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 VERBOSE_SCALEOUT_ERRSTRING(s) \
  54         do { if (verbose) pr_alert("%s" SCALE_FLAG "!!! %s\n", scale_type, s); } while (0)
  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 /*
 272  * Definitions for RCU-tasks scalability testing.
 273  */
 274
 275 static int tasks_scale_read_lock(void)
 276 {
 277         return 0;
 278 }
 279
 280 static void tasks_scale_read_unlock(int idx)
 281 {
 282 }
 283
 284 static struct rcu_scale_ops tasks_ops = {
 285         .ptype          = RCU_TASKS_FLAVOR,
 286         .init           = rcu_sync_scale_init,
 287         .readlock       = tasks_scale_read_lock,
 288         .readunlock     = tasks_scale_read_unlock,
 289         .get_gp_seq     = rcu_no_completed,
 290         .gp_diff        = rcu_seq_diff,
 291         .async          = call_rcu_tasks,
 292         .gp_barrier     = rcu_barrier_tasks,
 293         .sync           = synchronize_rcu_tasks,
 294         .exp_sync       = synchronize_rcu_tasks,
 295         .name           = "tasks"
 296 };
 297
 298 /*
 299  * Definitions for RCU-tasks-trace scalability testing.
 300  */
 301
 302 static int tasks_trace_scale_read_lock(void)
 303 {
 304         rcu_read_lock_trace();
 305         return 0;
 306 }
 307
 308 static void tasks_trace_scale_read_unlock(int idx)
 309 {
 310         rcu_read_unlock_trace();
 311 }
 312
 313 static struct rcu_scale_ops tasks_tracing_ops = {
 314         .ptype          = RCU_TASKS_FLAVOR,
 315         .init           = rcu_sync_scale_init,
 316         .readlock       = tasks_trace_scale_read_lock,
 317         .readunlock     = tasks_trace_scale_read_unlock,
 318         .get_gp_seq     = rcu_no_completed,
 319         .gp_diff        = rcu_seq_diff,
 320         .async          = call_rcu_tasks_trace,
 321         .gp_barrier     = rcu_barrier_tasks_trace,
 322         .sync           = synchronize_rcu_tasks_trace,
 323         .exp_sync       = synchronize_rcu_tasks_trace,
 324         .name           = "tasks-tracing"
 325 };
 326
 327 static unsigned long rcuscale_seq_diff(unsigned long new, unsigned long old)
 328 {
 329         if (!cur_ops->gp_diff)
 330                 return new - old;
 331         return cur_ops->gp_diff(new, old);
 332 }
 333
 334 /*
 335  * If scalability tests complete, wait for shutdown to commence.
 336  */
 337 static void rcu_scale_wait_shutdown(void)
 338 {
 339         cond_resched_tasks_rcu_qs();
 340         if (atomic_read(&n_rcu_scale_writer_finished) < nrealwriters)
 341                 return;
 342         while (!torture_must_stop())
 343                 schedule_timeout_uninterruptible(1);
 344 }
 345
 346 /*
 347  * RCU scalability reader kthread.  Repeatedly does empty RCU read-side
 348  * critical section, minimizing update-side interference.  However, the
 349  * point of this test is not to evaluate reader scalability, but instead
 350  * to serve as a test load for update-side scalability testing.
 351  */
 352 static int
 353 rcu_scale_reader(void *arg)
 354 {
 355         unsigned long flags;
 356         int idx;
 357         long me = (long)arg;
 358
 359         VERBOSE_SCALEOUT_STRING("rcu_scale_reader task started");
 360         set_cpus_allowed_ptr(current, cpumask_of(me % nr_cpu_ids));
 361         set_user_nice(current, MAX_NICE);
 362         atomic_inc(&n_rcu_scale_reader_started);
 363
 364         do {
 365                 local_irq_save(flags);
 366                 idx = cur_ops->readlock();
 367                 cur_ops->readunlock(idx);
 368                 local_irq_restore(flags);
 369                 rcu_scale_wait_shutdown();
 370         } while (!torture_must_stop());
 371         torture_kthread_stopping("rcu_scale_reader");
 372         return 0;
 373 }
 374
 375 /*
 376  * Callback function for asynchronous grace periods from rcu_scale_writer().
