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->has_dirty_rate = true;
  73         info->dirty_rate = dirty_rate;
  74     }
  75
  76     info->status = CalculatingState;
  77     info->start_time = DirtyStat.start_time;
  78     info->calc_time = DirtyStat.calc_time;
  79
  80     trace_query_dirty_rate_info(DirtyRateStatus_str(CalculatingState));
  81
  82     return info;
  83 }
  84
  85 static void init_dirtyrate_stat(int64_t start_time, int64_t calc_time)
  86 {
  87     DirtyStat.total_dirty_samples = 0;
  88     DirtyStat.total_sample_count = 0;
  89     DirtyStat.total_block_mem_MB = 0;
  90     DirtyStat.dirty_rate = -1;
  91     DirtyStat.start_time = start_time;
  92     DirtyStat.calc_time = calc_time;
  93 }
  94
  95 static void update_dirtyrate_stat(struct RamblockDirtyInfo *info)
  96 {
  97     DirtyStat.total_dirty_samples += info->sample_dirty_count;
  98     DirtyStat.total_sample_count += info->sample_pages_count;
  99     /* size of total pages in MB */
 100     DirtyStat.total_block_mem_MB += (info->ramblock_pages *
 101                                      TARGET_PAGE_SIZE) >> 20;
 102 }
 103
 104 static void update_dirtyrate(uint64_t msec)
 105 {
 106     uint64_t dirtyrate;
 107     uint64_t total_dirty_samples = DirtyStat.total_dirty_samples;
 108     uint64_t total_sample_count = DirtyStat.total_sample_count;
 109     uint64_t total_block_mem_MB = DirtyStat.total_block_mem_MB;
 110
 111     dirtyrate = total_dirty_samples * total_block_mem_MB *
 112                 1000 / (total_sample_count * msec);
 113
 114     DirtyStat.dirty_rate = dirtyrate;
 115 }
 116
 117 /*
 118  * get hash result for the sampled memory with length of TARGET_PAGE_SIZE
 119  * in ramblock, which starts from ramblock base address.
 120  */
 121 static uint32_t get_ramblock_vfn_hash(struct RamblockDirtyInfo *info,
 122                                       uint64_t vfn)
 123 {
 124     uint32_t crc;
 125
 126     crc = crc32(0, (info->ramblock_addr +
 127                 vfn * TARGET_PAGE_SIZE), TARGET_PAGE_SIZE);
 128
 129     trace_get_ramblock_vfn_hash(info->idstr, vfn, crc);
 130     return crc;
 131 }
 132
 133 static bool save_ramblock_hash(struct RamblockDirtyInfo *info)
 134 {
 135     unsigned int sample_pages_count;
 136     int i;
 137     GRand *rand;
 138
 139     sample_pages_count = info->sample_pages_count;
 140
 141     /* ramblock size less than one page, return success to skip this ramblock */
 142     if (unlikely(info->ramblock_pages == 0 || sample_pages_count == 0)) {
 143         return true;
 144     }
 145
 146     info->hash_result = g_try_malloc0_n(sample_pages_count,
 147                                         sizeof(uint32_t));
 148     if (!info->hash_result) {
 149         return false;
 150     }
 151
 152     info->sample_page_vfn = g_try_malloc0_n(sample_pages_count,
 153                                             sizeof(uint64_t));
 154     if (!info->sample_page_vfn) {
 155         g_free(info->hash_result);
 156         return false;
 157     }
 158
 159     rand  = g_rand_new();
 160     for (i = 0; i < sample_pages_count; i++) {
 161         info->sample_page_vfn[i] = g_rand_int_range(rand, 0,
 162                                                     info->ramblock_pages - 1);
 163         info->hash_result[i] = get_ramblock_vfn_hash(info,
 164                                                      info->sample_page_vfn[i]);
 165     }
 166     g_rand_free(rand);
 167
 168     return true;
 169 }
 170
 171 static void get_ramblock_dirty_info(RAMBlock *block,
 172                                     struct RamblockDirtyInfo *info,
 173                                     struct DirtyRateConfig *config)
 174 {
 175     uint64_t sample_pages_per_gigabytes = config->sample_pages_per_gigabytes;
 176
 177     /* Right shift 30 bits to calc ramblock size in GB */
 178     info->sample_pages_count = (qemu_ram_get_used_length(block) *
 179                                 sample_pages_per_gigabytes) >> 30;
 180     /* Right shift TARGET_PAGE_BITS to calc page count */
 181     info->ramblock_pages = qemu_ram_get_used_length(block) >>
 182                            TARGET_PAGE_BITS;
 183     info->ramblock_addr = qemu_ram_get_host_addr(block);
 184     strcpy(info->idstr, qemu_ram_get_idstr(block));
 185 }
 186
 187 static void free_ramblock_dirty_info(struct RamblockDirtyInfo *infos, int count)
 188 {
 189     int i;
 190
 191     if (!infos) {
 192         return;
 193     }
 194
 195     for (i = 0; i < count; i++) {
 196         g_free(infos[i].sample_page_vfn);
 197         g_free(infos[i].hash_result);
 198     }
 199     g_free(infos);
 200 }
 201
 202 static bool skip_sample_ramblock(RAMBlock *block)
 203 {
 204     /*
 205      * Sample only blocks larger than MIN_RAMBLOCK_SIZE.
