diff options
| -rw-r--r-- | migration/multifd.c | 79 | ||||
| -rw-r--r-- | migration/multifd.h | 3 | ||||
| -rw-r--r-- | migration/ram.c | 2 |
3 files changed, 50 insertions, 34 deletions
diff --git a/migration/multifd.c b/migration/multifd.c index 3a164c124d..cb7a121eb0 100644 --- a/migration/multifd.c +++ b/migration/multifd.c @@ -49,7 +49,6 @@ typedef struct { struct { MultiFDSendParams *params; - MultiFDSendData *data; /* * Global number of generated multifd packets. * @@ -97,6 +96,8 @@ struct { MultiFDMethods *ops; } *multifd_recv_state; +static MultiFDSendData *multifd_ram_send; + static size_t multifd_ram_payload_size(void) { uint32_t n = multifd_ram_page_count(); @@ -130,6 +131,17 @@ static MultiFDSendData *multifd_send_data_alloc(void) return g_malloc0(size_minus_payload + max_payload_size); } +void multifd_ram_save_setup(void) +{ + multifd_ram_send = multifd_send_data_alloc(); +} + +void multifd_ram_save_cleanup(void) +{ + g_free(multifd_ram_send); + multifd_ram_send = NULL; +} + static bool multifd_use_packets(void) { return !migrate_mapped_ram(); @@ -610,25 +622,20 @@ static void multifd_send_kick_main(MultiFDSendParams *p) } /* - * How we use multifd_send_state->pages and channel->pages? + * multifd_send() works by exchanging the MultiFDSendData object + * provided by the caller with an unused MultiFDSendData object from + * the next channel that is found to be idle. * - * We create a pages for each channel, and a main one. Each time that - * we need to send a batch of pages we interchange the ones between - * multifd_send_state and the channel that is sending it. There are - * two reasons for that: - * - to not have to do so many mallocs during migration - * - to make easier to know what to free at the end of migration + * The channel owns the data until it finishes transmitting and the + * caller owns the empty object until it fills it with data and calls + * this function again. No locking necessary. * - * This way we always know who is the owner of each "pages" struct, - * and we don't need any locking. It belongs to the migration thread - * or to the channel thread. Switching is safe because the migration - * thread is using the channel mutex when changing it, and the channel - * have to had finish with its own, otherwise pending_job can't be - * false. + * Switching is safe because both the migration thread and the channel + * thread have barriers in place to serialize access. * * Returns true if succeed, false otherwise. */ -static bool multifd_send_pages(void) +static bool multifd_send(MultiFDSendData **send_data) { int i; static int next_channel; @@ -669,11 +676,16 @@ static bool multifd_send_pages(void) */ smp_mb_acquire(); - assert(!p->data->u.ram.num); + assert(multifd_payload_empty(p->data)); - tmp = multifd_send_state->data; - multifd_send_state->data = p->data; + /* + * Swap the pointers. The channel gets the client data for + * transferring and the client gets back an unused data slot. + */ + tmp = *send_data; + *send_data = p->data; p->data = tmp; + /* * Making sure p->data is setup before marking pending_job=true. Pairs * with the qatomic_load_acquire() in multifd_send_thread(). @@ -705,7 +717,12 @@ bool multifd_queue_page(RAMBlock *block, ram_addr_t offset) MultiFDPages_t *pages; retry: - pages = &multifd_send_state->data->u.ram; + pages = &multifd_ram_send->u.ram; + + if (multifd_payload_empty(multifd_ram_send)) { + multifd_pages_reset(pages); + multifd_set_payload_type(multifd_ram_send, MULTIFD_PAYLOAD_RAM); + } /* If the queue is empty, we can already enqueue now */ if (multifd_queue_empty(pages)) { @@ -723,7 +740,7 @@ retry: * After flush, always retry. */ if (pages->block != block || multifd_queue_full(pages)) { - if (!multifd_send_pages()) { + if (!multifd_send(&multifd_ram_send)) { return false; } goto retry; @@ -853,8 +870,6 @@ static void multifd_send_cleanup_state(void) qemu_sem_destroy(&multifd_send_state->channels_ready); g_free(multifd_send_state->params); multifd_send_state->params = NULL; - g_free(multifd_send_state->data); - multifd_send_state->data = NULL; g_free(multifd_send_state); multifd_send_state = NULL; } @@ -903,15 +918,14 @@ int multifd_send_sync_main(void) { int i; bool flush_zero_copy; - MultiFDPages_t *pages; if (!migrate_multifd()) { return 0; } - pages = &multifd_send_state->data->u.ram; - if (pages->num) { - if (!multifd_send_pages()) { - error_report("%s: multifd_send_pages fail", __func__); + + if (!multifd_payload_empty(multifd_ram_send)) { + if (!multifd_send(&multifd_ram_send)) { + error_report("%s: multifd_send fail", __func__); return -1; } } @@ -985,13 +999,11 @@ static void *multifd_send_thread(void *opaque) /* * Read pending_job flag before p->data. Pairs with the - * qatomic_store_release() in multifd_send_pages(). + * qatomic_store_release() in multifd_send(). */ if (qatomic_load_acquire(&p->pending_job)) { - MultiFDPages_t *pages = &p->data->u.ram; - p->iovs_num = 0; - assert(pages->num); + assert(!multifd_payload_empty(p->data)); ret = multifd_send_state->ops->send_prepare(p, &local_err); if (ret != 0) { @@ -1014,13 +1026,13 @@ static void *multifd_send_thread(void *opaque) stat64_add(&mig_stats.multifd_bytes, p->next_packet_size + p->packet_len); - multifd_pages_reset(pages); p->next_packet_size = 0; + multifd_set_payload_type(p->data, MULTIFD_PAYLOAD_NONE); /* * Making sure p->data is published before saying "we're * free". Pairs with the smp_mb_acquire() in - * multifd_send_pages(). + * multifd_send(). */ qatomic_store_release(&p->pending_job, false); } else { @@ -1212,7 +1224,6 @@ bool multifd_send_setup(void) thread_count = migrate_multifd_channels(); multifd_send_state = g_malloc0(sizeof(*multifd_send_state)); multifd_send_state->params = g_new0(MultiFDSendParams, thread_count); - multifd_send_state->data = multifd_send_data_alloc(); qemu_sem_init(&multifd_send_state->channels_created, 0); qemu_sem_init(&multifd_send_state->channels_ready, 0); qatomic_set(&multifd_send_state->exiting, 0); diff --git a/migration/multifd.h b/migration/multifd.h index 9175104aea..5fa384d9af 100644 --- a/migration/multifd.h +++ b/migration/multifd.h @@ -267,4 +267,7 @@ static inline uint32_t multifd_ram_page_count(void) { return MULTIFD_PACKET_SIZE / qemu_target_page_size(); } + +void multifd_ram_save_setup(void); +void multifd_ram_save_cleanup(void); #endif diff --git a/migration/ram.c b/migration/ram.c index edec1a2d07..1815b2557b 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -2387,6 +2387,7 @@ static void ram_save_cleanup(void *opaque) ram_bitmaps_destroy(); xbzrle_cleanup(); + multifd_ram_save_cleanup(); ram_state_cleanup(rsp); g_free(migration_ops); migration_ops = NULL; @@ -3058,6 +3059,7 @@ static int ram_save_setup(QEMUFile *f, void *opaque, Error **errp) migration_ops = g_malloc0(sizeof(MigrationOps)); if (migrate_multifd()) { + multifd_ram_save_setup(); migration_ops->ram_save_target_page = ram_save_target_page_multifd; } else { migration_ops->ram_save_target_page = ram_save_target_page_legacy; |