migration/dirtyrate.c

   1 /*
   2  * Dirtyrate implement code
   3  *
   4  * Copyright (c) 2020 HUAWEI TECHNOLOGIES CO.,LTD.
   5  *
   6  * Authors:
   7  *  Chuan Zheng <zhengchuan@huawei.com>
   8  *
   9  * This work is licensed under the terms of the GNU GPL, version 2 or later.
  10  * See the COPYING file in the top-level directory.
  11  */
  12
  13 #include <zlib.h>
  14 #include "qemu/osdep.h"
  15 #include "qapi/error.h"
  16 #include "cpu.h"
  17 #include "qemu/config-file.h"
  18 #include "exec/memory.h"
  19 #include "exec/ramblock.h"
  20 #include "exec/target_page.h"
  21 #include "qemu/rcu_queue.h"
  22 #include "qapi/qapi-commands-migration.h"
  23 #include "migration.h"
  24 #include "ram.h"
  25 #include "trace.h"
  26 #include "dirtyrate.h"
  27
  28 static int CalculatingState = DIRTY_RATE_STATUS_UNSTARTED;
  29 static struct DirtyRateStat DirtyStat;
  30
  31 static int64_t set_sample_page_period(int64_t msec, int64_t initial_time)
  32 {
  33     int64_t current_time;
  34
  35     current_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
  36     if ((current_time - initial_time) >= msec) {
  37         msec = current_time - initial_time;
  38     } else {
  39         g_usleep((msec + initial_time - current_time) * 1000);
  40     }
  41
  42     return msec;
  43 }
  44
  45 static bool is_sample_period_valid(int64_t sec)
  46 {
  47     if (sec < MIN_FETCH_DIRTYRATE_TIME_SEC ||
  48         sec > MAX_FETCH_DIRTYRATE_TIME_SEC) {
  49         return false;
  50     }
  51
  52     return true;
  53 }
  54
  55 static int dirtyrate_set_state(int *state, int old_state, int new_state)
  56 {
  57     assert(new_state < DIRTY_RATE_STATUS__MAX);
  58     trace_dirtyrate_set_state(DirtyRateStatus_str(new_state));
  59     if (qatomic_cmpxchg(state, old_state, new_state) == old_state) {
  60         return 0;
  61     } else {
  62         return -1;
  63     }
  64 }
  65
  66 static struct DirtyRateInfo *query_dirty_rate_info(void)
  67 {
  68     int64_t dirty_rate = DirtyStat.dirty_rate;
  69     struct DirtyRateInfo *info = g_malloc0(sizeof(DirtyRateInfo));
  70
  71     if (qatomic_read(&CalculatingState) == DIRTY_RATE_STATUS_MEASURED) {
  72         info->dirty_rate = dirty_rate;
  73     } else {
  74         info->dirty_rate = -1;
  75     }
  76
  77     info->status = CalculatingState;
  78     info->start_time = DirtyStat.start_time;
  79     info->calc_time = DirtyStat.calc_time;
  80
  81     trace_query_dirty_rate_info(DirtyRateStatus_str(CalculatingState));
  82
  83     return info;
  84 }
  85
  86 static void reset_dirtyrate_stat(void)
  87 {
  88     DirtyStat.total_dirty_samples = 0;
  89     DirtyStat.total_sample_count = 0;
  90     DirtyStat.total_block_mem_MB = 0;
  91     DirtyStat.dirty_rate = -1;
  92     DirtyStat.start_time = 0;
  93     DirtyStat.calc_time = 0;
  94 }
  95
  96 static void update_dirtyrate_stat(struct RamblockDirtyInfo *info)
  97 {
  98     DirtyStat.total_dirty_samples += info->sample_dirty_count;
  99     DirtyStat.total_sample_count += info->sample_pages_count;
 100     /* size of total pages in MB */
 101     DirtyStat.total_block_mem_MB += (info->ramblock_pages *
 102                                      TARGET_PAGE_SIZE) >> 20;
 103 }
 104
 105 static void update_dirtyrate(uint64_t msec)
 106 {
 107     uint64_t dirtyrate;
 108     uint64_t total_dirty_samples = DirtyStat.total_dirty_samples;
 109     uint64_t total_sample_count = DirtyStat.total_sample_count;
 110     uint64_t total_block_mem_MB = DirtyStat.total_block_mem_MB;
 111
 112     dirtyrate = total_dirty_samples * total_block_mem_MB *
 113                 1000 / (total_sample_count * msec);
 114
 115     DirtyStat.dirty_rate = dirtyrate;
 116 }
 117
 118 /*
 119  * get hash result for the sampled memory with length of TARGET_PAGE_SIZE
 120  * in ramblock, which starts from ramblock base address.
