier,
 281         .sync           = srcu_perf_synchronize,
 282         .exp_sync       = srcu_perf_synchronize_expedited,
 283         .name           = "srcud"
 284 };
 285
 286 /*
 287  * Definitions for sched perf testing.
 288  */
 289
 290 static int sched_perf_read_lock(void)
 291 {
 292         preempt_disable();
 293         return 0;
 294 }
 295
 296 static void sched_perf_read_unlock(int idx)
 297 {
 298         preempt_enable();
 299 }
 300
 301 static struct rcu_perf_ops sched_ops = {
 302         .ptype          = RCU_SCHED_FLAVOR,
 303         .init           = rcu_sync_perf_init,
 304         .readlock       = sched_perf_read_lock,
 305         .readunlock     = sched_perf_read_unlock,
 306         .started        = rcu_batches_started_sched,
 307         .completed      = rcu_batches_completed_sched,
 308         .exp_completed  = rcu_exp_batches_completed_sched,
 309         .async          = call_rcu_sched,
 310         .gp_barrier     = rcu_barrier_sched,
 311         .sync           = synchronize_sched,
 312         .exp_sync       = synchronize_sched_expedited,
 313         .name           = "sched"
 314 };
 315
 316 /*
 317  * Definitions for RCU-tasks perf testing.
 318  */
 319
 320 static int tasks_perf_read_lock(void)
 321 {
 322         return 0;
 323 }
 324
 325 static void tasks_perf_read_unlock(int idx)
 326 {
 327 }
 328
 329 static struct rcu_perf_ops tasks_ops = {
 330         .ptype          = RCU_TASKS_FLAVOR,
 331         .init           = rcu_sync_perf_init,
 332         .readlock       = tasks_perf_read_lock,
 333         .readunlock     = tasks_perf_read_unlock,
 334         .started        = rcu_no_completed,
 335         .completed      = rcu_no_completed,
 336         .async          = call_rcu_tasks,
 337         .gp_barrier     = rcu_barrier_tasks,
 338         .sync           = synchronize_rcu_tasks,
 339         .exp_sync       = synchronize_rcu_tasks,
 340         .name           = "tasks"
 341 };
 342
 343 static bool __maybe_unused torturing_tasks(void)
 344 {
 345         return cur_ops == &tasks_ops;
 346 }
 347
 348 /*
 349  * If performance tests complete, wait for shutdown to commence.
 350  */
 351 static void rcu_perf_wait_shutdown(void)
 352 {
 353         cond_resched_rcu_qs();
 354         if (atomic_read(&n_rcu_perf_writer_finished) < nrealwriters)
 355                 return;
 356         while (!torture_must_stop())
 357                 schedule_timeout_uninterruptible(1);
 358 }
 359
 360 /*
 361  * RCU perf reader kthread.  Repeatedly does empty RCU read-side
 362  * critical section, minimizing update-side interference.
 363  */
 364 static int
 365 rcu_perf_reader(void *arg)
 366 {
 367         unsigned long flags;
 368         int idx;
 369         long me = (long)arg;
 370
 371         VERBOSE_PERFOUT_STRING("rcu_perf_reader task started");
 372         set_cpus_allowed_ptr(current, cpumask_of(me % nr_cpu_ids));
 373         set_user_nice(current, MAX_NICE);
 374         atomic_inc(&n_rcu_perf_reader_started);
 375
 376         do {
 377                 local_irq_save(flags);
 378                 idx = cur_ops->readlock();
 379                 cur_ops->readunlock(idx);
 380                 local_irq_restore(flags);
 381                 rcu_perf_wait_shutdown();
 382         } while (!torture_must_stop());
 383         torture_kthread_stopping("rcu_perf_reader");
 384         return 0;
 385 }
 386
 387 /*
 388  * Callback function for asynchronous grace periods from rcu_perf_writer().
 389  */
 390 static void rcu_perf_async_cb(struct rcu_head *rhp)
 391 {
 392         atomic_dec(this_cpu_ptr(&n_async_inflight));
 393         kfree(rhp);
 394 }
 395
 396 /*
 397  * RCU perf writer kthread.  Repeatedly does a grace period.
