diff options
Diffstat (limited to 'qemu/migration/ram.c')
| -rw-r--r-- | qemu/migration/ram.c | 1670 |
1 files changed, 1670 insertions, 0 deletions
diff --git a/qemu/migration/ram.c b/qemu/migration/ram.c new file mode 100644 index 000000000..7f007e643 --- /dev/null +++ b/qemu/migration/ram.c @@ -0,0 +1,1670 @@ +/* + * QEMU System Emulator + * + * Copyright (c) 2003-2008 Fabrice Bellard + * Copyright (c) 2011-2015 Red Hat Inc + * + * Authors: + * Juan Quintela <quintela@redhat.com> + * + * Permission is hereby granted, free of charge, to any person obtaining a copy + * of this software and associated documentation files (the "Software"), to deal + * in the Software without restriction, including without limitation the rights + * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell + * copies of the Software, and to permit persons to whom the Software is + * furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice shall be included in + * all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN + * THE SOFTWARE. + */ +#include <stdint.h> +#include <zlib.h> +#include "qemu/bitops.h" +#include "qemu/bitmap.h" +#include "qemu/timer.h" +#include "qemu/main-loop.h" +#include "migration/migration.h" +#include "exec/address-spaces.h" +#include "migration/page_cache.h" +#include "qemu/error-report.h" +#include "trace.h" +#include "exec/ram_addr.h" +#include "qemu/rcu_queue.h" + +#ifdef DEBUG_MIGRATION_RAM +#define DPRINTF(fmt, ...) \ + do { fprintf(stdout, "migration_ram: " fmt, ## __VA_ARGS__); } while (0) +#else +#define DPRINTF(fmt, ...) \ + do { } while (0) +#endif + +static bool mig_throttle_on; +static int dirty_rate_high_cnt; +static void check_guest_throttling(void); + +static uint64_t bitmap_sync_count; + +/***********************************************************/ +/* ram save/restore */ + +#define RAM_SAVE_FLAG_FULL 0x01 /* Obsolete, not used anymore */ +#define RAM_SAVE_FLAG_COMPRESS 0x02 +#define RAM_SAVE_FLAG_MEM_SIZE 0x04 +#define RAM_SAVE_FLAG_PAGE 0x08 +#define RAM_SAVE_FLAG_EOS 0x10 +#define RAM_SAVE_FLAG_CONTINUE 0x20 +#define RAM_SAVE_FLAG_XBZRLE 0x40 +/* 0x80 is reserved in migration.h start with 0x100 next */ +#define RAM_SAVE_FLAG_COMPRESS_PAGE 0x100 + +static const uint8_t ZERO_TARGET_PAGE[TARGET_PAGE_SIZE]; + +static inline bool is_zero_range(uint8_t *p, uint64_t size) +{ + return buffer_find_nonzero_offset(p, size) == size; +} + +/* struct contains XBZRLE cache and a static page + used by the compression */ +static struct { + /* buffer used for XBZRLE encoding */ + uint8_t *encoded_buf; + /* buffer for storing page content */ + uint8_t *current_buf; + /* Cache for XBZRLE, Protected by lock. */ + PageCache *cache; + QemuMutex lock; +} XBZRLE; + +/* buffer used for XBZRLE decoding */ +static uint8_t *xbzrle_decoded_buf; + +static void XBZRLE_cache_lock(void) +{ + if (migrate_use_xbzrle()) + qemu_mutex_lock(&XBZRLE.lock); +} + +static void XBZRLE_cache_unlock(void) +{ + if (migrate_use_xbzrle()) + qemu_mutex_unlock(&XBZRLE.lock); +} + +/* + * called from qmp_migrate_set_cache_size in main thread, possibly while + * a migration is in progress. + * A running migration maybe using the cache and might finish during this + * call, hence changes to the cache are protected by XBZRLE.lock(). + */ +int64_t xbzrle_cache_resize(int64_t new_size) +{ + PageCache *new_cache; + int64_t ret; + + if (new_size < TARGET_PAGE_SIZE) { + return -1; + } + + XBZRLE_cache_lock(); + + if (XBZRLE.cache != NULL) { + if (pow2floor(new_size) == migrate_xbzrle_cache_size()) { + goto out_new_size; + } + new_cache = cache_init(new_size / TARGET_PAGE_SIZE, + TARGET_PAGE_SIZE); + if (!new_cache) { + error_report("Error creating cache"); + ret = -1; + goto out; + } + + cache_fini(XBZRLE.cache); + XBZRLE.cache = new_cache; + } + +out_new_size: + ret = pow2floor(new_size); +out: + XBZRLE_cache_unlock(); + return ret; +} + +/* accounting for migration statistics */ +typedef struct AccountingInfo { + uint64_t dup_pages; + uint64_t skipped_pages; + uint64_t norm_pages; + uint64_t iterations; + uint64_t xbzrle_bytes; + uint64_t xbzrle_pages; + uint64_t xbzrle_cache_miss; + double xbzrle_cache_miss_rate; + uint64_t xbzrle_overflows; +} AccountingInfo; + +static AccountingInfo acct_info; + +static void acct_clear(void) +{ + memset(&acct_info, 0, sizeof(acct_info)); +} + +uint64_t dup_mig_bytes_transferred(void) +{ + return acct_info.dup_pages * TARGET_PAGE_SIZE; +} + +uint64_t dup_mig_pages_transferred(void) +{ + return acct_info.dup_pages; +} + +uint64_t skipped_mig_bytes_transferred(void) +{ + return acct_info.skipped_pages * TARGET_PAGE_SIZE; +} + +uint64_t skipped_mig_pages_transferred(void) +{ + return acct_info.skipped_pages; +} + +uint64_t norm_mig_bytes_transferred(void) +{ + return acct_info.norm_pages * TARGET_PAGE_SIZE; +} + +uint64_t norm_mig_pages_transferred(void) +{ + return acct_info.norm_pages; +} + +uint64_t xbzrle_mig_bytes_transferred(void) +{ + return acct_info.xbzrle_bytes; +} + +uint64_t xbzrle_mig_pages_transferred(void) +{ + return acct_info.xbzrle_pages; +} + +uint64_t xbzrle_mig_pages_cache_miss(void) +{ + return acct_info.xbzrle_cache_miss; +} + +double xbzrle_mig_cache_miss_rate(void) +{ + return acct_info.xbzrle_cache_miss_rate; +} + +uint64_t xbzrle_mig_pages_overflow(void) +{ + return acct_info.xbzrle_overflows; +} + +/* This is the last block that we have visited serching for dirty pages + */ +static RAMBlock *last_seen_block; +/* This is the last block from where we have sent data */ +static RAMBlock *last_sent_block; +static ram_addr_t last_offset; +static unsigned long *migration_bitmap; +static QemuMutex migration_bitmap_mutex; +static uint64_t migration_dirty_pages; +static uint32_t last_version; +static bool ram_bulk_stage; + +struct CompressParam { + bool start; + bool done; + QEMUFile *file; + QemuMutex mutex; + QemuCond cond; + RAMBlock *block; + ram_addr_t offset; +}; +typedef struct CompressParam CompressParam; + +struct DecompressParam { + bool start; + QemuMutex mutex; + QemuCond cond; + void *des; + uint8 *compbuf; + int len; +}; +typedef struct DecompressParam DecompressParam; + +static CompressParam *comp_param; +static QemuThread *compress_threads; +/* comp_done_cond is used to wake up the migration thread when + * one of the compression threads has finished the compression. + * comp_done_lock is used to co-work with comp_done_cond. + */ +static QemuMutex *comp_done_lock; +static QemuCond *comp_done_cond; +/* The empty QEMUFileOps will be used by file in CompressParam */ +static const QEMUFileOps empty_ops = { }; + +static bool compression_switch; +static bool quit_comp_thread; +static bool quit_decomp_thread; +static DecompressParam *decomp_param; +static QemuThread *decompress_threads; +static uint8_t *compressed_data_buf; + +static int do_compress_ram_page(CompressParam *param); + +static void *do_data_compress(void *opaque) +{ + CompressParam *param = opaque; + + while (!quit_comp_thread) { + qemu_mutex_lock(¶m->mutex); + /* Re-check the quit_comp_thread in case of + * terminate_compression_threads is called just before + * qemu_mutex_lock(¶m->mutex) and after + * while(!quit_comp_thread), re-check it here can make + * sure the compression thread terminate as expected. + */ + while (!param->start && !quit_comp_thread) { + qemu_cond_wait(¶m->cond, ¶m->mutex); + } + if (!quit_comp_thread) { + do_compress_ram_page(param); + } + param->start = false; + qemu_mutex_unlock(¶m->mutex); + + qemu_mutex_lock(comp_done_lock); + param->done = true; + qemu_cond_signal(comp_done_cond); + qemu_mutex_unlock(comp_done_lock); + } + + return NULL; +} + +static inline void terminate_compression_threads(void) +{ + int idx, thread_count; + + thread_count = migrate_compress_threads(); + quit_comp_thread = true; + for (idx = 0; idx < thread_count; idx++) { + qemu_mutex_lock(&comp_param[idx].mutex); + qemu_cond_signal(&comp_param[idx].cond); + qemu_mutex_unlock(&comp_param[idx].mutex); + } +} + +void migrate_compress_threads_join(void) +{ + int i, thread_count; + + if (!migrate_use_compression()) { + return; + } + terminate_compression_threads(); + thread_count = migrate_compress_threads(); + for (i = 0; i < thread_count; i++) { + qemu_thread_join(compress_threads + i); + qemu_fclose(comp_param[i].file); + qemu_mutex_destroy(&comp_param[i].mutex); + qemu_cond_destroy(&comp_param[i].cond); + } + qemu_mutex_destroy(comp_done_lock); + qemu_cond_destroy(comp_done_cond); + g_free(compress_threads); + g_free(comp_param); + g_free(comp_done_cond); + g_free(comp_done_lock); + compress_threads = NULL; + comp_param = NULL; + comp_done_cond = NULL; + comp_done_lock = NULL; +} + +void migrate_compress_threads_create(void) +{ + int i, thread_count; + + if (!migrate_use_compression()) { + return; + } + quit_comp_thread = false; + compression_switch = true; + thread_count = migrate_compress_threads(); + compress_threads = g_new0(QemuThread, thread_count); + comp_param = g_new0(CompressParam, thread_count); + comp_done_cond = g_new0(QemuCond, 1); + comp_done_lock = g_new0(QemuMutex, 1); + qemu_cond_init(comp_done_cond); + qemu_mutex_init(comp_done_lock); + for (i = 0; i < thread_count; i++) { + /* com_param[i].file is just used as a dummy buffer to save data, set + * it's ops to empty. + */ + comp_param[i].file = qemu_fopen_ops(NULL, &empty_ops); + comp_param[i].done = true; + qemu_mutex_init(&comp_param[i].mutex); + qemu_cond_init(&comp_param[i].cond); + qemu_thread_create(compress_threads + i, "compress", + do_data_compress, comp_param + i, + QEMU_THREAD_JOINABLE); + } +} + +/** + * save_page_header: Write page header to wire + * + * If this is the 1st block, it also writes the block identification + * + * Returns: Number of bytes written + * + * @f: QEMUFile where to send the data + * @block: block that contains the page we want to send + * @offset: offset inside the block for the page + * in the lower bits, it contains flags + */ +static size_t save_page_header(QEMUFile *f, RAMBlock *block, ram_addr_t offset) +{ + size_t size, len; + + qemu_put_be64(f, offset); + size = 8; + + if (!