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Re: [Qemu-devel] [PATCH COLO-Frame v9 05/32] migration: Integrate COLO c

From: zhanghailiang
Subject: Re: [Qemu-devel] [PATCH COLO-Frame v9 05/32] migration: Integrate COLO checkpoint process into migration
Date: Sat, 10 Oct 2015 14:25:12 +0800
User-agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:38.0) Gecko/20100101 Thunderbird/38.1.0 
On 2015/10/10 0:53, Dr. David Alan Gilbert wrote:

* zhanghailiang (address@hidden) wrote:

Add a migrate state: MIGRATION_STATUS_COLO, enter this migration state
after the first live migration successfully finished.

Signed-off-by: zhanghailiang <address@hidden>
Signed-off-by: Li Zhijian <address@hidden>
Signed-off-by: Gonglei <address@hidden>


If I understand this correctly, I think what you're doing is:
      migration_thread
            does initial migrate
            init_checkpointer
              creates a bh

      main thread
        bh
          start_checkpointer
              creates colo_thread

      colo thread
        outbound side loop

Why not just keep the migration thread going and reuse that?
Couldn't you just call the colo_thread() function at the place you
currently call colo_init_checkpointer, and add the init code
to the start of colo_thread?
It seems simpler.



Of course, it is really a good idea to reuse migration thread,
i will fix it like that. and the helper function colo_thread will be renamed :)

Thanks,
zhanghailiang


Other than that it's OK.

Dave



---
  include/migration/colo.h |  3 +++
  migration/colo.c         | 58 ++++++++++++++++++++++++++++++++++++++++++++++++
  migration/migration.c    | 23 ++++++++++++++-----
  qapi-schema.json         |  2 +-
  stubs/migration-colo.c   |  9 ++++++++
  trace-events             |  3 +++
  6 files changed, 92 insertions(+), 6 deletions(-)

diff --git a/include/migration/colo.h b/include/migration/colo.h
index 9b6662d..dface19 100644
--- a/include/migration/colo.h
+++ b/include/migration/colo.h
@@ -19,4 +19,7 @@
  bool colo_supported(void);
  void colo_info_mig_init(void);

+void colo_init_checkpointer(MigrationState *s);
+bool migration_in_colo_state(void);
+
  #endif
diff --git a/migration/colo.c b/migration/colo.c
index 2c40d2e..97e64a3 100644
--- a/migration/colo.c
+++ b/migration/colo.c
@@ -10,9 +10,67 @@
   * later.  See the COPYING file in the top-level directory.
   */

+#include "sysemu/sysemu.h"
  #include "migration/colo.h"
+#include "trace.h"
+
+static QEMUBH *colo_bh;

  bool colo_supported(void)
  {
      return true;
  }
+
+bool migration_in_colo_state(void)
+{
+    MigrationState *s = migrate_get_current();
+
+    return (s->state == MIGRATION_STATUS_COLO);
+}
+
+static void *colo_thread(void *opaque)
+{
+    MigrationState *s = opaque;
+
+    qemu_mutex_lock_iothread();
+    vm_start();
+    qemu_mutex_unlock_iothread();
+    trace_colo_vm_state_change("stop", "run");
+
+    /*TODO: COLO checkpoint savevm loop*/
+
+    migrate_set_state(&s->state, MIGRATION_STATUS_COLO,
+                      MIGRATION_STATUS_COMPLETED);
+
+    qemu_mutex_lock_iothread();
+    qemu_bh_schedule(s->cleanup_bh);
+    qemu_mutex_unlock_iothread();
+
+    return NULL;
+}
+
+static void colo_start_checkpointer(void *opaque)
+{
+    MigrationState *s = opaque;
+
+    if (colo_bh) {
+        qemu_bh_delete(colo_bh);
+        colo_bh = NULL;
+    }
+
+    qemu_mutex_unlock_iothread();
+    qemu_thread_join(&s->thread);
+    qemu_mutex_lock_iothread();
+
+    migrate_set_state(&s->state, MIGRATION_STATUS_ACTIVE,
+                      MIGRATION_STATUS_COLO);
+
+    qemu_thread_create(&s->thread, "colo", colo_thread, s,
+                       QEMU_THREAD_JOINABLE);
+}
+
+void colo_init_checkpointer(MigrationState *s)
+{
+    colo_bh = qemu_bh_new(colo_start_checkpointer, s);
+    qemu_bh_schedule(colo_bh);
+}
diff --git a/migration/migration.c b/migration/migration.c
index 98133f1..bee61aa 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -446,6 +446,10 @@ MigrationInfo *qmp_query_migrate(Error **errp)

          get_xbzrle_cache_stats(info);
          break;
+    case MIGRATION_STATUS_COLO:
+        info->has_status = true;
+        /* TODO: display COLO specific information (checkpoint info etc.) */
+        break;
      case MIGRATION_STATUS_COMPLETED:
          get_xbzrle_cache_stats(info);

