From: Peter Xu Date: Thu, 7 Jul 2022 18:55:02 +0000 (-0400) Subject: migration: Postcopy preemption preparation on channel creation X-Git-Url: http://git.osdn.net/view?a=commitdiff_plain;h=36f62f11e44b8a0a653998da100be307ac98704d;p=qmiga%2Fqemu.git migration: Postcopy preemption preparation on channel creation Create a new socket for postcopy to be prepared to send postcopy requested pages via this specific channel, so as to not get blocked by precopy pages. A new thread is also created on dest qemu to receive data from this new channel based on the ram_load_postcopy() routine. The ram_load_postcopy(POSTCOPY) branch and the thread has not started to function, and that'll be done in follow up patches. Cleanup the new sockets on both src/dst QEMUs, meanwhile look after the new thread too to make sure it'll be recycled properly. Reviewed-by: Daniel P. Berrangé Reviewed-by: Juan Quintela Signed-off-by: Peter Xu Message-Id: <20220707185502.27149-1-peterx@redhat.com> Signed-off-by: Dr. David Alan Gilbert dgilbert: With Peter's fix to quieten compiler warning on start_migration --- diff --git a/migration/migration.c b/migration/migration.c index ce7bb68cdc..c965cae1d4 100644 --- a/migration/migration.c +++ b/migration/migration.c @@ -321,6 +321,12 @@ void migration_incoming_state_destroy(void) mis->page_requested = NULL; } + if (mis->postcopy_qemufile_dst) { + migration_ioc_unregister_yank_from_file(mis->postcopy_qemufile_dst); + qemu_fclose(mis->postcopy_qemufile_dst); + mis->postcopy_qemufile_dst = NULL; + } + yank_unregister_instance(MIGRATION_YANK_INSTANCE); } @@ -714,15 +720,21 @@ void migration_fd_process_incoming(QEMUFile *f, Error **errp) migration_incoming_process(); } +static bool migration_needs_multiple_sockets(void) +{ + return migrate_use_multifd() || migrate_postcopy_preempt(); +} + void migration_ioc_process_incoming(QIOChannel *ioc, Error **errp) { MigrationIncomingState *mis = migration_incoming_get_current(); Error *local_err = NULL; bool start_migration; + QEMUFile *f; if (!mis->from_src_file) { /* The first connection (multifd may have multiple) */ - QEMUFile *f = qemu_file_new_input(ioc); + f = qemu_file_new_input(ioc); if (!migration_incoming_setup(f, errp)) { return; @@ -730,13 +742,19 @@ void migration_ioc_process_incoming(QIOChannel *ioc, Error **errp) /* * Common migration only needs one channel, so we can start - * right now. Multifd needs more than one channel, we wait. + * right now. Some features need more than one channel, we wait. */ - start_migration = !migrate_use_multifd(); + start_migration = !migration_needs_multiple_sockets(); } else { /* Multiple connections */ - assert(migrate_use_multifd()); - start_migration = multifd_recv_new_channel(ioc, &local_err); + assert(migration_needs_multiple_sockets()); + if (migrate_use_multifd()) { + start_migration = multifd_recv_new_channel(ioc, &local_err); + } else { + assert(migrate_postcopy_preempt()); + f = qemu_file_new_input(ioc); + start_migration = postcopy_preempt_new_channel(mis, f); + } if (local_err) { error_propagate(errp, local_err); return; @@ -761,11 +779,20 @@ void migration_ioc_process_incoming(QIOChannel *ioc, Error **errp) bool migration_has_all_channels(void) { MigrationIncomingState *mis = migration_incoming_get_current(); - bool all_channels; - all_channels = multifd_recv_all_channels_created(); + if (!mis->from_src_file) { + return false; + } + + if (migrate_use_multifd()) { + return multifd_recv_all_channels_created(); + } + + if (migrate_postcopy_preempt()) { + return mis->postcopy_qemufile_dst != NULL; + } - return all_channels && mis->from_src_file != NULL; + return