(offset & RAM_SAVE_FLAG_CONTINUE)) { + len = strlen(block->idstr); + qemu_put_byte(f, len); + qemu_put_buffer(f, (uint8_t *)block->idstr, len); + size += 1 + len; + } + return size; +} + +/* Update the xbzrle cache to reflect a page that's been sent as all 0. + * The important thing is that a stale (not-yet-0'd) page be replaced + * by the new data. + * As a bonus, if the page wasn't in the cache it gets added so that + * when a small write is made into the 0'd page it gets XBZRLE sent + */ +static void xbzrle_cache_zero_page(ram_addr_t current_addr) +{ + if (ram_bulk_stage || !migrate_use_xbzrle()) { + return; + } + + /* We don't care if this fails to allocate a new cache page + * as long as it updated an old one */ + cache_insert(XBZRLE.cache, current_addr, ZERO_TARGET_PAGE, + bitmap_sync_count); +} + +#define ENCODING_FLAG_XBZRLE 0x1 + +/** + * save_xbzrle_page: compress and send current page + * + * Returns: 1 means that we wrote the page + * 0 means that page is identical to the one already sent + * -1 means that xbzrle would be longer than normal + * + * @f: QEMUFile where to send the data + * @current_data: + * @current_addr: + * @block: block that contains the page we want to send + * @offset: offset inside the block for the page + * @last_stage: if we are at the completion stage + * @bytes_transferred: increase it with the number of transferred bytes + */ +static int save_xbzrle_page(QEMUFile *f, uint8_t **current_data, + ram_addr_t current_addr, RAMBlock *block, + ram_addr_t offset, bool last_stage, + uint64_t *bytes_transferred) +{ + int encoded_len = 0, bytes_xbzrle; + uint8_t *prev_cached_page; + + if (!cache_is_cached(XBZRLE.cache, current_addr, bitmap_sync_count)) { + acct_info.xbzrle_cache_miss++; + if (!last_stage) { + if (cache_insert(XBZRLE.cache, current_addr, *current_data, + bitmap_sync_count) == -1) { + return -1; + } else { + /* update *current_data when the page has been + inserted into cache */ + *current_data = get_cached_data(XBZRLE.cache, current_addr); + } + } + return -1; + } + + prev_cached_page = get_cached_data(XBZRLE.cache, current_addr); + + /* save current buffer into memory */ + memcpy(XBZRLE.current_buf, *current_data, TARGET_PAGE_SIZE); + + /* XBZRLE encoding (if there is no overflow) */ + encoded_len = xbzrle_encode_buffer(prev_cached_page, XBZRLE.current_buf, + TARGET_PAGE_SIZE, XBZRLE.encoded_buf, + TARGET_PAGE_SIZE); + if (encoded_len == 0) { + DPRINTF("Skipping unmodified page\n"); + return 0; + } else if (encoded_len == -1) { + DPRINTF("Overflow\n"); + acct_info.xbzrle_overflows++; + /* update data in the cache */ + if (!last_stage) { + memcpy(prev_cached_page, *current_data, TARGET_PAGE_SIZE); + *current_data = prev_cached_page; + } + return -1; + } + + /* we need to update the data in the cache, in order to get the same data */ + if (!last_stage) { + memcpy(prev_cached_page, XBZRLE.current_buf, TARGET_PAGE_SIZE); + } + + /* Send XBZRLE based compressed page */ + bytes_xbzrle = save_page_header(f, block, offset | RAM_SAVE_FLAG_XBZRLE); + qemu_put_byte(f, ENCODING_FLAG_XBZRLE); + qemu_put_be16(f, encoded_len); + qemu_put_buffer(f, XBZRLE.encoded_buf, encoded_len); + bytes_xbzrle += encoded_len + 1 + 2; + acct_info.xbzrle_pages++; + acct_info.xbzrle_bytes += bytes_xbzrle; + *bytes_transferred += bytes_xbzrle; + + return 1; +} + +/* Called with rcu_read_lock() to protect migration_bitmap */ +static inline +ram_addr_t migration_bitmap_find_and_reset_dirty(MemoryRegion *mr, + ram_addr_t start) +{ + unsigned long base = mr->ram_addr >> TARGET_PAGE_BITS; + unsigned long nr = base + (start >> TARGET_PAGE_BITS); + uint64_t mr_size = TARGET_PAGE_ALIGN(memory_region_size(mr)); + unsigned long size = base + (mr_size >> TARGET_PAGE_BITS); + unsigned long *bitmap; + + unsigned long next; + + bitmap = atomic_rcu_read(&migration_bitmap); + if (ram_bulk_stage && nr > base) { + next = nr + 1; + } else { + next = find_next_bit(bitmap, size, nr); + } + + if (next < size) { + clear_bit(next, bitmap); + migration_dirty_pages--; + } + return (next - base) << TARGET_PAGE_BITS; +} + +/* Called with rcu_read_lock() to protect migration_bitmap */ +static void migration_bitmap_sync_range(ram_addr_t start, ram_addr_t length) +{ + unsigned long *bitmap; + bitmap = atomic_rcu_read(&migration_bitmap); + migration_dirty_pages += + cpu_physical_memory_sync_dirty_bitmap(bitmap, start, length); +} + + +/* Fix me: there are too many global variables used in migration process. */ +static int64_t start_time; +static int64_t bytes_xfer_prev; +static int64_t num_dirty_pages_period; +static uint64_t xbzrle_cache_miss_prev; +static uint64_t iterations_prev; + +static void migration_bitmap_sync_init(void) +{ + start_time = 0; + bytes_xfer_prev = 0; + num_dirty_pages_period = 0; + xbzrle_cache_miss_prev = 0; + iterations_prev = 0; +} + +/* Called with iothread lock held, to protect ram_list.dirty_memory[] */ +static void migration_bitmap_sync(void) +{ + RAMBlock *block; + uint64_t num_dirty_pages_init = migration_dirty_pages; + MigrationState *s = migrate_get_current(); + int64_t end_time; + int64_t bytes_xfer_now; + + bitmap_sync_count++; + + if (!bytes_xfer_prev) { + bytes_xfer_prev = ram_bytes_transferred(); + } + + if (!start_time) { + start_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME); + } + + trace_migration_bitmap_sync_start(); + address_space_sync_dirty_bitmap(&address_space_memory); + + qemu_mutex_lock(&migration_bitmap_mutex); + rcu_read_lock(); + QLIST_FOREACH_RCU(block, &ram_list.blocks, next) { + migration_bitmap_sync_range(block->mr->ram_addr, block->used_length); + } + rcu_read_unlock(); + qemu_mutex_unlock(&migration_bitmap_mutex); + + trace_migration_bitmap_sync_end(migration_dirty_pages + - num_dirty_pages_init); + num_dirty_pages_period += migration_dirty_pages - num_dirty_pages_init; + end_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME); + + /* more than 1 second = 1000 millisecons */ + if (end_time > start_time + 1000) { + if (migrate_auto_converge()) { + /* The following detection logic can be refined later. For now: + Check to see if the dirtied bytes is 50% more than the approx. + amount of bytes that just got transferred since the last time we + were in this routine. If that happens >N times (for now N==4) + we turn on the throttle down logic */ + bytes_xfer_now = ram_bytes_transferred(); + if (s->dirty_pages_rate && + (num_dirty_pages_period * TARGET_PAGE_SIZE > + (bytes_xfer_now - bytes_xfer_prev)/2) && + (dirty_rate_high_cnt++ > 4)) { + trace_migration_throttle(); + mig_throttle_on = true; + dirty_rate_high_cnt = 0; + } + bytes_xfer_prev = bytes_xfer_now; + } else { + mig_throttle_on = false; + } + if (migrate_use_xbzrle()) { + if (iterations_prev != acct_info.iterations) { + acct_info.xbzrle_cache_miss_rate = + (double)(acct_info.xbzrle_cache_miss - + xbzrle_cache_miss_prev) / + (acct_info.iterations - iterations_prev); + } + iterations_prev = acct_info.iterations; + xbzrle_cache_miss_prev = acct_info.xbzrle_cache_miss; + } + s->dirty_pages_rate = num_dirty_pages_period * 1000 + / (end_time - start_time); + s->dirty_bytes_rate = s->dirty_pages_rate * TARGET_PAGE_SIZE; + start_time = end_time; + num_dirty_pages_period = 0; + } + s->dirty_sync_count = bitmap_sync_count; +} + +/** + * save_zero_page: Send the zero page to the stream + * + * Returns: Number of pages written. + * + * @f: QEMUFile where to send the data + * @block: block that contains the page we want to send + * @offset: offset inside the block for the page + * @p: pointer to the page + * @bytes_transferred: increase it with the number of transferred bytes + */ +static int save_zero_page(QEMUFile *f, RAMBlock *block, ram_addr_t offset, + uint8_t *p, uint64_t *bytes_transferred) +{ + int pages = -1; + + if (is_zero_range(p, TARGET_PAGE_SIZE)) { + acct_info.dup_pages++; + *bytes_transferred += save_page_header(f, block, + offset | RAM_SAVE_FLAG_COMPRESS); + qemu_put_byte(f, 0); + *bytes_transferred += 1; + pages = 1; + } + + return pages; +} + +/** + * ram_save_page: Send the given page to the stream + * + * Returns: Number of pages written. + * + * @f: QEMUFile where to send the data + * @block: block that contains the page we want to send + * @offset: offset inside the block for the page + * @last_stage: if we are at the completion stage + * @bytes_transferred: increase it with the number of transferred bytes + */ +static int ram_save_page(QEMUFile *f, RAMBlock* block, ram_addr_t offset, + bool last_stage, uint64_t *bytes_transferred) +{ + int pages = -1; + uint64_t bytes_xmit; + ram_addr_t current_addr; + MemoryRegion *mr = block->mr; + uint8_t *p; + int ret; + bool send_async = true; + + p = memory_region_get_ram_ptr(mr) + offset; + + /* In doubt sent page as normal */ + bytes_xmit = 0; + ret = ram_control_save_page(f, block->offset, + offset, TARGET_PAGE_SIZE, &bytes_xmit); + if (bytes_xmit) { + *bytes_transferred += bytes_xmit; + pages = 1; + } + + XBZRLE_cache_lock(); + + current_addr = block->offset + offset; + + if (block == last_sent_block) { + offset |= RAM_SAVE_FLAG_CONTINUE; + } + if (ret != RAM_SAVE_CONTROL_NOT_SUPP) { + if (ret != RAM_SAVE_CONTROL_DELAYED) { + if (bytes_xmit > 0) { + acct_info.norm_pages++; + } else if (bytes_xmit == 0) { + acct_info.dup_pages++; + } + } + } else { + pages = save_zero_page(f, block, offset, p, bytes_transferred); + if (pages > 0) { + /* Must let xbzrle know, otherwise a previous (now 0'd) cached + * page would be stale + */ + xbzrle_cache_zero_page(current_addr); + } else if (!ram_bulk_stage && migrate_use_xbzrle()) { + pages = save_xbzrle_page(f, &p, current_addr, block, + offset, last_stage, bytes_transferred); + if (!last_stage) { + /* Can't send this cached data async, since the cache page + * might get updated before it gets to the wire + */ + send_async = false; + } + } + } + + /* XBZRLE overflow or normal page */ + if (pages == -1) { + *bytes_transferred += save_page_header(f, block, + offset | RAM_SAVE_FLAG_PAGE); + if (send_async) { + qemu_put_buffer_async(f, p, TARGET_PAGE_SIZE); + } else { + qemu_put_buffer(f, p, TARGET_PAGE_SIZE); + } + *bytes_transferred += TARGET_PAGE_SIZE; + pages = 1; + acct_info.norm_pages++; + } + + XBZRLE_cache_unlock(); + + return pages; +} + +static int do_compress_ram_page(CompressParam *param) +{ + int bytes_sent, blen; + uint8_t *p; + RAMBlock *block = param->block; + ram_addr_t offset = param->offset; + + p = memory_region_get_ram_ptr(block->mr) + (offset & TARGET_PAGE_MASK); + + bytes_sent = save_page_header(param->file, block, offset | + RAM_SAVE_FLAG_COMPRESS_PAGE); + blen = qemu_put_compression_data(param->file, p, TARGET_PAGE_SIZE, + migrate_compress_level()); + bytes_sent += blen; + + return bytes_sent; +} + +static inline void start_compression(CompressParam *param) +{ + param->done = false; + qemu_mutex_lock(¶m->mutex); + param->start = true; + qemu_cond_signal(¶m->cond); + qemu_mutex_unlock(¶m->mutex); +} + +static inline void start_decompression(DecompressParam *param) +{ + qemu_mutex_lock(¶m->mutex); + param->start = true; + qemu_cond_signal(¶m->cond); + qemu_mutex_unlock(¶m->mutex); +} + +static uint64_t bytes_transferred; + +static void flush_compressed_data(QEMUFile *f) +{ + int idx, len, thread_count; + + if (!migrate_use_compression()) { + return; + } + thread_count = migrate_compress_threads(); + for (idx = 0; idx < thread_count; idx++) { + if (!comp_param[idx].done) { + qemu_mutex_lock(comp_done_lock); + while (!comp_param[idx].done && !quit_comp_thread) { + qemu_cond_wait(comp_done_cond, comp_done_lock); + } + qemu_mutex_unlock(comp_done_lock); + } + if (!quit_comp_thread) { + len = qemu_put_qemu_file(f, comp_param[idx].file); + bytes_transferred += len; + } + } +} + +static inline void set_compress_params(CompressParam *param, RAMBlock *block, + ram_addr_t offset) +{ + param->block = block; + param->offset = offset; +} + +static int compress_page_with_multi_thread(QEMUFile *f, RAMBlock *block, + ram_addr_t offset, + uint64_t *bytes_transferred) +{ + int idx, thread_count, bytes_xmit = -1, pages = -1; + + thread_count = migrate_compress_threads(); + qemu_mutex_lock(comp_done_lock); + while (true) { + for (idx = 0; idx < thread_count; idx++) { + if (comp_param[idx].done) { + bytes_xmit = qemu_put_qemu_file(f, comp_param[idx].file); + set_compress_params(&comp_param[idx], block, offset); + start_compression(&comp_param[idx]); + pages = 1; + acct_info.norm_pages++; + *bytes_transferred += bytes_xmit; + break; + } + } + if (pages > 0) { + break; + } else { + qemu_cond_wait(comp_done_cond, comp_done_lock); + } + } + qemu_mutex_unlock(comp_done_lock); + + return pages; +} + +/** + * ram_save_compressed_page: compress the given page and send it to the stream + * + * Returns: Number of pages written. + * + * @f: QEMUFile where to send the data + * @block: block that contains the page we want to send + * @offset: offset inside the block for the page + * @last_stage: if we are at the completion stage + * @bytes_transferred: increase it with the number of transferred bytes + */ +static int ram_save_compressed_page(QEMUFile *f, RAMBlock *block, + ram_addr_t offset, bool last_stage, + uint64_t *bytes_transferred) +{ + int pages = -1; + uint64_t bytes_xmit; + MemoryRegion *mr = block->mr; + uint8_t *p; + int ret; + + p = memory_region_get_ram_ptr(mr) + offset; + + bytes_xmit = 0; + ret = ram_control_save_page(f, block->offset, + offset, TARGET_PAGE_SIZE, &bytes_xmit); + if (bytes_xmit) { + *bytes_transferred += bytes_xmit; + pages = 1; + } + if (block == last_sent_block) { + offset |= RAM_SAVE_FLAG_CONTINUE; + } + if (ret != RAM_SAVE_CONTROL_NOT_SUPP) { + if (ret != RAM_SAVE_CONTROL_DELAYED) { + if (bytes_xmit > 0) { + acct_info.norm_pages++; + } else if (bytes_xmit == 0) { + acct_info.dup_pages++; + } + } + } else { + /* When starting the process of a new block, the first page of + * the block should be sent out before other pages in the same + * block, and all the pages in last block should have been sent + * out, keeping this order is important, because the 'cont' flag + * is used to avoid resending the block name. + */ + if (block != last_sent_block) { + flush_compressed_data(f); + pages = save_zero_page(f, block, offset, p, bytes_transferred); + if (pages == -1) { + set_compress_params(&comp_param[0], block, offset); + /* Use the qemu thread to compress the data to make sure the + * first page is sent out before other pages + */ + bytes_xmit = do_compress_ram_page(&comp_param[0]); + acct_info.norm_pages++; + qemu_put_qemu_file(f, comp_param[0].file); + *bytes_transferred += bytes_xmit; + pages = 1; + } + } else { + pages = save_zero_page(f, block, offset, p, bytes_transferred); + if (pages == -1) { + pages = compress_page_with_multi_thread(f, block, offset, + bytes_transferred); + } + } + } + + return pages; +} + +/** + * ram_find_and_save_block: Finds a dirty page and sends it to f + * + * Called within an RCU critical section. + * + * Returns: The number of pages written + * 0 means no dirty pages + * + * @f: QEMUFile where to send the data + * @last_stage: if we are at the completion stage + * @bytes_transferred: increase it with the number of transferred bytes + */ + +static int ram_find_and_save_block(QEMUFile *f, bool last_stage, + uint64_t *bytes_transferred) +{ + RAMBlock *block = last_seen_block; + ram_addr_t offset = last_offset; + bool complete_round = false; + int pages = 0; + MemoryRegion *mr; + + if (!block) + block = QLIST_FIRST_RCU(&ram_list.blocks); + + while (true) { + mr = block->mr; + offset = migration_bitmap_find_and_reset_dirty(mr, offset); + if (complete_round && block == last_seen_block && + offset >= last_offset) { + break; + } + if (offset >= block->used_length) { + offset = 0; + block = QLIST_NEXT_RCU(block, next); + if (!block) { + block = QLIST_FIRST_RCU(&ram_list.blocks); + complete_round = true; + ram_bulk_stage = false; + if (migrate_use_xbzrle()) { + /* If xbzrle is on, stop using the data compression at this + * point. In theory, xbzrle can do better than compression. + */ + flush_compressed_data(f); + compression_switch = false; + } + } + } else { + if (compression_switch && migrate_use_compression()) { + pages = ram_save_compressed_page(f, block, offset, last_stage, + bytes_transferred); + } else { + pages = ram_save_page(f, block, offset, last_stage, + bytes_transferred); + } + + /* if page is unmodified, continue to the next */ + if (pages > 0) { + last_sent_block = block; + break; + } + } + } + + last_seen_block = block; + last_offset = offset; + + return pages; +} + +void acct_update_position(QEMUFile *f, size_t size, bool zero) +{ + uint64_t pages = size / TARGET_PAGE_SIZE; + if (zero) { + acct_info.dup_pages += pages; + } else { + acct_info.norm_pages += pages; + bytes_transferred += size; + qemu_update_position(f, size); + } +} + +static ram_addr_t ram_save_remaining(void) +{ + return migration_dirty_pages; +} + +uint64_t ram_bytes_remaining(void) +{ + return ram_save_remaining() * TARGET_PAGE_SIZE; +} + +uint64_t ram_bytes_transferred(void) +{ + return bytes_transferred; +} + +uint64_t