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 <peterx@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@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 75d9185c3a..e27aa306bc 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;
}
/*
@@ -1862,6 +1888,12 @@ 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) {
@@ -3237,6 +3269,11 @@ 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;
@@ -4124,6 +4161,15 @@ 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 a66dd536d9..e92db0556b 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-channel.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_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 a2489a2699..f5615e0a76 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -3644,15 +3644,15 @@ 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;
@@ -3676,7 +3676,7 @@ 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);
@@ -3717,10 +3717,10 @@ 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;
@@ -4107,7 +4107,12 @@ 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);
}
@@ -4269,6 +4274,12 @@ 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 d9076897b8..ecee05e631 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -2575,16 +2575,6 @@ 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());
@@ -2613,6 +2603,16 @@ 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 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..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"