migration: Synchronize multifd threads with main thread
We synchronize all threads each RAM_SAVE_FLAG_EOS. Bitmap synchronizations don't happen inside a ram section, so we are safe about two channels trying to overwrite the same memory. Signed-off-by: Juan Quintela <quintela@redhat.com> Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com> -- seq needs to be atomic now, will also be accessed from main thread. Fix the if (true || ...) leftover We are back to non-atomics
This commit is contained in:
Juan Quintela
parent
0beb5ed327
commit
6df264ac5a
147
migration/ram.c
147
migration/ram.c
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@ -510,6 +510,8 @@ exit:
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#define MULTIFD_MAGIC 0x11223344U
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#define MULTIFD_VERSION 1
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#define MULTIFD_FLAG_SYNC (1 << 0)
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typedef struct {
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uint32_t magic;
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uint32_t version;
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@ -577,6 +579,8 @@ typedef struct {
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uint64_t num_packets;
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/* pages sent through this channel */
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uint64_t num_pages;
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/* syncs main thread and channels */
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QemuSemaphore sem_sync;
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} MultiFDSendParams;
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typedef struct {
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@ -614,6 +618,8 @@ typedef struct {
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uint64_t num_packets;
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/* pages sent through this channel */
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uint64_t num_pages;
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/* syncs main thread and channels */
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QemuSemaphore sem_sync;
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} MultiFDRecvParams;
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static int multifd_send_initial_packet(MultiFDSendParams *p, Error **errp)
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@ -801,6 +807,10 @@ struct {
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int count;
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/* array of pages to sent */
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MultiFDPages_t *pages;
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/* syncs main thread and channels */
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QemuSemaphore sem_sync;
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/* global number of generated multifd packets */
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uint64_t packet_num;
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} *multifd_send_state;
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static void multifd_send_terminate_threads(Error *err)
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@ -848,6 +858,7 @@ int multifd_save_cleanup(Error **errp)
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p->c = NULL;
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qemu_mutex_destroy(&p->mutex);
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qemu_sem_destroy(&p->sem);
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qemu_sem_destroy(&p->sem_sync);
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g_free(p->name);
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p->name = NULL;
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multifd_pages_clear(p->pages);
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@ -856,6 +867,7 @@ int multifd_save_cleanup(Error **errp)
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g_free(p->packet);
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p->packet = NULL;
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}
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qemu_sem_destroy(&multifd_send_state->sem_sync);
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g_free(multifd_send_state->params);
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multifd_send_state->params = NULL;
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multifd_pages_clear(multifd_send_state->pages);
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@ -865,6 +877,33 @@ int multifd_save_cleanup(Error **errp)
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return ret;
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}
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static void multifd_send_sync_main(void)
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{
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int i;
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if (!migrate_use_multifd()) {
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return;
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}
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for (i = 0; i < migrate_multifd_channels(); i++) {
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MultiFDSendParams *p = &multifd_send_state->params[i];
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trace_multifd_send_sync_main_signal(p->id);
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qemu_mutex_lock(&p->mutex);
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p->flags |= MULTIFD_FLAG_SYNC;
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p->pending_job++;
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qemu_mutex_unlock(&p->mutex);
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qemu_sem_post(&p->sem);
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}
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for (i = 0; i < migrate_multifd_channels(); i++) {
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MultiFDSendParams *p = &multifd_send_state->params[i];
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trace_multifd_send_sync_main_wait(p->id);
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qemu_sem_wait(&multifd_send_state->sem_sync);
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}
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trace_multifd_send_sync_main(multifd_send_state->packet_num);
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}
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static void *multifd_send_thread(void *opaque)
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{
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MultiFDSendParams *p = opaque;
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@ -901,15 +940,17 @@ static void *multifd_send_thread(void *opaque)
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qemu_mutex_lock(&p->mutex);
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p->pending_job--;
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qemu_mutex_unlock(&p->mutex);
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continue;
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if (flags & MULTIFD_FLAG_SYNC) {
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qemu_sem_post(&multifd_send_state->sem_sync);
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}
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} else if (p->quit) {
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qemu_mutex_unlock(&p->mutex);
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break;
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} else {
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qemu_mutex_unlock(&p->mutex);
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/* sometimes there are spurious wakeups */
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}
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qemu_mutex_unlock(&p->mutex);
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/* this is impossible */
