kernel/rcu/rcuperf.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * Read-Copy Update module-based performance-test facility
   4  *
   5  * Copyright (C) IBM Corporation, 2015
   6  *
   7  * Authors: Paul E. McKenney <paulmck@linux.ibm.com>
   8  */
   9
  10 #define pr_fmt(fmt) fmt
  11
  12 #include <linux/types.h>
  13 #include <linux/kernel.h>
  14 #include <linux/init.h>
  15 #include <linux/mm.h>
  16 #include <linux/module.h>
  17 #include <linux/kthread.h>
  18 #include <linux/err.h>
  19 #include <linux/spinlock.h>
  20 #include <linux/smp.h>
  21 #include <linux/rcupdate.h>
  22 #include <linux/interrupt.h>
  23 #include <linux/sched.h>
  24 #include <uapi/linux/sched/types.h>
  25 #include <linux/atomic.h>
  26 #include <linux/bitops.h>
  27 #include <linux/completion.h>
  28 #include <linux/moduleparam.h>
  29 #include <linux/percpu.h>
  30 #include <linux/notifier.h>
  31 #include <linux/reboot.h>
  32 #include <linux/freezer.h>
  33 #include <linux/cpu.h>
  34 #include <linux/delay.h>
  35 #include <linux/stat.h>
  36 #include <linux/srcu.h>
  37 #include <linux/slab.h>
  38 #include <asm/byteorder.h>
  39 #include <linux/torture.h>
  40 #include <linux/vmalloc.h>
  41
  42 #include "rcu.h"
  43
  44 MODULE_LICENSE("GPL");
  45 MODULE_AUTHOR("Paul E. McKenney <paulmck@linux.ibm.com>");
  46
  47 #define PERF_FLAG "-perf:"
  48 #define PERFOUT_STRING(s) \
  49         pr_alert("%s" PERF_FLAG " %s\n", perf_type, s)
  50 #define VERBOSE_PERFOUT_STRING(s) \
  51         do { if (verbose) pr_alert("%s" PERF_FLAG " %s\n", perf_type, s); } while (0)
  52 #define VERBOSE_PERFOUT_ERRSTRING(s) \
  53         do { if (verbose) pr_alert("%s" PERF_FLAG "!!! %s\n", perf_type, s); } while (0)
  54
  55 /*
  56  * The intended use cases for the nreaders and nwriters module parameters
  57  * are as follows:
  58  *
  59  * 1.   Specify only the nr_cpus kernel boot parameter.  This will
  60  *      set both nreaders and nwriters to the value specified by
  61  *      nr_cpus for a mixed reader/writer test.
  62  *
  63  * 2.   Specify the nr_cpus kernel boot parameter, but set
  64  *      rcuperf.nreaders to zero.  This will set nwriters to the
  65  *      value specified by nr_cpus for an update-only test.
  66  *
  67  * 3.   Specify the nr_cpus kernel boot parameter, but set
  68  *      rcuperf.nwriters to zero.  This will set nreaders to the
  69  *      value specified by nr_cpus for a read-only test.
  70  *
  71  * Various other use cases may of course be specified.
  72  */
  73
  74 #ifdef MODULE
  75 # define RCUPERF_SHUTDOWN 0
  76 #else
  77 # define RCUPERF_SHUTDOWN 1
  78 #endif
  79
  80 torture_param(bool, gp_async, false, "Use asynchronous GP wait primitives");
  81 torture_param(int, gp_async_max, 1000, "Max # outstanding waits per reader");
  82 torture_param(bool, gp_exp, false, "Use expedited GP wait primitives");
  83 torture_param(int, holdoff, 10, "Holdoff time before test start (s)");
  84 torture_param(int, nreaders, -1, "Number of RCU reader threads");
  85 torture_param(int, nwriters, -1, "Number of RCU updater threads");
  86 torture_param(bool, shutdown, RCUPERF_SHUTDOWN,
  87               "Shutdown at end of performance tests.");
  88 torture_param(int, verbose, 1, "Enable verbose debugging printk()s");
  89 torture_param(int, writer_holdoff, 0, "Holdoff (us) between GPs, zero to disable");
  90 torture_param(int, kfree_rcu_test, 0, "Do we run a kfree_rcu() perf test?");
  91 torture_param(int, kfree_mult, 1, "Multiple of kfree_obj size to allocate.");
  92
  93 static char *perf_type = "rcu";
  94 module_param(perf_type, charp, 0444);
  95 MODULE_PARM_DESC(perf_type, "Type of RCU to performance-test (rcu, srcu, ...)");
  96
  97 static int nrealreaders;
  98 static int nrealwriters;
  99 static struct task_struct **writer_tasks;
 100 static struct task_struct **reader_tasks;
 101 static struct task_struct *shutdown_task;
 102
 103 static u64 **writer_durations;
 104 static int *writer_n_durations;
 105 static atomic_t n_rcu_perf_reader_started;
 106 static atomic_t n_rcu_perf_writer_started;
 107 static atomic_t n_rcu_perf_writer_finished;
 108 static wait_queue_head_t shutdown_wq;
 109 static u64 t_rcu_perf_writer_started;
 110 static u64 t_rcu_perf_writer_finished;
 111 static unsigned long b_rcu_gp_test_started;
 112 static unsigned long b_rcu_gp_test_finished;
 113 static DEFINE_PER_CPU(atomic_t, n_async_inflight);
 114
 115 #define MAX_MEAS 10000
 116 #define MIN_MEAS 100
 117
 118 /*
 119  * Operations vector for selecting different types of tests.
