Peter Xu <pet...@redhat.com> writes: > On Mon, Nov 27, 2023 at 05:25:53PM -0300, Fabiano Rosas wrote: >> For the upcoming support to the new 'fixed-ram' migration stream >> format, we cannot use multifd packets because each write into the >> ramblock section in the migration file is expected to contain only the >> guest pages. They are written at their respective offsets relative to >> the ramblock section header. >> >> There is no space for the packet information and the expected gains >> from the new approach come partly from being able to write the pages >> sequentially without extraneous data in between. >> >> The new format also doesn't need the packets and all necessary >> information can be taken from the standard migration headers with some >> (future) changes to multifd code. >> >> Use the presence of the fixed-ram capability to decide whether to send >> packets. For now this has no effect as fixed-ram cannot yet be enabled >> with multifd. >> >> Signed-off-by: Fabiano Rosas <faro...@suse.de> >> --- >> - moved more of the packet code under use_packets >> --- >> migration/multifd.c | 138 +++++++++++++++++++++++++++----------------- >> migration/options.c | 5 ++ >> migration/options.h | 1 + >> 3 files changed, 91 insertions(+), 53 deletions(-) >> >> diff --git a/migration/multifd.c b/migration/multifd.c >> index ec58c58082..9625640d61 100644 >> --- a/migration/multifd.c >> +++ b/migration/multifd.c >> @@ -654,18 +654,22 @@ static void *multifd_send_thread(void *opaque) >> Error *local_err = NULL; >> int ret = 0; >> bool use_zero_copy_send = migrate_zero_copy_send(); >> + bool use_packets = migrate_multifd_packets(); >> >> thread = migration_threads_add(p->name, qemu_get_thread_id()); >> >> trace_multifd_send_thread_start(p->id); >> rcu_register_thread(); >> >> - if (multifd_send_initial_packet(p, &local_err) < 0) { >> - ret = -1; >> - goto out; >> + if (use_packets) { >> + if (multifd_send_initial_packet(p, &local_err) < 0) { >> + ret = -1; >> + goto out; >> + } >> + >> + /* initial packet */ >> + p->num_packets = 1; >> } >> - /* initial packet */ >> - p->num_packets = 1; >> >> while (true) { >> qemu_sem_post(&multifd_send_state->channels_ready); >> @@ -677,11 +681,10 @@ static void *multifd_send_thread(void *opaque) >> qemu_mutex_lock(&p->mutex); >> >> if (p->pending_job) { >> - uint64_t packet_num = p->packet_num; >> uint32_t flags; >> p->normal_num = 0; >> >> - if (use_zero_copy_send) { >> + if (!use_packets || use_zero_copy_send) { >> p->iovs_num = 0; >> } else { >> p->iovs_num = 1; >> @@ -699,16 +702,20 @@ static void *multifd_send_thread(void *opaque) >> break; >> } >> } >> - multifd_send_fill_packet(p); >> + >> + if (use_packets) { >> + multifd_send_fill_packet(p); >> + p->num_packets++; >> + } >> + >> flags = p->flags; >> p->flags = 0; >> - p->num_packets++; >> p->total_normal_pages += p->normal_num; >> p->pages->num = 0; >> p->pages->block = NULL; >> qemu_mutex_unlock(&p->mutex); >> >> - trace_multifd_send(p->id, packet_num, p->normal_num, flags, >> + trace_multifd_send(p->id, p->packet_num, p->normal_num, flags, >> p->next_packet_size); >> >> if (use_zero_copy_send) { >> @@ -718,7 +725,7 @@ static void *multifd_send_thread(void *opaque) >> if (ret != 0) { >> break; >> } >> - } else { >> + } else if (use_packets) { >> /* Send header using the same writev call */ >> p->iov[0].iov_len = p->packet_len; >> p->iov[0].iov_base = p->packet; >> @@ -904,6 +911,7 @@ int multifd_save_setup(Error **errp) >> { >> int thread_count; >> uint32_t page_count = MULTIFD_PACKET_SIZE / qemu_target_page_size(); >> + bool use_packets = migrate_multifd_packets(); >> uint8_t i; >> >> if (!migrate_multifd()) { >> @@ -928,14 +936,20 @@ int multifd_save_setup(Error **errp) >> p->pending_job = 0; >> p->id = i; >> p->pages = multifd_pages_init(page_count); >> - p->packet_len = sizeof(MultiFDPacket_t) >> - + sizeof(uint64_t) * page_count; >> - p->packet = g_malloc0(p->packet_len); >> - p->packet->magic = cpu_to_be32(MULTIFD_MAGIC); >> - p->packet->version = cpu_to_be32(MULTIFD_VERSION); >> + >> + if (use_packets) { >> + p->packet_len = sizeof(MultiFDPacket_t) >> + + sizeof(uint64_t) * page_count; >> + p->packet = g_malloc0(p->packet_len); >> + p->packet->magic = cpu_to_be32(MULTIFD_MAGIC); >> + p->packet->version = cpu_to_be32(MULTIFD_VERSION); >> + >> + /* We need one extra place for the packet header */ >> + p->iov = g_new0(struct iovec, page_count + 1); >> + } else { >> + p->iov = g_new0(struct iovec, page_count); >> + } >> p->name = g_strdup_printf("multifdsend_%d", i); >> - /* We need one extra place for the packet header */ >> - p->iov = g_new0(struct iovec, page_count + 1); >> p->normal = g_new0(ram_addr_t, page_count); >> p->page_size = qemu_target_page_size(); >> p->page_count = page_count; >> @@ -1067,7 +1081,7 @@ void multifd_recv_sync_main(void) >> { >> int i; >> >> - if (!migrate_multifd()) { >> + if (!migrate_multifd() || !migrate_multifd_packets()) { >> return; >> } >> for (i = 0; i < migrate_multifd_channels(); i++) { > > This noops the recv sync when use_packets=1, makes sense. > > How about multifd_send_sync_main()? Should we do the same? >
It seems it got lost during rebase. >> @@ -1094,38 +1108,44 @@ static void *multifd_recv_thread(void *opaque) >> { >> MultiFDRecvParams *p = opaque; >> Error *local_err = NULL; >> + bool use_packets = migrate_multifd_packets(); >> int ret; >> >> trace_multifd_recv_thread_start(p->id); >> rcu_register_thread(); >> >> while (true) { >> - uint32_t flags; >> + uint32_t flags = 0; >> + p->normal_num = 0; >> >> if (p->quit) { >> break; >> } >> >> - ret = qio_channel_read_all_eof(p->c, (void *)p->packet, >> - p->packet_len, &local_err); >> - if (ret == 0 || ret == -1) { /* 0: EOF -1: Error */ >> - break; >> - } >> + if (use_packets) { >> + ret = qio_channel_read_all_eof(p->c, (void *)p->packet, >> + p->packet_len, &local_err); >> + if (ret == 0 || ret == -1) { /* 0: EOF -1: Error */ >> + break; >> + } >> + >> + qemu_mutex_lock(&p->mutex); >> + ret = multifd_recv_unfill_packet(p, &local_err); >> + if (ret) { >> + qemu_mutex_unlock(&p->mutex); >> + break; >> + } >> + p->num_packets++; >> + >> + flags = p->flags; >> + /* recv methods don't know how to handle the SYNC flag */ >> + p->flags &= ~MULTIFD_FLAG_SYNC; >> + trace_multifd_recv(p->id, p->packet_num, p->normal_num, flags, >> + p->next_packet_size); >> >> - qemu_mutex_lock(&p->mutex); >> - ret = multifd_recv_unfill_packet(p, &local_err); >> - if (ret) { >> - qemu_mutex_unlock(&p->mutex); >> - break; >> + p->total_normal_pages += p->normal_num; >> } >> >> - flags = p->flags; >> - /* recv methods don't know how to handle the SYNC flag */ >> - p->flags &= ~MULTIFD_FLAG_SYNC; >> - trace_multifd_recv(p->id, p->packet_num, p->normal_num, flags, >> - p->next_packet_size); >> - p->num_packets++; >> - p->total_normal_pages += p->normal_num; >> qemu_mutex_unlock(&p->mutex); >> >> if (p->normal_num) { >> @@ -1135,7 +1155,7 @@ static void *multifd_recv_thread(void *opaque) >> } >> } >> >> - if (flags & MULTIFD_FLAG_SYNC) { >> + if (use_packets && (flags & MULTIFD_FLAG_SYNC)) { >> qemu_sem_post(&multifd_recv_state->sem_sync); >> qemu_sem_wait(&p->sem_sync); >> } >> @@ -1159,6 +1179,7 @@ int multifd_load_setup(Error **errp) >> { >> int thread_count; >> uint32_t page_count = MULTIFD_PACKET_SIZE / qemu_target_page_size(); >> + bool use_packets = migrate_multifd_packets(); >> uint8_t i; >> >> /* >> @@ -1183,9 +1204,12 @@ int multifd_load_setup(Error **errp) >> qemu_sem_init(&p->sem_sync, 0); >> p->quit = false; >> p->id = i; >> - p->packet_len = sizeof(MultiFDPacket_t) >> - + sizeof(uint64_t) * page_count; >> - p->packet = g_malloc0(p->packet_len); >> + >> + if (use_packets) { >> + p->packet_len = sizeof(MultiFDPacket_t) >> + + sizeof(uint64_t) * page_count; >> + p->packet = g_malloc0(p->packet_len); >> + } >> p->name = g_strdup_printf("multifdrecv_%d", i); >> p->iov = g_new0(struct iovec, page_count); >> p->normal = g_new0(ram_addr_t, page_count); >> @@ -1231,18 +1255,27 @@ void multifd_recv_new_channel(QIOChannel *ioc, Error >> **errp) >> { >> MultiFDRecvParams *p; >> Error *local_err = NULL; >> - int id; >> + bool use_packets = migrate_multifd_packets(); >> + int id, num_packets = 0; >> >> - id = multifd_recv_initial_packet(ioc, &local_err); >> - if (id < 0) { >> - multifd_recv_terminate_threads(local_err); >> - error_propagate_prepend(errp, local_err, >> - "failed to receive packet" >> - " via multifd channel %d: ", >> - qatomic_read(&multifd_recv_state->count)); >> - return; >> + if (use_packets) { >> + id = multifd_recv_initial_packet(ioc, &local_err); >> + if (id < 0) { >> + multifd_recv_terminate_threads(local_err); >> + error_propagate_prepend(errp, local_err, >> + "failed to receive packet" >> + " via multifd channel %d: ", >> + >> qatomic_read(&multifd_recv_state->count)); >> + return; >> + } >> + trace_multifd_recv_new_channel(id); >> + >> + /* initial packet */ >> + num_packets = 1; >> + } else { >> + /* next patch gives this a meaningful value */ >> + id = 0; >> } >> - trace_multifd_recv_new_channel(id); >> >> p = &multifd_recv_state->params[id]; >> if (p->c != NULL) { >> @@ -1253,9 +1286,8 @@ void multifd_recv_new_channel(QIOChannel *ioc, Error >> **errp) >> return; >> } >> p->c = ioc; >> + p->num_packets = num_packets; >> object_ref(OBJECT(ioc)); >> - /* initial packet */ >> - p->num_packets = 1; >> >> p->running = true; >> qemu_thread_create(&p->thread, p->name, multifd_recv_thread, p, >> diff --git a/migration/options.c b/migration/options.c >> index 775428a8a5..10730b13ba 100644 >> --- a/migration/options.c >> +++ b/migration/options.c >> @@ -385,6 +385,11 @@ bool migrate_multifd_flush_after_each_section(void) >> return s->multifd_flush_after_each_section; >> } >> >> +bool migrate_multifd_packets(void) > > Maybe multifd_use_packets()? Dropping the migrate_ prefix as this is not a > global API but multifd-only. Then if multifd_packets() reads too weird and > unclear, "add" makes it clear. > We removed all the instances of migrate_use_* from the migration code recently. Not sure we should introduce them back, it seems like a step back. We're setting 'use_packets = migrate_multifd_packets()' in most places, so I guess 'use_packets = multifd_packets()' wouldn't be too bad. >> +{ >> + return !migrate_fixed_ram(); >> +} >> + >> bool migrate_postcopy(void) >> { >> return migrate_postcopy_ram() || migrate_dirty_bitmaps(); >> diff --git a/migration/options.h b/migration/options.h >> index 8680a10b79..8a19d6939c 100644 >> --- a/migration/options.h >> +++ b/migration/options.h >> @@ -56,6 +56,7 @@ bool migrate_zero_copy_send(void); >> */ >> >> bool migrate_multifd_flush_after_each_section(void); >> +bool migrate_multifd_packets(void); >> bool migrate_postcopy(void); >> bool migrate_rdma(void); >> bool migrate_tls(void); >> -- >> 2.35.3 >>