xref: /openbmc/qemu/migration/dirtyrate.c (revision 259ebed4)
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 "qemu/error-report.h"
15 #include <zlib.h>
16 #include "hw/core/cpu.h"
17 #include "qapi/error.h"
18 #include "exec/ramblock.h"
19 #include "exec/target_page.h"
20 #include "qemu/rcu_queue.h"
21 #include "qemu/main-loop.h"
22 #include "qapi/qapi-commands-migration.h"
23 #include "ram.h"
24 #include "trace.h"
25 #include "dirtyrate.h"
26 #include "monitor/hmp.h"
27 #include "monitor/monitor.h"
28 #include "qapi/qmp/qdict.h"
29 #include "sysemu/kvm.h"
30 #include "sysemu/runstate.h"
31 #include "exec/memory.h"
32 #include "qemu/xxhash.h"
33 
34 /*
35  * total_dirty_pages is procted by BQL and is used
36  * to stat dirty pages during the period of two
37  * memory_global_dirty_log_sync
38  */
39 uint64_t total_dirty_pages;
40 
41 typedef struct DirtyPageRecord {
42     uint64_t start_pages;
43     uint64_t end_pages;
44 } DirtyPageRecord;
45 
46 static int CalculatingState = DIRTY_RATE_STATUS_UNSTARTED;
47 static struct DirtyRateStat DirtyStat;
48 static DirtyRateMeasureMode dirtyrate_mode =
49                 DIRTY_RATE_MEASURE_MODE_PAGE_SAMPLING;
50 
51 static int64_t dirty_stat_wait(int64_t msec, int64_t initial_time)
52 {
53     int64_t current_time;
54 
55     current_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
56     if ((current_time - initial_time) >= msec) {
57         msec = current_time - initial_time;
58     } else {
59         g_usleep((msec + initial_time - current_time) * 1000);
60         /* g_usleep may overshoot */
61         msec = qemu_clock_get_ms(QEMU_CLOCK_REALTIME) - initial_time;
62     }
63 
64     return msec;
65 }
66 
67 static inline void record_dirtypages(DirtyPageRecord *dirty_pages,
68                                      CPUState *cpu, bool start)
69 {
70     if (start) {
71         dirty_pages[cpu->cpu_index].start_pages = cpu->dirty_pages;
72     } else {
73         dirty_pages[cpu->cpu_index].end_pages = cpu->dirty_pages;
74     }
75 }
76 
77 static int64_t do_calculate_dirtyrate(DirtyPageRecord dirty_pages,
78                                       int64_t calc_time_ms)
79 {
80     uint64_t increased_dirty_pages =
81         dirty_pages.end_pages - dirty_pages.start_pages;
82 
83     /*
84      * multiply by 1000ms/s _before_ converting down to megabytes
85      * to avoid losing precision
86      */
87     return qemu_target_pages_to_MiB(increased_dirty_pages * 1000) /
88         calc_time_ms;
89 }
90 
91 void global_dirty_log_change(unsigned int flag, bool start)
92 {
93     qemu_mutex_lock_iothread();
94     if (start) {
95         memory_global_dirty_log_start(flag);
96     } else {
97         memory_global_dirty_log_stop(flag);
98     }
99     qemu_mutex_unlock_iothread();
100 }
101 
102 /*
103  * global_dirty_log_sync
104  * 1. sync dirty log from kvm
105  * 2. stop dirty tracking if needed.
