kernel/rcu/rcuscale.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * Read-Copy Update module-based scalability-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 SCALE_FLAG "-scale:"
  48 #define SCALEOUT_STRING(s) \
  49         pr_alert("%s" SCALE_FLAG " %s\n", scale_type, s)
  50 #define VERBOSE_SCALEOUT_STRING(s) \
  51         do { if (verbose) pr_alert("%s" SCALE_FLAG " %s\n", scale_type, s); } while (0)
  52 #define VERBOSE_SCALEOUT_ERRSTRING(s) \
  53         do { if (verbose) pr_alert("%s" SCALE_FLAG "!!! %s\n", scale_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  *      rcuscale.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  *      rcuscale.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  * Note that this test's readers are intended only as a test load for
  74  * the writers.  The reader scalability statistics will be overly
  75  * pessimistic due to the per-critical-section interrupt disabling,
  76  * test-end checks, and the pair of calls through pointers.
  77  */
  78
  79 #ifdef MODULE
  80 # define RCUSCALE_SHUTDOWN 0
  81 #else
  82 # define RCUSCALE_SHUTDOWN 1
  83 #endif
  84
  85 torture_param(bool, gp_async, false, "Use asynchronous GP wait primitives");
  86 torture_param(int, gp_async_max, 1000, "Max # outstanding waits per reader");
  87 torture_param(bool, gp_exp, false, "Use expedited GP wait primitives");
  88 torture_param(int, holdoff, 10, "Holdoff time before test start (s)");
  89 torture_param(int, nreaders, -1, "Number of RCU reader threads");
  90 torture_param(int, nwriters, -1, "Number of RCU updater threads");
  91 torture_param(bool, shutdown, RCUSCALE_SHUTDOWN,
  92               "Shutdown at end of scalability tests.");
  93 torture_param(int, verbose, 1, "Enable verbose debugging printk()s");
  94 torture_param(int, writer_holdoff, 0, "Holdoff (us) between GPs, zero to disable");
  95 torture_param(int, kfree_rcu_test, 0, "Do we run a kfree_rcu() scale test?");
  96 torture_param(int, kfree_mult, 1, "Multiple of kfree_obj size to allocate.");
  97
  98 static char *scale_type = "rcu";
  99 module_param(scale_type, charp, 0444);
 100 MODULE_PARM_DESC(scale_type, "Type of RCU to scalability-test (rcu, srcu, ...)");
 101
 102 static int nrealreaders;
 103 static int nrealwriters;
 104 static struct task_struct **writer_tasks;
 105 static struct task_struct **reader_tasks;
 106 static struct task_struct *shutdown_task;
 107
 108 static u64 **writer_durations;
 109 static int *writer_n_durations;
 110 static atomic_t n_rcu_scale_reader_started;
 111 static atomic_t n_rcu_scale_writer_started;
 112 static atomic_t n_rcu_scale_writer_finished;
 113 static wait_queue_head_t shutdown_wq;
 114 static u64 t_rcu_scale_writer_started;
 115 static u64 t_rcu_scale_writer_finished;
 116 static unsigned long b_rcu_gp_test_started;
 117 static unsigned long b_rcu_gp_test_finished;
 118 static DEFINE_PER_CPU(atomic_t, n_async_inflight);
 119
 120 #define MAX_MEAS 10000
 121 #define MIN_MEAS 100
 122
 123 /*
 124  * Operations vector for selecting different types of tests.
 125  */
 126
 127 struct rcu_scale_ops {
 128         int ptype;
 129         void (*init)(void);
 130         void (*cleanup)(void);
 131         int (*readlock)(void);
 132         void (*readunlock)(int idx);
 133         unsigned long (*get_gp_seq)(void);
 134         unsigned long (*gp_diff)(unsigned long new, unsigned long old);
 135         unsigned long (*exp_completed)(void);
 136         void (*async)(struct rcu_head *head, rcu_callback_t func);
 137         void (*gp_barrier)(void);
 138         void (*sync)(void);
 139         void (*exp_sync)(void);
 140         const char *name;
 141 };
 142
 143 static struct rcu_scale_ops *cur_ops;
 144
 145 /*
 146  * Definitions for rcu scalability testing.