 398  */
 399 static int
 400 rcu_perf_writer(void *arg)
 401 {
 402         int i = 0;
 403         int i_max;
 404         long me = (long)arg;
 405         struct rcu_head *rhp = NULL;
 406         struct sched_param sp;
 407         bool started = false, done = false, alldone = false;
 408         u64 t;
 409         u64 *wdp;
 410         u64 *wdpp = writer_durations[me];
 411
 412         VERBOSE_PERFOUT_STRING("rcu_perf_writer task started");
 413         WARN_ON(!wdpp);
 414         set_cpus_allowed_ptr(current, cpumask_of(me % nr_cpu_ids));
 415         sp.sched_priority = 1;
 416         sched_setscheduler_nocheck(current, SCHED_FIFO, &sp);
 417
 418         if (holdoff)
 419                 schedule_timeout_uninterruptible(holdoff * HZ);
 420
 421         t = ktime_get_mono_fast_ns();
 422         if (atomic_inc_return(&n_rcu_perf_writer_started) >= nrealwriters) {
 423                 t_rcu_perf_writer_started = t;
 424                 if (gp_exp) {
 425                         b_rcu_perf_writer_started =
 426                                 cur_ops->exp_completed() / 2;
 427                 } else {
 428                         b_rcu_perf_writer_started =
 429                                 cur_ops->completed();
 430                 }
 431         }
 432
 433         do {
 434                 if (writer_holdoff)
 435                         udelay(writer_holdoff);
 436                 wdp = &wdpp[i];
 437                 *wdp = ktime_get_mono_fast_ns();
 438                 if (gp_async) {
 439 retry:
 440                         if (!rhp)
 441                                 rhp = kmalloc(sizeof(*rhp), GFP_KERNEL);
 442                         if (rhp && atomic_read(this_cpu_ptr(&n_async_inflight)) < gp_async_max) {
 443                                 rcu_perf_writer_state = RTWS_ASYNC;
 444                                 atomic_inc(this_cpu_ptr(&n_async_inflight));
 445                                 cur_ops->async(rhp, rcu_perf_async_cb);
 446                                 rhp = NULL;
 447                         } else if (!kthread_should_stop()) {
 448                                 rcu_perf_writer_state = RTWS_BARRIER;
 449                                 cur_ops->gp_barrier();
 450                                 goto retry;
 451                         } else {
 452                                 kfree(rhp); /* Because we are stopping. */
 453                         }
 454                 } else if (gp_exp) {
 455                         rcu_perf_writer_state = RTWS_EXP_SYNC;
 456                         cur_ops->exp_sync();
 457                 } else {
 458                         rcu_perf_writer_state = RTWS_SYNC;
 459                         cur_ops->sync();
 460                 }
 461                 rcu_perf_writer_state = RTWS_IDLE;
 462                 t = ktime_get_mono_fast_ns();
 463                 *wdp = t - *wdp;
 464                 i_max = i;
 465                 if (!started &&
 466                     atomic_read(&n_rcu_perf_writer_started) >= nrealwriters)
 467                         started = true;
 468                 if (!done && i >= MIN_MEAS) {
 469                         done = true;
 470                         sp.sched_priority = 0;
 471                         sched_setscheduler_nocheck(current,
 472                                                    SCHED_NORMAL, &sp);
 473                         pr_alert("%s%s rcu_perf_writer %ld has %d measurements\n",
 474                                  perf_type, PERF_FLAG, me, MIN_MEAS);
 475                         if (atomic_inc_return(&n_rcu_perf_writer_finished) >=
 476                             nrealwriters) {
 477                                 schedule_timeout_interruptible(10);
 478                                 rcu_ftrace_dump(DUMP_ALL);
 479                                 PERFOUT_STRING("Test complete");
 480                                 t_rcu_perf_writer_finished = t;
 481                                 if (gp_exp) {
 482                                         b_rcu_perf_writer_finished =
 483                                                 cur_ops->exp_completed() / 2;
 484                                 } else {
 485                                         b_rcu_perf_writer_finished =
 486                                                 cur_ops->completed();
 487                                 }
 488                                 if (shutdown) {
 489                                         smp_mb(); /* Assign before wake. */
 490                                         wake_up(&shutdown_wq);
 491                                 }
 492                         }
 493                 }
 494                 if (done && !alldone &&
 495                     atomic_read(&n_rcu_perf_writer_finished) >= nrealwriters)
 496                         alldone = true;
 497                 if (started && !alldone && i < MAX_MEAS - 1)
 498                         i++;
 499                 rcu_perf_wait_shutdown();
 500         } while (!torture_must_stop());
 501         if (gp_async) {
 502                 rcu_perf_writer_state = RTWS_BARRIER;
 503                 cur_ops->gp_barrier();
 504         }
 505         rcu_perf_writer_state = RTWS_STOPPING;
 506         writer_n_durations[me] = i_max;
 507         torture_kthread_stopping("rcu_perf_writer");
 508         return 0;
 509 }
 510
 511 static inline void
 512 rcu_perf_print_module_parms(struct rcu_perf_ops *cur_ops, const char *tag)
 513 {
 514         pr_alert("%s" PERF_FLAG
 515                  "--- %s: nreaders=%d nwriters=%d verbose=%d shutdown=%d\n",
 516                  perf_type, tag, nrealreaders, nrealwriters, verbose, shutdown);
 517 }
 518
 519 static void
 520 rcu_perf_cleanup(void)
 521 {
 522         int i;
 523         int j;
 524         int ngps = 0;
 525         u64 *wdp;
 526         u64 *wdpp;
 527
 528         /*
 529          * Would like warning at start, but everything is expedited
 530          * during the mid-boot phase, so have to wait till the end.