106  */
107 static void global_dirty_log_sync(unsigned int flag, bool one_shot)
108 {
109     qemu_mutex_lock_iothread();
110     memory_global_dirty_log_sync(false);
111     if (one_shot) {
112         memory_global_dirty_log_stop(flag);
113     }
114     qemu_mutex_unlock_iothread();
115 }
116 
117 static DirtyPageRecord *vcpu_dirty_stat_alloc(VcpuStat *stat)
118 {
119     CPUState *cpu;
120     int nvcpu = 0;
121 
122     CPU_FOREACH(cpu) {
123         nvcpu++;
124     }
125 
126     stat->nvcpu = nvcpu;
127     stat->rates = g_new0(DirtyRateVcpu, nvcpu);
128 
129     return g_new0(DirtyPageRecord, nvcpu);
130 }
131 
132 static void vcpu_dirty_stat_collect(VcpuStat *stat,
133                                     DirtyPageRecord *records,
134                                     bool start)
135 {
136     CPUState *cpu;
137 
138     CPU_FOREACH(cpu) {
139         record_dirtypages(records, cpu, start);
140     }
141 }
142 
143 int64_t vcpu_calculate_dirtyrate(int64_t calc_time_ms,
144                                  VcpuStat *stat,
145                                  unsigned int flag,
146                                  bool one_shot)
147 {
148     DirtyPageRecord *records;
149     int64_t init_time_ms;
150     int64_t duration;
151     int64_t dirtyrate;
152     int i = 0;
153     unsigned int gen_id;
154 
155 retry:
156     init_time_ms = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
157 
158     WITH_QEMU_LOCK_GUARD(&qemu_cpu_list_lock) {
159         gen_id = cpu_list_generation_id_get();
160         records = vcpu_dirty_stat_alloc(stat);
161         vcpu_dirty_stat_collect(stat, records, true);
162     }
163 
164     duration = dirty_stat_wait(calc_time_ms, init_time_ms);
165 
166     global_dirty_log_sync(flag, one_shot);
167 
168     WITH_QEMU_LOCK_GUARD(&qemu_cpu_list_lock) {
169         if (gen_id != cpu_list_generation_id_get()) {
170             g_free(records);
171             g_free(stat->rates);
172             cpu_list_unlock();
173             goto retry;
174         }
175         vcpu_dirty_stat_collect(stat, records, false);
176     }
177 
178     for (i = 0; i < stat->nvcpu; i++) {
179         dirtyrate = do_calculate_dirtyrate(records[i], duration);
180 
181         stat->rates[i].id = i;
182         stat->rates[i].dirty_rate = dirtyrate;
183 
184         trace_dirtyrate_do_calculate_vcpu(i, dirtyrate);
185     }
186 
187     g_free(records);
188 
189     return duration;
190 }
191 
192 static bool is_calc_time_valid(int64_t msec)
193 {
194     if ((msec < MIN_CALC_TIME_MS) || (msec > MAX_CALC_TIME_MS)) {
195         return false;
196     }
197 
198     return true;
199 }
200 
201 static bool is_sample_pages_valid(int64_t pages)
202 {
203     return pages >= MIN_SAMPLE_PAGE_COUNT &&
204            pages <= MAX_SAMPLE_PAGE_COUNT;
205 }
206 
207 static int dirtyrate_set_state(int *state, int old_state, int new_state)
208 {
209     assert(new_state < DIRTY_RATE_STATUS__MAX);
210     trace_dirtyrate_set_state(DirtyRateStatus_str(new_state));
211     if (qatomic_cmpxchg(state, old_state, new_state) == old_state) {
212         return 0;
213     } else {
214         return -1;
215     }
216 }
217 
218 /* Decimal power of given time unit relative to one second */
219 static int time_unit_to_power(TimeUnit time_unit)
220 {
221     switch (time_unit) {
222     case TIME_UNIT_SECOND:
223         return 0;
224     case TIME_UNIT_MILLISECOND:
225         return -3;
226     default:
227         assert(false); /* unreachable */
228         return 0;
229     }
230 }
231 
232 static int64_t convert_time_unit(int64_t value, TimeUnit unit_from,
233                                  TimeUnit unit_to)
234 {
235     int power = time_unit_to_power(unit_from) -
236                 time_unit_to_power(unit_to);
237     while (power < 0) {
238         value /= 10;
239         power += 1;
240     }
241     while (power > 0) {
242         value *= 10;
243         power -= 1;
244     }
245     return value;
