tools/testing/selftests/kvm/dirty_log_perf_test.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * KVM dirty page logging performance test
   4  *
   5  * Based on dirty_log_test.c
   6  *
   7  * Copyright (C) 2018, Red Hat, Inc.
   8  * Copyright (C) 2020, Google, Inc.
   9  */
  10
  11 #include <stdio.h>
  12 #include <stdlib.h>
  13 #include <time.h>
  14 #include <pthread.h>
  15 #include <linux/bitmap.h>
  16
  17 #include "kvm_util.h"
  18 #include "test_util.h"
  19 #include "memstress.h"
  20 #include "guest_modes.h"
  21
  22 #ifdef __aarch64__
  23 #include "aarch64/vgic.h"
  24
  25 #define GICD_BASE_GPA                   0x8000000ULL
  26 #define GICR_BASE_GPA                   0x80A0000ULL
  27
  28 static int gic_fd;
  29
  30 static void arch_setup_vm(struct kvm_vm *vm, unsigned int nr_vcpus)
  31 {
  32         /*
  33          * The test can still run even if hardware does not support GICv3, as it
  34          * is only an optimization to reduce guest exits.
  35          */
  36         gic_fd = vgic_v3_setup(vm, nr_vcpus, 64, GICD_BASE_GPA, GICR_BASE_GPA);
  37 }
  38
  39 static void arch_cleanup_vm(struct kvm_vm *vm)
  40 {
  41         if (gic_fd > 0)
  42                 close(gic_fd);
  43 }
  44
  45 #else /* __aarch64__ */
  46
  47 static void arch_setup_vm(struct kvm_vm *vm, unsigned int nr_vcpus)
  48 {
  49 }
  50
  51 static void arch_cleanup_vm(struct kvm_vm *vm)
  52 {
  53 }
  54
  55 #endif
  56
  57 /* How many host loops to run by default (one KVM_GET_DIRTY_LOG for each loop)*/
  58 #define TEST_HOST_LOOP_N                2UL
  59
  60 static int nr_vcpus = 1;
  61 static uint64_t guest_percpu_mem_size = DEFAULT_PER_VCPU_MEM_SIZE;
  62 static bool run_vcpus_while_disabling_dirty_logging;
  63
  64 /* Host variables */
  65 static u64 dirty_log_manual_caps;
  66 static bool host_quit;
  67 static int iteration;
  68 static int vcpu_last_completed_iteration[KVM_MAX_VCPUS];
  69
  70 static void vcpu_worker(struct memstress_vcpu_args *vcpu_args)
  71 {
  72         struct kvm_vcpu *vcpu = vcpu_args->vcpu;
  73         int vcpu_idx = vcpu_args->vcpu_idx;
  74         uint64_t pages_count = 0;
  75         struct kvm_run *run;
  76         struct timespec start;
  77         struct timespec ts_diff;
  78         struct timespec total = (struct timespec){0};
  79         struct timespec avg;
  80         int ret;
  81
  82         run = vcpu->run;
  83
  84         while (!READ_ONCE(host_quit)) {
  85                 int current_iteration = READ_ONCE(iteration);
  86
  87                 clock_gettime(CLOCK_MONOTONIC, &start);
  88                 ret = _vcpu_run(vcpu);
  89                 ts_diff = timespec_elapsed(start);
  90
  91                 TEST_ASSERT(ret == 0, "vcpu_run failed: %d", ret);
  92                 TEST_ASSERT(get_ucall(vcpu, NULL) == UCALL_SYNC,
  93                             "Invalid guest sync status: exit_reason=%s",
  94                             exit_reason_str(run->exit_reason));
  95
  96                 pr_debug("Got sync event from vCPU %d\n", vcpu_idx);
  97                 vcpu_last_completed_iteration[vcpu_idx] = current_iteration;
  98                 pr_debug("vCPU %d updated last completed iteration to %d\n",
  99                          vcpu_idx, vcpu_last_completed_iteration[vcpu_idx]);
 100
 101                 if (current_iteration) {
 102                         pages_count += vcpu_args->pages;
 103                         total = timespec_add(total, ts_diff);
 104                         pr_debug("vCPU %d iteration %d dirty memory time: %ld.%.9lds\n",
 105                                 vcpu_idx, current_iteration, ts_diff.tv_sec,
 106                                 ts_diff.tv_nsec);
 107                 } else {
 108                         pr_debug("vCPU %d iteration %d populate memory time: %ld.%.9lds\n",
 109                                 vcpu_idx, current_iteration, ts_diff.tv_sec,
 110                                 ts_diff.tv_nsec);
 111                 }
 112
 113                 /*
 114                  * Keep running the guest while dirty logging is being disabled
 115                  * (iteration is negative) so that vCPUs are accessing memory
 116                  * for the entire duration of zapping collapsible SPTEs.