 147  */
 148
 149 static int rcu_scale_read_lock(void) __acquires(RCU)
 150 {
 151         rcu_read_lock();
 152         return 0;
 153 }
 154
 155 static void rcu_scale_read_unlock(int idx) __releases(RCU)
 156 {
 157         rcu_read_unlock();
 158 }
 159
 160 static unsigned long __maybe_unused rcu_no_completed(void)
 161 {
 162         return 0;
 163 }
 164
 165 static void rcu_sync_scale_init(void)
 166 {
 167 }
 168
 169 static struct rcu_scale_ops rcu_ops = {
 170         .ptype          = RCU_FLAVOR,
 171         .init           = rcu_sync_scale_init,
 172         .readlock       = rcu_scale_read_lock,
 173         .readunlock     = rcu_scale_read_unlock,
 174         .get_gp_seq     = rcu_get_gp_seq,
 175         .gp_diff        = rcu_seq_diff,
 176         .exp_completed  = rcu_exp_batches_completed,
 177         .async          = call_rcu,
 178         .gp_barrier     = rcu_barrier,
 179         .sync           = synchronize_rcu,
 180         .exp_sync       = synchronize_rcu_expedited,
 181         .name           = "rcu"
 182 };
 183
 184 /*
 185  * Definitions for srcu scalability testing.
 186  */
 187
 188 DEFINE_STATIC_SRCU(srcu_ctl_scale);
 189 static struct srcu_struct *srcu_ctlp = &srcu_ctl_scale;
 190
 191 static int srcu_scale_read_lock(void) __acquires(srcu_ctlp)
 192 {
 193         return srcu_read_lock(srcu_ctlp);
 194 }
 195
 196 static void srcu_scale_read_unlock(int idx) __releases(srcu_ctlp)
 197 {
 198         srcu_read_unlock(srcu_ctlp, idx);
 199 }
 200
 201 static unsigned long srcu_scale_completed(void)
 202 {
 203         return srcu_batches_completed(srcu_ctlp);
 204 }
 205
 206 static void srcu_call_rcu(struct rcu_head *head, rcu_callback_t func)
 207 {
 208         call_srcu(srcu_ctlp, head, func);
 209 }
 210
 211 static void srcu_rcu_barrier(void)
 212 {
 213         srcu_barrier(srcu_ctlp);
 214 }
 215
 216 static void srcu_scale_synchronize(void)
 217 {
 218         synchronize_srcu(srcu_ctlp);
 219 }
 220
 221 static void srcu_scale_synchronize_expedited(void)
 222 {
 223         synchronize_srcu_expedited(srcu_ctlp);
 224 }
 225
 226 static struct rcu_scale_ops srcu_ops = {
 227         .ptype          = SRCU_FLAVOR,
 228         .init           = rcu_sync_scale_init,
 229         .readlock       = srcu_scale_read_lock,
 230         .readunlock     = srcu_scale_read_unlock,
 231         .get_gp_seq     = srcu_scale_completed,
 232         .gp_diff        = rcu_seq_diff,
 233         .exp_completed  = srcu_scale_completed,
 234         .async          = srcu_call_rcu,
 235         .gp_barrier     = srcu_rcu_barrier,
 236         .sync           = srcu_scale_synchronize,
 237         .exp_sync       = srcu_scale_synchronize_expedited,
 238         .name           = "srcu"
 239 };
 240
 241 static struct srcu_struct srcud;
 242
 243 static void srcu_sync_scale_init(void)
 244 {
 245         srcu_ctlp = &srcud;
 246         init_srcu_struct(srcu_ctlp);
 247 }
 248
 249 static void srcu_sync_scale_cleanup(void)
 250 {
 251         cleanup_srcu_struct(srcu_ctlp);
 252 }
 253
 254 static struct rcu_scale_ops srcud_ops = {
 255         .ptype          = SRCU_FLAVOR,
 256         .init           = srcu_sync_scale_init,
 257         .cleanup        = srcu_sync_scale_cleanup,
 258         .readlock       = srcu_scale_read_lock,
 259         .readunlock     = srcu_scale_read_unlock,
 260         .get_gp_seq     = srcu_scale_completed,
 261         .gp_diff        = rcu_seq_diff,
 262         .exp_completed  = srcu_scale_completed,
 263         .async          = srcu_call_rcu,
 264         .gp_barrier     = srcu_rcu_barrier,
 265         .sync           = srcu_scale_synchronize,
 266         .exp_sync       = srcu_scale_synchronize_expedited,
 267         .name           = "srcud"
 268 };
 269
 270 /*
 271  * Definitions for RCU-tasks scalability testing.