246 }
247 
248 
249 static struct DirtyRateInfo *
250 query_dirty_rate_info(TimeUnit calc_time_unit)
251 {
252     int i;
253     int64_t dirty_rate = DirtyStat.dirty_rate;
254     struct DirtyRateInfo *info = g_new0(DirtyRateInfo, 1);
255     DirtyRateVcpuList *head = NULL, **tail = &head;
256 
257     info->status = CalculatingState;
258     info->start_time = DirtyStat.start_time;
259     info->calc_time = convert_time_unit(DirtyStat.calc_time_ms,
260                                         TIME_UNIT_MILLISECOND,
261                                         calc_time_unit);
262     info->calc_time_unit = calc_time_unit;
263     info->sample_pages = DirtyStat.sample_pages;
264     info->mode = dirtyrate_mode;
265 
266     if (qatomic_read(&CalculatingState) == DIRTY_RATE_STATUS_MEASURED) {
267         info->has_dirty_rate = true;
268         info->dirty_rate = dirty_rate;
269 
270         if (dirtyrate_mode == DIRTY_RATE_MEASURE_MODE_DIRTY_RING) {
271             /*
272              * set sample_pages with 0 to indicate page sampling
273              * isn't enabled
274              **/
275             info->sample_pages = 0;
276             info->has_vcpu_dirty_rate = true;
277             for (i = 0; i < DirtyStat.dirty_ring.nvcpu; i++) {
278                 DirtyRateVcpu *rate = g_new0(DirtyRateVcpu, 1);
279                 rate->id = DirtyStat.dirty_ring.rates[i].id;
280                 rate->dirty_rate = DirtyStat.dirty_ring.rates[i].dirty_rate;
281                 QAPI_LIST_APPEND(tail, rate);
282             }
283             info->vcpu_dirty_rate = head;
284         }
285 
286         if (dirtyrate_mode == DIRTY_RATE_MEASURE_MODE_DIRTY_BITMAP) {
287             info->sample_pages = 0;
288         }
289     }
290 
291     trace_query_dirty_rate_info(DirtyRateStatus_str(CalculatingState));
292 
293     return info;
294 }
295 
296 static void init_dirtyrate_stat(struct DirtyRateConfig config)
297 {
298     DirtyStat.dirty_rate = -1;
299     DirtyStat.start_time = qemu_clock_get_ms(QEMU_CLOCK_HOST) / 1000;
300     DirtyStat.calc_time_ms = config.calc_time_ms;
301     DirtyStat.sample_pages = config.sample_pages_per_gigabytes;
302 
303     switch (config.mode) {
304     case DIRTY_RATE_MEASURE_MODE_PAGE_SAMPLING:
305         DirtyStat.page_sampling.total_dirty_samples = 0;
306         DirtyStat.page_sampling.total_sample_count = 0;
307         DirtyStat.page_sampling.total_block_mem_MB = 0;
308         break;
309     case DIRTY_RATE_MEASURE_MODE_DIRTY_RING:
310         DirtyStat.dirty_ring.nvcpu = -1;
311         DirtyStat.dirty_ring.rates = NULL;
312         break;
313     default:
314         break;
315     }
316 }
317 
318 static void cleanup_dirtyrate_stat(struct DirtyRateConfig config)
319 {
320     /* last calc-dirty-rate qmp use dirty ring mode */
321     if (dirtyrate_mode == DIRTY_RATE_MEASURE_MODE_DIRTY_RING) {
322         free(DirtyStat.dirty_ring.rates);
323         DirtyStat.dirty_ring.rates = NULL;
324     }
325 }
326 
327 static void update_dirtyrate_stat(struct RamblockDirtyInfo *info)
328 {
329     DirtyStat.page_sampling.total_dirty_samples += info->sample_dirty_count;
330     DirtyStat.page_sampling.total_sample_count += info->sample_pages_count;
331     /* size of total pages in MB */
332     DirtyStat.page_sampling.total_block_mem_MB +=
333         qemu_target_pages_to_MiB(info->ramblock_pages);
334 }
335 
336 static void update_dirtyrate(uint64_t msec)
337 {
338     uint64_t dirtyrate;
339     uint64_t total_dirty_samples = DirtyStat.page_sampling.total_dirty_samples;
340     uint64_t total_sample_count = DirtyStat.page_sampling.total_sample_count;
341     uint64_t total_block_mem_MB = DirtyStat.page_sampling.total_block_mem_MB;
342 
343     dirtyrate = total_dirty_samples * total_block_mem_MB *
344                 1000 / (total_sample_count * msec);
345 
346     DirtyStat.dirty_rate = dirtyrate;
347 }
348 
349 /*
350  * Compute hash of a single page of size TARGET_PAGE_SIZE.