 120  */
 121
 122 struct rcu_perf_ops {
 123         int ptype;
 124         void (*init)(void);
 125         void (*cleanup)(void);
 126         int (*readlock)(void);
 127         void (*readunlock)(int idx);
 128         unsigned long (*get_gp_seq)(void);
 129         unsigned long (*gp_diff)(unsigned long new, unsigned long old);
 130         unsigned long (*exp_completed)(void);
 131         void (*async)(struct rcu_head *head, rcu_callback_t func);
 132         void (*gp_barrier)(void);
 133         void (*sync)(void);
 134         void (*exp_sync)(void);
 135         const char *name;
 136 };
 137
 138 static struct rcu_perf_ops *cur_ops;
 139
 140 /*
 141  * Definitions for rcu perf testing.
 142  */
 143
 144 static int rcu_perf_read_lock(void) __acquires(RCU)
 145 {
 146         rcu_read_lock();
 147         return 0;
 148 }
 149
 150 static void rcu_perf_read_unlock(int idx) __releases(RCU)
 151 {
 152         rcu_read_unlock();
 153 }
 154
 155 static unsigned long __maybe_unused rcu_no_completed(void)
 156 {
 157         return 0;
 158 }
 159
 160 static void rcu_sync_perf_init(void)
 161 {
 162 }
 163
 164 static struct rcu_perf_ops rcu_ops = {
 165         .ptype          = RCU_FLAVOR,
 166         .init           = rcu_sync_perf_init,
 167         .readlock       = rcu_perf_read_lock,
 168         .readunlock     = rcu_perf_read_unlock,
 169         .get_gp_seq     = rcu_get_gp_seq,
 170         .gp_diff        = rcu_seq_diff,
 171         .exp_completed  = rcu_exp_batches_completed,
 172         .async          = call_rcu,
 173         .gp_barrier     = rcu_barrier,
 174         .sync           = synchronize_rcu,
 175         .exp_sync       = synchronize_rcu_expedited,
 176         .name           = "rcu"
 177 };
 178
 179 /*
 180  * Definitions for srcu perf testing.
