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 #include <linux/rcupdate_trace.h>
  42
  43 #include "rcu.h"
  44
  45 MODULE_LICENSE("GPL");
  46 MODULE_AUTHOR("Paul E. McKenney <paulmck@linux.ibm.com>");
  47
  48 #define SCALE_FLAG "-scale:"
  49 #define SCALEOUT_STRING(s) \
  50         pr_alert("%s" SCALE_FLAG " %s\n", scale_type, s)
  51 #define VERBOSE_SCALEOUT_STRING(s) \
  52         do { if (verbose) pr_alert("%s" SCALE_FLAG " %s\n", scale_type, s); } while (0)
  53 #define SCALEOUT_ERRSTRING(s) \
  54         pr_alert("%s" SCALE_FLAG "!!! %s\n", scale_type, s)
  55
  56 /*
  57  * The intended use cases for the nreaders and nwriters module parameters
  58  * are as follows:
  59  *
  60  * 1.   Specify only the nr_cpus kernel boot parameter.  This will
  61  *      set both nreaders and nwriters to the value specified by
  62  *      nr_cpus for a mixed reader/writer test.
  63  *
  64  * 2.   Specify the nr_cpus kernel boot parameter, but set
  65  *      rcuscale.nreaders to zero.  This will set nwriters to the
  66  *      value specified by nr_cpus for an update-only test.
  67  *
  68  * 3.   Specify the nr_cpus kernel boot parameter, but set
  69  *      rcuscale.nwriters to zero.  This will set nreaders to the
  70  *      value specified by nr_cpus for a read-only test.
  71  *
  72  * Various other use cases may of course be specified.
  73  *
  74  * Note that this test's readers are intended only as a test load for
  75  * the writers.  The reader scalability statistics will be overly
  76  * pessimistic due to the per-critical-section interrupt disabling,
  77  * test-end checks, and the pair of calls through pointers.
  78  */
  79
  80 #ifdef MODULE
  81 # define RCUSCALE_SHUTDOWN 0
  82 #else
  83 # define RCUSCALE_SHUTDOWN 1
  84 #endif
  85
  86 torture_param(bool, gp_async, false, "Use asynchronous GP wait primitives");
  87 torture_param(int, gp_async_max, 1000, "Max # outstanding waits per reader");
  88 torture_param(bool, gp_exp, false, "Use expedited GP wait primitives");
  89 torture_param(int, holdoff, 10, "Holdoff time before test start (s)");
  90 torture_param(int, nreaders, -1, "Number of RCU reader threads");
  91 torture_param(int, nwriters, -1, "Number of RCU updater threads");
  92 torture_param(bool, shutdown, RCUSCALE_SHUTDOWN,
  93               "Shutdown at end of scalability tests.");
  94 torture_param(int, verbose, 1, "Enable verbose debugging printk()s");
  95 torture_param(int, writer_holdoff, 0, "Holdoff (us) between GPs, zero to disable");
  96 torture_param(int, kfree_rcu_test, 0, "Do we run a kfree_rcu() scale test?");
  97 torture_param(int, kfree_mult, 1, "Multiple of kfree_obj size to allocate.");
  98
  99 static char *scale_type = "rcu";
 100 module_param(scale_type, charp, 0444);
 101 MODULE_PARM_DESC(scale_type, "Type of RCU to scalability-test (rcu, srcu, ...)");
 102
 103 static int nrealreaders;
 104 static int nrealwriters;
 105 static struct task_struct **writer_tasks;
 106 static struct task_struct **reader_tasks;
 107 static struct task_struct *shutdown_task;
 108
 109 static u64 **writer_durations;
 110 static int *writer_n_durations;
 111 static atomic_t n_rcu_scale_reader_started;
 112 static atomic_t n_rcu_scale_writer_started;
 113 static atomic_t n_rcu_scale_writer_finished;
 114 static wait_queue_head_t shutdown_wq;
 115 static u64 t_rcu_scale_writer_started;
 116 static u64 t_rcu_scale_writer_finished;
 117 static unsigned long b_rcu_gp_test_started;
 118 static unsigned long b_rcu_gp_test_finished;
 119 static DEFINE_PER_CPU(atomic_t, n_async_inflight);
 120
 121 #define MAX_MEAS 10000
 122 #define MIN_MEAS 100
 123
 124 /*
 125  * Operations vector for selecting different types of tests.