351  */
352 static uint32_t compute_page_hash(void *ptr)
353 {
354     size_t page_size = qemu_target_page_size();
355     uint32_t i;
356     uint64_t v1, v2, v3, v4;
357     uint64_t res;
358     const uint64_t *p = ptr;
359 
360     v1 = QEMU_XXHASH_SEED + XXH_PRIME64_1 + XXH_PRIME64_2;
361     v2 = QEMU_XXHASH_SEED + XXH_PRIME64_2;
362     v3 = QEMU_XXHASH_SEED + 0;
363     v4 = QEMU_XXHASH_SEED - XXH_PRIME64_1;
364     for (i = 0; i < page_size / 8; i += 4) {
365         v1 = XXH64_round(v1, p[i + 0]);
366         v2 = XXH64_round(v2, p[i + 1]);
367         v3 = XXH64_round(v3, p[i + 2]);
368         v4 = XXH64_round(v4, p[i + 3]);
369     }
370     res = XXH64_mergerounds(v1, v2, v3, v4);
371     res += page_size;
372     res = XXH64_avalanche(res);
373     return (uint32_t)(res & UINT32_MAX);
374 }
375 
376 
377 /*
378  * get hash result for the sampled memory with length of TARGET_PAGE_SIZE
379  * in ramblock, which starts from ramblock base address.
380  */
381 static uint32_t get_ramblock_vfn_hash(struct RamblockDirtyInfo *info,
382                                       uint64_t vfn)
383 {
384     uint32_t hash;
385 
386     hash = compute_page_hash(info->ramblock_addr +
387                              vfn * qemu_target_page_size());
388 
389     trace_get_ramblock_vfn_hash(info->idstr, vfn, hash);
390     return hash;
391 }
392 
393 static bool save_ramblock_hash(struct RamblockDirtyInfo *info)
394 {
395     unsigned int sample_pages_count;
396     int i;
397     GRand *rand;
398 
399     sample_pages_count = info->sample_pages_count;
400 
401     /* ramblock size less than one page, return success to skip this ramblock */
402     if (unlikely(info->ramblock_pages == 0 || sample_pages_count == 0)) {
403         return true;
404     }
405 
406     info->hash_result = g_try_malloc0_n(sample_pages_count,
407                                         sizeof(uint32_t));
408     if (!info->hash_result) {
409         return false;
410     }
411 
412     info->sample_page_vfn = g_try_malloc0_n(sample_pages_count,
413                                             sizeof(uint64_t));
414     if (!info->sample_page_vfn) {
415         g_free(info->hash_result);
416         return false;
417     }
418 
419     rand  = g_rand_new();
420     for (i = 0; i < sample_pages_count; i++) {
421         info->sample_page_vfn[i] = g_rand_int_range(rand, 0,
422                                                     info->ramblock_pages - 1);
423         info->hash_result[i] = get_ramblock_vfn_hash(info,
424                                                      info->sample_page_vfn[i]);
425     }
426     g_rand_free(rand);
427 
428     return true;
429 }
430 
431 static void get_ramblock_dirty_info(RAMBlock *block,
432                                     struct RamblockDirtyInfo *info,
433                                     struct DirtyRateConfig *config)
434 {
435     uint64_t sample_pages_per_gigabytes = config->sample_pages_per_gigabytes;
436 
437     /* Right shift 30 bits to calc ramblock size in GB */
438     info->sample_pages_count = (qemu_ram_get_used_length(block) *
439                                 sample_pages_per_gigabytes) >> 30;
440     /* Right shift TARGET_PAGE_BITS to calc page count */
441     info->ramblock_pages = qemu_ram_get_used_length(block) >>
442                            qemu_target_page_bits();
443     info->ramblock_addr = qemu_ram_get_host_addr(block);
444     strcpy(info->idstr, qemu_ram_get_idstr(block));
445 }
446 
447 static void free_ramblock_dirty_info(struct RamblockDirtyInfo *infos, int count)
448 {
449     int i;
450 
451     if (!infos) {
452         return;
453     }
454 
455     for (i = 0; i < count; i++) {
456         g_free(infos[i].sample_page_vfn);
457         g_free(infos[i].hash_result);
458     }
459     g_free(infos);
460 }
461 
462 static bool skip_sample_ramblock(RAMBlock *block)
463 {
464     /*
465      * Sample only blocks larger than MIN_RAMBLOCK_SIZE.