 181  */
 182
 183 DEFINE_STATIC_SRCU(srcu_ctl_perf);
 184 static struct srcu_struct *srcu_ctlp = &srcu_ctl_perf;
 185
 186 static int srcu_perf_read_lock(void) __acquires(srcu_ctlp)
 187 {
 188         return srcu_read_lock(srcu_ctlp);
 189 }
 190
 191 static void srcu_perf_read_unlock(int idx) __releases(srcu_ctlp)
 192 {
 193         srcu_read_unlock(srcu_ctlp, idx);
 194 }
 195
 196 static unsigned long srcu_perf_completed(void)
 197 {
 198         return srcu_batches_completed(srcu_ctlp);
 199 }
 200
 201 static void srcu_call_rcu(struct rcu_head *head, rcu_callback_t func)
 202 {
 203         call_srcu(srcu_ctlp, head, func);
 204 }
 205
 206 static void srcu_rcu_barrier(void)
 207 {
 208         srcu_barrier(srcu_ctlp);
 209 }
 210
 211 static void srcu_perf_synchronize(void)
 212 {
 213         synchronize_srcu(srcu_ctlp);
 214 }
 215
 216 static void srcu_perf_synchronize_expedited(void)
 217 {
 218         synchronize_srcu_expedited(srcu_ctlp);
 219 }
 220
 221 static struct rcu_perf_ops srcu_ops = {
 222         .ptype          = SRCU_FLAVOR,
 223         .init           = rcu_sync_perf_init,
 224         .readlock       = srcu_perf_read_lock,
 225         .readunlock     = srcu_perf_read_unlock,
 226         .get_gp_seq     = srcu_perf_completed,
 227         .gp_diff        = rcu_seq_diff,
 228         .exp_completed  = srcu_perf_completed,
 229         .async          = srcu_call_rcu,
 230         .gp_barrier     = srcu_rcu_barrier,
 231         .sync           = srcu_perf_synchronize,
 232         .exp_sync       = srcu_perf_synchronize_expedited,
 233         .name           = "srcu"
 234 };
 235
 236 static struct srcu_struct srcud;
 237
 238 static void srcu_sync_perf_init(void)
 239 {
 240         srcu_ctlp = &srcud;
 241         init_srcu_struct(srcu_ctlp);
 242 }
 243
 244 static void srcu_sync_perf_cleanup(void)
 245 {
 246         cleanup_srcu_struct(srcu_ctlp);
 247 }
 248
 249 static struct rcu_perf_ops srcud_ops = {
 250         .ptype          = SRCU_FLAVOR,
 251         .init           = srcu_sync_perf_init,
 252         .cleanup        = srcu_sync_perf_cleanup,
 253         .readlock       = srcu_perf_read_lock,
 254         .readunlock     = srcu_perf_read_unlock,
 255         .get_gp_seq     = srcu_perf_completed,
 256         .gp_diff        = rcu_seq_diff,
 257         .exp_completed  = srcu_perf_completed,
 258         .async          = srcu_call_rcu,
 259         .gp_barrier     = srcu_rcu_barrier,
 260         .sync           = srcu_perf_synchronize,
 261         .exp_sync       = srcu_perf_synchronize_expedited,
 262         .name           = "srcud"
 263 };
 264
 265 /*
 266  * Definitions for RCU-tasks perf testing.
 267  */
 268
 269 static int tasks_perf_read_lock(void)
 270 {
 271         return 0;
 272 }
 273
 274 static void tasks_perf_read_unlock(int idx)
 275 {
 276 }
 277
 278 static struct rcu_perf_ops tasks_ops = {
 279         .ptype          = RCU_TASKS_FLAVOR,
 280         .init           = rcu_sync_perf_init,
 281         .readlock       = tasks_perf_read_lock,
 282         .readunlock     = tasks_perf_read_unlock,
 283         .get_gp_seq     = rcu_no_completed,
 284         .gp_diff        = rcu_seq_diff,
 285         .async          = call_rcu_tasks,
 286         .gp_barrier     = rcu_barrier_tasks,
 287         .sync           = synchronize_rcu_tasks,
 288         .exp_sync       = synchronize_rcu_tasks,
 289         .name           = "tasks"
 290 };
 291
 292 static unsigned long rcuperf_seq_diff(unsigned long new, unsigned long old)
 293 {
 294         if (!cur_ops->gp_diff)
 295                 return new - old;
 296         return cur_ops->gp_diff(new, old);
 297 }
 298
 299 /*
 300  * If performance tests complete, wait for shutdown to commence.
 301  */
 302 static void rcu_perf_wait_shutdown(void)
 303 {
 304         cond_resched_tasks_rcu_qs();
 305         if (atomic_read(&n_rcu_perf_writer_finished) < nrealwriters)
 306                 return;
 307         while (!torture_must_stop())
 308                 schedule_timeout_uninterruptible(1);
 309 }
 310
 311 /*
 312  * RCU perf reader kthread.  Repeatedly does empty RCU read-side
 313  * critical section, minimizing update-side interference.
