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