 377  */
 378 static void rcu_scale_async_cb(struct rcu_head *rhp)
 379 {
 380         atomic_dec(this_cpu_ptr(&n_async_inflight));
 381         kfree(rhp);
 382 }
 383
 384 /*
 385  * RCU scale writer kthread.  Repeatedly does a grace period.
 386  */
 387 static int
 388 rcu_scale_writer(void *arg)
 389 {
 390         int i = 0;
 391         int i_max;
 392         long me = (long)arg;
 393         struct rcu_head *rhp = NULL;
 394         bool started = false, done = false, alldone = false;
 395         u64 t;
 396         u64 *wdp;
 397         u64 *wdpp = writer_durations[me];
 398
 399         VERBOSE_SCALEOUT_STRING("rcu_scale_writer task started");
 400         WARN_ON(!wdpp);
 401         set_cpus_allowed_ptr(current, cpumask_of(me % nr_cpu_ids));
 402         sched_set_fifo_low(current);
 403
 404         if (holdoff)
 405                 schedule_timeout_uninterruptible(holdoff * HZ);
 406
 407         /*
 408          * Wait until rcu_end_inkernel_boot() is called for normal GP tests
 409          * so that RCU is not always expedited for normal GP tests.
 410          * The system_state test is approximate, but works well in practice.
 411          */
 412         while (!gp_exp && system_state != SYSTEM_RUNNING)
 413                 schedule_timeout_uninterruptible(1);
 414
 415         t = ktime_get_mono_fast_ns();
 416         if (atomic_inc_return(&n_rcu_scale_writer_started) >= nrealwriters) {
 417                 t_rcu_scale_writer_started = t;
 418                 if (gp_exp) {
 419                         b_rcu_gp_test_started =
 420                                 cur_ops->exp_completed() / 2;
 421                 } else {
 422                         b_rcu_gp_test_started = cur_ops->get_gp_seq();
 423                 }
 424         }
 425
 426         do {
 427                 if (writer_holdoff)
 428                         udelay(writer_holdoff);
 429                 wdp = &wdpp[i];
 430                 *wdp = ktime_get_mono_fast_ns();
 431                 if (gp_async) {
 432 retry:
 433                         if (!rhp)
 434                                 rhp = kmalloc(sizeof(*rhp), GFP_KERNEL);
 435                         if (rhp && atomic_read(this_cpu_ptr(&n_async_inflight)) < gp_async_max) {
 436                                 atomic_inc(this_cpu_ptr(&n_async_inflight));
 437                                 cur_ops->async(rhp, rcu_scale_async_cb);
 438                                 rhp = NULL;
 439                         } else if (!kthread_should_stop()) {
 440                                 cur_ops->gp_barrier();
 441                                 goto retry;
 442                         } else {
 443                                 kfree(rhp); /* Because we are stopping. */
 444                         }
 445                 } else if (gp_exp) {
 446                         cur_ops->exp_sync();
 447                 } else {
 448                         cur_ops->sync();
 449                 }
 450                 t = ktime_get_mono_fast_ns();
 451                 *wdp = t - *wdp;
 452                 i_max = i;
 453                 if (!started &&
 454                     atomic_read(&n_rcu_scale_writer_started) >= nrealwriters)
 455                         started = true;
 456                 if (!done && i >= MIN_MEAS) {
 457                         done = true;
 458                         sched_set_normal(current, 0);
 459                         pr_alert("%s%s rcu_scale_writer %ld has %d measurements\n",
 460                                  scale_type, SCALE_FLAG, me, MIN_MEAS);
 461                         if (atomic_inc_return(&n_rcu_scale_writer_finished) >=
 462                             nrealwriters) {
 463                                 schedule_timeout_interruptible(10);
 464                                 rcu_ftrace_dump(DUMP_ALL);
 465                                 SCALEOUT_STRING("Test complete");
 466                                 t_rcu_scale_writer_finished = t;
 467                                 if (gp_exp) {
 468                                         b_rcu_gp_test_finished =
 469                                                 cur_ops->exp_completed() / 2;
 470                                 } else {
 471                                         b_rcu_gp_test_finished =
 472                                                 cur_ops->get_gp_seq();
 473                                 }
 474                                 if (shutdown) {
 475                                         smp_mb(); /* Assign before wake. */
 476                                         wake_up(&shutdown_wq);
 477                                 }
 478                         }
 479                 }