 206      */
 207     if (qemu_ram_get_used_length(block) < (MIN_RAMBLOCK_SIZE << 10)) {
 208         trace_skip_sample_ramblock(block->idstr,
 209                                    qemu_ram_get_used_length(block));
 210         return true;
 211     }
 212
 213     return false;
 214 }
 215
 216 static bool record_ramblock_hash_info(struct RamblockDirtyInfo **block_dinfo,
 217                                       struct DirtyRateConfig config,
 218                                       int *block_count)
 219 {
 220     struct RamblockDirtyInfo *info = NULL;
 221     struct RamblockDirtyInfo *dinfo = NULL;
 222     RAMBlock *block = NULL;
 223     int total_count = 0;
 224     int index = 0;
 225     bool ret = false;
 226
 227     RAMBLOCK_FOREACH_MIGRATABLE(block) {
 228         if (skip_sample_ramblock(block)) {
 229             continue;
 230         }
 231         total_count++;
 232     }
 233
 234     dinfo = g_try_malloc0_n(total_count, sizeof(struct RamblockDirtyInfo));
 235     if (dinfo == NULL) {
 236         goto out;
 237     }
 238
 239     RAMBLOCK_FOREACH_MIGRATABLE(block) {
 240         if (skip_sample_ramblock(block)) {
 241             continue;
 242         }
 243         if (index >= total_count) {
 244             break;
 245         }
 246         info = &dinfo[index];
 247         get_ramblock_dirty_info(block, info, &config);
 248         if (!save_ramblock_hash(info)) {
 249             goto out;
 250         }
 251         index++;
 252     }
 253     ret = true;
 254
 255 out:
 256     *block_count = index;
 257     *block_dinfo = dinfo;
 258     return ret;
 259 }
 260
 261 static void calc_page_dirty_rate(struct RamblockDirtyInfo *info)
 262 {
 263     uint32_t crc;
 264     int i;
 265
 266     for (i = 0; i < info->sample_pages_count; i++) {
 267         crc = get_ramblock_vfn_hash(info, info->sample_page_vfn[i]);
 268         if (crc != info->hash_result[i]) {
 269             trace_calc_page_dirty_rate(info->idstr, crc, info->hash_result[i]);
 270             info->sample_dirty_count++;
 271         }
 272     }
 273 }
 274
 275 static struct RamblockDirtyInfo *
 276 find_block_matched(RAMBlock *block, int count,
 277                   struct RamblockDirtyInfo *infos)
 278 {
 279     int i;
 280     struct RamblockDirtyInfo *matched;
 281
 282     for (i = 0; i < count; i++) {
 283         if (!strcmp(infos[i].idstr, qemu_ram_get_idstr(block))) {
 284             break;
 285         }
 286     }
 287
 288     if (i == count) {
 289         return NULL;
 290     }
 291
 292     if (infos[i].ramblock_addr != qemu_ram_get_host_addr(block) ||
 293         infos[i].ramblock_pages !=
 294             (qemu_ram_get_used_length(block) >> TARGET_PAGE_BITS)) {
 295         trace_find_page_matched(block->idstr);
 296         return NULL;
 297     }
 298
 299     matched = &infos[i];
 300
 301     return matched;
 302 }
 303
 304 static bool compare_page_hash_info(struct RamblockDirtyInfo *info,
 305                                   int block_count)
 306 {
 307     struct RamblockDirtyInfo *block_dinfo = NULL;
 308     RAMBlock *block = NULL;
 309
 310     RAMBLOCK_FOREACH_MIGRATABLE(block) {
 311         if (skip_sample_ramblock(block)) {
 312             continue;
 313         }
 314         block_dinfo = find_block_matched(block, block_count, info);
 315         if (block_dinfo == NULL) {
 316             continue;
 317         }
 318         calc_page_dirty_rate(block_dinfo);