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error_setg(&local_err, "multifd_send_thread: Unknown command");
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break;
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}
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out:
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@ -961,12 +1002,14 @@ int multifd_save_setup(void)
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multifd_send_state->params = g_new0(MultiFDSendParams, thread_count);
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atomic_set(&multifd_send_state->count, 0);
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multifd_send_state->pages = multifd_pages_init(page_count);
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qemu_sem_init(&multifd_send_state->sem_sync, 0);
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for (i = 0; i < thread_count; i++) {
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MultiFDSendParams *p = &multifd_send_state->params[i];
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qemu_mutex_init(&p->mutex);
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qemu_sem_init(&p->sem, 0);
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qemu_sem_init(&p->sem_sync, 0);
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p->quit = false;
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p->pending_job = 0;
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p->id = i;
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@ -984,6 +1027,10 @@ struct {
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MultiFDRecvParams *params;
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/* number of created threads */
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int count;
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/* syncs main thread and channels */
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QemuSemaphore sem_sync;
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/* global number of generated multifd packets */
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uint64_t packet_num;
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} *multifd_recv_state;
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static void multifd_recv_terminate_threads(Error *err)
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@ -1029,6 +1076,7 @@ int multifd_load_cleanup(Error **errp)
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p->c = NULL;
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qemu_mutex_destroy(&p->mutex);
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qemu_sem_destroy(&p->sem);
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qemu_sem_destroy(&p->sem_sync);
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g_free(p->name);
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p->name = NULL;
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multifd_pages_clear(p->pages);
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@ -1037,6 +1085,7 @@ int multifd_load_cleanup(Error **errp)
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g_free(p->packet);
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p->packet = NULL;
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}
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qemu_sem_destroy(&multifd_recv_state->sem_sync);
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g_free(multifd_recv_state->params);
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multifd_recv_state->params = NULL;
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g_free(multifd_recv_state);
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@ -1045,6 +1094,42 @@ int multifd_load_cleanup(Error **errp)
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return ret;
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}
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static void multifd_recv_sync_main(void)
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{
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int i;
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if (!migrate_use_multifd()) {
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return;
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}
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for (i = 0; i < migrate_multifd_channels(); i++) {
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MultiFDRecvParams *p = &multifd_recv_state->params[i];
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trace_multifd_recv_sync_main_signal(p->id);
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qemu_mutex_lock(&p->mutex);
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p->pending_job = true;
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qemu_mutex_unlock(&p->mutex);
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}
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for (i = 0; i < migrate_multifd_channels(); i++) {
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MultiFDRecvParams *p = &multifd_recv_state->params[i];
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trace_multifd_recv_sync_main_wait(p->id);
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qemu_sem_wait(&multifd_recv_state->sem_sync);
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qemu_mutex_lock(&p->mutex);
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if (multifd_recv_state->packet_num < p->packet_num) {
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multifd_recv_state->packet_num = p->packet_num;
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}
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qemu_mutex_unlock(&p->mutex);
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}
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for (i = 0; i < migrate_multifd_channels(); i++) {
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MultiFDRecvParams *p = &multifd_recv_state->params[i];
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trace_multifd_recv_sync_main_signal(p->id);
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qemu_sem_post(&p->sem_sync);
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}
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trace_multifd_recv_sync_main(multifd_recv_state->packet_num);
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}
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static void *multifd_recv_thread(void *opaque)
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{
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MultiFDRecvParams *p = opaque;
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@ -1054,37 +1139,30 @@ static void *multifd_recv_thread(void *opaque)
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trace_multifd_recv_thread_start(p->id);
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while (true) {
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qemu_sem_wait(&p->sem);
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uint32_t used;
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uint32_t flags;
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/* ToDo: recv packet here */
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qemu_mutex_lock(&p->mutex);
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if (p->pending_job) {
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uint32_t used;
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uint32_t flags;
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qemu_mutex_unlock(&p->mutex);
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/* ToDo: recv packet here */
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qemu_mutex_lock(&p->mutex);
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ret = multifd_recv_unfill_packet(p, &local_err);
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if (ret) {
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qemu_mutex_unlock(&p->mutex);
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break;
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}
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used = p->pages->used;
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flags = p->flags;