 126  */
 127
 128 struct rcu_scale_ops {
 129         int ptype;
 130         void (*init)(void);
 131         void (*cleanup)(void);
 132         int (*readlock)(void);
 133         void (*readunlock)(int idx);
 134         unsigned long (*get_gp_seq)(void);
 135         unsigned long (*gp_diff)(unsigned long new, unsigned long old);
 136         unsigned long (*exp_completed)(void);
 137         void (*async)(struct rcu_head *head, rcu_callback_t func);
 138         void (*gp_barrier)(void);
 139         void (*sync)(void);
 140         void (*exp_sync)(void);
 141         const char *name;
 142 };
 143
 144 static struct rcu_scale_ops *cur_ops;
 145
 146 /*
 147  * Definitions for rcu scalability testing.
 148  */
 149
 150 static int rcu_scale_read_lock(void) __acquires(RCU)
 151 {
 152         rcu_read_lock();
 153         return 0;
 154 }
 155
 156 static void rcu_scale_read_unlock(int idx) __releases(RCU)
 157 {
 158         rcu_read_unlock();
 159 }
 160
 161 static unsigned long __maybe_unused rcu_no_completed(void)
 162 {
 163         return 0;
 164 }
 165
 166 static void rcu_sync_scale_init(void)
 167 {
 168 }
 169
 170 static struct rcu_scale_ops rcu_ops = {
 171         .ptype          = RCU_FLAVOR,
 172         .init           = rcu_sync_scale_init,
 173         .readlock       = rcu_scale_read_lock,
 174         .readunlock     = rcu_scale_read_unlock,
 175         .get_gp_seq     = rcu_get_gp_seq,
 176         .gp_diff        = rcu_seq_diff,
 177         .exp_completed  = rcu_exp_batches_completed,
 178         .async          = call_rcu,
 179         .gp_barrier     = rcu_barrier,
 180         .sync           = synchronize_rcu,
 181         .exp_sync       = synchronize_rcu_expedited,
 182         .name           = "rcu"
 183 };
 184
 185 /*
 186  * Definitions for srcu scalability testing.
 187  */
 188
 189 DEFINE_STATIC_SRCU(srcu_ctl_scale);
 190 static struct srcu_struct *srcu_ctlp = &srcu_ctl_scale;
 191
 192 static int srcu_scale_read_lock(void) __acquires(srcu_ctlp)
 193 {
 194         return srcu_read_lock(srcu_ctlp);
 195 }
 196
 197 static void srcu_scale_read_unlock(int idx) __releases(srcu_ctlp)
 198 {
 199         srcu_read_unlock(srcu_ctlp, idx);
 200 }
 201
 202 static unsigned long srcu_scale_completed(void)
 203 {
 204         return srcu_batches_completed(srcu_ctlp);
 205 }
 206
 207 static void srcu_call_rcu(struct rcu_head *head, rcu_callback_t func)
 208 {
 209         call_srcu(srcu_ctlp, head, func);
 210 }
 211
 212 static void srcu_rcu_barrier(void)
 213 {
 214         srcu_barrier(srcu_ctlp);
 215 }
 216
 217 static void srcu_scale_synchronize(void)
 218 {
 219         synchronize_srcu(srcu_ctlp);
 220 }
 221
 222 static void srcu_scale_synchronize_expedited(void)
 223 {
 224         synchronize_srcu_expedited(srcu_ctlp);
 225 }
 226
 227 static struct rcu_scale_ops srcu_ops = {
 228         .ptype          = SRCU_FLAVOR,
 229         .init           = rcu_sync_scale_init,
 230         .readlock       = srcu_scale_read_lock,
 231         .readunlock     = srcu_scale_read_unlock,
 232         .get_gp_seq     = srcu_scale_completed,
 233         .gp_diff        = rcu_seq_diff,
 234         .exp_completed  = srcu_scale_completed,
 235         .async          = srcu_call_rcu,
 236         .gp_barrier     = srcu_rcu_barrier,
 237         .sync           = srcu_scale_synchronize,
 238         .exp_sync       = srcu_scale_synchronize_expedited,
 239         .name           = "srcu"
 240 };
 241
 242 static struct srcu_struct srcud;
 243
 244 static void srcu_sync_scale_init(void)
 245 {
 246         srcu_ctlp = &srcud;
 247         init_srcu_struct(srcu_ctlp);
 248 }
 249
 250 static void srcu_sync_scale_cleanup(void)
 251 {
 252         cleanup_srcu_struct(srcu_ctlp);
 253 }
 254
 255 static struct rcu_scale_ops srcud_ops = {
 256         .ptype          = SRCU_FLAVOR,
 257         .init           = srcu_sync_scale_init,
 258         .cleanup        = srcu_sync_scale_cleanup,
 259         .readlock       = srcu_scale_read_lock,
 260         .readunlock     = srcu_scale_read_unlock,
 261         .get_gp_seq     = srcu_scale_completed,
 262         .gp_diff        = rcu_seq_diff,
 263         .exp_completed  = srcu_scale_completed,
 264         .async          = srcu_call_rcu,
 265         .gp_barrier     = srcu_rcu_barrier,
 266         .sync           = srcu_scale_synchronize,
 267         .exp_sync       = srcu_scale_synchronize_expedited,
 268         .name           = "srcud"
 269 };
 270
 271 #ifdef CONFIG_TASKS_RCU
 272
 273 /*
 274  * Definitions for RCU-tasks scalability testing.