 272  */
 273
 274 static int tasks_scale_read_lock(void)
 275 {
 276         return 0;
 277 }
 278
 279 static void tasks_scale_read_unlock(int idx)
 280 {
 281 }
 282
 283 static struct rcu_scale_ops tasks_ops = {
 284         .ptype          = RCU_TASKS_FLAVOR,
 285         .init           = rcu_sync_scale_init,
 286         .readlock       = tasks_scale_read_lock,
 287         .readunlock     = tasks_scale_read_unlock,
 288         .get_gp_seq     = rcu_no_completed,
 289         .gp_diff        = rcu_seq_diff,
 290         .async          = call_rcu_tasks,
 291         .gp_barrier     = rcu_barrier_tasks,
 292         .sync           = synchronize_rcu_tasks,
 293         .exp_sync       = synchronize_rcu_tasks,
 294         .name           = "tasks"
 295 };
 296
 297 static unsigned long rcuscale_seq_diff(unsigned long new, unsigned long old)
 298 {
 299         if (!cur_ops->gp_diff)
 300                 return new - old;
 301         return cur_ops->gp_diff(new, old);
 302 }
 303
 304 /*
 305  * If scalability tests complete, wait for shutdown to commence.
 306  */
 307 static void rcu_scale_wait_shutdown(void)
 308 {
 309         cond_resched_tasks_rcu_qs();
 310         if (atomic_read(&n_rcu_scale_writer_finished) < nrealwriters)
 311                 return;
 312         while (!torture_must_stop())
 313                 schedule_timeout_uninterruptible(1);
 314 }
 315
 316 /*
 317  * RCU scalability reader kthread.  Repeatedly does empty RCU read-side
 318  * critical section, minimizing update-side interference.  However, the
 319  * point of this test is not to evaluate reader scalability, but instead
 320  * to serve as a test load for update-side scalability testing.
 321  */
 322 static int
 323 rcu_scale_reader(void *arg)
 324 {
 325         unsigned long flags;
 326         int idx;
 327         long me = (long)arg;
 328
 329         VERBOSE_SCALEOUT_STRING("rcu_scale_reader task started");
 330         set_cpus_allowed_ptr(current, cpumask_of(me % nr_cpu_ids));
 331         set_user_nice(current, MAX_NICE);
 332         atomic_inc(&n_rcu_scale_reader_started);
 333
 334         do {
 335                 local_irq_save(flags);
 336                 idx = cur_ops->readlock();
 337                 cur_ops->readunlock(idx);
 338                 local_irq_restore(flags);
 339                 rcu_scale_wait_shutdown();
 340         } while (!torture_must_stop());
 341         torture_kthread_stopping("rcu_scale_reader");
 342         return 0;
 343 }
 344
 345 /*
 346  * Callback function for asynchronous grace periods from rcu_scale_writer().
 347  */
 348 static void rcu_scale_async_cb(struct rcu_head *rhp)
 349 {
 350         atomic_dec(this_cpu_ptr(&n_async_inflight));
 351         kfree(rhp);
 352 }
 353
 354 /*
 355  * RCU scale writer kthread.  Repeatedly does a grace period.