 531          */
 532         if (rcu_gp_is_expedited() && !rcu_gp_is_normal() && !gp_exp)
 533                 VERBOSE_PERFOUT_ERRSTRING("All grace periods expedited, no normal ones to measure!");
 534         if (rcu_gp_is_normal() && gp_exp)
 535                 VERBOSE_PERFOUT_ERRSTRING("All grace periods normal, no expedited ones to measure!");
 536         if (gp_exp && gp_async)
 537                 VERBOSE_PERFOUT_ERRSTRING("No expedited async GPs, so went with async!");
 538
 539         if (torture_cleanup_begin())
 540                 return;
 541
 542         if (reader_tasks) {
 543                 for (i = 0; i < nrealreaders; i++)
 544                         torture_stop_kthread(rcu_perf_reader,
 545                                              reader_tasks[i]);
 546                 kfree(reader_tasks);
 547         }
 548
 549         if (writer_tasks) {
 550                 for (i = 0; i < nrealwriters; i++) {
 551                         torture_stop_kthread(rcu_perf_writer,
 552                                              writer_tasks[i]);
 553                         if (!writer_n_durations)
 554                                 continue;
 555                         j = writer_n_durations[i];
 556                         pr_alert("%s%s writer %d gps: %d\n",
 557                                  perf_type, PERF_FLAG, i, j);
 558                         ngps += j;
 559                 }
 560                 pr_alert("%s%s start: %llu end: %llu duration: %llu gps: %d batches: %ld\n",
 561                          perf_type, PERF_FLAG,
 562                          t_rcu_perf_writer_started, t_rcu_perf_writer_finished,
 563                          t_rcu_perf_writer_finished -
 564                          t_rcu_perf_writer_started,
 565                          ngps,
 566                          b_rcu_perf_writer_finished -
 567                          b_rcu_perf_writer_started);
 568                 for (i = 0; i < nrealwriters; i++) {
 569                         if (!writer_durations)
 570                                 break;
 571                         if (!writer_n_durations)
 572                                 continue;
 573                         wdpp = writer_durations[i];
 574                         if (!wdpp)
 575                                 continue;
 576                         for (j = 0; j <= writer_n_durations[i]; j++) {
 577                                 wdp = &wdpp[j];
 578                                 pr_alert("%s%s %4d writer-duration: %5d %llu\n",
 579                                         perf_type, PERF_FLAG,
 580                                         i, j, *wdp);
 581                                 if (j % 100 == 0)
 582                                         schedule_timeout_uninterruptible(1);
 583                         }
 584                         kfree(writer_durations[i]);
 585                 }
 586                 kfree(writer_tasks);
 587                 kfree(writer_durations);
 588                 kfree(writer_n_durations);
 589         }
 590
 591         /* Do flavor-specific cleanup operations.  */
 592         if (cur_ops->cleanup != NULL)
 593                 cur_ops->cleanup();
 594
 595         torture_cleanup_end();
 596 }
 597
 598 /*
 599  * Return the number if non-negative.  If -1, the number of CPUs.
 600  * If less than -1, that much less than the number of CPUs, but
 601  * at least one.
 602  */
 603 static int compute_real(int n)
 604 {
 605         int nr;
 606
 607         if (n >= 0) {
 608                 nr = n;
 609         } else {
 610                 nr = num_online_cpus() + 1 + n;
 611                 if (nr <= 0)
 612                         nr = 1;
 613         }
 614         return nr;
 615 }
 616
 617 /*
 618  * RCU perf shutdown kthread.  Just waits to be awakened, then shuts
 619  * down system.