 275  */
 276
 277 static int tasks_scale_read_lock(void)
 278 {
 279         return 0;
 280 }
 281
 282 static void tasks_scale_read_unlock(int idx)
 283 {
 284 }
 285
 286 static struct rcu_scale_ops tasks_ops = {
 287         .ptype          = RCU_TASKS_FLAVOR,
 288         .init           = rcu_sync_scale_init,
 289         .readlock       = tasks_scale_read_lock,
 290         .readunlock     = tasks_scale_read_unlock,
 291         .get_gp_seq     = rcu_no_completed,
 292         .gp_diff        = rcu_seq_diff,
 293         .async          = call_rcu_tasks,
 294         .gp_barrier     = rcu_barrier_tasks,
 295         .sync           = synchronize_rcu_tasks,
 296         .exp_sync       = synchronize_rcu_tasks,
 297         .name           = "tasks"
 298 };
 299
 300 #define TASKS_OPS &tasks_ops,
 301
 302 #else // #ifdef CONFIG_TASKS_RCU
 303
 304 #define TASKS_OPS
 305
 306 #endif // #else // #ifdef CONFIG_TASKS_RCU
 307
 308 #ifdef CONFIG_TASKS_TRACE_RCU
 309
 310 /*
 311  * Definitions for RCU-tasks-trace scalability testing.
 312  */
 313
 314 static int tasks_trace_scale_read_lock(void)
 315 {
 316         rcu_read_lock_trace();
 317         return 0;
 318 }
 319
 320 static void tasks_trace_scale_read_unlock(int idx)
 321 {
 322         rcu_read_unlock_trace();
 323 }
 324
 325 static struct rcu_scale_ops tasks_tracing_ops = {
 326         .ptype          = RCU_TASKS_FLAVOR,
 327         .init           = rcu_sync_scale_init,
 328         .readlock       = tasks_trace_scale_read_lock,
 329         .readunlock     = tasks_trace_scale_read_unlock,
 330         .get_gp_seq     = rcu_no_completed,
 331         .gp_diff        = rcu_seq_diff,
 332         .async          = call_rcu_tasks_trace,
 333         .gp_barrier     = rcu_barrier_tasks_trace,
 334         .sync           = synchronize_rcu_tasks_trace,
 335         .exp_sync       = synchronize_rcu_tasks_trace,
 336         .name           = "tasks-tracing"
 337 };
 338
 339 #define TASKS_TRACING_OPS &tasks_tracing_ops,
 340
 341 #else // #ifdef CONFIG_TASKS_TRACE_RCU
 342
 343 #define TASKS_TRACING_OPS
 344
 345 #endif // #else // #ifdef CONFIG_TASKS_TRACE_RCU
 346
 347 static unsigned long rcuscale_seq_diff(unsigned long new, unsigned long old)
 348 {
 349         if (!cur_ops->gp_diff)
 350                 return new - old;
 351         return cur_ops->gp_diff(new, old);
 352 }
 353
 354 /*
 355  * If scalability tests complete, wait for shutdown to commence.
 356  */
 357 static void rcu_scale_wait_shutdown(void)
 358 {
 359         cond_resched_tasks_rcu_qs();
 360         if (atomic_read(&n_rcu_scale_writer_finished) < nrealwriters)
 361                 return;
 362         while (!torture_must_stop())
 363                 schedule_timeout_uninterruptible(1);
 364 }
 365
 366 /*
 367  * RCU scalability reader kthread.  Repeatedly does empty RCU read-side
 368  * critical section, minimizing update-side interference.  However, the
 369  * point of this test is not to evaluate reader scalability, but instead
 370  * to serve as a test load for update-side scalability testing.