 314  */
 315 static int
 316 rcu_perf_reader(void *arg)
 317 {
 318         unsigned long flags;
 319         int idx;
 320         long me = (long)arg;
 321
 322         VERBOSE_PERFOUT_STRING("rcu_perf_reader task started");
 323         set_cpus_allowed_ptr(current, cpumask_of(me % nr_cpu_ids));
 324         set_user_nice(current, MAX_NICE);
 325         atomic_inc(&n_rcu_perf_reader_started);
 326
 327         do {
 328                 local_irq_save(flags);
 329                 idx = cur_ops->readlock();
 330                 cur_ops->readunlock(idx);
 331                 local_irq_restore(flags);
 332                 rcu_perf_wait_shutdown();
 333         } while (!torture_must_stop());
 334         torture_kthread_stopping("rcu_perf_reader");
 335         return 0;
 336 }
 337
 338 /*
 339  * Callback function for asynchronous grace periods from rcu_perf_writer().
 340  */
 341 static void rcu_perf_async_cb(struct rcu_head *rhp)
 342 {
 343         atomic_dec(this_cpu_ptr(&n_async_inflight));
 344         kfree(rhp);
 345 }
 346
 347 /*
 348  * RCU perf writer kthread.  Repeatedly does a grace period.
 349  */
 350 static int
 351 rcu_perf_writer(void *arg)
 352 {
 353         int i = 0;
 354         int i_max;
 355         long me = (long)arg;
 356         struct rcu_head *rhp = NULL;
 357         struct sched_param sp;
 358         bool started = false, done = false, alldone = false;
 359         u64 t;
 360         u64 *wdp;
 361         u64 *wdpp = writer_durations[me];
 362
 363         VERBOSE_PERFOUT_STRING("rcu_perf_writer task started");
 364         WARN_ON(!wdpp);
 365         set_cpus_allowed_ptr(current, cpumask_of(me % nr_cpu_ids));
 366         sp.sched_priority = 1;
 367         sched_setscheduler_nocheck(current, SCHED_FIFO, &sp);
 368
 369         if (holdoff)
 370                 schedule_timeout_uninterruptible(holdoff * HZ);
 371
 372         /*
 373          * Wait until rcu_end_inkernel_boot() is called for normal GP tests
 374          * so that RCU is not always expedited for normal GP tests.
 375          * The system_state test is approximate, but works well in practice.
 376          */
 377         while (!gp_exp && system_state != SYSTEM_RUNNING)
 378                 schedule_timeout_uninterruptible(1);
 379
 380         t = ktime_get_mono_fast_ns();
 381         if (atomic_inc_return(&n_rcu_perf_writer_started) >= nrealwriters) {
 382                 t_rcu_perf_writer_started = t;
 383                 if (gp_exp) {
 384                         b_rcu_gp_test_started =
 385                                 cur_ops->exp_completed() / 2;
 386                 } else {
 387                         b_rcu_gp_test_started = cur_ops->get_gp_seq();
 388                 }
 389         }
 390
 391         do {
 392                 if (writer_holdoff)
 393                         udelay(writer_holdoff);
 394                 wdp = &wdpp[i];
 395                 *wdp = ktime_get_mono_fast_ns();
 396                 if (gp_async) {
 397 retry:
 398                         if (!rhp)
 399                                 rhp = kmalloc(sizeof(*rhp), GFP_KERNEL);
 400                         if (rhp && atomic_read(this_cpu_ptr(&n_async_inflight)) < gp_async_max) {
 401                                 atomic_inc(this_cpu_ptr(&n_async_inflight));
 402                                 cur_ops->async(rhp, rcu_perf_async_cb);
 403                                 rhp = NULL;
 404                         } else if (!kthread_should_stop()) {
 405                                 cur_ops->gp_barrier();
 406                                 goto retry;
 407                         } else {
 408                                 kfree(rhp); /* Because we are stopping. */
 409                         }
 410                 } else if (gp_exp) {
 411                         cur_ops->exp_sync();
 412                 } else {
 413                         cur_ops->sync();
 414                 }
 415                 t = ktime_get_mono_fast_ns();
 416                 *wdp = t - *wdp;
 417                 i_max = i;
 418                 if (!started &&
 419                     atomic_read(&n_rcu_perf_writer_started) >= nrealwriters)
 420                         started = true;
 421                 if (!done && i >= MIN_MEAS) {
 422                         done = true;
 423                         sp.sched_priority = 0;
 424                         sched_setscheduler_nocheck(current,
 425                                                    SCHED_NORMAL, &sp);
 426                         pr_alert("%s%s rcu_perf_writer %ld has %d measurements\n",
 427                                  perf_type, PERF_FLAG, me, MIN_MEAS);
 428                         if (atomic_inc_return(&n_rcu_perf_writer_finished) >=
 429                             nrealwriters) {
 430                                 schedule_timeout_interruptible(10);
 431                                 rcu_ftrace_dump(DUMP_ALL);
 432                                 PERFOUT_STRING("Test complete");
 433                                 t_rcu_perf_writer_finished = t;
 434                                 if (gp_exp) {
 435                                         b_rcu_gp_test_finished =
 436                                                 cur_ops->exp_completed() / 2;