 480                 if (done && !alldone &&
 481                     atomic_read(&n_rcu_scale_writer_finished) >= nrealwriters)
 482                         alldone = true;
 483                 if (started && !alldone && i < MAX_MEAS - 1)
 484                         i++;
 485                 rcu_scale_wait_shutdown();
 486         } while (!torture_must_stop());
 487         if (gp_async) {
 488                 cur_ops->gp_barrier();
 489         }
 490         writer_n_durations[me] = i_max;
 491         torture_kthread_stopping("rcu_scale_writer");
 492         return 0;
 493 }
 494
 495 static void
 496 rcu_scale_print_module_parms(struct rcu_scale_ops *cur_ops, const char *tag)
 497 {
 498         pr_alert("%s" SCALE_FLAG
 499                  "--- %s: nreaders=%d nwriters=%d verbose=%d shutdown=%d\n",
 500                  scale_type, tag, nrealreaders, nrealwriters, verbose, shutdown);
 501 }
 502
 503 static void
 504 rcu_scale_cleanup(void)
 505 {
 506         int i;
 507         int j;
 508         int ngps = 0;
 509         u64 *wdp;
 510         u64 *wdpp;
 511
 512         /*
 513          * Would like warning at start, but everything is expedited
 514          * during the mid-boot phase, so have to wait till the end.
 515          */
 516         if (rcu_gp_is_expedited() && !rcu_gp_is_normal() && !gp_exp)
 517                 VERBOSE_SCALEOUT_ERRSTRING("All grace periods expedited, no normal ones to measure!");
 518         if (rcu_gp_is_normal() && gp_exp)
 519                 VERBOSE_SCALEOUT_ERRSTRING("All grace periods normal, no expedited ones to measure!");
 520         if (gp_exp && gp_async)
 521                 VERBOSE_SCALEOUT_ERRSTRING("No expedited async GPs, so went with async!");
 522
 523         if (torture_cleanup_begin())
 524                 return;
 525         if (!cur_ops) {
 526                 torture_cleanup_end();
 527                 return;
 528         }
 529
 530         if (reader_tasks) {
 531                 for (i = 0; i < nrealreaders; i++)
 532                         torture_stop_kthread(rcu_scale_reader,
 533                                              reader_tasks[i]);
 534                 kfree(reader_tasks);
 535         }
 536
 537         if (writer_tasks) {
 538                 for (i = 0; i < nrealwriters; i++) {
 539                         torture_stop_kthread(rcu_scale_writer,
 540                                              writer_tasks[i]);
 541                         if (!writer_n_durations)
 542                                 continue;
 543                         j = writer_n_durations[i];
 544                         pr_alert("%s%s writer %d gps: %d\n",
 545                                  scale_type, SCALE_FLAG, i, j);
 546                         ngps += j;
 547                 }
 548                 pr_alert("%s%s start: %llu end: %llu duration: %llu gps: %d batches: %ld\n",
 549                          scale_type, SCALE_FLAG,
 550                          t_rcu_scale_writer_started, t_rcu_scale_writer_finished,
 551                          t_rcu_scale_writer_finished -
 552                          t_rcu_scale_writer_started,
 553                          ngps,
 554                          rcuscale_seq_diff(b_rcu_gp_test_finished,
 555                                            b_rcu_gp_test_started));
 556                 for (i = 0; i < nrealwriters; i++) {
 557                         if (!writer_durations)
 558                                 break;
 559                         if (!writer_n_durations)
 560                                 continue;
 561                         wdpp = writer_durations[i];
 562                         if (!wdpp)
 563                                 continue;
 564                         for (j = 0; j <= writer_n_durations[i]; j++) {
 565                                 wdp = &wdpp[j];
 566                                 pr_alert("%s%s %4d writer-duration: %5d %llu\n",
 567                                         scale_type, SCALE_FLAG,
 568                                         i, j, *wdp);
 569                                 if (j % 100 == 0)
 570                                         schedule_timeout_uninterruptible(1);
 571                         }
 572                         kfree(writer_durations[i]);
 573                 }
 574                 kfree(writer_tasks);
 575                 kfree(writer_durations);
 576                 kfree(writer_n_durations);
 577         }
 578
 579         /* Do torture-type-specific cleanup operations.  */
 580         if (cur_ops->cleanup != NULL)
 581                 cur_ops->cleanup();
 582
 583         torture_cleanup_end();
 584 }
 585
 586 /*
 587  * Return the number if non-negative.  If -1, the number of CPUs.