 356  */
 357 static int
 358 rcu_scale_writer(void *arg)
 359 {
 360         int i = 0;
 361         int i_max;
 362         long me = (long)arg;
 363         struct rcu_head *rhp = NULL;
 364         bool started = false, done = false, alldone = false;
 365         u64 t;
 366         u64 *wdp;
 367         u64 *wdpp = writer_durations[me];
 368
 369         VERBOSE_SCALEOUT_STRING("rcu_scale_writer task started");
 370         WARN_ON(!wdpp);
 371         set_cpus_allowed_ptr(current, cpumask_of(me % nr_cpu_ids));
 372         sched_set_fifo_low(current);
 373
 374         if (holdoff)
 375                 schedule_timeout_uninterruptible(holdoff * HZ);
 376
 377         /*
 378          * Wait until rcu_end_inkernel_boot() is called for normal GP tests
 379          * so that RCU is not always expedited for normal GP tests.
 380          * The system_state test is approximate, but works well in practice.
 381          */
 382         while (!gp_exp && system_state != SYSTEM_RUNNING)
 383                 schedule_timeout_uninterruptible(1);
 384
 385         t = ktime_get_mono_fast_ns();
 386         if (atomic_inc_return(&n_rcu_scale_writer_started) >= nrealwriters) {
 387                 t_rcu_scale_writer_started = t;
 388                 if (gp_exp) {
 389                         b_rcu_gp_test_started =
 390                                 cur_ops->exp_completed() / 2;
 391                 } else {
 392                         b_rcu_gp_test_started = cur_ops->get_gp_seq();
 393                 }
 394         }
 395
 396         do {
 397                 if (writer_holdoff)
 398                         udelay(writer_holdoff);
 399                 wdp = &wdpp[i];
 400                 *wdp = ktime_get_mono_fast_ns();
 401                 if (gp_async) {
 402 retry:
 403                         if (!rhp)
 404                                 rhp = kmalloc(sizeof(*rhp), GFP_KERNEL);
 405                         if (rhp && atomic_read(this_cpu_ptr(&n_async_inflight)) < gp_async_max) {
 406                                 atomic_inc(this_cpu_ptr(&n_async_inflight));
 407                                 cur_ops->async(rhp, rcu_scale_async_cb);
 408                                 rhp = NULL;
 409                         } else if (!kthread_should_stop()) {
 410                                 cur_ops->gp_barrier();
 411                                 goto retry;
 412                         } else {
 413                                 kfree(rhp); /* Because we are stopping. */
 414                         }
 415                 } else if (gp_exp) {
 416                         cur_ops->exp_sync();
 417                 } else {
 418                         cur_ops->sync();
 419                 }
 420                 t = ktime_get_mono_fast_ns();
 421                 *wdp = t - *wdp;
 422                 i_max = i;
 423                 if (!started &&
 424                     atomic_read(&n_rcu_scale_writer_started) >= nrealwriters)
 425                         started = true;
 426                 if (!done && i >= MIN_MEAS) {
 427                         done = true;
 428                         sched_set_normal(current, 0);
 429                         pr_alert("%s%s rcu_scale_writer %ld has %d measurements\n",
 430                                  scale_type, SCALE_FLAG, me, MIN_MEAS);
 431                         if (atomic_inc_return(&n_rcu_scale_writer_finished) >=
 432                             nrealwriters) {
 433                                 schedule_timeout_interruptible(10);
 434                                 rcu_ftrace_dump(DUMP_ALL);
 435                                 SCALEOUT_STRING("Test complete");
 436                                 t_rcu_scale_writer_finished = t;
 437                                 if (gp_exp) {
 438                                         b_rcu_gp_test_finished =
 439                                                 cur_ops->exp_completed() / 2;
 440                                 } else {
 441                                         b_rcu_gp_test_finished =
 442                                                 cur_ops->get_gp_seq();
 443                                 }
 444                                 if (shutdown) {
 445                                         smp_mb(); /* Assign before wake. */
 446                                         wake_up(&shutdown_wq);
 447                                 }
 448                         }
 449                 }
 450                 if (done && !alldone &&
 451                     atomic_read(&n_rcu_scale_writer_finished) >= nrealwriters)
 452                         alldone = true;
 453                 if (started && !alldone && i < MAX_MEAS - 1)
 454                         i++;
 455                 rcu_scale_wait_shutdown();
 456         } while (!torture_must_stop());
 457         if (gp_async) {
 458                 cur_ops->gp_barrier();
 459         }
 460         writer_n_durations[me] = i_max;
 461         torture_kthread_stopping("rcu_scale_writer");
 462         return 0;
 463 }
 464
 465 static void
 466 rcu_scale_print_module_parms(struct rcu_scale_ops *cur_ops, const char *tag)
 467 {
 468         pr_alert("%s" SCALE_FLAG
 469                  "--- %s: nreaders=%d nwriters=%d verbose=%d shutdown=%d\n",
 470                  scale_type, tag, nrealreaders, nrealwriters, verbose, shutdown);
 471 }
 472
 473 static void
 474 rcu_scale_cleanup(void)
 475 {
 476         int i;
 477         int j;
 478         int ngps = 0;
 479         u64 *wdp;
 480         u64 *wdpp;
 481
 482         /*
 483          * Would like warning at start, but everything is expedited
 484          * during the mid-boot phase, so have to wait till the end.