true; } /* @@ -1874,6 +1901,12 @@ static void migrate_fd_cleanup(MigrationState *s) qemu_fclose(tmp); } + if (s->postcopy_qemufile_src) { + migration_ioc_unregister_yank_from_file(s->postcopy_qemufile_src); + qemu_fclose(s->postcopy_qemufile_src); + s->postcopy_qemufile_src = NULL; + } + assert(!migration_is_active(s)); if (s->state == MIGRATION_STATUS_CANCELLING) { @@ -3269,6 +3302,11 @@ static void migration_completion(MigrationState *s) qemu_savevm_state_complete_postcopy(s->to_dst_file); qemu_mutex_unlock_iothread(); + /* Shutdown the postcopy fast path thread */ + if (migrate_postcopy_preempt()) { + postcopy_preempt_shutdown_file(s); + } + trace_migration_completion_postcopy_end_after_complete(); } else { goto fail; @@ -4157,6 +4195,15 @@ void migrate_fd_connect(MigrationState *s, Error *error_in) } } + /* This needs to be done before resuming a postcopy */ + if (postcopy_preempt_setup(s, &local_err)) { + error_report_err(local_err); + migrate_set_state(&s->state, MIGRATION_STATUS_SETUP, + MIGRATION_STATUS_FAILED); + migrate_fd_cleanup(s); + return; + } + if (resume) { /* Wakeup the main migration thread to do the recovery */ migrate_set_state(&s->state, MIGRATION_STATUS_POSTCOPY_PAUSED, diff --git a/migration/migration.h b/migration/migration.h index d2269c826c..941c61e543 100644 --- a/migration/migration.h +++ b/migration/migration.h @@ -23,6 +23,7 @@ #include "io/channel-buffer.h" #include "net/announce.h" #include "qom/object.h" +#include "postcopy-ram.h" struct PostcopyBlocktimeContext; @@ -112,6 +113,11 @@ struct MigrationIncomingState { * enabled. */ unsigned int postcopy_channels; + /* QEMUFile for postcopy only; it'll be handled by a separate thread */ + QEMUFile *postcopy_qemufile_dst; + /* Postcopy priority thread is used to receive postcopy requested pages */ + QemuThread postcopy_prio_thread; + bool postcopy_prio_thread_created; /* * An array of temp host huge pages to be used, one for each postcopy * channel. @@ -192,6 +198,8 @@ struct MigrationState { QEMUBH *cleanup_bh; /* Protected by qemu_file_lock */ QEMUFile *to_dst_file; + /* Postcopy specific transfer channel */ + QEMUFile *postcopy_qemufile_src; QIOChannelBuffer *bioc; /* * Protects to_dst_file/from_dst_file pointers. We need to make sure we diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c index a66dd536d9..a3561410fe 100644 --- a/migration/postcopy-ram.c +++ b/migration/postcopy-ram.c @@ -33,6 +33,9 @@ #include "trace.h" #include "hw/boards.h" #include "exec/ramblock.h" +#include "socket.h" +#include "qemu-file.h" +#include "yank_functions.h" /* Arbitrary limit on size of each discard command, * keeps them around ~200 bytes @@ -567,6 +570,11 @@ int postcopy_ram_incoming_cleanup(MigrationIncomingState *mis) { trace_postcopy_ram_incoming_cleanup_entry(); + if (mis->postcopy_prio_thread_created) { + qemu_thread_join(&mis->postcopy_prio_thread); + mis->postcopy_prio_thread_created = false; + } + if (mis->have_fault_thread) { Error *local_err = NULL; @@ -1102,8 +1110,13 @@ static int postcopy_temp_pages_setup(MigrationIncomingState *mis) int err, i, channels; void *temp_page; - /* TODO: will be boosted when enable postcopy preemption */ - mis->postcopy_channels = 1; + if (migrate_postcopy_preempt()) { + /* If preemption enabled, need extra channel for urgent requests */ + mis->postcopy_channels = RAM_CHANNEL_MAX; + } else { + /* Both precopy/postcopy on the same channel */ + mis->postcopy_channels = 1; + } channels = mis->postcopy_channels; mis->postcopy_tmp_pages = g_malloc0_n(sizeof(PostcopyTmpPage), channels); @@ -1170,7 +1183,7 @@ int postcopy_ram_incoming_setup(MigrationIncomingState *mis) return -1; } - postcopy_thread_create(mis, &mis->fault_thread, "postcopy/fault", + postcopy_thread_create(mis, &mis->fault_thread, "fault-default", postcopy_ram_fault_thread, QEMU_THREAD_JOINABLE); mis->have_fault_thread = true; @@ -1185,6 +1198,16 @@ int postcopy_ram_incoming_setup(MigrationIncomingState *mis) return -1; } + if (migrate_postcopy_preempt()) { + /* + * This thread needs to be created after the temp pages because + * it'll fetch RAM_CHANNEL_POSTCOPY PostcopyTmpPage immediately. + */ + postcopy_thread_create(mis, &mis->postcopy_prio_thread, "fault-fast", + postcopy_preempt_thread, QEMU_THREAD_JOINABLE); + mis->postcopy_prio_thread_created = true; + } + trace_postcopy_ram_enable_notify(); return 0; @@ -1514,3 +1537,66 @@ void postcopy_unregister_shared_ufd(struct PostCopyFD *pcfd) } } } + +bool postcopy_preempt_new_channel(MigrationIncomingState *mis, QEMUFile *file) +{ + /* + * The new loading channel has its own threads, so it needs to be + * blocked too. It's by default true, just be explicit. + */ + qemu_file_set_blocking(file, true); + mis->postcopy_qemufile_dst = file; + trace_postcopy_preempt_new_channel(); + + /* Start the migration immediately */ + return true; +} + +int postcopy_preempt_setup(MigrationState *s, Error **errp) +{ + QIOChannel *ioc; + + if (!migrate_postcopy_preempt()) { + return 0; + } + + if (!migrate_multi_channels_is_allowed()) { + error_setg(errp, "Postcopy preempt is not supported as current " + "migration stream does not support multi-channels."); + return -1; + } + + ioc = socket_send_channel_create_sync(errp); + + if (ioc == NULL) { + return -1; + } + + migration_ioc_register_yank(ioc); + s->postcopy_qemufile_src = qemu_file_new_output(ioc); + + trace_postcopy_preempt_new_channel(); + + return 0; +} + +void *postcopy_preempt_thread(void *opaque) +{ + MigrationIncomingState *mis = opaque; + int ret; + + trace_postcopy_preempt_thread_entry(); + + rcu_register_thread(); + + qemu_sem_post(&mis->thread_sync_sem); + + /* Sending RAM_SAVE_FLAG_EOS to terminate this thread */ + ret = ram_load_postcopy(mis->postcopy_qemufile_dst, RAM_CHANNEL_POSTCOPY); + + rcu_unregister_thread(); + + trace_postcopy_preempt_thread_exit(); + + return ret == 0 ? NULL : (void *)-1; +} diff --git a/migration/postcopy-ram.h b/migration/postcopy-ram.h index 07684c0e1d..34b1080cde 100644 --- a/migration/postcopy-ram.h +++ b/migration/postcopy-ram.h @@ -183,4 +183,14 @@ int postcopy_wake_shared(struct PostCopyFD *pcfd, uint64_t client_addr, int postcopy_request_shared_page(struct PostCopyFD *pcfd, RAMBlock *rb, uint64_t client_addr, uint64_t offset); +/* Hard-code channels for now for postcopy preemption */ +enum PostcopyChannels { + RAM_CHANNEL_PRECOPY = 0, + RAM_CHANNEL_POSTCOPY = 1, + RAM_CHANNEL_MAX, +}; + +bool postcopy_preempt_new_channel(MigrationIncomingState *mis, QEMUFile *file); +int postcopy_preempt_setup(MigrationState *s, Error **errp); + #endif diff --git a/migration/ram.c b/migration/ram.c index 01f9cc1d72..e4364c0bff 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -3659,15 +3659,15 @@ int ram_postcopy_incoming_init(MigrationIncomingState *mis) * rcu_read_lock is taken prior to this being called. * * @f: QEMUFile where to send the data + * @channel: the channel to use for loading */ -int ram_load_postcopy(QEMUFile *f) +int ram_load_postcopy(QEMUFile *f, int channel) { int flags = 0, ret = 0; bool place_needed = false; bool matches_target_page_size = false; MigrationIncomingState *mis = migration_incoming_get_current(); - /* Currently we only use channel 0. TODO: use all the channels */ - PostcopyTmpPage *tmp_page = &mis->postcopy_tmp_pages[0]; + PostcopyTmpPage *tmp_page = &mis->postcopy_tmp_pages[channel]; while (!ret && !