466      */
467     if (qemu_ram_get_used_length(block) < (MIN_RAMBLOCK_SIZE << 10)) {
468         trace_skip_sample_ramblock(block->idstr,
469                                    qemu_ram_get_used_length(block));
470         return true;
471     }
472 
473     return false;
474 }
475 
476 static bool record_ramblock_hash_info(struct RamblockDirtyInfo **block_dinfo,
477                                       struct DirtyRateConfig config,
478                                       int *block_count)
479 {
480     struct RamblockDirtyInfo *info = NULL;
481     struct RamblockDirtyInfo *dinfo = NULL;
482     RAMBlock *block = NULL;
483     int total_count = 0;
484     int index = 0;
485     bool ret = false;
486 
487     RAMBLOCK_FOREACH_MIGRATABLE(block) {
488         if (skip_sample_ramblock(block)) {
489             continue;
490         }
491         total_count++;
492     }
493 
494     dinfo = g_try_malloc0_n(total_count, sizeof(struct RamblockDirtyInfo));
495     if (dinfo == NULL) {
496         goto out;
497     }
498 
499     RAMBLOCK_FOREACH_MIGRATABLE(block) {
500         if (skip_sample_ramblock(block)) {
501             continue;
502         }
503         if (index >= total_count) {
504             break;
505         }
506         info = &dinfo[index];
507         get_ramblock_dirty_info(block, info, &config);
508         if (!save_ramblock_hash(info)) {
509             goto out;
510         }
511         index++;
512     }
513     ret = true;
514 
515 out:
516     *block_count = index;
517     *block_dinfo = dinfo;
518     return ret;
519 }
520 
521 static void calc_page_dirty_rate(struct RamblockDirtyInfo *info)
522 {
523     uint32_t hash;
524     int i;
525 
526     for (i = 0; i < info->sample_pages_count; i++) {
527         hash = get_ramblock_vfn_hash(info, info->sample_page_vfn[i]);
528         if (hash != info->hash_result[i]) {
529             trace_calc_page_dirty_rate(info->idstr, hash, info->hash_result[i]);
530             info->sample_dirty_count++;
531         }
532     }
533 }
534 
535 static struct RamblockDirtyInfo *
536 find_block_matched(RAMBlock *block, int count,
537                   struct RamblockDirtyInfo *infos)
538 {
539     int i;
540 
541     for (i = 0; i < count; i++) {
542         if (!strcmp(infos[i].idstr, qemu_ram_get_idstr(block))) {
543             break;
544         }
545     }
546 
547     if (i == count) {
548         return NULL;
549     }
550 
551     if (infos[i].ramblock_addr != qemu_ram_get_host_addr(block) ||
552         infos[i].ramblock_pages !=
553             (qemu_ram_get_used_length(block) >> qemu_target_page_bits())) {
554         trace_find_page_matched(block->idstr);
555         return NULL;
556     }
557 
558     return &infos[i];
559 }
560 
561 static bool compare_page_hash_info(struct RamblockDirtyInfo *info,
562                                   int block_count)
563 {
564     struct RamblockDirtyInfo *block_dinfo = NULL;
565     RAMBlock *block = NULL;
566 
567     RAMBLOCK_FOREACH_MIGRATABLE(block) {
568         if (skip_sample_ramblock(block)) {
569             continue;
570         }
571         block_dinfo = find_block_matched(block, block_count, info);
572         if (block_dinfo == NULL) {
573             continue;
574         }
575         calc_page_dirty_rate(block_dinfo);
576         update_dirtyrate_stat(block_dinfo);
577     }
578 
579     if (DirtyStat.page_sampling.total_sample_count == 0) {
580         return false;
581     }
582 
583     return true;
584 }
585 
586 static inline void record_dirtypages_bitmap(DirtyPageRecord *dirty_pages,
587                                             bool start)
588 {
589     if (start) {
590         dirty_pages->start_pages = total_dirty_pages;
591     } else {
592         dirty_pages->end_pages = total_dirty_pages;
593     }
594 }
595 
596 static inline void dirtyrate_manual_reset_protect(void)
597 {
598     RAMBlock *block = NULL;
599 
600     WITH_RCU_READ_LOCK_GUARD() {
601         RAMBLOCK_FOREACH_MIGRATABLE(block) {
602             memory_region_clear_dirty_bitmap(block->mr, 0,
603                                              block->used_length);
604         }
605     }
606 }
607 
608 static void calculate_dirtyrate_dirty_bitmap(struct DirtyRateConfig config)
609 {
610     int64_t start_time;
611     DirtyPageRecord dirty_pages;
612 
613     qemu_mutex_lock_iothread();
614     memory_global_dirty_log_start(GLOBAL_DIRTY_DIRTY_RATE);
615 
616     /*
617      * 1'round of log sync may return all 1 bits with
618      * KVM_DIRTY_LOG_INITIALLY_SET enable
619      * skip it unconditionally and start dirty tracking
620      * from 2'round of log sync
621      */
622     memory_global_dirty_log_sync(false);
623 
624     /*
625      * reset page protect manually and unconditionally.