 117                  */
 118                 while (current_iteration == READ_ONCE(iteration) &&
 119                        READ_ONCE(iteration) >= 0 && !READ_ONCE(host_quit)) {}
 120         }
 121
 122         avg = timespec_div(total, vcpu_last_completed_iteration[vcpu_idx]);
 123         pr_debug("\nvCPU %d dirtied 0x%lx pages over %d iterations in %ld.%.9lds. (Avg %ld.%.9lds/iteration)\n",
 124                 vcpu_idx, pages_count, vcpu_last_completed_iteration[vcpu_idx],
 125                 total.tv_sec, total.tv_nsec, avg.tv_sec, avg.tv_nsec);
 126 }
 127
 128 struct test_params {
 129         unsigned long iterations;
 130         uint64_t phys_offset;
 131         bool partition_vcpu_memory_access;
 132         enum vm_mem_backing_src_type backing_src;
 133         int slots;
 134         uint32_t write_percent;
 135         uint32_t random_seed;
 136         bool random_access;
 137 };
 138
 139 static void run_test(enum vm_guest_mode mode, void *arg)
 140 {
 141         struct test_params *p = arg;
 142         struct kvm_vm *vm;
 143         unsigned long **bitmaps;
 144         uint64_t guest_num_pages;
 145         uint64_t host_num_pages;
 146         uint64_t pages_per_slot;
 147         struct timespec start;
 148         struct timespec ts_diff;
 149         struct timespec get_dirty_log_total = (struct timespec){0};
 150         struct timespec vcpu_dirty_total = (struct timespec){0};
 151         struct timespec avg;
 152         struct timespec clear_dirty_log_total = (struct timespec){0};
 153         int i;
 154
 155         vm = memstress_create_vm(mode, nr_vcpus, guest_percpu_mem_size,
 156                                  p->slots, p->backing_src,
 157                                  p->partition_vcpu_memory_access);
 158
 159         pr_info("Random seed: %u\n", p->random_seed);
 160         memstress_set_random_seed(vm, p->random_seed);
 161         memstress_set_write_percent(vm, p->write_percent);
 162
 163         guest_num_pages = (nr_vcpus * guest_percpu_mem_size) >> vm->page_shift;
 164         guest_num_pages = vm_adjust_num_guest_pages(mode, guest_num_pages);
 165         host_num_pages = vm_num_host_pages(mode, guest_num_pages);
 166         pages_per_slot = host_num_pages / p->slots;
 167
 168         bitmaps = memstress_alloc_bitmaps(p->slots, pages_per_slot);
 169
 170         if (dirty_log_manual_caps)
 171                 vm_enable_cap(vm, KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2,
 172                               dirty_log_manual_caps);
 173
 174         arch_setup_vm(vm, nr_vcpus);
 175
 176         /* Start the iterations */
 177         iteration = 0;
 178         host_quit = false;
 179
 180         clock_gettime(CLOCK_MONOTONIC, &start);
 181         for (i = 0; i < nr_vcpus; i++)
 182                 vcpu_last_completed_iteration[i] = -1;
 183
 184         /*
 185          * Use 100% writes during the population phase to ensure all
 186          * memory is actually populated and not just mapped to the zero
 187          * page. The prevents expensive copy-on-write faults from
 188          * occurring during the dirty memory iterations below, which
 189          * would pollute the performance results.
