* Peter Xu (pet...@redhat.com) wrote: > 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.
I'm hitting a CI failure here: https://gitlab.com/dagrh/qemu/-/jobs/2741659845 c.o -c ../migration/migration.c ../migration/migration.c: In function ‘migration_ioc_process_incoming’: ../migration/migration.c:766:8: error: ‘start_migration’ may be used uninitialized in this function [-Werror=maybe-uninitialized] 766 | if (start_migration) { | ^ > Reviewed-by: Daniel P. Berrang?? <berra...@redhat.com> > Reviewed-by: Juan Quintela <quint...@redhat.com> > Signed-off-by: Peter Xu <pet...@redhat.com> > --- > migration/migration.c | 62 +++++++++++++++++++++++---- > migration/migration.h | 8 ++++ > migration/postcopy-ram.c | 92 ++++++++++++++++++++++++++++++++++++++-- > migration/postcopy-ram.h | 10 +++++ > migration/ram.c | 25 ++++++++--- > migration/ram.h | 4 +- > migration/savevm.c | 20 ++++----- > migration/socket.c | 22 +++++++++- > migration/socket.h | 1 + > migration/trace-events | 5 ++- > 10 files changed, 218 insertions(+), 31 deletions(-) > > diff --git a/migration/migration.c b/migration/migration.c > index ce7bb68cdc..9484fec0b2 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 +742,18 @@ 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 if (migrate_postcopy_preempt()) { > + f = qemu_file_new_input(ioc); > + start_migration = postcopy_preempt_new_channel(mis, f); > + } So that doesn't always set start_migration? Dave > if (local_err) { > error_propagate(errp, local_err); > return; > @@ -761,11 +778,20 @@ 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 +1900,12 @@ 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 +3301,11 @@ 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 +4194,15 @@ 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" > > -- > 2.32.0 > > -- Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