 437                                 } else {
 438                                         b_rcu_gp_test_finished =
 439                                                 cur_ops->get_gp_seq();
 440                                 }
 441                                 if (shutdown) {
 442                                         smp_mb(); /* Assign before wake. */
 443                                         wake_up(&shutdown_wq);
 444                                 }
 445                         }
 446                 }
 447                 if (done && !alldone &&
 448                     atomic_read(&n_rcu_perf_writer_finished) >= nrealwriters)
 449                         alldone = true;
 450                 if (started && !alldone && i < MAX_MEAS - 1)
 451                         i++;
 452                 rcu_perf_wait_shutdown();
 453         } while (!torture_must_stop());
 454         if (gp_async) {
 455                 cur_ops->gp_barrier();
 456         }
 457         writer_n_durations[me] = i_max;
 458         torture_kthread_stopping("rcu_perf_writer");
 459         return 0;
 460 }
 461
 462 static void
 463 rcu_perf_print_module_parms(struct rcu_perf_ops *cur_ops, const char *tag)
 464 {
 465         pr_alert("%s" PERF_FLAG
 466                  "--- %s: nreaders=%d nwriters=%d verbose=%d shutdown=%d\n",
 467                  perf_type, tag, nrealreaders, nrealwriters, verbose, shutdown);
 468 }
 469
 470 static void
 471 rcu_perf_cleanup(void)
 472 {
 473         int i;
 474         int j;
 475         int ngps = 0;
 476         u64 *wdp;
 477         u64 *wdpp;
 478
 479         /*
 480          * Would like warning at start, but everything is expedited
 481          * during the mid-boot phase, so have to wait till the end.
 482          */
 483         if (rcu_gp_is_expedited() && !rcu_gp_is_normal() && !gp_exp)
 484                 VERBOSE_PERFOUT_ERRSTRING("All grace periods expedited, no normal ones to measure!");
 485         if (rcu_gp_is_normal() && gp_exp)
 486                 VERBOSE_PERFOUT_ERRSTRING("All grace periods normal, no expedited ones to measure!");
 487         if (gp_exp && gp_async)
 488                 VERBOSE_PERFOUT_ERRSTRING("No expedited async GPs, so went with async!");
 489
 490         if (torture_cleanup_begin())
 491                 return;
 492         if (!cur_ops) {
 493                 torture_cleanup_end();
 494                 return;
 495         }
 496
 497         if (reader_tasks) {
 498                 for (i = 0; i < nrealreaders; i++)
 499                         torture_stop_kthread(rcu_perf_reader,
 500                                              reader_tasks[i]);
 501                 kfree(reader_tasks);
 502         }
 503
 504         if (writer_tasks) {
 505                 for (i = 0; i < nrealwriters; i++) {
 506                         torture_stop_kthread(rcu_perf_writer,
 507                                              writer_tasks[i]);
 508                         if (!writer_n_durations)
 509                                 continue;
 510                         j = writer_n_durations[i];
 511                         pr_alert("%s%s writer %d gps: %d\n",
 512                                  perf_type, PERF_FLAG, i, j);
 513                         ngps += j;
 514                 }
 515                 pr_alert("%s%s start: %llu end: %llu duration: %llu gps: %d batches: %ld\n",
 516                          perf_type, PERF_FLAG,
 517                          t_rcu_perf_writer_started, t_rcu_perf_writer_finished,
 518                          t_rcu_perf_writer_finished -
 519                          t_rcu_perf_writer_started,
 520                          ngps,
 521                          rcuperf_seq_diff(b_rcu_gp_test_finished,
 522                                           b_rcu_gp_test_started));
 523                 for (i = 0; i < nrealwriters; i++) {
 524                         if (!writer_durations)
 525                                 break;
 526                         if (!writer_n_durations)
 527                                 continue;
 528                         wdpp = writer_durations[i];
 529                         if (!wdpp)
 530                                 continue;
 531                         for (j = 0; j <= writer_n_durations[i]; j++) {
 532                                 wdp = &wdpp[j];
 533                                 pr_alert("%s%s %4d writer-duration: %5d %llu\n",
 534                                         perf_type, PERF_FLAG,
 535                                         i, j, *wdp);
 536                                 if (j % 100 == 0)
 537                                         schedule_timeout_uninterruptible(1);
 538                         }
 539                         kfree(writer_durations[i]);
 540                 }
 541                 kfree(writer_tasks);
 542                 kfree(writer_durations);
 543                 kfree(writer_n_durations);
 544         }
 545
 546         /* Do torture-type-specific cleanup operations.  */
 547         if (cur_ops->cleanup != NULL)
 548                 cur_ops->cleanup();
 549
 550         torture_cleanup_end();
 551 }
 552
 553 /*
 554  * Return the number if non-negative.  If -1, the number of CPUs.