 371  */
 372 static int
 373 rcu_scale_reader(void *arg)
 374 {
 375         unsigned long flags;
 376         int idx;
 377         long me = (long)arg;
 378
 379         VERBOSE_SCALEOUT_STRING("rcu_scale_reader task started");
 380         set_cpus_allowed_ptr(current, cpumask_of(me % nr_cpu_ids));
 381         set_user_nice(current, MAX_NICE);
 382         atomic_inc(&n_rcu_scale_reader_started);
 383
 384         do {
 385                 local_irq_save(flags);
 386                 idx = cur_ops->readlock();
 387                 cur_ops->readunlock(idx);
 388                 local_irq_restore(flags);
 389                 rcu_scale_wait_shutdown();
 390         } while (!torture_must_stop());
 391         torture_kthread_stopping("rcu_scale_reader");
 392         return 0;
 393 }
 394
 395 /*
 396  * Callback function for asynchronous grace periods from rcu_scale_writer().
 397  */
 398 static void rcu_scale_async_cb(struct rcu_head *rhp)
 399 {
 400         atomic_dec(this_cpu_ptr(&n_async_inflight));
 401         kfree(rhp);
 402 }
 403
 404 /*
 405  * RCU scale writer kthread.  Repeatedly does a grace period.
 406  */
 407 static int
 408 rcu_scale_writer(void *arg)
 409 {
 410         int i = 0;
 411         int i_max;
 412         long me = (long)arg;
 413         struct rcu_head *rhp = NULL;
 414         bool started = false, done = false, alldone = false;
 415         u64 t;
 416         u64 *wdp;
 417         u64 *wdpp = writer_durations[me];
 418
 419         VERBOSE_SCALEOUT_STRING("rcu_scale_writer task started");
 420         WARN_ON(!wdpp);
 421         set_cpus_allowed_ptr(current, cpumask_of(me % nr_cpu_ids));
 422         current->flags |= PF_NO_SETAFFINITY;
 423         sched_set_fifo_low(current);
 424
 425         if (holdoff)
 426                 schedule_timeout_uninterruptible(holdoff * HZ);
 427
 428         /*
 429          * Wait until rcu_end_inkernel_boot() is called for normal GP tests
 430          * so that RCU is not always expedited for normal GP tests.
 431          * The system_state test is approximate, but works well in practice.
 432          */
 433         while (!gp_exp && system_state != SYSTEM_RUNNING)
 434                 schedule_timeout_uninterruptible(1);
 435
 436         t = ktime_get_mono_fast_ns();
 437         if (atomic_inc_return(&n_rcu_scale_writer_started) >= nrealwriters) {
 438                 t_rcu_scale_writer_started = t;
 439                 if (gp_exp) {
 440                         b_rcu_gp_test_started =
 441                                 cur_ops->exp_completed() / 2;
 442                 } else {
 443                         b_rcu_gp_test_started = cur_ops->get_gp_seq();
 444                 }
 445         }
 446
 447         do {
 448                 if (writer_holdoff)
 449                         udelay(writer_holdoff);
 450                 wdp = &wdpp[i];
 451                 *wdp = ktime_get_mono_fast_ns();
 452                 if (gp_async) {
 453 retry:
 454                         if (!rhp)
 455                                 rhp = kmalloc(sizeof(*rhp), GFP_KERNEL);
 456                         if (rhp && atomic_read(this_cpu_ptr(&n_async_inflight)) < gp_async_max) {
 457                                 atomic_inc(this_cpu_ptr(&n_async_inflight));
 458                                 cur_ops->async(rhp, rcu_scale_async_cb);
 459                                 rhp = NULL;
 460                         } else if (!kthread_should_stop()) {
 461                                 cur_ops->gp_barrier();
 462                                 goto retry;
 463                         } else {
 464                                 kfree(rhp); /* Because we are stopping. */
 465                         }
 466                 } else if (gp_exp) {
 467                         cur_ops->exp_sync();
 468                 } else {
 469                         cur_ops->sync();
 470                 }
 471                 t = ktime_get_mono_fast_ns();
 472                 *wdp = t - *wdp;
 473                 i_max = i;
 474                 if (!started &&
 475                     atomic_read(&n_rcu_scale_writer_started) >= nrealwriters)
 476                         started = true;
 477                 if (!done && i >= MIN_MEAS) {
 478                         done = true;
 479                         sched_set_normal(current, 0);
 480                         pr_alert("%s%s rcu_scale_writer %ld has %d measurements\n",
 481                                  scale_type, SCALE_FLAG, me, MIN_MEAS);
 482                         if (atomic_inc_return(&n_rcu_scale_writer_finished) >=
 483                             nrealwriters) {
 484                                 schedule_timeout_interruptible(10);
 485                                 rcu_ftrace_dump(DUMP_ALL);
 486                                 SCALEOUT_STRING("Test complete");
 487                                 t_rcu_scale_writer_finished = t;
 488                                 if (gp_exp) {