 190          */
 191         memstress_set_write_percent(vm, 100);
 192         memstress_set_random_access(vm, false);
 193         memstress_start_vcpu_threads(nr_vcpus, vcpu_worker);
 194
 195         /* Allow the vCPUs to populate memory */
 196         pr_debug("Starting iteration %d - Populating\n", iteration);
 197         for (i = 0; i < nr_vcpus; i++) {
 198                 while (READ_ONCE(vcpu_last_completed_iteration[i]) !=
 199                        iteration)
 200                         ;
 201         }
 202
 203         ts_diff = timespec_elapsed(start);
 204         pr_info("Populate memory time: %ld.%.9lds\n",
 205                 ts_diff.tv_sec, ts_diff.tv_nsec);
 206
 207         /* Enable dirty logging */
 208         clock_gettime(CLOCK_MONOTONIC, &start);
 209         memstress_enable_dirty_logging(vm, p->slots);
 210         ts_diff = timespec_elapsed(start);
 211         pr_info("Enabling dirty logging time: %ld.%.9lds\n\n",
 212                 ts_diff.tv_sec, ts_diff.tv_nsec);
 213
 214         memstress_set_write_percent(vm, p->write_percent);
 215         memstress_set_random_access(vm, p->random_access);
 216
 217         while (iteration < p->iterations) {
 218                 /*
 219                  * Incrementing the iteration number will start the vCPUs
 220                  * dirtying memory again.
 221                  */
 222                 clock_gettime(CLOCK_MONOTONIC, &start);
 223                 iteration++;
 224
 225                 pr_debug("Starting iteration %d\n", iteration);
 226                 for (i = 0; i < nr_vcpus; i++) {
 227                         while (READ_ONCE(vcpu_last_completed_iteration[i])
 228                                != iteration)
 229                                 ;
 230                 }
 231
 232                 ts_diff = timespec_elapsed(start);
 233                 vcpu_dirty_total = timespec_add(vcpu_dirty_total, ts_diff);
 234                 pr_info("Iteration %d dirty memory time: %ld.%.9lds\n",
 235                         iteration, ts_diff.tv_sec, ts_diff.tv_nsec);
 236
 237                 clock_gettime(CLOCK_MONOTONIC, &start);
 238                 memstress_get_dirty_log(vm, bitmaps, p->slots);
 239                 ts_diff = timespec_elapsed(start);
 240                 get_dirty_log_total = timespec_add(get_dirty_log_total,
 241                                                    ts_diff);
 242                 pr_info("Iteration %d get dirty log time: %ld.%.9lds\n",
 243                         iteration, ts_diff.tv_sec, ts_diff.tv_nsec);
 244
 245                 if (dirty_log_manual_caps) {
 246                         clock_gettime(CLOCK_MONOTONIC, &start);
 247                         memstress_clear_dirty_log(vm, bitmaps, p->slots,
 248                                                   pages_per_slot);
 249                         ts_diff = timespec_elapsed(start);
 250                         clear_dirty_log_total = timespec_add(clear_dirty_log_total,
 251                                                              ts_diff);
 252                         pr_info("Iteration %d clear dirty log time: %ld.%.9lds\n",
 253                                 iteration, ts_diff.tv_sec, ts_diff.tv_nsec);
 254                 }
 255         }
 256
 257         /*
 258          * Run vCPUs while dirty logging is being disabled to stress disabling
 259          * in terms of both performance and correctness.  Opt-in via command
 260          * line as this significantly increases time to disable dirty logging.