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trace_multifd_recv(p->id, p->packet_num, used, flags);
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p->pending_job = false;
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p->num_packets++;
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p->num_pages += used;
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qemu_mutex_unlock(&p->mutex);
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} else if (p->quit) {
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ret = multifd_recv_unfill_packet(p, &local_err);
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if (ret) {
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qemu_mutex_unlock(&p->mutex);
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break;
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}
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used = p->pages->used;
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flags = p->flags;
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trace_multifd_recv(p->id, p->packet_num, used, flags);
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p->pending_job = false;
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p->num_packets++;
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p->num_pages += used;
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qemu_mutex_unlock(&p->mutex);
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/* this is impossible */
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error_setg(&local_err, "multifd_recv_thread: Unknown command");
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break;
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if (flags & MULTIFD_FLAG_SYNC) {
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qemu_sem_post(&multifd_recv_state->sem_sync);
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qemu_sem_wait(&p->sem_sync);
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}
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}
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if (local_err) {
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@ -1112,12 +1190,14 @@ int multifd_load_setup(void)
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multifd_recv_state = g_malloc0(sizeof(*multifd_recv_state));
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multifd_recv_state->params = g_new0(MultiFDRecvParams, thread_count);
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atomic_set(&multifd_recv_state->count, 0);
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qemu_sem_init(&multifd_recv_state->sem_sync, 0);
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for (i = 0; i < thread_count; i++) {
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MultiFDRecvParams *p = &multifd_recv_state->params[i];
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qemu_mutex_init(&p->mutex);
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qemu_sem_init(&p->sem, 0);
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qemu_sem_init(&p->sem_sync, 0);
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p->quit = false;
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p->pending_job = false;
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p->id = i;
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@ -2875,6 +2955,7 @@ static int ram_save_setup(QEMUFile *f, void *opaque)
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ram_control_before_iterate(f, RAM_CONTROL_SETUP);
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ram_control_after_iterate(f, RAM_CONTROL_SETUP);
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multifd_send_sync_main();
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qemu_put_be64(f, RAM_SAVE_FLAG_EOS);
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return 0;
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@ -2955,6 +3036,7 @@ static int ram_save_iterate(QEMUFile *f, void *opaque)
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*/
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ram_control_after_iterate(f, RAM_CONTROL_ROUND);
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multifd_send_sync_main();
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out:
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qemu_put_be64(f, RAM_SAVE_FLAG_EOS);
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ram_counters.transferred += 8;
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@ -3008,6 +3090,7 @@ static int ram_save_complete(QEMUFile *f, void *opaque)
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rcu_read_unlock();
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multifd_send_sync_main();
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qemu_put_be64(f, RAM_SAVE_FLAG_EOS);
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return 0;
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@ -3497,6 +3580,7 @@ static int ram_load_postcopy(QEMUFile *f)
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break;
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case RAM_SAVE_FLAG_EOS:
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/* normal exit */
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multifd_recv_sync_main();
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break;
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default:
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error_report("Unknown combination of migration flags: %#x"
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@ -3685,6 +3769,7 @@ static int ram_load(QEMUFile *f, void *opaque, int version_id)
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break;
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case RAM_SAVE_FLAG_EOS:
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/* normal exit */
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multifd_recv_sync_main();
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break;
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default:
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if (flags & RAM_SAVE_FLAG_HOOK) {
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@ -77,9 +77,15 @@ migration_bitmap_sync_start(void) ""
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migration_bitmap_sync_end(uint64_t dirty_pages) "dirty_pages %" PRIu64
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migration_throttle(void) ""
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multifd_recv(uint8_t id, uint64_t packet_num, uint32_t used, uint32_t flags) "channel %d packet number %" PRIu64 " pages %d flags 0x%x"
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multifd_recv_sync_main(long packet_num) "packet num %ld"
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multifd_recv_sync_main_signal(uint8_t id) "channel %d"
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multifd_recv_sync_main_wait(uint8_t id) "channel %d"
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multifd_recv_thread_end(uint8_t id, uint64_t packets, uint64_t pages) "channel %d packets %" PRIu64 " pages %" PRIu64
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multifd_recv_thread_start(uint8_t id) "%d"
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multifd_send(uint8_t id, uint64_t packet_num, uint32_t used, uint32_t flags) "channel %d packet_num %" PRIu64 " pages %d flags 0x%x"
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multifd_send_sync_main(long packet_num) "packet num %ld"
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multifd_send_sync_main_signal(uint8_t id) "channel %d"
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multifd_send_sync_main_wait(uint8_t id) "channel %d"
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multifd_send_thread_end(uint8_t id, uint64_t packets, uint64_t pages) "channel %d packets %" PRIu64 " pages %" PRIu64
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multifd_send_thread_start(uint8_t id) "%d"
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ram_discard_range(const char *rbname, uint64_t start, size_t len) "%s: start: %" PRIx64 " %zx"
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