 485          */
 486         if (rcu_gp_is_expedited() && !rcu_gp_is_normal() && !gp_exp)
 487                 VERBOSE_SCALEOUT_ERRSTRING("All grace periods expedited, no normal ones to measure!");
 488         if (rcu_gp_is_normal() && gp_exp)
 489                 VERBOSE_SCALEOUT_ERRSTRING("All grace periods normal, no expedited ones to measure!");
 490         if (gp_exp && gp_async)
 491                 VERBOSE_SCALEOUT_ERRSTRING("No expedited async GPs, so went with async!");
 492
 493         if (torture_cleanup_begin())
 494                 return;
 495         if (!cur_ops) {
 496                 torture_cleanup_end();
 497                 return;
 498         }
 499
 500         if (reader_tasks) {
 501                 for (i = 0; i < nrealreaders; i++)
 502                         torture_stop_kthread(rcu_scale_reader,
 503                                              reader_tasks[i]);
 504                 kfree(reader_tasks);
 505         }
 506
 507         if (writer_tasks) {
 508                 for (i = 0; i < nrealwriters; i++) {
 509                         torture_stop_kthread(rcu_scale_writer,
 510                                              writer_tasks[i]);
 511                         if (!writer_n_durations)
 512                                 continue;
 513                         j = writer_n_durations[i];
 514                         pr_alert("%s%s writer %d gps: %d\n",
 515                                  scale_type, SCALE_FLAG, i, j);
 516                         ngps += j;
 517                 }
 518                 pr_alert("%s%s start: %llu end: %llu duration: %llu gps: %d batches: %ld\n",
 519                          scale_type, SCALE_FLAG,
 520                          t_rcu_scale_writer_started, t_rcu_scale_writer_finished,
 521                          t_rcu_scale_writer_finished -
 522                          t_rcu_scale_writer_started,
 523                          ngps,
 524                          rcuscale_seq_diff(b_rcu_gp_test_finished,
 525                                            b_rcu_gp_test_started));
 526                 for (i = 0; i < nrealwriters; i++) {
 527                         if (!writer_durations)
 528                                 break;
 529                         if (!writer_n_durations)
 530                                 continue;
 531                         wdpp = writer_durations[i];
 532                         if (!wdpp)
 533                                 continue;
 534                         for (j = 0; j <= writer_n_durations[i]; j++) {
 535                                 wdp = &wdpp[j];
 536                                 pr_alert("%s%s %4d writer-duration: %5d %llu\n",
 537                                         scale_type, SCALE_FLAG,
 538                                         i, j, *wdp);
 539                                 if (j % 100 == 0)
 540                                         schedule_timeout_uninterruptible(1);
 541                         }
 542                         kfree(writer_durations[i]);
 543                 }
 544                 kfree(writer_tasks);
 545                 kfree(writer_durations);
 546                 kfree(writer_n_durations);
 547         }
 548
 549         /* Do torture-type-specific cleanup operations.  */
 550         if (cur_ops->cleanup != NULL)
 551                 cur_ops->cleanup();
 552
 553         torture_cleanup_end();
 554 }
 555
 556 /*
 557  * Return the number if non-negative.  If -1, the number of CPUs.
