[Qemu-devel] [PATCH RFC 3/4] Curling: the sender

[Jules Wang]

By leveraging live migration feature, the sender simply starts a
new migration when the previous migration is completed.

We need to handle the variables related to live migration very
carefully. So the new migration does not restart from the very
begin of the migration, instead, it continues the previous
migration.

Signed-off-by: Jules Wang <address@hidden>
---
 arch_init.c | 18 +++++++++++++-----
 migration.c | 23 ++++++++++++++++++++++-
 savevm.c    |  4 ++++
 3 files changed, 39 insertions(+), 6 deletions(-)

diff --git a/arch_init.c b/arch_init.c
index e47e139..5d006f6 100644
--- a/arch_init.c
+++ b/arch_init.c
@@ -611,10 +611,14 @@ static int ram_save_setup(QEMUFile *f, void *opaque)
 {
     RAMBlock *block;
     int64_t ram_pages = last_ram_offset() >> TARGET_PAGE_BITS;
+    bool create = false;
 
-    migration_bitmap = bitmap_new(ram_pages);
-    bitmap_set(migration_bitmap, 0, ram_pages);
-    migration_dirty_pages = ram_pages;
+    if (!ft_enabled() || !migration_bitmap)  {
+        migration_bitmap = bitmap_new(ram_pages);
+        bitmap_set(migration_bitmap, 0, ram_pages);
+        migration_dirty_pages = ram_pages;
+        create = true;
+    }
     mig_throttle_on = false;
     dirty_rate_high_cnt = 0;
 
@@ -634,7 +638,9 @@ static int ram_save_setup(QEMUFile *f, void *opaque)
     qemu_mutex_lock_iothread();
     qemu_mutex_lock_ramlist();
     bytes_transferred = 0;
-    reset_ram_globals();
+    if (!ft_enabled() || create) {
+        reset_ram_globals();
+    }
 
     memory_global_dirty_log_start();
     migration_bitmap_sync();
@@ -744,7 +750,9 @@ static int ram_save_complete(QEMUFile *f, void *opaque)
     }
 
     ram_control_after_iterate(f, RAM_CONTROL_FINISH);
-    migration_end();
+    if (!ft_enabled()) {
+        migration_end();
+    }
 
     qemu_mutex_unlock_ramlist();
     qemu_put_be64(f, RAM_SAVE_FLAG_EOS);
diff --git a/migration.c b/migration.c
index 59c8f32..d8a9b2d 100644
--- a/migration.c
+++ b/migration.c
@@ -567,6 +567,7 @@ static void *migration_thread(void *opaque)
     int64_t max_size = 0;
     int64_t start_time = initial_time;
     bool old_vm_running = false;
+    int  time_window = 100;
 
     DPRINTF("beginning savevm\n");
     qemu_savevm_state_begin(s->file, &s->params);
@@ -578,6 +579,8 @@ static void *migration_thread(void *opaque)
 
     while (s->state == MIG_STATE_ACTIVE) {
         int64_t current_time;
+        int64_t time_spent;
+        int64_t migration_start_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
         uint64_t pending_size;
 
         if (!qemu_file_rate_limit(s->file)) {
@@ -607,10 +610,28 @@ static void *migration_thread(void *opaque)
                     break;
                 }
 
-                if (!qemu_file_get_error(s->file)) {
+                if (!qemu_file_get_error(s->file) && !ft_enabled()) {
                     migrate_set_state(s, MIG_STATE_ACTIVE, 
MIG_STATE_COMPLETED);
                     break;
                 }
+
+                if (ft_enabled()) {
+                    if (old_vm_running) {
+                        qemu_mutex_lock_iothread();
+                        vm_start();
+                        qemu_mutex_unlock_iothread();
+
+                        current_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
+                        time_spent = current_time - migration_start_time;
+                        DPRINTF("this migration lasts for %" PRId64 "ms\n",
+                                time_spent);
+                        if (time_spent < time_window) {
+                            g_usleep((time_window - time_spent)*1000);
+                            initial_time += time_window - time_spent;
+                        }
+                    }
+                    qemu_savevm_state_begin(s->file, &s->params);
+                }
             }
         }
 
diff --git a/savevm.c b/savevm.c
index c536aa4..6daf690 100644
--- a/savevm.c
+++ b/savevm.c
@@ -1824,6 +1824,7 @@ static void vmstate_save(QEMUFile *f, SaveStateEntry *se)
 #define QEMU_VM_SECTION_END          0x03
 #define QEMU_VM_SECTION_FULL         0x04
 #define QEMU_VM_SUBSECTION           0x05
+#define QEMU_VM_EOF_MAGIC            0xFeedCafe
 
 bool qemu_savevm_state_blocked(Error **errp)
 {
@@ -1983,6 +1984,9 @@ void qemu_savevm_state_complete(QEMUFile *f)
     }
 
     qemu_put_byte(f, QEMU_VM_EOF);
+    if (ft_enabled()) {
+        qemu_put_be32(f, QEMU_VM_EOF_MAGIC);
+    }
     qemu_fflush(f);
 }
 
-- 
1.8.0.1