 489                                         b_rcu_gp_test_finished =
 490                                                 cur_ops->exp_completed() / 2;
 491                                 } else {
 492                                         b_rcu_gp_test_finished =
 493                                                 cur_ops->get_gp_seq();
 494                                 }
 495                                 if (shutdown) {
 496                                         smp_mb(); /* Assign before wake. */
 497                                         wake_up(&shutdown_wq);
 498                                 }
 499                         }
 500                 }
 501                 if (done && !alldone &&
 502                     atomic_read(&n_rcu_scale_writer_finished) >= nrealwriters)
 503                         alldone = true;
 504                 if (started && !alldone && i < MAX_MEAS - 1)
 505                         i++;
 506                 rcu_scale_wait_shutdown();
 507         } while (!torture_must_stop());
 508         if (gp_async) {
 509                 cur_ops->gp_barrier();
 510         }
 511         writer_n_durations[me] = i_max + 1;
 512         torture_kthread_stopping("rcu_scale_writer");
 513         return 0;
 514 }
 515
 516 static void
 517 rcu_scale_print_module_parms(struct rcu_scale_ops *cur_ops, const char *tag)
 518 {
 519         pr_alert("%s" SCALE_FLAG
 520                  "--- %s: nreaders=%d nwriters=%d verbose=%d shutdown=%d\n",
 521                  scale_type, tag, nrealreaders, nrealwriters, verbose, shutdown);
 522 }
 523
 524 /*
 525  * Return the number if non-negative.  If -1, the number of CPUs.
 526  * If less than -1, that much less than the number of CPUs, but
 527  * at least one.
 528  */
 529 static int compute_real(int n)
 530 {
 531         int nr;
 532
 533         if (n >= 0) {
 534                 nr = n;
 535         } else {
 536                 nr = num_online_cpus() + 1 + n;
 537                 if (nr <= 0)
 538                         nr = 1;
 539         }
 540         return nr;
 541 }
 542
 543 /*
 544  * kfree_rcu() scalability tests: Start a kfree_rcu() loop on all CPUs for number
 545  * of iterations and measure total time and number of GP for all iterations to complete.
 546  */
 547
 548 torture_param(int, kfree_nthreads, -1, "Number of threads running loops of kfree_rcu().");
 549 torture_param(int, kfree_alloc_num, 8000, "Number of allocations and frees done in an iteration.");
 550 torture_param(int, kfree_loops, 10, "Number of loops doing kfree_alloc_num allocations and frees.");
 551 torture_param(bool, kfree_rcu_test_double, false, "Do we run a kfree_rcu() double-argument scale test?");
 552 torture_param(bool, kfree_rcu_test_single, false, "Do we run a kfree_rcu() single-argument scale test?");
 553
 554 static struct task_struct **kfree_reader_tasks;
 555 static int kfree_nrealthreads;
 556 static atomic_t n_kfree_scale_thread_started;
 557 static atomic_t n_kfree_scale_thread_ended;
 558
 559 struct kfree_obj {
 560         char kfree_obj[8];
 561         struct rcu_head rh;
 562 };
 563
 564 static int
 565 kfree_scale_thread(void *arg)
 566 {
 567         int i, loop = 0;
 568         long me = (long)arg;
 569         struct kfree_obj *alloc_ptr;
 570         u64 start_time, end_time;
 571         long long mem_begin, mem_during = 0;
 572         bool kfree_rcu_test_both;
 573         DEFINE_TORTURE_RANDOM(tr);
 574
 575         VERBOSE_SCALEOUT_STRING("kfree_scale_thread task started");
 576         set_cpus_allowed_ptr(current, cpumask_of(me % nr_cpu_ids));
 577         set_user_nice(current, MAX_NICE);
 578         kfree_rcu_test_both = (kfree_rcu_test_single == kfree_rcu_test_double);
 579
 580         start_time = ktime_get_mono_fast_ns();
 581
 582         if (atomic_inc_return(&n_kfree_scale_thread_started) >= kfree_nrealthreads) {
 583                 if (gp_exp)
 584                         b_rcu_gp_test_started = cur_ops->exp_completed() / 2;
 585                 else
 586                         b_rcu_gp_test_started = cur_ops->get_gp_seq();
 587         }
 588
 589         do {
 590                 if (!mem_during) {
 591                         mem_during = mem_begin = si_mem_available();
 592                 } else if (loop % (kfree_loops / 4) == 0) {
 593                         mem_during = (mem_during + si_mem_available()) / 2;
 594                 }
 595
 596                 for (i = 0; i < kfree_alloc_num; i++) {
 597                         alloc_ptr = kmalloc(kfree_mult * sizeof(struct kfree_obj), GFP_KERNEL);
 598                         if (!alloc_ptr)
 599                                 return -ENOMEM;
 600
 601                         // By default kfree_rcu_test_single and kfree_rcu_test_double are
 602                         // initialized to false. If both have the same value (false or true)
 603                         // both are randomly tested, otherwise only the one with value true
 604                         // is tested.