 558  * If less than -1, that much less than the number of CPUs, but
 559  * at least one.
 560  */
 561 static int compute_real(int n)
 562 {
 563         int nr;
 564
 565         if (n >= 0) {
 566                 nr = n;
 567         } else {
 568                 nr = num_online_cpus() + 1 + n;
 569                 if (nr <= 0)
 570                         nr = 1;
 571         }
 572         return nr;
 573 }
 574
 575 /*
 576  * RCU scalability shutdown kthread.  Just waits to be awakened, then shuts
 577  * down system.
 578  */
 579 static int
 580 rcu_scale_shutdown(void *arg)
 581 {
 582         wait_event(shutdown_wq,
 583                    atomic_read(&n_rcu_scale_writer_finished) >= nrealwriters);
 584         smp_mb(); /* Wake before output. */
 585         rcu_scale_cleanup();
 586         kernel_power_off();
 587         return -EINVAL;
 588 }
 589
 590 /*
 591  * kfree_rcu() scalability 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_scale_thread_started;
 602 static atomic_t n_kfree_scale_thread_ended;
 603
 604 struct kfree_obj {
 605         char kfree_obj[8];
 606         struct rcu_head rh;
 607 };
 608
 609 static int
 610 kfree_scale_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_SCALEOUT_STRING("kfree_scale_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_scale_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_scale_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                        rcuscale_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_scale_thread");
 669         return 0;
 670 }
 671
 672 static void
 673 kfree_scale_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_scale_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_scale_shutdown(void *arg)
 695 {
 696         wait_event(shutdown_wq,
 697                    atomic_read(&n_kfree_scale_thread_ended) >= kfree_nrealthreads);
 698
 699         smp_mb(); /* Wake before output. */
 700
 701         kfree_scale_cleanup();
 702         kernel_power_off();
 703         return -EINVAL;
 704 }
 705
 706 static int __init
 707 kfree_scale_init(void)
 708 {
 709         long i;
 710         int firsterr = 0;
 711
 712         kfree_nrealthreads = compute_real(kfree_nthreads);
 713         /* Start up the kthreads. */
 714         if (shutdown) {
 715                 init_waitqueue_head(&shutdown_wq);
 716                 firsterr = torture_create_kthread(kfree_scale_shutdown, NULL,
 717                                                   shutdown_task);
 718                 if (firsterr)
 719                         goto unwind;
 720                 schedule_timeout_uninterruptible(1);
 721         }
 722
 723         pr_alert("kfree object size=%zu\n", kfree_mult * sizeof(struct kfree_obj));
 724
 725         kfree_reader_tasks = kcalloc(kfree_nrealthreads, sizeof(kfree_reader_tasks[0]),
 726                                GFP_KERNEL);
 727         if (kfree_reader_tasks == NULL) {
 728                 firsterr = -ENOMEM;
 729                 goto unwind;
 730         }
 731
 732         for (i = 0; i < kfree_nrealthreads; i++) {
 733                 firsterr = torture_create_kthread(kfree_scale_thread, (void *)i,
 734                                                   kfree_reader_tasks[i]);
 735                 if (firsterr)
 736                         goto unwind;
 737         }
 738
 739         while (atomic_read(&n_kfree_scale_thread_started) < kfree_nrealthreads)
 740                 schedule_timeout_uninterruptible(1);
 741
 742         torture_init_end();
 743         return 0;
 744
 745 unwind:
 746         torture_init_end();
 747         kfree_scale_cleanup();
 748         return firsterr;
 749 }
 750
 751 static int __init
 752 rcu_scale_init(void)
 753 {
 754         long i;
 755         int firsterr = 0;
 756         static struct rcu_scale_ops *scale_ops[] = {
 757                 &rcu_ops, &srcu_ops, &srcud_ops, &tasks_ops,
 758         };
 759
 760         if (!torture_init_begin(scale_type, verbose))
 761                 return -EBUSY;
 762
