From: "Maciej S. Szmigiero" <maciej.szmigiero@oracle.com>
This SaveVMHandler helps device provide its own asynchronous transmission
of the remaining data at the end of a precopy phase via multifd channels,
in parallel with the transfer done by save_live_complete_precopy handlers.
These threads are launched only when multifd device state transfer is
supported.
Management of these threads in done in the multifd migration code,
wrapping them in the generic thread pool.
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
---
include/migration/misc.h | 8 +++
include/migration/register.h | 23 +++++++++
include/qemu/typedefs.h | 4 ++
migration/multifd-device-state.c | 85 ++++++++++++++++++++++++++++++++
migration/savevm.c | 33 ++++++++++++-
5 files changed, 152 insertions(+), 1 deletion(-)
diff --git a/include/migration/misc.h b/include/migration/misc.h
index 43558d9198f7..67014122dcff 100644
--- a/include/migration/misc.h
+++ b/include/migration/misc.h
@@ -114,4 +114,12 @@ bool multifd_queue_device_state(char *idstr, uint32_t
instance_id,
char *data, size_t len);
bool migration_has_device_state_support(void);
+void
+multifd_spawn_device_state_save_thread(SaveLiveCompletePrecopyThreadHandler
hdlr,
+ char *idstr, uint32_t instance_id,
+ void *opaque);
+
+void multifd_abort_device_state_save_threads(void);
+int multifd_join_device_state_save_threads(void);
+
#endif
diff --git a/include/migration/register.h b/include/migration/register.h
index 761e4e4d8bcb..ab702e0a930b 100644
--- a/include/migration/register.h
+++ b/include/migration/register.h
@@ -105,6 +105,29 @@ typedef struct SaveVMHandlers {
*/
int (*save_live_complete_precopy)(QEMUFile *f, void *opaque);
+ /* This runs in a separate thread. */
+
+ /**
+ * @save_live_complete_precopy_thread
+ *
+ * Called at the end of a precopy phase from a separate worker thread
+ * in configurations where multifd device state transfer is supported
+ * in order to perform asynchronous transmission of the remaining data in
+ * parallel with @save_live_complete_precopy handlers.
+ * When postcopy is enabled, devices that support postcopy will skip this
+ * step.
+ *
+ * @idstr: this device section idstr
+ * @instance_id: this device section instance_id
+ * @abort_flag: flag indicating that the migration core wants to abort
+ * the transmission and so the handler should exit ASAP. To be read by
+ * qatomic_read() or similar.
+ * @opaque: data pointer passed to register_savevm_live()
+ *
+ * Returns zero to indicate success and negative for error
+ */
+ SaveLiveCompletePrecopyThreadHandler save_live_complete_precopy_thread;
+
/* This runs both outside and inside the BQL. */
/**
diff --git a/include/qemu/typedefs.h b/include/qemu/typedefs.h
index 8c8ea5c2840d..926baaad211f 100644
--- a/include/qemu/typedefs.h
+++ b/include/qemu/typedefs.h
@@ -132,5 +132,9 @@ typedef struct IRQState *qemu_irq;
*/
typedef void (*qemu_irq_handler)(void *opaque, int n, int level);
typedef int (*MigrationLoadThread)(bool *abort_flag, void *opaque);
+typedef int (*SaveLiveCompletePrecopyThreadHandler)(char *idstr,
+ uint32_t instance_id,
+ bool *abort_flag,
+ void *opaque);
#endif /* QEMU_TYPEDEFS_H */
diff --git a/migration/multifd-device-state.c b/migration/multifd-device-state.c
index bcbea926b6be..74a4aef346c8 100644
--- a/migration/multifd-device-state.c
+++ b/migration/multifd-device-state.c
@@ -9,12 +9,17 @@
#include "qemu/osdep.h"
#include "qemu/lockable.h"
+#include "block/thread-pool.h"
#include "migration/misc.h"
#include "multifd.h"
#include "options.h"
static QemuMutex queue_job_mutex;
+static ThreadPool *send_threads;
+static int send_threads_ret;
+static bool send_threads_abort;
+
static MultiFDSendData *device_state_send;
void multifd_device_state_send_setup(void)
@@ -22,6 +27,10 @@ void multifd_device_state_send_setup(void)
qemu_mutex_init(&queue_job_mutex);
device_state_send = multifd_send_data_alloc();
+
+ send_threads = thread_pool_new();
+ send_threads_ret = 0;
+ send_threads_abort = false;
}
void multifd_device_state_clear(MultiFDDeviceState_t *device_state)
@@ -32,6 +41,7 @@ void multifd_device_state_clear(MultiFDDeviceState_t
*device_state)
void multifd_device_state_send_cleanup(void)
{
+ g_clear_pointer(&send_threads, thread_pool_free);
g_clear_pointer(&device_state_send, multifd_send_data_free);
qemu_mutex_destroy(&queue_job_mutex);
@@ -106,3 +116,78 @@ bool migration_has_device_state_support(void)
return migrate_multifd() && !migrate_mapped_ram() &&
migrate_multifd_compression() == MULTIFD_COMPRESSION_NONE;
}
+
+struct MultiFDDSSaveThreadData {
+ SaveLiveCompletePrecopyThreadHandler hdlr;
+ char *idstr;
+ uint32_t instance_id;
+ void *handler_opaque;
+};
+
+static void multifd_device_state_save_thread_data_free(void *opaque)
+{
+ struct MultiFDDSSaveThreadData *data = opaque;
+
+ g_clear_pointer(&data->idstr, g_free);
+ g_free(data);
+}
+
+static int multifd_device_state_save_thread(void *opaque)
+{
+ struct MultiFDDSSaveThreadData *data = opaque;
+ int ret;
+
+ ret = data->hdlr(data->idstr, data->instance_id, &send_threads_abort,
+ data->handler_opaque);
+ if (ret && !qatomic_read(&send_threads_ret)) {
+ /*
+ * Racy with the above read but that's okay - which thread error
+ * return we report is purely arbitrary anyway.
+ */
+ qatomic_set(&send_threads_ret, ret);
+ }
+
+ return 0;
+}
+
+void
+multifd_spawn_device_state_save_thread(SaveLiveCompletePrecopyThreadHandler
hdlr,
+ char *idstr, uint32_t instance_id,
+ void *opaque)
+{
+ struct MultiFDDSSaveThreadData *data;
+
+ assert(migration_has_device_state_support());
+
+ data = g_new(struct MultiFDDSSaveThreadData, 1);
+ data->hdlr = hdlr;
+ data->idstr = g_strdup(idstr);
+ data->instance_id = instance_id;
+ data->handler_opaque = opaque;
+
+ thread_pool_submit(send_threads,
+ multifd_device_state_save_thread,
+ data, multifd_device_state_save_thread_data_free);
+
+ /*
+ * Make sure that this new thread is actually spawned immediately so it
+ * can start its work right now.
+ */
+ thread_pool_adjust_max_threads_to_work(send_threads);
+}
+
+void multifd_abort_device_state_save_threads(void)
+{
+ assert(migration_has_device_state_support());
+
+ qatomic_set(&send_threads_abort, true);
+}
+
+int multifd_join_device_state_save_threads(void)
+{
+ assert(migration_has_device_state_support());
+
+ thread_pool_wait(send_threads);
+
+ return send_threads_ret;
+}