 261          */
 262         if (run_vcpus_while_disabling_dirty_logging)
 263                 WRITE_ONCE(iteration, -1);
 264
 265         /* Disable dirty logging */
 266         clock_gettime(CLOCK_MONOTONIC, &start);
 267         memstress_disable_dirty_logging(vm, p->slots);
 268         ts_diff = timespec_elapsed(start);
 269         pr_info("Disabling dirty logging time: %ld.%.9lds\n",
 270                 ts_diff.tv_sec, ts_diff.tv_nsec);
 271
 272         /*
 273          * Tell the vCPU threads to quit.  No need to manually check that vCPUs
 274          * have stopped running after disabling dirty logging, the join will
 275          * wait for them to exit.
 276          */
 277         host_quit = true;
 278         memstress_join_vcpu_threads(nr_vcpus);
 279
 280         avg = timespec_div(get_dirty_log_total, p->iterations);
 281         pr_info("Get dirty log over %lu iterations took %ld.%.9lds. (Avg %ld.%.9lds/iteration)\n",
 282                 p->iterations, get_dirty_log_total.tv_sec,
 283                 get_dirty_log_total.tv_nsec, avg.tv_sec, avg.tv_nsec);
 284
 285         if (dirty_log_manual_caps) {
 286                 avg = timespec_div(clear_dirty_log_total, p->iterations);
 287                 pr_info("Clear dirty log over %lu iterations took %ld.%.9lds. (Avg %ld.%.9lds/iteration)\n",
 288                         p->iterations, clear_dirty_log_total.tv_sec,
 289                         clear_dirty_log_total.tv_nsec, avg.tv_sec, avg.tv_nsec);
 290         }
 291
 292         memstress_free_bitmaps(bitmaps, p->slots);
 293         arch_cleanup_vm(vm);
 294         memstress_destroy_vm(vm);
 295 }
 296
 297 static void help(char *name)
 298 {
 299         puts("");
 300         printf("usage: %s [-h] [-a] [-i iterations] [-p offset] [-g] "
 301                "[-m mode] [-n] [-b vcpu bytes] [-v vcpus] [-o] [-r random seed ] [-s mem type]"
 302                "[-x memslots] [-w percentage] [-c physical cpus to run test on]\n", name);
 303         puts("");
 304         printf(" -a: access memory randomly rather than in order.\n");
 305         printf(" -i: specify iteration counts (default: %"PRIu64")\n",
 306                TEST_HOST_LOOP_N);
 307         printf(" -g: Do not enable KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2. This\n"
 308                "     makes KVM_GET_DIRTY_LOG clear the dirty log (i.e.\n"
 309                "     KVM_DIRTY_LOG_MANUAL_PROTECT_ENABLE is not enabled)\n"
 310                "     and writes will be tracked as soon as dirty logging is\n"
 311                "     enabled on the memslot (i.e. KVM_DIRTY_LOG_INITIALLY_SET\n"
 312                "     is not enabled).\n");
 313         printf(" -p: specify guest physical test memory offset\n"
 314                "     Warning: a low offset can conflict with the loaded test code.\n");
 315         guest_modes_help();
 316         printf(" -n: Run the vCPUs in nested mode (L2)\n");
 317         printf(" -e: Run vCPUs while dirty logging is being disabled.  This\n"
 318                "     can significantly increase runtime, especially if there\n"
 319                "     isn't a dedicated pCPU for the main thread.\n");
 320         printf(" -b: specify the size of the memory region which should be\n"
 321                "     dirtied by each vCPU. e.g. 10M or 3G.\n"
 322                "     (default: 1G)\n");
 323         printf(" -v: specify the number of vCPUs to run.\n");
 324         printf(" -o: Overlap guest memory accesses instead of partitioning\n"
 325                "     them into a separate region of memory for each vCPU.\n");
 326         printf(" -r: specify the starting random seed.\n");
 327         backing_src_help("-s");
 328         printf(" -x: Split the memory region into this number of memslots.\n"
 329                "     (default: 1)\n");
 330         printf(" -w: specify the percentage of pages which should be written to\n"
 331                "     as an integer from 0-100 inclusive. This is probabilistic,\n"
 332                "     so -w X means each page has an X%% chance of writing\n"
 333                "     and a (100-X)%% chance of reading.\n"
 334                "     (default: 100 i.e. all pages are written to.)\n");