 763         /* Process args and announce that the scalability'er is on the job. */
 764         for (i = 0; i < ARRAY_SIZE(scale_ops); i++) {
 765                 cur_ops = scale_ops[i];
 766                 if (strcmp(scale_type, cur_ops->name) == 0)
 767                         break;
 768         }
 769         if (i == ARRAY_SIZE(scale_ops)) {
 770                 pr_alert("rcu-scale: invalid scale type: \"%s\"\n", scale_type);
 771                 pr_alert("rcu-scale types:");
 772                 for (i = 0; i < ARRAY_SIZE(scale_ops); i++)
 773                         pr_cont(" %s", scale_ops[i]->name);
 774                 pr_cont("\n");
 775                 WARN_ON(!IS_MODULE(CONFIG_RCU_SCALE_TEST));
 776                 firsterr = -EINVAL;
 777                 cur_ops = NULL;
 778                 goto unwind;
 779         }
 780         if (cur_ops->init)
 781                 cur_ops->init();
 782
 783         if (kfree_rcu_test)
 784                 return kfree_scale_init();
 785
 786         nrealwriters = compute_real(nwriters);
 787         nrealreaders = compute_real(nreaders);
 788         atomic_set(&n_rcu_scale_reader_started, 0);
 789         atomic_set(&n_rcu_scale_writer_started, 0);
 790         atomic_set(&n_rcu_scale_writer_finished, 0);
 791         rcu_scale_print_module_parms(cur_ops, "Start of test");
 792
 793         /* Start up the kthreads. */
 794
 795         if (shutdown) {
 796                 init_waitqueue_head(&shutdown_wq);
 797                 firsterr = torture_create_kthread(rcu_scale_shutdown, NULL,
 798                                                   shutdown_task);
 799                 if (firsterr)
 800                         goto unwind;
 801                 schedule_timeout_uninterruptible(1);
 802         }
 803         reader_tasks = kcalloc(nrealreaders, sizeof(reader_tasks[0]),
 804                                GFP_KERNEL);
 805         if (reader_tasks == NULL) {
 806                 VERBOSE_SCALEOUT_ERRSTRING("out of memory");
 807                 firsterr = -ENOMEM;
 808                 goto unwind;
 809         }
 810         for (i = 0; i < nrealreaders; i++) {
 811                 firsterr = torture_create_kthread(rcu_scale_reader, (void *)i,
 812                                                   reader_tasks[i]);
 813                 if (firsterr)
 814                         goto unwind;
 815         }
 816         while (atomic_read(&n_rcu_scale_reader_started) < nrealreaders)
 817                 schedule_timeout_uninterruptible(1);
 818         writer_tasks = kcalloc(nrealwriters, sizeof(reader_tasks[0]),
 819                                GFP_KERNEL);
 820         writer_durations = kcalloc(nrealwriters, sizeof(*writer_durations),
 821                                    GFP_KERNEL);
 822         writer_n_durations =
 823                 kcalloc(nrealwriters, sizeof(*writer_n_durations),
 824                         GFP_KERNEL);
 825         if (!writer_tasks || !writer_durations || !writer_n_durations) {
 826                 VERBOSE_SCALEOUT_ERRSTRING("out of memory");
 827                 firsterr = -ENOMEM;
 828                 goto unwind;
 829         }
 830         for (i = 0; i < nrealwriters; i++) {
 831                 writer_durations[i] =
 832                         kcalloc(MAX_MEAS, sizeof(*writer_durations[i]),
 833                                 GFP_KERNEL);
 834                 if (!writer_durations[i]) {
 835                         firsterr = -ENOMEM;
 836                         goto unwind;
 837                 }
 838                 firsterr = torture_create_kthread(rcu_scale_writer, (void *)i,
 839                                                   writer_tasks[i]);
 840                 if (firsterr)
 841                         goto unwind;
 842         }
 843         torture_init_end();
 844         return 0;
 845
 846 unwind:
 847         torture_init_end();
 848         rcu_scale_cleanup();
 849         return firsterr;
 850 }
 851
 852 module_init(rcu_scale_init);
 853 module_exit(rcu_scale_cleanup);