 319         update_dirtyrate_stat(block_dinfo);
 320     }
 321
 322     if (DirtyStat.total_sample_count == 0) {
 323         return false;
 324     }
 325
 326     return true;
 327 }
 328
 329 static void calculate_dirtyrate(struct DirtyRateConfig config)
 330 {
 331     struct RamblockDirtyInfo *block_dinfo = NULL;
 332     int block_count = 0;
 333     int64_t msec = 0;
 334     int64_t initial_time;
 335
 336     rcu_register_thread();
 337     rcu_read_lock();
 338     initial_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
 339     if (!record_ramblock_hash_info(&block_dinfo, config, &block_count)) {
 340         goto out;
 341     }
 342     rcu_read_unlock();
 343
 344     msec = config.sample_period_seconds * 1000;
 345     msec = set_sample_page_period(msec, initial_time);
 346     DirtyStat.start_time = initial_time / 1000;
 347     DirtyStat.calc_time = msec / 1000;
 348
 349     rcu_read_lock();
 350     if (!compare_page_hash_info(block_dinfo, block_count)) {
 351         goto out;
 352     }
 353
 354     update_dirtyrate(msec);
 355
 356 out:
 357     rcu_read_unlock();
 358     free_ramblock_dirty_info(block_dinfo, block_count);
 359     rcu_unregister_thread();
 360 }
 361
 362 void *get_dirtyrate_thread(void *arg)
 363 {
 364     struct DirtyRateConfig config = *(struct DirtyRateConfig *)arg;
 365     int ret;
 366     int64_t start_time;
 367     int64_t calc_time;
 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     start_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME) / 1000;
 377     calc_time = config.sample_period_seconds;
 378     init_dirtyrate_stat(start_time, calc_time);
 379
 380     calculate_dirtyrate(config);
 381
 382     ret = dirtyrate_set_state(&CalculatingState, DIRTY_RATE_STATUS_MEASURING,
 383                               DIRTY_RATE_STATUS_MEASURED);
 384     if (ret == -1) {
 385         error_report("change dirtyrate state failed.");
 386     }
 387     return NULL;
 388 }
 389
 390 void qmp_calc_dirty_rate(int64_t calc_time, Error **errp)
 391 {
 392     static struct DirtyRateConfig config;
 393     QemuThread thread;
 394     int ret;
 395
 396     /*
 397      * If the dirty rate is already being measured, don't attempt to start.
 398      */
 399     if (qatomic_read(&CalculatingState) == DIRTY_RATE_STATUS_MEASURING) {
 400         error_setg(errp, "the dirty rate is already being measured.");
 401         return;
 402     }
 403
 404     if (!is_sample_period_valid(calc_time)) {
 405         error_setg(errp, "calc-time is out of range[%d, %d].",
 406                          MIN_FETCH_DIRTYRATE_TIME_SEC,
 407                          MAX_FETCH_DIRTYRATE_TIME_SEC);
 408         return;
 409     }
 410
 411     /*
 412      * Init calculation state as unstarted.
 413      */
 414     ret = dirtyrate_set_state(&CalculatingState, CalculatingState,
 415                               DIRTY_RATE_STATUS_UNSTARTED);
 416     if (ret == -1) {
 417         error_setg(errp, "init dirty rate calculation state failed.");
 418         return;
 419     }
 420
 421     config.sample_period_seconds = calc_time;
 422     config.sample_pages_per_gigabytes = DIRTYRATE_DEFAULT_SAMPLE_PAGES;
 423     qemu_thread_create(&thread, "get_dirtyrate", get_dirtyrate_thread,
 424                        (void *)&config, QEMU_THREAD_DETACHED);
 425 }
 426
 427 struct DirtyRateInfo *qmp_query_dirty_rate(Error **errp)
 428 {
 429     return query_dirty_rate_info();
 430 }