 605                         if ((kfree_rcu_test_single && !kfree_rcu_test_double) ||
 606                                         (kfree_rcu_test_both && torture_random(&tr) & 0x800))
 607                                 kfree_rcu(alloc_ptr);
 608                         else
 609                                 kfree_rcu(alloc_ptr, rh);
 610                 }
 611
 612                 cond_resched();
 613         } while (!torture_must_stop() && ++loop < kfree_loops);
 614
 615         if (atomic_inc_return(&n_kfree_scale_thread_ended) >= kfree_nrealthreads) {
 616                 end_time = ktime_get_mono_fast_ns();
 617
 618                 if (gp_exp)
 619                         b_rcu_gp_test_finished = cur_ops->exp_completed() / 2;
 620                 else
 621                         b_rcu_gp_test_finished = cur_ops->get_gp_seq();
 622
 623                 pr_alert("Total time taken by all kfree'ers: %llu ns, loops: %d, batches: %ld, memory footprint: %lldMB\n",
 624                        (unsigned long long)(end_time - start_time), kfree_loops,
 625                        rcuscale_seq_diff(b_rcu_gp_test_finished, b_rcu_gp_test_started),
 626                        (mem_begin - mem_during) >> (20 - PAGE_SHIFT));
 627
 628                 if (shutdown) {
 629                         smp_mb(); /* Assign before wake. */
 630                         wake_up(&shutdown_wq);
 631                 }
 632         }
 633
 634         torture_kthread_stopping("kfree_scale_thread");
 635         return 0;
 636 }
 637
 638 static void
 639 kfree_scale_cleanup(void)
 640 {
 641         int i;
 642
 643         if (torture_cleanup_begin())
 644                 return;
 645
 646         if (kfree_reader_tasks) {
 647                 for (i = 0; i < kfree_nrealthreads; i++)
 648                         torture_stop_kthread(kfree_scale_thread,
 649                                              kfree_reader_tasks[i]);
 650                 kfree(kfree_reader_tasks);
 651         }
 652
 653         torture_cleanup_end();
 654 }
 655
 656 /*
 657  * shutdown kthread.  Just waits to be awakened, then shuts down system.
 658  */
 659 static int
 660 kfree_scale_shutdown(void *arg)
 661 {
 662         wait_event_idle(shutdown_wq,
 663                         atomic_read(&n_kfree_scale_thread_ended) >= kfree_nrealthreads);
 664
 665         smp_mb(); /* Wake before output. */
 666
 667         kfree_scale_cleanup();
 668         kernel_power_off();
 669         return -EINVAL;
 670 }
 671
 672 static int __init
 673 kfree_scale_init(void)
 674 {
 675         long i;
 676         int firsterr = 0;
 677
 678         kfree_nrealthreads = compute_real(kfree_nthreads);
 679         /* Start up the kthreads. */
 680         if (shutdown) {
 681                 init_waitqueue_head(&shutdown_wq);
 682                 firsterr = torture_create_kthread(kfree_scale_shutdown, NULL,
 683                                                   shutdown_task);
 684                 if (torture_init_error(firsterr))
 685                         goto unwind;
 686                 schedule_timeout_uninterruptible(1);
 687         }
 688
 689         pr_alert("kfree object size=%zu\n", kfree_mult * sizeof(struct kfree_obj));
 690
 691         kfree_reader_tasks = kcalloc(kfree_nrealthreads, sizeof(kfree_reader_tasks[0]),
 692                                GFP_KERNEL);
 693         if (kfree_reader_tasks == NULL) {
 694                 firsterr = -ENOMEM;
 695                 goto unwind;
 696         }
 697
 698         for (i = 0; i < kfree_nrealthreads; i++) {
 699                 firsterr = torture_create_kthread(kfree_scale_thread, (void *)i,
 700                                                   kfree_reader_tasks[i]);
 701                 if (torture_init_error(firsterr))
 702                         goto unwind;
 703         }
 704
 705         while (atomic_read(&n_kfree_scale_thread_started) < kfree_nrealthreads)
 706                 schedule_timeout_uninterruptible(1);
 707
 708         torture_init_end();
 709         return 0;
 710
 711 unwind:
 712         torture_init_end();
 713         kfree_scale_cleanup();
 714         return firsterr;
 715 }
 716
 717 static void
 718 rcu_scale_cleanup(void)
 719 {
 720         int i;
 721         int j;
 722         int ngps = 0;
 723         u64 *wdp;
 724         u64 *wdpp;
 725
 726         /*
 727          * Would like warning at start, but everything is expedited
 728          * during the mid-boot phase, so have to wait till the end.
