* 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.
>
> Signed-off-by: Peter Xu <pet...@redhat.com>
> ---
> migration/migration.c | 62 ++++++++++++++++++++++++----
> migration/migration.h | 8 ++++
> migration/postcopy-ram.c | 88 ++++++++++++++++++++++++++++++++++++++--
> migration/postcopy-ram.h | 10 +++++
> migration/ram.c | 25 ++++++++----
> migration/ram.h | 4 +-
> migration/socket.c | 22 +++++++++-
> migration/socket.h | 1 +
> migration/trace-events | 3 ++
> 9 files changed, 203 insertions(+), 20 deletions(-)
>
> diff --git a/migration/migration.c b/migration/migration.c
> index 4c22bad304..3d7f897b72 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_fopen_channel_input(ioc);
> + f = qemu_fopen_channel_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_fopen_channel_input(ioc);
> + start_migration = postcopy_preempt_new_channel(mis, f);
> + }
> 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;
> }
>
> /*
> @@ -1858,6 +1884,12 @@ 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) {
> @@ -3233,6 +3265,11 @@ 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;
> @@ -4120,6 +4157,15 @@ 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 af4bcb19c2..caa910d956 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 738cc55fa6..30eddaacd1 100644
> --- a/migration/postcopy-ram.c
> +++ b/migration/postcopy-ram.c
> @@ -32,6 +32,9 @@
> #include "trace.h"
> #include "hw/boards.h"
> #include "exec/ramblock.h"
> +#include "socket.h"
> +#include "qemu-file-channel.h"
> +#include "yank_functions.h"
>
> /* Arbitrary limit on size of each discard command,
> * keeps them around ~200 bytes
> @@ -566,6 +569,11 @@ 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;
>
> @@ -1101,8 +1109,13 @@ 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);
> @@ -1169,7 +1182,7 @@ 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, "qemu/fault-default",
That name is still too long; I'd lose the 'qemu/'
> postcopy_ram_fault_thread, QEMU_THREAD_JOINABLE);
> mis->have_fault_thread = true;
>
> @@ -1184,6 +1197,16 @@ 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,
> "qemu/fault-fast",
and that one.
> + postcopy_preempt_thread,
> QEMU_THREAD_JOINABLE);
> + mis->postcopy_prio_thread_created = true;
> + }
> +
> trace_postcopy_ram_enable_notify();
>
> return 0;
> @@ -1513,3 +1536,62 @@ void postcopy_unregister_shared_ufd(struct PostCopyFD
> *pcfd)
> }
> }
> }
> +
> +bool postcopy_preempt_new_channel(MigrationIncomingState *mis, QEMUFile
> *file)
> +{
> + 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);
How do we get away with doing this sync here, but have to use async for
multifd?
Dave
> + if (ioc == NULL) {
> + return -1;
> + }
> +
> + migration_ioc_register_yank(ioc);
> + s->postcopy_qemufile_src = qemu_fopen_channel_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 f8bc3cd882..36e3da6bb0 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -3643,15 +3643,15 @@ 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;
> @@ -3716,10 +3716,10 @@ 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. Target host page
> %p, "
> - "received host page %p "
> + 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;
> @@ -4106,7 +4106,12 @@ 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);
> }
> @@ -4268,6 +4273,12 @@ 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/socket.c b/migration/socket.c
> index 05705a32d8..a7f345b353 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 */
> @@ -158,6 +176,8 @@ 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..4474a76614 100644
> --- a/migration/trace-events
> +++ b/migration/trace-events
> @@ -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