626      * this make sure kvm dirty log be cleared if
627      * KVM_DIRTY_LOG_MANUAL_PROTECT_ENABLE cap is enabled.
628      */
629     dirtyrate_manual_reset_protect();
630     qemu_mutex_unlock_iothread();
631 
632     record_dirtypages_bitmap(&dirty_pages, true);
633 
634     start_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
635     DirtyStat.start_time = qemu_clock_get_ms(QEMU_CLOCK_HOST) / 1000;
636 
637     DirtyStat.calc_time_ms = dirty_stat_wait(config.calc_time_ms, start_time);
638 
639     /*
640      * do two things.
641      * 1. fetch dirty bitmap from kvm
642      * 2. stop dirty tracking
643      */
644     global_dirty_log_sync(GLOBAL_DIRTY_DIRTY_RATE, true);
645 
646     record_dirtypages_bitmap(&dirty_pages, false);
647 
648     DirtyStat.dirty_rate = do_calculate_dirtyrate(dirty_pages,
649                                                   DirtyStat.calc_time_ms);
650 }
651 
652 static void calculate_dirtyrate_dirty_ring(struct DirtyRateConfig config)
653 {
654     uint64_t dirtyrate = 0;
655     uint64_t dirtyrate_sum = 0;
656     int i = 0;
657 
658     /* start log sync */
659     global_dirty_log_change(GLOBAL_DIRTY_DIRTY_RATE, true);
660 
661     DirtyStat.start_time = qemu_clock_get_ms(QEMU_CLOCK_HOST) / 1000;
662 
663     /* calculate vcpu dirtyrate */
664     DirtyStat.calc_time_ms = vcpu_calculate_dirtyrate(config.calc_time_ms,
665                                                       &DirtyStat.dirty_ring,
666                                                       GLOBAL_DIRTY_DIRTY_RATE,
667                                                       true);
668 
669     /* calculate vm dirtyrate */
670     for (i = 0; i < DirtyStat.dirty_ring.nvcpu; i++) {
671         dirtyrate = DirtyStat.dirty_ring.rates[i].dirty_rate;
672         DirtyStat.dirty_ring.rates[i].dirty_rate = dirtyrate;
673         dirtyrate_sum += dirtyrate;
674     }
675 
676     DirtyStat.dirty_rate = dirtyrate_sum;
677 }
678 
679 static void calculate_dirtyrate_sample_vm(struct DirtyRateConfig config)
680 {
681     struct RamblockDirtyInfo *block_dinfo = NULL;
682     int block_count = 0;
683     int64_t initial_time;
684 
685     rcu_read_lock();
686     initial_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
687     DirtyStat.start_time = qemu_clock_get_ms(QEMU_CLOCK_HOST) / 1000;
688     if (!record_ramblock_hash_info(&block_dinfo, config, &block_count)) {
689         goto out;
690     }
691     rcu_read_unlock();
692 
693     DirtyStat.calc_time_ms = dirty_stat_wait(config.calc_time_ms,
694                                              initial_time);
695 
696     rcu_read_lock();
697     if (!compare_page_hash_info(block_dinfo, block_count)) {
698         goto out;
699     }
700 
701     update_dirtyrate(DirtyStat.calc_time_ms);
702 
703 out:
704     rcu_read_unlock();
705     free_ramblock_dirty_info(block_dinfo, block_count);
706 }
707 
708 static void calculate_dirtyrate(struct DirtyRateConfig config)
709 {
710     if (config.mode == DIRTY_RATE_MEASURE_MODE_DIRTY_BITMAP) {
711         calculate_dirtyrate_dirty_bitmap(config);
712     } else if (config.mode == DIRTY_RATE_MEASURE_MODE_DIRTY_RING) {
713         calculate_dirtyrate_dirty_ring(config);
714     } else {
715         calculate_dirtyrate_sample_vm(config);
716     }
717 
718     trace_dirtyrate_calculate(DirtyStat.dirty_rate);