(flags & RAM_SAVE_FLAG_EOS)) { ram_addr_t addr; @@ -3691,7 +3691,7 @@ int ram_load_postcopy(QEMUFile *f) flags = addr & ~TARGET_PAGE_MASK; addr &= TARGET_PAGE_MASK; - trace_ram_load_postcopy_loop((uint64_t)addr, flags); + trace_ram_load_postcopy_loop(channel, (uint64_t)addr, flags); if (flags & (RAM_SAVE_FLAG_ZERO | RAM_SAVE_FLAG_PAGE | RAM_SAVE_FLAG_COMPRESS_PAGE)) { block = ram_block_from_stream(mis, f, flags); @@ -3732,10 +3732,10 @@ int ram_load_postcopy(QEMUFile *f) } else if (tmp_page->host_addr != host_page_from_ram_block_offset(block, addr)) { /* not the 1st TP within the HP */ - error_report("Non-same host page detected. " + error_report("Non-same host page detected on channel %d: " "Target host page %p, received host page %p " "(rb %s offset 0x"RAM_ADDR_FMT" target_pages %d)", - tmp_page->host_addr, + channel, tmp_page->host_addr, host_page_from_ram_block_offset(block, addr), block->idstr, addr, tmp_page->target_pages); ret = -EINVAL; @@ -4122,7 +4122,12 @@ static int ram_load(QEMUFile *f, void *opaque, int version_id) */ WITH_RCU_READ_LOCK_GUARD() { if (postcopy_running) { - ret = ram_load_postcopy(f); + /* + * Note! Here RAM_CHANNEL_PRECOPY is the precopy channel of + * postcopy migration, we have another RAM_CHANNEL_POSTCOPY to + * service fast page faults. + */ + ret = ram_load_postcopy(f, RAM_CHANNEL_PRECOPY); } else { ret = ram_load_precopy(f); } @@ -4284,6 +4289,12 @@ static int ram_resume_prepare(MigrationState *s, void *opaque) return 0; } +void postcopy_preempt_shutdown_file(MigrationState *s) +{ + qemu_put_be64(s->postcopy_qemufile_src, RAM_SAVE_FLAG_EOS); + qemu_fflush(s->postcopy_qemufile_src); +} + static SaveVMHandlers savevm_ram_handlers = { .save_setup = ram_save_setup, .save_live_iterate = ram_save_iterate, diff --git a/migration/ram.h b/migration/ram.h index ded0a3a086..5d90945a6e 100644 --- a/migration/ram.h +++ b/migration/ram.h @@ -61,7 +61,7 @@ void ram_postcopy_send_discard_bitmap(MigrationState *ms); /* For incoming postcopy discard */ int ram_discard_range(const char *block_name, uint64_t start, size_t length); int ram_postcopy_incoming_init(MigrationIncomingState *mis); -int ram_load_postcopy(QEMUFile *f); +int ram_load_postcopy(QEMUFile *f, int channel); void ram_handle_compressed(void *host, uint8_t ch, uint64_t size); @@ -73,6 +73,8 @@ int64_t ramblock_recv_bitmap_send(QEMUFile *file, const char *block_name); int ram_dirty_bitmap_reload(MigrationState *s, RAMBlock *rb); bool ramblock_page_is_discarded(RAMBlock *rb, ram_addr_t start); +void postcopy_preempt_shutdown_file(MigrationState *s); +void *postcopy_preempt_thread(void *opaque); /* ram cache */ int colo_init_ram_cache(void); diff --git a/migration/savevm.c b/migration/savevm.c index e8a1b96fcd..e3af03cb9b 100644 --- a/migration/savevm.c +++ b/migration/savevm.c @@ -2540,16 +2540,6 @@ static bool postcopy_pause_incoming(MigrationIncomingState *mis) { int i; - /* - * If network is interrupted, any temp page we received will be useless - * because we didn't mark them as "received" in receivedmap. After a - * proper recovery later (which will sync src dirty bitmap with receivedmap - * on dest) these cached small pages will be resent again. - */ - for (i = 0; i < mis->postcopy_channels; i++) { - postcopy_temp_page_reset(&mis->postcopy_tmp_pages[i]); - } - trace_postcopy_pause_incoming(); assert(migrate_postcopy_ram()); @@ -2578,6 +2568,16 @@ static bool postcopy_pause_incoming(MigrationIncomingState *mis) /* Notify the fault thread