 335         kvm_print_vcpu_pinning_help();
 336         puts("");
 337         exit(0);
 338 }
 339
 340 int main(int argc, char *argv[])
 341 {
 342         int max_vcpus = kvm_check_cap(KVM_CAP_MAX_VCPUS);
 343         const char *pcpu_list = NULL;
 344         struct test_params p = {
 345                 .iterations = TEST_HOST_LOOP_N,
 346                 .partition_vcpu_memory_access = true,
 347                 .backing_src = DEFAULT_VM_MEM_SRC,
 348                 .slots = 1,
 349                 .random_seed = 1,
 350                 .write_percent = 100,
 351         };
 352         int opt;
 353
 354         dirty_log_manual_caps =
 355                 kvm_check_cap(KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2);
 356         dirty_log_manual_caps &= (KVM_DIRTY_LOG_MANUAL_PROTECT_ENABLE |
 357                                   KVM_DIRTY_LOG_INITIALLY_SET);
 358
 359         guest_modes_append_default();
 360
 361         while ((opt = getopt(argc, argv, "ab:c:eghi:m:nop:r:s:v:x:w:")) != -1) {
 362                 switch (opt) {
 363                 case 'a':
 364                         p.random_access = true;
 365                         break;
 366                 case 'b':
 367                         guest_percpu_mem_size = parse_size(optarg);
 368                         break;
 369                 case 'c':
 370                         pcpu_list = optarg;
 371                         break;
 372                 case 'e':
 373                         /* 'e' is for evil. */
 374                         run_vcpus_while_disabling_dirty_logging = true;
 375                         break;
 376                 case 'g':
 377                         dirty_log_manual_caps = 0;
 378                         break;
 379                 case 'h':
 380                         help(argv[0]);
 381                         break;
 382                 case 'i':
 383                         p.iterations = atoi_positive("Number of iterations", optarg);
 384                         break;
 385                 case 'm':
 386                         guest_modes_cmdline(optarg);
 387                         break;
 388                 case 'n':
 389                         memstress_args.nested = true;
 390                         break;
 391                 case 'o':
 392                         p.partition_vcpu_memory_access = false;
 393                         break;
 394                 case 'p':
 395                         p.phys_offset = strtoull(optarg, NULL, 0);
 396                         break;
 397                 case 'r':
 398                         p.random_seed = atoi_positive("Random seed", optarg);
 399                         break;
 400                 case 's':
 401                         p.backing_src = parse_backing_src_type(optarg);
 402                         break;
 403                 case 'v':
 404                         nr_vcpus = atoi_positive("Number of vCPUs", optarg);
 405                         TEST_ASSERT(nr_vcpus <= max_vcpus,
 406                                     "Invalid number of vcpus, must be between 1 and %d", max_vcpus);
 407                         break;
 408                 case 'w':
 409                         p.write_percent = atoi_non_negative("Write percentage", optarg);
 410                         TEST_ASSERT(p.write_percent <= 100,
 411                                     "Write percentage must be between 0 and 100");
 412                         break;
 413                 case 'x':
 414                         p.slots = atoi_positive("Number of slots", optarg);
 415                         break;
 416                 default:
 417                         help(argv[0]);
 418                         break;
 419                 }
 420         }
 421
 422         if (pcpu_list) {
 423                 kvm_parse_vcpu_pinning(pcpu_list, memstress_args.vcpu_to_pcpu,
 424                                        nr_vcpus);
 425                 memstress_args.pin_vcpus = true;
 426         }
 427
 428         TEST_ASSERT(p.iterations >= 2, "The test should have at least two iterations");
 429
 430         pr_info("Test iterations: %"PRIu64"\n", p.iterations);
 431
 432         for_each_guest_mode(run_test, &p);
 433
 434         return 0;
 435 }