diff --git a/migration/multifd-nocomp.c b/migration/multifd-nocomp.c index 58372db0f4..c1f686c0ce 100644 --- a/migration/multifd-nocomp.c +++ b/migration/multifd-nocomp.c @@ -344,6 +344,48 @@ retry: return true; } +/* + * We have two modes for multifd flushes: + * + * - Per-section mode: this is the legacy way to flush, it requires one + * MULTIFD_FLAG_SYNC message for each RAM_SAVE_FLAG_EOS. + * + * - Per-round mode: this is the modern way to flush, it requires one + * MULTIFD_FLAG_SYNC message only for each round of RAM scan. Normally + * it's paired with a new RAM_SAVE_FLAG_MULTIFD_FLUSH message in network + * based migrations. + * + * One thing to mention is mapped-ram always use the modern way to sync. + */ + +/* Do we need a per-section multifd flush (legacy way)? */ +bool multifd_ram_sync_per_section(void) +{ + if (!migrate_multifd()) { + return false; + } + + if (migrate_mapped_ram()) { + return false; + } + + return migrate_multifd_flush_after_each_section(); +} + +/* Do we need a per-round multifd flush (modern way)? */ +bool multifd_ram_sync_per_round(void) +{ + if (!migrate_multifd()) { + return false; + } + + if (migrate_mapped_ram()) { + return true; + } + + return !migrate_multifd_flush_after_each_section(); +} + int multifd_ram_flush_and_sync(QEMUFile *f) { MultiFDSyncReq req; diff --git a/migration/multifd.h b/migration/multifd.h index 0fef431f6b..bd785b9873 100644 --- a/migration/multifd.h +++ b/migration/multifd.h @@ -355,6 +355,8 @@ static inline uint32_t multifd_ram_page_count(void) void multifd_ram_save_setup(void); void multifd_ram_save_cleanup(void); int multifd_ram_flush_and_sync(QEMUFile *f); +bool multifd_ram_sync_per_round(void); +bool multifd_ram_sync_per_section(void); size_t multifd_ram_payload_size(void); void multifd_ram_fill_packet(MultiFDSendParams *p); int multifd_ram_unfill_packet(MultiFDRecvParams *p, Error **errp); diff --git a/migration/ram.c b/migration/ram.c index 9eeb77665b..d9336d8a09 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -1302,9 +1302,7 @@ static int find_dirty_block(RAMState *rs, PageSearchStatus *pss) pss->page = 0; pss->block = QLIST_NEXT_RCU(pss->block, next); if (!pss->block) { - if (migrate_multifd() && - (!migrate_multifd_flush_after_each_section() || - migrate_mapped_ram())) { + if (multifd_ram_sync_per_round()) { QEMUFile *f = rs->pss[RAM_CHANNEL_PRECOPY].pss_channel; int ret = multifd_ram_flush_and_sync(f); if (ret < 0) { @@ -3178,8 +3176,7 @@ static int ram_save_iterate(QEMUFile *f, void *opaque) out: if (ret >= 0 && migration_is_running()) { - if (migrate_multifd() && migrate_multifd_flush_after_each_section() && - !migrate_mapped_ram()) { + if (multifd_ram_sync_per_section()) { ret = multifd_ram_flush_and_sync(f); if (ret < 0) { return ret; @@ -3252,8 +3249,7 @@ static int ram_save_complete(QEMUFile *f, void *opaque) } } - if (migrate_multifd() && - migrate_multifd_flush_after_each_section()) { + if (multifd_ram_sync_per_section()) { /* * Only the old dest QEMU will need this sync, because each EOS * will require one SYNC message on each channel.