for the invalidated file handle */ postcopy_fault_thread_notify(mis); + /* + * If network is interrupted, any temp page we received will be useless + * because we didn't mark them as "received" in receivedmap. After a + * proper recovery later (which will sync src dirty bitmap with receivedmap + * on dest) these cached small pages will be resent again. + */ + for (i = 0; i < mis->postcopy_channels; i++) { + postcopy_temp_page_reset(&mis->postcopy_tmp_pages[i]); + } + error_report("Detected IO failure for postcopy. " "Migration paused."); diff --git a/migration/socket.c b/migration/socket.c index 4fd5e85f50..e6fdf3c5e1 100644 --- a/migration/socket.c +++ b/migration/socket.c @@ -26,7 +26,7 @@ #include "io/channel-socket.h" #include "io/net-listener.h" #include "trace.h" - +#include "postcopy-ram.h" struct SocketOutgoingArgs { SocketAddress *saddr; @@ -39,6 +39,24 @@ void socket_send_channel_create(QIOTaskFunc f, void *data) f, data, NULL, NULL); } +QIOChannel *socket_send_channel_create_sync(Error **errp) +{ + QIOChannelSocket *sioc = qio_channel_socket_new(); + + if (!outgoing_args.saddr) { + object_unref(OBJECT(sioc)); + error_setg(errp, "Initial sock address not set!"); + return NULL; + } + + if (qio_channel_socket_connect_sync(sioc, outgoing_args.saddr, errp) < 0) { + object_unref(OBJECT(sioc)); + return NULL; + } + + return QIO_CHANNEL(sioc); +} + int socket_send_channel_destroy(QIOChannel *send) { /* Remove channel */ @@ -166,6 +184,8 @@ socket_start_incoming_migration_internal(SocketAddress *saddr, if (migrate_use_multifd()) { num = migrate_multifd_channels(); + } else if (migrate_postcopy_preempt()) { + num = RAM_CHANNEL_MAX; } if (qio_net_listener_open_sync(listener, saddr, num, errp) < 0) { diff --git a/migration/socket.h b/migration/socket.h index 891dbccceb..dc54df4e6c 100644 --- a/migration/socket.h +++ b/migration/socket.h @@ -21,6 +21,7 @@ #include "io/task.h" void socket_send_channel_create(QIOTaskFunc f, void *data); +QIOChannel *socket_send_channel_create_sync(Error **errp); int socket_send_channel_destroy(QIOChannel *send); void socket_start_incoming_migration(const char *str, Error **errp); diff --git a/migration/trace-events b/migration/trace-events index 1aec580e92..4bc787cf0c 100644 --- a/migration/trace-events +++ b/migration/trace-events @@ -91,7 +91,7 @@ migration_bitmap_clear_dirty(char *str, uint64_t start, uint64_t size, unsigned migration_throttle(void) "" ram_discard_range(const char *rbname, uint64_t start, size_t len) "%s: start: %" PRIx64 " %zx" ram_load_loop(const char *rbname, uint64_t addr, int flags, void *host) "%s: addr: 0x%" PRIx64 " flags: 0x%x host: %p" -ram_load_postcopy_loop(uint64_t addr, int flags) "@%" PRIx64 " %x" +ram_load_postcopy_loop(int channel, uint64_t addr, int flags) "chan=%d addr=0x%" PRIx64 " flags=0x%x" ram_postcopy_send_discard_bitmap(void) "" ram_save_page(const char *rbname, uint64_t offset, void *host) "%s: offset: 0x%" PRIx64 " host: %p" ram_save_queue_pages(const char *rbname, size_t start, size_t len) "%s: start: 0x%zx len: 0x%zx" @@ -278,6 +278,9 @@ postcopy_request_shared_page(const char *sharer, const char *rb, uint64_t rb_off postcopy_request_shared_page_present(const char *sharer, const char *rb, uint64_t rb_offset) "%s already %s offset 0x%"PRIx64 postcopy_wake_shared(uint64_t client_addr, const char *rb) "at 0x%"PRIx64" in %s" postcopy_page_req_del(void *addr, int count) "resolved page req %p total %d" +postcopy_preempt_new_channel(void) "" +postcopy_preempt_thread_entry(void) "" +postcopy_preempt_thread_exit(void) "" get_mem_fault_cpu_index(int cpu, uint32_t pid) "cpu: %d, pid: %u"