 121  */
 122 static uint32_t get_ramblock_vfn_hash(struct RamblockDirtyInfo *info,
 123                                       uint64_t vfn)
 124 {
 125     uint32_t crc;
 126
 127     crc = crc32(0, (info->ramblock_addr +
 128                 vfn * TARGET_PAGE_SIZE), TARGET_PAGE_SIZE);
 129
 130     trace_get_ramblock_vfn_hash(info->idstr, vfn, crc);
 131     return crc;
 132 }
 133
 134 static bool save_ramblock_hash(struct RamblockDirtyInfo *info)
 135 {
 136     unsigned int sample_pages_count;
 137     int i;
 138     GRand *rand;
 139
 140     sample_pages_count = info->sample_pages_count;
 141
 142     /* ramblock size less than one page, return success to skip this ramblock */
 143     if (unlikely(info->ramblock_pages == 0 || sample_pages_count == 0)) {
 144         return true;
 145     }
 146
 147     info->hash_result = g_try_malloc0_n(sample_pages_count,
 148                                         sizeof(uint32_t));
 149     if (!info->hash_result) {
 150         return false;
 151     }
 152
 153     info->sample_page_vfn = g_try_malloc0_n(sample_pages_count,
 154                                             sizeof(uint64_t));
 155     if (!info->sample_page_vfn) {
 156         g_free(info->hash_result);
 157         return false;
 158     }
 159
 160     rand  = g_rand_new();
 161     for (i = 0; i < sample_pages_count; i++) {
 162         info->sample_page_vfn[i] = g_rand_int_range(rand, 0,
 163                                                     info->ramblock_pages - 1);
 164         info->hash_result[i] = get_ramblock_vfn_hash(info,
 165                                                      info->sample_page_vfn[i]);
 166     }
 167     g_rand_free(rand);
 168
 169     return true;
 170 }
 171
 172 static void get_ramblock_dirty_info(RAMBlock *block,
 173                                     struct RamblockDirtyInfo *info,
 174                                     struct DirtyRateConfig *config)
 175 {
 176     uint64_t sample_pages_per_gigabytes = config->sample_pages_per_gigabytes;
 177
 178     /* Right shift 30 bits to calc ramblock size in GB */
 179     info->sample_pages_count = (qemu_ram_get_used_length(block) *
 180                                 sample_pages_per_gigabytes) >> 30;
 181     /* Right shift TARGET_PAGE_BITS to calc page count */
 182     info->ramblock_pages = qemu_ram_get_used_length(block) >>
 183                            TARGET_PAGE_BITS;
 184     info->ramblock_addr = qemu_ram_get_host_addr(block);
 185     strcpy(info->idstr, qemu_ram_get_idstr(block));
 186 }
 187
 188 static void free_ramblock_dirty_info(struct RamblockDirtyInfo *infos, int count)
 189 {
 190     int i;
 191
 192     if (!infos) {
 193         return;
 194     }
 195
 196     for (i = 0; i < count; i++) {
 197         g_free(infos[i].sample_page_vfn);
 198         g_free(infos[i].hash_result);
 199     }
 200     g_free(infos);
 201 }
 202
 203 static bool skip_sample_ramblock(RAMBlock *block)
 204 {
 205     /*
 206      * Sample only blocks larger than MIN_RAMBLOCK_SIZE.