@@ -731,7 +735,8 @@ void qmp_migrate(const char *uri, bool has_blk, bool blk,

      if (s->state == MIGRATION_STATUS_ACTIVE ||
          s->state == MIGRATION_STATUS_SETUP ||
-        s->state == MIGRATION_STATUS_CANCELLING) {
+        s->state == MIGRATION_STATUS_CANCELLING ||
+        s->state == MIGRATION_STATUS_COLO) {
          error_setg(errp, QERR_MIGRATION_ACTIVE);
          return;
      }
@@ -948,6 +953,7 @@ static void *migration_thread(void *opaque)
      int64_t max_size = 0;
      int64_t start_time = initial_time;
      bool old_vm_running = false;
+    bool enable_colo = migrate_enable_colo();

      rcu_register_thread();

@@ -992,8 +998,10 @@ static void *migration_thread(void *opaque)
                  }

                  if (!qemu_file_get_error(s->file)) {
-                    migrate_set_state(&s->state, MIGRATION_STATUS_ACTIVE,
-                                      MIGRATION_STATUS_COMPLETED);
+                    if (!enable_colo) {
+                        migrate_set_state(&s->state, MIGRATION_STATUS_ACTIVE,
+                                          MIGRATION_STATUS_COMPLETED);
+                    }
                      break;
                  }
              }
@@ -1044,11 +1052,16 @@ static void *migration_thread(void *opaque)
          }
          runstate_set(RUN_STATE_POSTMIGRATE);
      } else {
-        if (old_vm_running) {
+        if (s->state == MIGRATION_STATUS_ACTIVE && enable_colo) {
+            colo_init_checkpointer(s);
+        } else if (old_vm_running) {
              vm_start();
          }
      }
-    qemu_bh_schedule(s->cleanup_bh);
+
+    if (!enable_colo || s->state != MIGRATION_STATUS_ACTIVE) {
+        qemu_bh_schedule(s->cleanup_bh);
+    }
      qemu_mutex_unlock_iothread();

      rcu_unregister_thread();
diff --git a/qapi-schema.json b/qapi-schema.json
index b14d1f4..6dd5c7c 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -433,7 +433,7 @@
  ##
  { 'enum': 'MigrationStatus',
    'data': [ 'none', 'setup', 'cancelling', 'cancelled',
-            'active', 'completed', 'failed' ] }
+            'active', 'completed', 'failed', 'colo' ] }

  ##
  # @MigrationInfo
diff --git a/stubs/migration-colo.c b/stubs/migration-colo.c
index 3d817df..51b8f66 100644
--- a/stubs/migration-colo.c
+++ b/stubs/migration-colo.c
@@ -16,3 +16,12 @@ bool colo_supported(void)
  {
      return false;
  }
+
+bool migration_in_colo_state(void)
+{
+    return false;
+}
+
+void colo_init_checkpointer(MigrationState *s)
+{
+}
diff --git a/trace-events b/trace-events
index 8f9614a..487d1c7 100644
--- a/trace-events
+++ b/trace-events
@@ -1472,6 +1472,9 @@ rdma_start_incoming_migration_after_rdma_listen(void) ""
  rdma_start_outgoing_migration_after_rdma_connect(void) ""
  rdma_start_outgoing_migration_after_rdma_source_init(void) ""

+# migration/colo.c
+colo_vm_state_change(const char *old, const char *new) "Change '%s' => '%s'"
+
  # kvm-all.c
  kvm_ioctl(int type, void *arg) "type 0x%x, arg %p"
  kvm_vm_ioctl(int type, void *arg) "type 0x%x, arg %p"
--
1.8.3.1



--
Dr. David Alan Gilbert / address@hidden / Manchester, UK

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