 555  * If less than -1, that much less than the number of CPUs, but
 556  * at least one.
 557  */
 558 static int compute_real(int n)
 559 {
 560         int nr;
 561
 562         if (n >= 0) {
 563                 nr = n;
 564         } else {
 565                 nr = num_online_cpus() + 1 + n;
 566                 if (nr <= 0)
 567                         nr = 1;
 568         }
 569         return nr;
 570 }
 571
 572 /*
 573  * RCU perf shutdown kthread.  Just waits to be awakened, then shuts
 574  * down system.
 575  */
 576 static int
 577 rcu_perf_shutdown(void *arg)
 578 {
 579         do {
 580                 wait_event(shutdown_wq,
 581                            atomic_read(&n_rcu_perf_writer_finished) >=
 582                            nrealwriters);
 583         } while (atomic_read(&n_rcu_perf_writer_finished) < nrealwriters);
 584         smp_mb(); /* Wake before output. */
 585         rcu_perf_cleanup();
 586         kernel_power_off();
 587         return -EINVAL;
 588 }
 589
 590 /*
 591  * kfree_rcu() performance tests: Start a kfree_rcu() loop on all CPUs for number
 592  * of iterations and measure total time and number of GP for all iterations to complete.
 593  */
 594
 595 torture_param(int, kfree_nthreads, -1, "Number of threads running loops of kfree_rcu().");
 596 torture_param(int, kfree_alloc_num, 8000, "Number of allocations and frees done in an iteration.");
 597 torture_param(int, kfree_loops, 10, "Number of loops doing kfree_alloc_num allocations and frees.");
 598
 599 static struct task_struct **kfree_reader_tasks;
 600 static int kfree_nrealthreads;
 601 static atomic_t n_kfree_perf_thread_started;
 602 static atomic_t n_kfree_perf_thread_ended;
 603
 604 struct kfree_obj {
 605         char kfree_obj[8];
 606         struct rcu_head rh;
 607 };
 608
 609 static int
 610 kfree_perf_thread(void *arg)
 611 {
 612         int i, loop = 0;
 613         long me = (long)arg;
 614         struct kfree_obj *alloc_ptr;
 615         u64 start_time, end_time;
 616         long long mem_begin, mem_during = 0;
 617
 618         VERBOSE_PERFOUT_STRING("kfree_perf_thread task started");
 619         set_cpus_allowed_ptr(current, cpumask_of(me % nr_cpu_ids));
 620         set_user_nice(current, MAX_NICE);
 621
 622         start_time = ktime_get_mono_fast_ns();
 623
 624         if (atomic_inc_return(&n_kfree_perf_thread_started) >= kfree_nrealthreads) {
 625                 if (gp_exp)
 626                         b_rcu_gp_test_started = cur_ops->exp_completed() / 2;
 627                 else
 628                         b_rcu_gp_test_started = cur_ops->get_gp_seq();
 629         }
 630
 631         do {
 632                 if (!mem_during) {
 633                         mem_during = mem_begin = si_mem_available();
 634                 } else if (loop % (kfree_loops / 4) == 0) {
 635                         mem_during = (mem_during + si_mem_available()) / 2;
 636                 }
 637
 638                 for (i = 0; i < kfree_alloc_num; i++) {
 639                         alloc_ptr = kmalloc(kfree_mult * sizeof(struct kfree_obj), GFP_KERNEL);
 640                         if (!alloc_ptr)
 641                                 return -ENOMEM;
 642
 643                         kfree_rcu(alloc_ptr, rh);
 644                 }
 645
 646                 cond_resched();
 647         } while (!torture_must_stop() && ++loop < kfree_loops);
 648
 649         if (atomic_inc_return(&n_kfree_perf_thread_ended) >= kfree_nrealthreads) {
 650                 end_time = ktime_get_mono_fast_ns();
 651
 652                 if (gp_exp)
 653                         b_rcu_gp_test_finished = cur_ops->exp_completed() / 2;
 654                 else
 655                         b_rcu_gp_test_finished = cur_ops->get_gp_seq();
 656
 657                 pr_alert("Total time taken by all kfree'ers: %llu ns, loops: %d, batches: %ld, memory footprint: %lldMB\n",