 207      */
 208     if (qemu_ram_get_used_length(block) < (MIN_RAMBLOCK_SIZE << 10)) {
 209         trace_skip_sample_ramblock(block->idstr,
 210                                    qemu_ram_get_used_length(block));
 211         return true;
 212     }
 213
 214     return false;
 215 }
 216
 217 static bool record_ramblock_hash_info(struct RamblockDirtyInfo **block_dinfo,
 218                                       struct DirtyRateConfig config,
 219                                       int *block_count)
 220 {
 221     struct RamblockDirtyInfo *info = NULL;
 222     struct RamblockDirtyInfo *dinfo = NULL;
 223     RAMBlock *block = NULL;
 224     int total_count = 0;
 225     int index = 0;
 226     bool ret = false;
 227
 228     RAMBLOCK_FOREACH_MIGRATABLE(block) {
 229         if (skip_sample_ramblock(block)) {
 230             continue;
 231         }
 232         total_count++;
 233     }
 234
 235     dinfo = g_try_malloc0_n(total_count, sizeof(struct RamblockDirtyInfo));
 236     if (dinfo == NULL) {
 237         goto out;
 238     }
 239
 240     RAMBLOCK_FOREACH_MIGRATABLE(block) {
 241         if (skip_sample_ramblock(block)) {
 242             continue;
 243         }
 244         if (index >= total_count) {
 245             break;
 246         }
 247         info = &dinfo[index];
 248         get_ramblock_dirty_info(block, info, &config);
 249         if (!save_ramblock_hash(info)) {
 250             goto out;
 251         }
 252         index++;
 253     }
 254     ret = true;
 255
 256 out:
 257     *block_count = index;
 258     *block_dinfo = dinfo;
 259     return ret;
 260 }
 261
 262 static void calc_page_dirty_rate(struct RamblockDirtyInfo *info)
 263 {
 264     uint32_t crc;
 265     int i;
 266
 267     for (i = 0; i < info->sample_pages_count; i++) {
 268         crc = get_ramblock_vfn_hash(info, info->sample_page_vfn[i]);
 269         if (crc != info->hash_result[i]) {
 270             trace_calc_page_dirty_rate(info->idstr, crc, info->hash_result[i]);
 271             info->sample_dirty_count++;
 272         }
 273     }
 274 }
 275
 276 static struct RamblockDirtyInfo *
 277 find_block_matched(RAMBlock *block, int count,
 278                   struct RamblockDirtyInfo *infos)
 279 {
 280     int i;
 281     struct RamblockDirtyInfo *matched;
 282
 283     for (i = 0; i < count; i++) {
 284         if (!strcmp(infos[i].idstr, qemu_ram_get_idstr(block))) {
 285             break;
 286         }
 287     }
 288
 289     if (i == count) {
 290         return NULL;
 291     }
 292
 293     if (infos[i].ramblock_addr != qemu_ram_get_host_addr(block) ||
 294         infos[i].ramblock_pages !=
 295             (qemu_ram_get_used_length(block) >> TARGET_PAGE_BITS)) {
 296         trace_find_page_matched(block->idstr);
 297         return NULL;
 298     }
 299
 300     matched = &infos[i];
 301
 302     return matched;
 303 }
 304
 305 static bool compare_page_hash_info(struct RamblockDirtyInfo *info,
 306                                   int block_count)
 307 {
 308     struct RamblockDirtyInfo *block_dinfo = NULL;
 309     RAMBlock *block = NULL;
 310
 311     RAMBLOCK_FOREACH_MIGRATABLE(block) {
 312         if (skip_sample_ramblock(block)) {
 313             continue;
 314         }
 315         block_dinfo = find_block_matched(block, block_count, info);
 316         if (block_dinfo == NULL) {
 317             continue;
 318         }
 319         calc_page_dirty_rate(block_dinfo);