719 }
720 
721 void *get_dirtyrate_thread(void *arg)
722 {
723     struct DirtyRateConfig config = *(struct DirtyRateConfig *)arg;
724     int ret;
725     rcu_register_thread();
726 
727     ret = dirtyrate_set_state(&CalculatingState, DIRTY_RATE_STATUS_UNSTARTED,
728                               DIRTY_RATE_STATUS_MEASURING);
729     if (ret == -1) {
730         error_report("change dirtyrate state failed.");
731         return NULL;
732     }
733 
734     calculate_dirtyrate(config);
735 
736     ret = dirtyrate_set_state(&CalculatingState, DIRTY_RATE_STATUS_MEASURING,
737                               DIRTY_RATE_STATUS_MEASURED);
738     if (ret == -1) {
739         error_report("change dirtyrate state failed.");
740     }
741 
742     rcu_unregister_thread();
743     return NULL;
744 }
745 
746 void qmp_calc_dirty_rate(int64_t calc_time,
747                          bool has_calc_time_unit,
748                          TimeUnit calc_time_unit,
749                          bool has_sample_pages,
750                          int64_t sample_pages,
751                          bool has_mode,
752                          DirtyRateMeasureMode mode,
753                          Error **errp)
754 {
755     static struct DirtyRateConfig config;
756     QemuThread thread;
757     int ret;
758 
759     /*
760      * If the dirty rate is already being measured, don't attempt to start.
761      */
762     if (qatomic_read(&CalculatingState) == DIRTY_RATE_STATUS_MEASURING) {
763         error_setg(errp, "the dirty rate is already being measured.");
764         return;
765     }
766 
767     int64_t calc_time_ms = convert_time_unit(
768         calc_time,
769         has_calc_time_unit ? calc_time_unit : TIME_UNIT_SECOND,
770         TIME_UNIT_MILLISECOND
771     );
772 
773     if (!is_calc_time_valid(calc_time_ms)) {
774         error_setg(errp, "Calculation time is out of range [%dms, %dms].",
775                          MIN_CALC_TIME_MS, MAX_CALC_TIME_MS);
776         return;
777     }
778 
779     if (!has_mode) {
780         mode =  DIRTY_RATE_MEASURE_MODE_PAGE_SAMPLING;
781     }
782 
783     if (has_sample_pages && mode != DIRTY_RATE_MEASURE_MODE_PAGE_SAMPLING) {
784         error_setg(errp, "sample-pages is used only in page-sampling mode");
785         return;
786     }
787 
788     if (has_sample_pages) {
789         if (!is_sample_pages_valid(sample_pages)) {
790             error_setg(errp, "sample-pages is out of range[%d, %d].",
791                             MIN_SAMPLE_PAGE_COUNT,
792                             MAX_SAMPLE_PAGE_COUNT);
793             return;
794         }
795     } else {
796         sample_pages = DIRTYRATE_DEFAULT_SAMPLE_PAGES;
797     }
798 
799     /*
800      * dirty ring mode only works when kvm dirty ring is enabled.
801      * on the contrary, dirty bitmap mode is not.
802      */
803     if (((mode == DIRTY_RATE_MEASURE_MODE_DIRTY_RING) &&
804         !kvm_dirty_ring_enabled()) ||
805         ((mode == DIRTY_RATE_MEASURE_MODE_DIRTY_BITMAP) &&
806          kvm_dirty_ring_enabled())) {
807         error_setg(errp, "mode %s is not enabled, use other method instead.",
808                          DirtyRateMeasureMode_str(mode));
809          return;
810     }
811 
812     /*
813      * Init calculation state as unstarted.