 588  * If less than -1, that much less than the number of CPUs, but
 589  * at least one.
 590  */
 591 static int compute_real(int n)
 592 {
 593         int nr;
 594
 595         if (n >= 0) {
 596                 nr = n;
 597         } else {
 598                 nr = num_online_cpus() + 1 + n;
 599                 if (nr <= 0)
 600                         nr = 1;
 601         }
 602         return nr;
 603 }
 604
 605 /*
 606  * RCU scalability shutdown kthread.  Just waits to be awakened, then shuts
 607  * down system.
 608  */
 609 static int
 610 rcu_scale_shutdown(void *arg)
 611 {
 612         wait_event(shutdown_wq,
 613                    atomic_read(&n_rcu_scale_writer_finished) >= nrealwriters);
 614         smp_mb(); /* Wake before output. */
 615         rcu_scale_cleanup();
 616         kernel_power_off();
 617         return -EINVAL;
 618 }
 619
 620 /*
 621  * kfree_rcu() scalability tests: Start a kfree_rcu() loop on all CPUs for number
 622  * of iterations and measure total time and number of GP for all iterations to complete.
 623  */
 624
 625 torture_param(int, kfree_nthreads, -1, "Number of threads running loops of kfree_rcu().");
 626 torture_param(int, kfree_alloc_num, 8000, "Number of allocations and frees done in an iteration.");
 627 torture_param(int, kfree_loops, 10, "Number of loops doing kfree_alloc_num allocations and frees.");
 628
 629 static struct task_struct **kfree_reader_tasks;
 630 static int kfree_nrealthreads;
 631 static atomic_t n_kfree_scale_thread_started;
 632 static atomic_t n_kfree_scale_thread_ended;
 633
 634 struct kfree_obj {
 635         char kfree_obj[8];
 636         struct rcu_head rh;
 637 };
 638
 639 static int
 640 kfree_scale_thread(void *arg)
 641 {
 642         int i, loop = 0;
 643         long me = (long)arg;
 644         struct kfree_obj *alloc_ptr;
 645         u64 start_time, end_time;
 646         long long mem_begin, mem_during = 0;
 647
 648         VERBOSE_SCALEOUT_STRING("kfree_scale_thread task started");
 649         set_cpus_allowed_ptr(current, cpumask_of(me % nr_cpu_ids));
 650         set_user_nice(current, MAX_NICE);
 651
 652         start_time = ktime_get_mono_fast_ns();
 653
 654         if (atomic_inc_return(&n_kfree_scale_thread_started) >= kfree_nrealthreads) {
 655                 if (gp_exp)
 656                         b_rcu_gp_test_started = cur_ops->exp_completed() / 2;
 657                 else
 658                         b_rcu_gp_test_started = cur_ops->get_gp_seq();
 659         }
 660
 661         do {
 662                 if (!mem_during) {
 663                         mem_during = mem_begin = si_mem_available();
 664                 } else if (loop % (kfree_loops / 4) == 0) {
 665                         mem_during = (mem_during + si_mem_available()) / 2;
 666                 }
 667
 668                 for (i = 0; i < kfree_alloc_num; i++) {
 669                         alloc_ptr = kmalloc(kfree_mult * sizeof(struct kfree_obj), GFP_KERNEL);
 670                         if (!alloc_ptr)
 671                                 return -ENOMEM;
 672
 673                         kfree_rcu(alloc_ptr, rh);
 674                 }
 675
 676                 cond_resched();
 677         } while (!torture_must_stop() && ++loop < kfree_loops);
 678
 679         if (atomic_inc_return(&n_kfree_scale_thread_ended) >= kfree_nrealthreads) {
 680                 end_time = ktime_get_mono_fast_ns();
 681
 682                 if (gp_exp)
 683                         b_rcu_gp_test_finished = cur_ops->exp_completed() / 2;
 684                 else
 685                         b_rcu_gp_test_finished = cur_ops->get_gp_seq();
 686
 687                 pr_alert("Total time taken by all kfree'ers: %llu ns, loops: %d, batches: %ld, memory footprint: %lldMB\n",