 729          */
 730         if (rcu_gp_is_expedited() && !rcu_gp_is_normal() && !gp_exp)
 731                 SCALEOUT_ERRSTRING("All grace periods expedited, no normal ones to measure!");
 732         if (rcu_gp_is_normal() && gp_exp)
 733                 SCALEOUT_ERRSTRING("All grace periods normal, no expedited ones to measure!");
 734         if (gp_exp && gp_async)
 735                 SCALEOUT_ERRSTRING("No expedited async GPs, so went with async!");
 736
 737         if (kfree_rcu_test) {
 738                 kfree_scale_cleanup();
 739                 return;
 740         }
 741
 742         if (torture_cleanup_begin())
 743                 return;
 744         if (!cur_ops) {
 745                 torture_cleanup_end();
 746                 return;
 747         }
 748
 749         if (reader_tasks) {
 750                 for (i = 0; i < nrealreaders; i++)
 751                         torture_stop_kthread(rcu_scale_reader,
 752                                              reader_tasks[i]);
 753                 kfree(reader_tasks);
 754         }
 755
 756         if (writer_tasks) {
 757                 for (i = 0; i < nrealwriters; i++) {
 758                         torture_stop_kthread(rcu_scale_writer,
 759                                              writer_tasks[i]);
 760                         if (!writer_n_durations)
 761                                 continue;
 762                         j = writer_n_durations[i];
 763                         pr_alert("%s%s writer %d gps: %d\n",
 764                                  scale_type, SCALE_FLAG, i, j);
 765                         ngps += j;
 766                 }
 767                 pr_alert("%s%s start: %llu end: %llu duration: %llu gps: %d batches: %ld\n",
 768                          scale_type, SCALE_FLAG,
 769                          t_rcu_scale_writer_started, t_rcu_scale_writer_finished,
 770                          t_rcu_scale_writer_finished -
 771                          t_rcu_scale_writer_started,
 772                          ngps,
 773                          rcuscale_seq_diff(b_rcu_gp_test_finished,
 774                                            b_rcu_gp_test_started));
 775                 for (i = 0; i < nrealwriters; i++) {
 776                         if (!writer_durations)
 777                                 break;
 778                         if (!writer_n_durations)
 779                                 continue;
 780                         wdpp = writer_durations[i];
 781                         if (!wdpp)
 782                                 continue;
 783                         for (j = 0; j < writer_n_durations[i]; j++) {
 784                                 wdp = &wdpp[j];
 785                                 pr_alert("%s%s %4d writer-duration: %5d %llu\n",
 786                                         scale_type, SCALE_FLAG,
 787                                         i, j, *wdp);
 788                                 if (j % 100 == 0)
 789                                         schedule_timeout_uninterruptible(1);
 790                         }
 791                         kfree(writer_durations[i]);
 792                 }
 793                 kfree(writer_tasks);
 794                 kfree(writer_durations);
 795                 kfree(writer_n_durations);
 796         }
 797
 798         /* Do torture-type-specific cleanup operations.  */
 799         if (cur_ops->cleanup != NULL)
 800                 cur_ops->cleanup();
 801
 802         torture_cleanup_end();
 803 }
 804
 805 /*
 806  * RCU scalability shutdown kthread.  Just waits to be awakened, then shuts
 807  * down system.