 658                        (unsigned long long)(end_time - start_time), kfree_loops,
 659                        rcuperf_seq_diff(b_rcu_gp_test_finished, b_rcu_gp_test_started),
 660                        (mem_begin - mem_during) >> (20 - PAGE_SHIFT));
 661
 662                 if (shutdown) {
 663                         smp_mb(); /* Assign before wake. */
 664                         wake_up(&shutdown_wq);
 665                 }
 666         }
 667
 668         torture_kthread_stopping("kfree_perf_thread");
 669         return 0;
 670 }
 671
 672 static void
 673 kfree_perf_cleanup(void)
 674 {
 675         int i;
 676
 677         if (torture_cleanup_begin())
 678                 return;
 679
 680         if (kfree_reader_tasks) {
 681                 for (i = 0; i < kfree_nrealthreads; i++)
 682                         torture_stop_kthread(kfree_perf_thread,
 683                                              kfree_reader_tasks[i]);
 684                 kfree(kfree_reader_tasks);
 685         }
 686
 687         torture_cleanup_end();
 688 }
 689
 690 /*
 691  * shutdown kthread.  Just waits to be awakened, then shuts down system.
 692  */
 693 static int
 694 kfree_perf_shutdown(void *arg)
 695 {
 696         do {
 697                 wait_event(shutdown_wq,
 698                            atomic_read(&n_kfree_perf_thread_ended) >=
 699                            kfree_nrealthreads);
 700         } while (atomic_read(&n_kfree_perf_thread_ended) < kfree_nrealthreads);
 701
 702         smp_mb(); /* Wake before output. */
 703
 704         kfree_perf_cleanup();
 705         kernel_power_off();
 706         return -EINVAL;
 707 }
 708
 709 static int __init
 710 kfree_perf_init(void)
 711 {
 712         long i;
 713         int firsterr = 0;
 714
 715         kfree_nrealthreads = compute_real(kfree_nthreads);
 716         /* Start up the kthreads. */
 717         if (shutdown) {
 718                 init_waitqueue_head(&shutdown_wq);
 719                 firsterr = torture_create_kthread(kfree_perf_shutdown, NULL,
 720                                                   shutdown_task);
 721                 if (firsterr)
 722                         goto unwind;
 723                 schedule_timeout_uninterruptible(1);
 724         }
 725
 726         pr_alert("kfree object size=%zu\n", kfree_mult * sizeof(struct kfree_obj));
 727
 728         kfree_reader_tasks = kcalloc(kfree_nrealthreads, sizeof(kfree_reader_tasks[0]),
 729                                GFP_KERNEL);
 730         if (kfree_reader_tasks == NULL) {
 731                 firsterr = -ENOMEM;
 732                 goto unwind;
 733         }
 734
 735         for (i = 0; i < kfree_nrealthreads; i++) {
 736                 firsterr = torture_create_kthread(kfree_perf_thread, (void *)i,
 737                                                   kfree_reader_tasks[i]);
 738                 if (firsterr)
 739                         goto unwind;
 740         }
 741
 742         while (atomic_read(&n_kfree_perf_thread_started) < kfree_nrealthreads)
 743                 schedule_timeout_uninterruptible(1);
 744
 745         torture_init_end();
 746         return 0;
 747
 748 unwind:
 749         torture_init_end();
 750         kfree_perf_cleanup();
 751         return firsterr;
 752 }
 753
 754 static int __init
 755 rcu_perf_init(void)
 756 {
 757         long i;
 758         int firsterr = 0;
 759         static struct rcu_perf_ops *perf_ops[] = {
 760                 &rcu_ops, &srcu_ops, &srcud_ops, &tasks_ops,
 761         };
 762
 763         if (!torture_init_begin(perf_type, verbose))
 764                 return -EBUSY;
 765
 766         /* Process args and tell the world that the perf'er is on the job. */
 767         for (i = 0; i < ARRAY_SIZE(perf_ops); i++) {
 768                 cur_ops = perf_ops[i];