 688                        (unsigned long long)(end_time - start_time), kfree_loops,
 689                        rcuscale_seq_diff(b_rcu_gp_test_finished, b_rcu_gp_test_started),
 690                        (mem_begin - mem_during) >> (20 - PAGE_SHIFT));
 691
 692                 if (shutdown) {
 693                         smp_mb(); /* Assign before wake. */
 694                         wake_up(&shutdown_wq);
 695                 }
 696         }
 697
 698         torture_kthread_stopping("kfree_scale_thread");
 699         return 0;
 700 }
 701
 702 static void
 703 kfree_scale_cleanup(void)
 704 {
 705         int i;
 706
 707         if (torture_cleanup_begin())
 708                 return;
 709
 710         if (kfree_reader_tasks) {
 711                 for (i = 0; i < kfree_nrealthreads; i++)
 712                         torture_stop_kthread(kfree_scale_thread,
 713                                              kfree_reader_tasks[i]);
 714                 kfree(kfree_reader_tasks);
 715         }
 716
 717         torture_cleanup_end();
 718 }
 719
 720 /*
 721  * shutdown kthread.  Just waits to be awakened, then shuts down system.
 722  */
 723 static int
 724 kfree_scale_shutdown(void *arg)
 725 {
 726         wait_event(shutdown_wq,
 727                    atomic_read(&n_kfree_scale_thread_ended) >= kfree_nrealthreads);
 728
 729         smp_mb(); /* Wake before output. */
 730
 731         kfree_scale_cleanup();
 732         kernel_power_off();
 733         return -EINVAL;
 734 }
 735
 736 static int __init
 737 kfree_scale_init(void)
 738 {
 739         long i;
 740         int firsterr = 0;
 741
 742         kfree_nrealthreads = compute_real(kfree_nthreads);
 743         /* Start up the kthreads. */
 744         if (shutdown) {
 745                 init_waitqueue_head(&shutdown_wq);
 746                 firsterr = torture_create_kthread(kfree_scale_shutdown, NULL,
 747                                                   shutdown_task);
 748                 if (firsterr)
 749                         goto unwind;
 750                 schedule_timeout_uninterruptible(1);
 751         }
 752
 753         pr_alert("kfree object size=%zu\n", kfree_mult * sizeof(struct kfree_obj));
 754
 755         kfree_reader_tasks = kcalloc(kfree_nrealthreads, sizeof(kfree_reader_tasks[0]),
 756                                GFP_KERNEL);
 757         if (kfree_reader_tasks == NULL) {
 758                 firsterr = -ENOMEM;
 759                 goto unwind;
 760         }
 761
 762         for (i = 0; i < kfree_nrealthreads; i++) {
 763                 firsterr = torture_create_kthread(kfree_scale_thread, (void *)i,
 764                                                   kfree_reader_tasks[i]);
 765                 if (firsterr)
 766                         goto unwind;
 767         }
 768
 769         while (atomic_read(&n_kfree_scale_thread_started) < kfree_nrealthreads)
 770                 schedule_timeout_uninterruptible(1);
 771
 772         torture_init_end();
 773         return 0;
 774
 775 unwind:
 776         torture_init_end();
 777         kfree_scale_cleanup();
 778         return firsterr;
 779 }
 780
 781 static int __init
 782 rcu_scale_init(void)
 783 {
 784         long i;
 785         int firsterr = 0;
 786         static struct rcu_scale_ops *scale_ops[] = {
 787                 &rcu_ops, &srcu_ops, &srcud_ops, &tasks_ops, &tasks_tracing_ops
 788         };
 789
 790         if (!torture_init_begin(scale_type, verbose))
 791                 return -EBUSY;
 792
 793         /* Process args and announce that the scalability'er is on the job. */
 794         for (i = 0; i < ARRAY_SIZE(scale_ops); i++) {
 795                 cur_ops = scale_ops[i];
 796                 if (strcmp(scale_type, cur_ops->name) == 0)
 797                         break;
 798         }