ram_bytes_total(void) +{ + RAMBlock *block; + uint64_t total = 0; + + rcu_read_lock(); + QLIST_FOREACH_RCU(block, &ram_list.blocks, next) + total += block->used_length; + rcu_read_unlock(); + return total; +} + +void free_xbzrle_decoded_buf(void) +{ + g_free(xbzrle_decoded_buf); + xbzrle_decoded_buf = NULL; +} + +static void migration_end(void) +{ + /* caller have hold iothread lock or is in a bh, so there is + * no writing race against this migration_bitmap + */ + unsigned long *bitmap = migration_bitmap; + atomic_rcu_set(&migration_bitmap, NULL); + if (bitmap) { + memory_global_dirty_log_stop(); + synchronize_rcu(); + g_free(bitmap); + } + + XBZRLE_cache_lock(); + if (XBZRLE.cache) { + cache_fini(XBZRLE.cache); + g_free(XBZRLE.encoded_buf); + g_free(XBZRLE.current_buf); + XBZRLE.cache = NULL; + XBZRLE.encoded_buf = NULL; + XBZRLE.current_buf = NULL; + } + XBZRLE_cache_unlock(); +} + +static void ram_migration_cancel(void *opaque) +{ + migration_end(); +} + +static void reset_ram_globals(void) +{ + last_seen_block = NULL; + last_sent_block = NULL; + last_offset = 0; + last_version = ram_list.version; + ram_bulk_stage = true; +} + +#define MAX_WAIT 50 /* ms, half buffered_file limit */ + +void migration_bitmap_extend(ram_addr_t old, ram_addr_t new) +{ + /* called in qemu main thread, so there is + * no writing race against this migration_bitmap + */ + if (migration_bitmap) { + unsigned long *old_bitmap = migration_bitmap, *bitmap; + bitmap = bitmap_new(new); + + /* prevent migration_bitmap content from being set bit + * by migration_bitmap_sync_range() at the same time. + * it is safe to migration if migration_bitmap is cleared bit + * at the same time. + */ + qemu_mutex_lock(&migration_bitmap_mutex); + bitmap_copy(bitmap, old_bitmap, old); + bitmap_set(bitmap, old, new - old); + atomic_rcu_set(&migration_bitmap, bitmap); + qemu_mutex_unlock(&migration_bitmap_mutex); + migration_dirty_pages += new - old; + synchronize_rcu(); + g_free(old_bitmap); + } +} + +/* Each of ram_save_setup, ram_save_iterate and ram_save_complete has + * long-running RCU critical section. When rcu-reclaims in the code + * start to become numerous it will be necessary to reduce the + * granularity of these critical sections. + */ + +static int ram_save_setup(QEMUFile *f, void *opaque) +{ + RAMBlock *block; + int64_t ram_bitmap_pages; /* Size of bitmap in pages, including gaps */ + + mig_throttle_on = false; + dirty_rate_high_cnt = 0; + bitmap_sync_count = 0; + migration_bitmap_sync_init(); + qemu_mutex_init(&migration_bitmap_mutex); + + if (migrate_use_xbzrle()) { + XBZRLE_cache_lock(); + XBZRLE.cache = cache_init(migrate_xbzrle_cache_size() / + TARGET_PAGE_SIZE, + TARGET_PAGE_SIZE); + if (!XBZRLE.cache) { + XBZRLE_cache_unlock(); + error_report("Error creating cache"); + return -1; + } + XBZRLE_cache_unlock(); + + /* We prefer not to abort if there is no memory */ + XBZRLE.encoded_buf = g_try_malloc0(TARGET_PAGE_SIZE); + if (!XBZRLE.encoded_buf) { + error_report("Error allocating encoded_buf"); + return -1; + } + + XBZRLE.current_buf = g_try_malloc(TARGET_PAGE_SIZE); + if (!XBZRLE.current_buf) { + error_report("Error allocating current_buf"); + g_free(XBZRLE.encoded_buf); + XBZRLE.encoded_buf = NULL; + return -1; + } + + acct_clear(); + } + + /* iothread lock needed for ram_list.dirty_memory[] */ + qemu_mutex_lock_iothread(); + qemu_mutex_lock_ramlist(); + rcu_read_lock(); + bytes_transferred = 0; + reset_ram_globals(); + + ram_bitmap_pages = last_ram_offset() >> TARGET_PAGE_BITS; + migration_bitmap = bitmap_new(ram_bitmap_pages); + bitmap_set(migration_bitmap, 0, ram_bitmap_pages); + + /* + * Count the total number of pages used by ram blocks not including any + * gaps due to alignment or unplugs. + */ + migration_dirty_pages = ram_bytes_total() >> TARGET_PAGE_BITS; + + memory_global_dirty_log_start(); + migration_bitmap_sync(); + qemu_mutex_unlock_ramlist(); + qemu_mutex_unlock_iothread(); + + qemu_put_be64(f, ram_bytes_total() | RAM_SAVE_FLAG_MEM_SIZE); + + QLIST_FOREACH_RCU(block, &ram_list.blocks, next) { + qemu_put_byte(f, strlen(block->idstr)); + qemu_put_buffer(f, (uint8_t *)block->idstr, strlen(block->idstr)); + qemu_put_be64(f, block->used_length); + } + + rcu_read_unlock(); + + ram_control_before_iterate(f, RAM_CONTROL_SETUP); + ram_control_after_iterate(f, RAM_CONTROL_SETUP); + + qemu_put_be64(f, RAM_SAVE_FLAG_EOS); + + return 0; +} + +static int ram_save_iterate(QEMUFile *f, void *opaque) +{ + int ret; + int i; + int64_t t0; + int pages_sent = 0; + + rcu_read_lock(); + if (ram_list.version != last_version) { + reset_ram_globals(); + } + + /* Read version before ram_list.blocks */ + smp_rmb(); + + ram_control_before_iterate(f, RAM_CONTROL_ROUND); + + t0 = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); + i = 0; + while ((ret = qemu_file_rate_limit(f)) == 0) { + int pages; + + pages = ram_find_and_save_block(f, false, &bytes_transferred); + /* no more pages to sent */ + if (pages == 0) { + break; + } + pages_sent += pages; + acct_info.iterations++; + check_guest_throttling(); + /* we want to check in the 1st loop, just in case it was the 1st time + and we had to sync the dirty bitmap. + qemu_get_clock_ns() is a bit expensive, so we only check each some + iterations + */ + if ((i & 63) == 0) { + uint64_t t1 = (qemu_clock_get_ns(QEMU_CLOCK_REALTIME) - t0) / 1000000; + if (t1 > MAX_WAIT) { + DPRINTF("big wait: %" PRIu64 " milliseconds, %d iterations\n", + t1, i); + break; + } + } + i++; + } + flush_compressed_data(f); + rcu_read_unlock(); + + /* + * Must occur before EOS (or any QEMUFile operation) + * because of RDMA protocol. + */ + ram_control_after_iterate(f, RAM_CONTROL_ROUND); + + qemu_put_be64(f, RAM_SAVE_FLAG_EOS); + bytes_transferred += 8; + + ret = qemu_file_get_error(f); + if (ret < 0) { + return ret; + } + + return pages_sent; +} + +/* Called with iothread lock */ +static int ram_save_complete(QEMUFile *f, void *opaque) +{ + rcu_read_lock(); + + migration_bitmap_sync(); + + ram_control_before_iterate(f, RAM_CONTROL_FINISH); + + /* try transferring iterative blocks of memory */ + + /* flush all remaining blocks regardless of rate limiting */ + while (true) { + int pages; + + pages = ram_find_and_save_block(f, true, &bytes_transferred); + /* no more blocks to sent */ + if (pages == 0) { + break; + } + } + + flush_compressed_data(f); + ram_control_after_iterate(f, RAM_CONTROL_FINISH); + + rcu_read_unlock(); + + migration_end(); + qemu_put_be64(f, RAM_SAVE_FLAG_EOS); + + return 0; +} + +static uint64_t ram_save_pending(QEMUFile *f, void *opaque, uint64_t max_size) +{ + uint64_t remaining_size; + + remaining_size = ram_save_remaining() * TARGET_PAGE_SIZE; + + if (remaining_size < max_size) { + qemu_mutex_lock_iothread(); + rcu_read_lock(); + migration_bitmap_sync(); + rcu_read_unlock(); + qemu_mutex_unlock_iothread(); + remaining_size = ram_save_remaining() * TARGET_PAGE_SIZE; + } + return remaining_size; +} + +static int load_xbzrle(QEMUFile *f, ram_addr_t addr, void *host) +{ + unsigned int xh_len; + int xh_flags; + + if (!xbzrle_decoded_buf) { + xbzrle_decoded_buf = g_malloc(TARGET_PAGE_SIZE); + } + + /* extract RLE header */ + xh_flags = qemu_get_byte(f); + xh_len = qemu_get_be16(f); + + if (xh_flags != ENCODING_FLAG_XBZRLE) { + error_report("Failed to load XBZRLE page - wrong compression!"); + return -1; + } + + if (xh_len > TARGET_PAGE_SIZE) { + error_report("Failed to load XBZRLE page - len overflow!"); + return -1; + } + /* load data and decode */ + qemu_get_buffer(f, xbzrle_decoded_buf, xh_len); + + /* decode RLE */ + if (xbzrle_decode_buffer(xbzrle_decoded_buf, xh_len, host, + TARGET_PAGE_SIZE) == -1) { + error_report("Failed to load XBZRLE page - decode error!"); + return -1; + } + + return 0; +} + +/* Must be called from within a rcu critical section. + * Returns a pointer from within the RCU-protected ram_list. + */ +static inline void *host_from_stream_offset(QEMUFile *f, + ram_addr_t offset, + int flags) +{ + static RAMBlock *block = NULL; + char id[256]; + uint8_t len; + + if (flags & RAM_SAVE_FLAG_CONTINUE) { + if (!block || block->max_length <= offset) { + error_report("Ack, bad migration stream!"); + return NULL; + } + + return memory_region_get_ram_ptr(block->mr) + offset; + } + + len = qemu_get_byte(f); + qemu_get_buffer(f, (uint8_t *)id, len); + id[len] = 0; + + QLIST_FOREACH_RCU(block, &ram_list.blocks, next) { + if (!strncmp(id, block->idstr, sizeof(id)) && + block->max_length > offset) { + return memory_region_get_ram_ptr(block->mr) + offset; + } + } + + error_report("Can't find block %s!", id); + return NULL; +} + +/* + * If a page (or a whole RDMA chunk) has been + * determined to be zero, then zap it. + */ +void ram_handle_compressed(void *host, uint8_t ch, uint64_t size) +{ + if (ch != 0 || !is_zero_range(host, size)) { + memset(host, ch, size); + } +} + +static void *do_data_decompress(void *opaque) +{ + DecompressParam *param = opaque; + unsigned long pagesize; + + while (!quit_decomp_thread) { + qemu_mutex_lock(¶m->mutex); + while (!param->start && !quit_decomp_thread) { + qemu_cond_wait(¶m->cond, ¶m->mutex); + pagesize = TARGET_PAGE_SIZE; + if (!quit_decomp_thread) { + /* uncompress() will return failed in some case, especially + * when the page is dirted when doing the compression, it's + * not a problem because the dirty page will be retransferred + * and uncompress() won't break the data in other pages. + */ + uncompress((Bytef *)param->des, &pagesize, + (const Bytef *)param->compbuf, param->len); + } + param->start = false; + } + qemu_mutex_unlock(¶m->mutex); + } + + return NULL; +} + +void migrate_decompress_threads_create(void) +{ + int i, thread_count; + + thread_count = migrate_decompress_threads(); + decompress_threads = g_new0(QemuThread, thread_count); + decomp_param = g_new0(DecompressParam, thread_count); + compressed_data_buf = g_malloc0(compressBound(TARGET_PAGE_SIZE)); + quit_decomp_thread = false; + for (i = 0; i < thread_count; i++) { + qemu_mutex_init(&decomp_param[i].mutex); + qemu_cond_init(&decomp_param[i].cond); + decomp_param[i].compbuf = g_malloc0(compressBound(TARGET_PAGE_SIZE)); + qemu_thread_create(decompress_threads + i, "decompress", + do_data_decompress, decomp_param + i, + QEMU_THREAD_JOINABLE); + } +} + +void migrate_decompress_threads_join(void) +{ + int i, thread_count; + + quit_decomp_thread = true; + thread_count = migrate_decompress_threads(); + for (i = 0; i < thread_count; i++) { + qemu_mutex_lock(&decomp_param[i].mutex); + qemu_cond_signal(&decomp_param[i].cond); + qemu_mutex_unlock(&decomp_param[i].mutex); + } + for (i = 0; i < thread_count; i++) { + qemu_thread_join(decompress_threads + i); + qemu_mutex_destroy(&decomp_param[i].mutex); + qemu_cond_destroy(&decomp_param[i].cond); + g_free(decomp_param[i].compbuf); + } + g_free(decompress_threads); + g_free(decomp_param); + g_free(compressed_data_buf); + decompress_threads = NULL; + decomp_param = NULL; + compressed_data_buf = NULL; +} + +static void decompress_data_with_multi_threads(uint8_t *compbuf, + void *host, int len) +{ + int idx, thread_count; + + thread_count = migrate_decompress_threads(); + while (true) { + for (idx = 0; idx < thread_count; idx++) { + if (!decomp_param[idx].start) { + memcpy(decomp_param[idx].compbuf, compbuf, len); + decomp_param[idx].des = host; + decomp_param[idx].len = len; + start_decompression(&decomp_param[idx]); + break; + } + } + if (idx < thread_count) { + break; + } + } +} + +static int ram_load(QEMUFile *f, void *opaque, int version_id) +{ + int flags = 0, ret = 0; + static uint64_t seq_iter; + int len = 0; + + seq_iter++; + + if (version_id != 4) { + ret = -EINVAL; + } + + /* This RCU critical section can be very long running. + * When RCU reclaims in the code start to become numerous, + * it will be necessary to reduce the granularity of this + * critical section. + */ + rcu_read_lock(); + while (!ret && !(flags & RAM_SAVE_FLAG_EOS)) { + ram_addr_t addr, total_ram_bytes; + void *host; + uint8_t ch; + + addr = qemu_get_be64(f); + flags = addr & ~TARGET_PAGE_MASK; + addr &= TARGET_PAGE_MASK; + + switch (flags & ~RAM_SAVE_FLAG_CONTINUE) { + case RAM_SAVE_FLAG_MEM_SIZE: + /* Synchronize RAM block list */ + total_ram_bytes = addr; + while (!ret && total_ram_bytes) { + RAMBlock *block; + char id[256]; + ram_addr_t length; + + len = qemu_get_byte(f); + qemu_get_buffer(f, (uint8_t *)id, len); + id[len] = 0; + length = qemu_get_be64(f); + + QLIST_FOREACH_RCU(block, &ram_list.blocks, next) { + if (!strncmp(id, block->idstr, sizeof(id))) { + if (length != block->used_length) { + Error *local_err = NULL; + + ret = qemu_ram_resize(block->offset, length, &local_err); + if (local_err) { + error_report_err(local_err); + } + } + ram_control_load_hook(f, RAM_CONTROL_BLOCK_REG, + block->idstr); + break; + } + } + + if (!block) { + error_report("Unknown ramblock \"%s\", cannot " + "accept migration", id); + ret = -EINVAL; + } + + total_ram_bytes -= length; + } + break; + case RAM_SAVE_FLAG_COMPRESS: + host = host_from_stream_offset(f, addr, flags); + if (!host) { + error_report("Illegal RAM offset " RAM_ADDR_FMT, addr); + ret = -EINVAL; + break; + } + ch = qemu_get_byte(f); + ram_handle_compressed(host, ch, TARGET_PAGE_SIZE); + break; + case RAM_SAVE_FLAG_PAGE: + host = host_from_stream_offset(f, addr, flags); + if (!host) { + error_report("Illegal RAM offset " RAM_ADDR_FMT, addr); + ret = -EINVAL; + break; + } + qemu_get_buffer(f, host, TARGET_PAGE_SIZE); + break; + case RAM_SAVE_FLAG_COMPRESS_PAGE: + host = host_from_stream_offset(f, addr, flags); + if (!host) { + error_report("Invalid RAM offset " RAM_ADDR_FMT, addr); + ret = -EINVAL; + break; + } + + len = qemu_get_be32(f); + if (len < 0 || len > compressBound(TARGET_PAGE_SIZE)) { + error_report("Invalid compressed data length: %d", len); + ret = -EINVAL; + break; + } + qemu_get_buffer(f, compressed_data_buf, len); + decompress_data_with_multi_threads(compressed_data_buf, host, len); + break; + case RAM_SAVE_FLAG_XBZRLE: + host = host_from_stream_offset(f, addr, flags); + if (!host) { + error_report("Illegal RAM offset " RAM_ADDR_FMT, addr); + ret = -EINVAL; + break; + } + if (load_xbzrle(f, addr, host) < 0) { + error_report("Failed to decompress XBZRLE page at " + RAM_ADDR_FMT, addr); + ret = -EINVAL; + break; + } + break; + case RAM_SAVE_FLAG_EOS: + /* normal exit */ + break; + default: + if (flags & RAM_SAVE_FLAG_HOOK) { + ram_control_load_hook(f, RAM_CONTROL_HOOK, NULL); + } else { + error_report("Unknown combination of migration flags: %#x", + flags); + ret = -EINVAL; + } + } + if (!ret) { + ret = qemu_file_get_error(f); + } + } + + rcu_read_unlock(); + DPRINTF("Completed load of VM with exit code %d seq iteration " + "%" PRIu64 "\n", ret, seq_iter); + return ret; +} + +static SaveVMHandlers savevm_ram_handlers = { + .save_live_setup = ram_save_setup, + .save_live_iterate = ram_save_iterate, + .save_live_complete = ram_save_complete, + .save_live_pending = ram_save_pending, + .load_state = ram_load, + .cancel = ram_migration_cancel, +}; + +void ram_mig_init(void) +{ + qemu_mutex_init(&XBZRLE.lock); + register_savevm_live(NULL, "ram", 0, 4, &savevm_ram_handlers, NULL); +} +/* Stub function that's gets run on the vcpu when its brought out of the + VM to run inside qemu via async_run_on_cpu()*/ + +static void mig_sleep_cpu(void *opq) +{ + qemu_mutex_unlock_iothread(); + g_usleep(30*1000); + qemu_mutex_lock_iothread(); +} + +/* To reduce the dirty rate explicitly disallow the VCPUs from spending + much time in the VM. The migration thread will try to catchup. + Workload will experience a performance drop. +*/ +static void mig_throttle_guest_down(void) +{ + CPUState *cpu; + + qemu_mutex_lock_iothread(); + CPU_FOREACH(cpu) { + async_run_on_cpu(cpu, mig_sleep_cpu, NULL); + } + qemu_mutex_unlock_iothread(); +} + +static void check_guest_throttling(void) +{ + static int64_t t0; + int64_t t1; + + if (!mig_throttle_on) { + return; + } + + if (!t0) { + t0 = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); + return; + } + + t1 = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); + + /* If it has been more than 40 ms since the last time the guest + * was throttled then do it again. + */ + if (40 < (t1-t0)/1000000) { + mig_throttle_guest_down(); + t0 = t1; + } +} |