814      */
815     ret = dirtyrate_set_state(&CalculatingState, CalculatingState,
816                               DIRTY_RATE_STATUS_UNSTARTED);
817     if (ret == -1) {
818         error_setg(errp, "init dirty rate calculation state failed.");
819         return;
820     }
821 
822     config.calc_time_ms = calc_time_ms;
823     config.sample_pages_per_gigabytes = sample_pages;
824     config.mode = mode;
825 
826     cleanup_dirtyrate_stat(config);
827 
828     /*
829      * update dirty rate mode so that we can figure out what mode has
830      * been used in last calculation
831      **/
832     dirtyrate_mode = mode;
833 
834     init_dirtyrate_stat(config);
835 
836     qemu_thread_create(&thread, "get_dirtyrate", get_dirtyrate_thread,
837                        (void *)&config, QEMU_THREAD_DETACHED);
838 }
839 
840 
841 struct DirtyRateInfo *qmp_query_dirty_rate(bool has_calc_time_unit,
842                                            TimeUnit calc_time_unit,
843                                            Error **errp)
844 {
845     return query_dirty_rate_info(
846         has_calc_time_unit ? calc_time_unit : TIME_UNIT_SECOND);
847 }
848 
849 void hmp_info_dirty_rate(Monitor *mon, const QDict *qdict)
850 {
851     DirtyRateInfo *info = query_dirty_rate_info(TIME_UNIT_SECOND);
852 
853     monitor_printf(mon, "Status: %s\n",
854                    DirtyRateStatus_str(info->status));
855     monitor_printf(mon, "Start Time: %"PRIi64" (ms)\n",
856                    info->start_time);
857     if (info->mode == DIRTY_RATE_MEASURE_MODE_PAGE_SAMPLING) {
858         monitor_printf(mon, "Sample Pages: %"PRIu64" (per GB)\n",
859                        info->sample_pages);
860     }
861     monitor_printf(mon, "Period: %"PRIi64" (sec)\n",
862                    info->calc_time);
863     monitor_printf(mon, "Mode: %s\n",
864                    DirtyRateMeasureMode_str(info->mode));
865     monitor_printf(mon, "Dirty rate: ");
866     if (info->has_dirty_rate) {
867         monitor_printf(mon, "%"PRIi64" (MB/s)\n", info->dirty_rate);
868         if (info->has_vcpu_dirty_rate) {
869             DirtyRateVcpuList *rate, *head = info->vcpu_dirty_rate;
870             for (rate = head; rate != NULL; rate = rate->next) {
871                 monitor_printf(mon, "vcpu[%"PRIi64"], Dirty rate: %"PRIi64
872                                " (MB/s)\n", rate->value->id,
873                                rate->value->dirty_rate);
874             }
875         }
876     } else {
877         monitor_printf(mon, "(not ready)\n");
878     }
879 
880     qapi_free_DirtyRateVcpuList(info->vcpu_dirty_rate);
881     g_free(info);
882 }
883 
884 void hmp_calc_dirty_rate(Monitor *mon, const QDict *qdict)
885 {
886     int64_t sec = qdict_get_try_int(qdict, "second", 0);
887     int64_t sample_pages = qdict_get_try_int(qdict, "sample_pages_per_GB", -1);
888     bool has_sample_pages = (sample_pages != -1);
889     bool dirty_ring = qdict_get_try_bool(qdict, "dirty_ring", false);
890     bool dirty_bitmap = qdict_get_try_bool(qdict, "dirty_bitmap", false);
891     DirtyRateMeasureMode mode = DIRTY_RATE_MEASURE_MODE_PAGE_SAMPLING;
892     Error *err = NULL;
893 
894     if (!sec) {
895         monitor_printf(mon, "Incorrect period length specified!\n");
896         return;
897     }
898 
899     if (dirty_ring && dirty_bitmap) {
900         monitor_printf(mon, "Either dirty ring or dirty bitmap "
901                        "can be specified!\n");
902         return;
903     }
904 
905     if (dirty_bitmap) {
906         mode = DIRTY_RATE_MEASURE_MODE_DIRTY_BITMAP;
907     } else if (dirty_ring) {
908         mode = DIRTY_RATE_MEASURE_MODE_DIRTY_RING;
909     }
910 
911     qmp_calc_dirty_rate(sec, /* calc-time */
912                         false, TIME_UNIT_SECOND, /* calc-time-unit */
913                         has_sample_pages, sample_pages,
914                         true, mode,
915                         &err);
916     if (err) {
917         hmp_handle_error(mon, err);
918         return;
919     }
920 
921     monitor_printf(mon, "Starting dirty rate measurement with period %"PRIi64
922                    " seconds\n", sec);
923     monitor_printf(mon, "[Please use 'info dirty_rate' to check results]\n");
924 }
925