 799         if (i == ARRAY_SIZE(scale_ops)) {
 800                 pr_alert("rcu-scale: invalid scale type: \"%s\"\n", scale_type);
 801                 pr_alert("rcu-scale types:");
 802                 for (i = 0; i < ARRAY_SIZE(scale_ops); i++)
 803                         pr_cont(" %s", scale_ops[i]->name);
 804                 pr_cont("\n");
 805                 firsterr = -EINVAL;
 806                 cur_ops = NULL;
 807                 goto unwind;
 808         }
 809         if (cur_ops->init)
 810                 cur_ops->init();
 811
 812         if (kfree_rcu_test)
 813                 return kfree_scale_init();
 814
 815         nrealwriters = compute_real(nwriters);
 816         nrealreaders = compute_real(nreaders);
 817         atomic_set(&n_rcu_scale_reader_started, 0);
 818         atomic_set(&n_rcu_scale_writer_started, 0);
 819         atomic_set(&n_rcu_scale_writer_finished, 0);
 820         rcu_scale_print_module_parms(cur_ops, "Start of test");
 821
 822         /* Start up the kthreads. */
 823
 824         if (shutdown) {
 825                 init_waitqueue_head(&shutdown_wq);
 826                 firsterr = torture_create_kthread(rcu_scale_shutdown, NULL,
 827                                                   shutdown_task);
 828                 if (firsterr)
 829                         goto unwind;
 830                 schedule_timeout_uninterruptible(1);
 831         }
 832         reader_tasks = kcalloc(nrealreaders, sizeof(reader_tasks[0]),
 833                                GFP_KERNEL);
 834         if (reader_tasks == NULL) {
 835                 VERBOSE_SCALEOUT_ERRSTRING("out of memory");
 836                 firsterr = -ENOMEM;
 837                 goto unwind;
 838         }
 839         for (i = 0; i < nrealreaders; i++) {
 840                 firsterr = torture_create_kthread(rcu_scale_reader, (void *)i,
 841                                                   reader_tasks[i]);
 842                 if (firsterr)
 843                         goto unwind;
 844         }
 845         while (atomic_read(&n_rcu_scale_reader_started) < nrealreaders)
 846                 schedule_timeout_uninterruptible(1);
 847         writer_tasks = kcalloc(nrealwriters, sizeof(reader_tasks[0]),
 848                                GFP_KERNEL);
 849         writer_durations = kcalloc(nrealwriters, sizeof(*writer_durations),
 850                                    GFP_KERNEL);
 851         writer_n_durations =
 852                 kcalloc(nrealwriters, sizeof(*writer_n_durations),
 853                         GFP_KERNEL);
 854         if (!writer_tasks || !writer_durations || !writer_n_durations) {
 855                 VERBOSE_SCALEOUT_ERRSTRING("out of memory");
 856                 firsterr = -ENOMEM;
 857                 goto unwind;
 858         }
 859         for (i = 0; i < nrealwriters; i++) {
 860                 writer_durations[i] =
 861                         kcalloc(MAX_MEAS, sizeof(*writer_durations[i]),
 862                                 GFP_KERNEL);
 863                 if (!writer_durations[i]) {
 864                         firsterr = -ENOMEM;
 865                         goto unwind;
 866                 }
 867                 firsterr = torture_create_kthread(rcu_scale_writer, (void *)i,
 868                                                   writer_tasks[i]);
 869                 if (firsterr)
 870                         goto unwind;
 871         }
 872         torture_init_end();
 873         return 0;
 874
 875 unwind:
 876         torture_init_end();
 877         rcu_scale_cleanup();
 878         if (shutdown) {
 879                 WARN_ON(!IS_MODULE(CONFIG_RCU_SCALE_TEST));
 880                 kernel_power_off();
 881         }
 882         return firsterr;
 883 }
 884
 885 module_init(rcu_scale_init);
 886 module_exit(rcu_scale_cleanup);