 808  */
 809 static int
 810 rcu_scale_shutdown(void *arg)
 811 {
 812         wait_event_idle(shutdown_wq, atomic_read(&n_rcu_scale_writer_finished) >= nrealwriters);
 813         smp_mb(); /* Wake before output. */
 814         rcu_scale_cleanup();
 815         kernel_power_off();
 816         return -EINVAL;
 817 }
 818
 819 static int __init
 820 rcu_scale_init(void)
 821 {
 822         long i;
 823         int firsterr = 0;
 824         static struct rcu_scale_ops *scale_ops[] = {
 825                 &rcu_ops, &srcu_ops, &srcud_ops, TASKS_OPS TASKS_TRACING_OPS
 826         };
 827
 828         if (!torture_init_begin(scale_type, verbose))
 829                 return -EBUSY;
 830
 831         /* Process args and announce that the scalability'er is on the job. */
 832         for (i = 0; i < ARRAY_SIZE(scale_ops); i++) {
 833                 cur_ops = scale_ops[i];
 834                 if (strcmp(scale_type, cur_ops->name) == 0)
 835                         break;
 836         }
 837         if (i == ARRAY_SIZE(scale_ops)) {
 838                 pr_alert("rcu-scale: invalid scale type: \"%s\"\n", scale_type);
 839                 pr_alert("rcu-scale types:");
 840                 for (i = 0; i < ARRAY_SIZE(scale_ops); i++)
 841                         pr_cont(" %s", scale_ops[i]->name);
 842                 pr_cont("\n");
 843                 firsterr = -EINVAL;
 844                 cur_ops = NULL;
 845                 goto unwind;
 846         }
 847         if (cur_ops->init)
 848                 cur_ops->init();
 849
 850         if (kfree_rcu_test)
 851                 return kfree_scale_init();
 852
 853         nrealwriters = compute_real(nwriters);
 854         nrealreaders = compute_real(nreaders);
 855         atomic_set(&n_rcu_scale_reader_started, 0);
 856         atomic_set(&n_rcu_scale_writer_started, 0);
 857         atomic_set(&n_rcu_scale_writer_finished, 0);
 858         rcu_scale_print_module_parms(cur_ops, "Start of test");
 859
 860         /* Start up the kthreads. */
 861
 862         if (shutdown) {
 863                 init_waitqueue_head(&shutdown_wq);
 864                 firsterr = torture_create_kthread(rcu_scale_shutdown, NULL,
 865                                                   shutdown_task);
 866                 if (torture_init_error(firsterr))
 867                         goto unwind;
 868                 schedule_timeout_uninterruptible(1);
 869         }
 870         reader_tasks = kcalloc(nrealreaders, sizeof(reader_tasks[0]),
 871                                GFP_KERNEL);
 872         if (reader_tasks == NULL) {
 873                 SCALEOUT_ERRSTRING("out of memory");
 874                 firsterr = -ENOMEM;
 875                 goto unwind;
 876         }
 877         for (i = 0; i < nrealreaders; i++) {
 878                 firsterr = torture_create_kthread(rcu_scale_reader, (void *)i,
 879                                                   reader_tasks[i]);
 880                 if (torture_init_error(firsterr))
 881                         goto unwind;
 882         }
 883         while (atomic_read(&n_rcu_scale_reader_started) < nrealreaders)
 884                 schedule_timeout_uninterruptible(1);
 885         writer_tasks = kcalloc(nrealwriters, sizeof(reader_tasks[0]),
 886                                GFP_KERNEL);
 887         writer_durations = kcalloc(nrealwriters, sizeof(*writer_durations),
 888                                    GFP_KERNEL);
 889         writer_n_durations =
 890                 kcalloc(nrealwriters, sizeof(*writer_n_durations),
 891                         GFP_KERNEL);
 892         if (!writer_tasks || !writer_durations || !writer_n_durations) {
 893                 SCALEOUT_ERRSTRING("out of memory");
 894                 firsterr = -ENOMEM;
 895                 goto unwind;
 896         }
 897         for (i = 0; i < nrealwriters; i++) {
 898                 writer_durations[i] =
 899                         kcalloc(MAX_MEAS, sizeof(*writer_durations[i]),
 900                                 GFP_KERNEL);
 901                 if (!writer_durations[i]) {
 902                         firsterr = -ENOMEM;
 903                         goto unwind;
 904                 }
 905                 firsterr = torture_create_kthread(rcu_scale_writer, (void *)i,
 906                                                   writer_tasks[i]);
 907                 if (torture_init_error(firsterr))
 908                         goto unwind;
 909         }
 910         torture_init_end();
 911         return 0;
 912
 913 unwind:
 914         torture_init_end();
 915         rcu_scale_cleanup();
 916         if (shutdown) {
 917                 WARN_ON(!IS_MODULE(CONFIG_RCU_SCALE_TEST));
 918                 kernel_power_off();
 919         }
 920         return firsterr;
 921 }
 922
 923 module_init(rcu_scale_init);
 924 module_exit(rcu_scale_cleanup);