 769                 if (strcmp(perf_type, cur_ops->name) == 0)
 770                         break;
 771         }
 772         if (i == ARRAY_SIZE(perf_ops)) {
 773                 pr_alert("rcu-perf: invalid perf type: \"%s\"\n", perf_type);
 774                 pr_alert("rcu-perf types:");
 775                 for (i = 0; i < ARRAY_SIZE(perf_ops); i++)
 776                         pr_cont(" %s", perf_ops[i]->name);
 777                 pr_cont("\n");
 778                 WARN_ON(!IS_MODULE(CONFIG_RCU_PERF_TEST));
 779                 firsterr = -EINVAL;
 780                 cur_ops = NULL;
 781                 goto unwind;
 782         }
 783         if (cur_ops->init)
 784                 cur_ops->init();
 785
 786         if (kfree_rcu_test)
 787                 return kfree_perf_init();
 788
 789         nrealwriters = compute_real(nwriters);
 790         nrealreaders = compute_real(nreaders);
 791         atomic_set(&n_rcu_perf_reader_started, 0);
 792         atomic_set(&n_rcu_perf_writer_started, 0);
 793         atomic_set(&n_rcu_perf_writer_finished, 0);
 794         rcu_perf_print_module_parms(cur_ops, "Start of test");
 795
 796         /* Start up the kthreads. */
 797
 798         if (shutdown) {
 799                 init_waitqueue_head(&shutdown_wq);
 800                 firsterr = torture_create_kthread(rcu_perf_shutdown, NULL,
 801                                                   shutdown_task);
 802                 if (firsterr)
 803                         goto unwind;
 804                 schedule_timeout_uninterruptible(1);
 805         }
 806         reader_tasks = kcalloc(nrealreaders, sizeof(reader_tasks[0]),
 807                                GFP_KERNEL);
 808         if (reader_tasks == NULL) {
 809                 VERBOSE_PERFOUT_ERRSTRING("out of memory");
 810                 firsterr = -ENOMEM;
 811                 goto unwind;
 812         }
 813         for (i = 0; i < nrealreaders; i++) {
 814                 firsterr = torture_create_kthread(rcu_perf_reader, (void *)i,
 815                                                   reader_tasks[i]);
 816                 if (firsterr)
 817                         goto unwind;
 818         }
 819         while (atomic_read(&n_rcu_perf_reader_started) < nrealreaders)
 820                 schedule_timeout_uninterruptible(1);
 821         writer_tasks = kcalloc(nrealwriters, sizeof(reader_tasks[0]),
 822                                GFP_KERNEL);
 823         writer_durations = kcalloc(nrealwriters, sizeof(*writer_durations),
 824                                    GFP_KERNEL);
 825         writer_n_durations =
 826                 kcalloc(nrealwriters, sizeof(*writer_n_durations),
 827                         GFP_KERNEL);
 828         if (!writer_tasks || !writer_durations || !writer_n_durations) {
 829                 VERBOSE_PERFOUT_ERRSTRING("out of memory");
 830                 firsterr = -ENOMEM;
 831                 goto unwind;
 832         }
 833         for (i = 0; i < nrealwriters; i++) {
 834                 writer_durations[i] =
 835                         kcalloc(MAX_MEAS, sizeof(*writer_durations[i]),
 836                                 GFP_KERNEL);
 837                 if (!writer_durations[i]) {
 838                         firsterr = -ENOMEM;
 839                         goto unwind;
 840                 }
 841                 firsterr = torture_create_kthread(rcu_perf_writer, (void *)i,
 842                                                   writer_tasks[i]);
 843                 if (firsterr)
 844                         goto unwind;
 845         }
 846         torture_init_end();
 847         return 0;
 848
 849 unwind:
 850         torture_init_end();
 851         rcu_perf_cleanup();
 852         return firsterr;
 853 }
 854
 855 module_init(rcu_perf_init);
 856 module_exit(rcu_perf_cleanup);