 620  */
 621 static int
 622 rcu_perf_shutdown(void *arg)
 623 {
 624         do {
 625                 wait_event(shutdown_wq,
 626                            atomic_read(&n_rcu_perf_writer_finished) >=
 627                            nrealwriters);
 628         } while (atomic_read(&n_rcu_perf_writer_finished) < nrealwriters);
 629         smp_mb(); /* Wake before output. */
 630         rcu_perf_cleanup();
 631         kernel_power_off();
 632         return -EINVAL;
 633 }
 634
 635 static int __init
 636 rcu_perf_init(void)
 637 {
 638         long i;
 639         int firsterr = 0;
 640         static struct rcu_perf_ops *perf_ops[] = {
 641                 &rcu_ops, &rcu_bh_ops, &srcu_ops, &srcud_ops, &sched_ops,
 642                 &tasks_ops,
 643         };
 644
 645         if (!torture_init_begin(perf_type, verbose))
 646                 return -EBUSY;
 647
 648         /* Process args and tell the world that the perf'er is on the job. */
 649         for (i = 0; i < ARRAY_SIZE(perf_ops); i++) {
 650                 cur_ops = perf_ops[i];
 651                 if (strcmp(perf_type, cur_ops->name) == 0)
 652                         break;
 653         }
 654         if (i == ARRAY_SIZE(perf_ops)) {
 655                 pr_alert("rcu-perf: invalid perf type: \"%s\"\n",
 656                          perf_type);
 657                 pr_alert("rcu-perf types:");
 658                 for (i = 0; i < ARRAY_SIZE(perf_ops); i++)
 659                         pr_alert(" %s", perf_ops[i]->name);
 660                 pr_alert("\n");
 661                 firsterr = -EINVAL;
 662                 goto unwind;
 663         }
 664         if (cur_ops->init)
 665                 cur_ops->init();
 666
 667         nrealwriters = compute_real(nwriters);
 668         nrealreaders = compute_real(nreaders);
 669         atomic_set(&n_rcu_perf_reader_started, 0);
 670         atomic_set(&n_rcu_perf_writer_started, 0);
 671         atomic_set(&n_rcu_perf_writer_finished, 0);
 672         rcu_perf_print_module_parms(cur_ops, "Start of test");
 673
 674         /* Start up the kthreads. */
 675
 676         if (shutdown) {
 677                 init_waitqueue_head(&shutdown_wq);
 678                 firsterr = torture_create_kthread(rcu_perf_shutdown, NULL,
 679                                                   shutdown_task);
 680                 if (firsterr)
 681                         goto unwind;
 682                 schedule_timeout_uninterruptible(1);
 683         }
 684         reader_tasks = kcalloc(nrealreaders, sizeof(reader_tasks[0]),
 685                                GFP_KERNEL);
 686         if (reader_tasks == NULL) {
 687                 VERBOSE_PERFOUT_ERRSTRING("out of memory");
 688                 firsterr = -ENOMEM;
 689                 goto unwind;
 690         }
 691         for (i = 0; i < nrealreaders; i++) {
 692                 firsterr = torture_create_kthread(rcu_perf_reader, (void *)i,
 693                                                   reader_tasks[i]);
 694                 if (firsterr)
 695                         goto unwind;
 696         }
 697         while (atomic_read(&n_rcu_perf_reader_started) < nrealreaders)
 698                 schedule_timeout_uninterruptible(1);
 699         writer_tasks = kcalloc(nrealwriters, sizeof(reader_tasks[0]),
 700                                GFP_KERNEL);
 701         writer_durations = kcalloc(nrealwriters, sizeof(*writer_durations),
 702                                    GFP_KERNEL);
 703         writer_n_durations =
 704                 kcalloc(nrealwriters, sizeof(*writer_n_durations),
 705                         GFP_KERNEL);
 706         if (!writer_tasks || !writer_durations || !writer_n_durations) {
 707                 VERBOSE_PERFOUT_ERRSTRING("out of memory");
 708                 firsterr = -ENOMEM;
 709                 goto unwind;
 710         }
 711         for (i = 0; i < nrealwriters; i++) {
 712                 writer_durations[i] =
 713                         kcalloc(MAX_MEAS, sizeof(*writer_durations[i]),
 714                                 GFP_KERNEL);
 715                 if (!writer_durations[i]) {
 716                         firsterr = -ENOMEM;
 717                         goto unwind;
 718                 }
 719                 firsterr = torture_create_kthread(rcu_perf_writer, (void *)i,
 720                                                   writer_tasks[i]);
 721                 if (firsterr)
 722                         goto unwind;
 723         }
 724         torture_init_end();
 725         return 0;
 726
 727 unwind:
 728         torture_init_end();
 729         rcu_perf_cleanup();
 730         return firsterr;
 731 }
 732
 733 module_init(rcu_perf_init);
 734 module_exit(rcu_perf_cleanup);