 320         update_dirtyrate_stat(block_dinfo);
 321     }
 322
 323     if (DirtyStat.total_sample_count == 0) {
 324         return false;
 325     }
 326
 327     return true;
 328 }
 329
 330 static void calculate_dirtyrate(struct DirtyRateConfig config)
 331 {
 332     struct RamblockDirtyInfo *block_dinfo = NULL;
 333     int block_count = 0;
 334     int64_t msec = 0;
 335     int64_t initial_time;
 336
 337     rcu_register_thread();
 338     reset_dirtyrate_stat();
 339     rcu_read_lock();
 340     initial_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
 341     if (!record_ramblock_hash_info(&block_dinfo, config, &block_count)) {
 342         goto out;
 343     }
 344     rcu_read_unlock();
 345
 346     msec = config.sample_period_seconds * 1000;
 347     msec = set_sample_page_period(msec, initial_time);
 348     DirtyStat.start_time = initial_time / 1000;
 349     DirtyStat.calc_time = msec / 1000;
 350
 351     rcu_read_lock();
 352     if (!compare_page_hash_info(block_dinfo, block_count)) {
 353         goto out;
 354     }
 355
 356     update_dirtyrate(msec);
 357
 358 out:
 359     rcu_read_unlock();
 360     free_ramblock_dirty_info(block_dinfo, block_count);
 361     rcu_unregister_thread();
 362 }
 363
 364 void *get_dirtyrate_thread(void *arg)
 365 {
 366     struct DirtyRateConfig config = *(struct DirtyRateConfig *)arg;
 367     int ret;
 368
 369     ret = dirtyrate_set_state(&CalculatingState, DIRTY_RATE_STATUS_UNSTARTED,
 370                               DIRTY_RATE_STATUS_MEASURING);
 371     if (ret == -1) {
 372         error_report("change dirtyrate state failed.");
 373         return NULL;
 374     }
 375
 376     calculate_dirtyrate(config);
 377
 378     ret = dirtyrate_set_state(&CalculatingState, DIRTY_RATE_STATUS_MEASURING,
 379                               DIRTY_RATE_STATUS_MEASURED);
 380     if (ret == -1) {
 381         error_report("change dirtyrate state failed.");
 382     }
 383     return NULL;
 384 }
 385
 386 void qmp_calc_dirty_rate(int64_t calc_time, Error **errp)
 387 {
 388     static struct DirtyRateConfig config;
 389     QemuThread thread;
 390     int ret;
 391
 392     /*
 393      * If the dirty rate is already being measured, don't attempt to start.
 394      */
 395     if (qatomic_read(&CalculatingState) == DIRTY_RATE_STATUS_MEASURING) {
 396         error_setg(errp, "the dirty rate is already being measured.");
 397         return;
 398     }
 399
 400     if (!is_sample_period_valid(calc_time)) {
 401         error_setg(errp, "calc-time is out of range[%d, %d].",
 402                          MIN_FETCH_DIRTYRATE_TIME_SEC,
 403                          MAX_FETCH_DIRTYRATE_TIME_SEC);
 404         return;
 405     }
 406
 407     /*
 408      * Init calculation state as unstarted.
 409      */
 410     ret = dirtyrate_set_state(&CalculatingState, CalculatingState,
 411                               DIRTY_RATE_STATUS_UNSTARTED);
 412     if (ret == -1) {
 413         error_setg(errp, "init dirty rate calculation state failed.");
 414         return;
 415     }
 416
 417     config.sample_period_seconds = calc_time;
 418     config.sample_pages_per_gigabytes = DIRTYRATE_DEFAULT_SAMPLE_PAGES;
 419     qemu_thread_create(&thread, "get_dirtyrate", get_dirtyrate_thread,
 420                        (void *)&config, QEMU_THREAD_DETACHED);
 421 }
 422
 423 struct DirtyRateInfo *qmp_query_dirty_rate(Error **errp)
 424 {
 425     return query_dirty_rate_info();
 426 }