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Re: [Qemu-devel] [PATCH] Add warmup phase for live migration of large me


From: Anthony Liguori
Subject: Re: [Qemu-devel] [PATCH] Add warmup phase for live migration of large memory apps
Date: Wed, 11 May 2011 08:35:19 -0500
User-agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.17) Gecko/20110424 Lightning/1.0b2 Thunderbird/3.1.10

On 05/11/2011 02:58 AM, Shribman, Aidan wrote:
From: Aidan Shribman<address@hidden>

[PATCH] Add warmup phase for live migration of large memory apps

By invoking "migrate -w<url>" we initiate a background live-migration
transferring of dirty pages continuously until invocation of "migrate_end"
which attempts to complete the live migration operation.

Qemu host: Ubuntu 10.10

Testing: live migration (with/without warmup phase) tested successfully.

Signed-off-by: Benoit Hudzia<address@hidden>
Signed-off-by: Petter Svard<address@hidden>
Signed-off-by: Aidan Shribman<address@hidden>

If you do:

migrate_set_downtime 0
migrate -d <url>

You'll achieve the same result. The migration will never converge because there's no way QEMU can meet the downtime expectation.

You can then do:

migrate_set_downtime 30ms

To let migration go. You can even use info migrate to figure out when migration has been sufficiently warmed up.

You can also always do migrate_cancel to abort the operation.

Regards,

Anthony Liguori

---
  hmp-commands.hx |   34 +++++++++++++++++++++++++---------
  migration.c     |   23 ++++++++++++++++++++++-
  migration.h     |    2 ++
  qmp-commands.hx |   41 ++++++++++++++++++++++++++++++++++-------
  savevm.c        |   12 ++++++++++++
  sysemu.h        |    1 +
  6 files changed, 96 insertions(+), 17 deletions(-)

diff --git a/hmp-commands.hx b/hmp-commands.hx
index e5585ba..234a952 100644
--- a/hmp-commands.hx
+++ b/hmp-commands.hx
@@ -717,24 +717,27 @@ ETEXI

      {
          .name       = "migrate",
-        .args_type  = "detach:-d,blk:-b,inc:-i,uri:s",
-        .params     = "[-d] [-b] [-i] uri",
-        .help       = "migrate to URI (using -d to not wait for completion)"
-                     "\n\t\t\t -b for migration without shared storage with"
-                     " full copy of disk\n\t\t\t -i for migration without "
-                     "shared storage with incremental copy of disk "
-                     "(base image shared between src and destination)",
+        .args_type  = "detach:-d,blk:-b,inc:-i,warmup:-w,uri:s",
+        .params     = "[-d] [-b] [-i] [-w] uri",
+        .help       = "migrate to URI"
+                      "\n\t -d to not wait for completion"
+                      "\n\t -b for migration without shared storage with"
+                      " full copy of disk"
+                      "\n\t -i for migration without"
+                      " shared storage with incremental copy of disk"
+                      " (base image shared between source and destination)"
+                      "\n\t -w to enter warmup phase",
          .user_print = monitor_user_noop,      
        .mhandler.cmd_new = do_migrate,
      },

-
  STEXI
address@hidden migrate [-d] [-b] [-i] @var{uri}
address@hidden migrate [-d] [-b] [-i] [-w] @var{uri}
  @findex migrate
  Migrate to @var{uri} (using -d to not wait for completion).
        -b for migration with full copy of disk
        -i for migration with incremental copy of disk (base image is shared)
+    -w to enter warmup phase
  ETEXI

      {
@@ -753,6 +756,19 @@ Cancel the current VM migration.
  ETEXI

      {
+        .name       = "migrate_end",
+        .args_type  = "",
+        .params     = "",
+        .help       = "Complete warmup and move to full live migration",
+        .mhandler.cmd = do_migrate_end,
+    },
+
+STEXI
address@hidden migrate_end
+Complete warmup and move to full live migration.
+ETEXI
+
+    {
          .name       = "migrate_set_speed",
          .args_type  = "value:o",
          .params     = "value",
diff --git a/migration.c b/migration.c
index 9ee8b17..7525b47 100644
--- a/migration.c
+++ b/migration.c
@@ -31,6 +31,8 @@
      do { } while (0)
  #endif

+static int is_migrate_warmup = 0;
+
  /* Migration speed throttling */
  static uint32_t max_throttle = (32<<  20);

@@ -81,6 +83,11 @@ int do_migrate(Monitor *mon, const QDict *qdict, QObject 
**ret_data)
      int blk = qdict_get_try_bool(qdict, "blk", 0);
      int inc = qdict_get_try_bool(qdict, "inc", 0);
      const char *uri = qdict_get_str(qdict, "uri");
+    is_migrate_warmup = qdict_get_try_bool(qdict, "warmup", 0);
+
+    if (is_migrate_warmup) {
+        detach = 1; /* as we need migrate_end to complte */
+       }

      if (current_migration&&
          current_migration->get_status(current_migration) == MIG_STATE_ACTIVE) 
{
@@ -361,7 +368,9 @@ void migrate_fd_put_ready(void *opaque)
      }

      DPRINTF("iterate\n");
-    if (qemu_savevm_state_iterate(s->mon, s->file) == 1) {
+    if (is_migrate_warmup) {
+            qemu_savevm_state_warmup(s->mon, s->file);
+       } else if (qemu_savevm_state_iterate(s->mon, s->file) == 1) {
          int state;
          int old_vm_running = vm_running;

@@ -448,3 +457,15 @@ int migrate_fd_close(void *opaque)
      qemu_set_fd_handler2(s->fd, NULL, NULL, NULL, NULL);
      return s->close(s);
  }
+
+void do_migrate_end(Monitor *mon, const QDict *qdict)
+{
+    if (!vm_running) {
+        return;
+       }
+    if (!is_migrate_warmup) {
+        return;
+       }
+    is_migrate_warmup = 0;
+}
+
diff --git a/migration.h b/migration.h
index d13ed4f..6a96b29 100644
--- a/migration.h
+++ b/migration.h
@@ -134,4 +134,6 @@ static inline FdMigrationState 
*migrate_to_fms(MigrationState *mig_state)
      return container_of(mig_state, FdMigrationState, mig_state);
  }

+void do_migrate_end(Monitor *mon, const QDict *qdict);
+
  #endif
diff --git a/qmp-commands.hx b/qmp-commands.hx
index 793cf1c..58fe696 100644
--- a/qmp-commands.hx
+++ b/qmp-commands.hx
@@ -431,13 +431,16 @@ EQMP

      {
          .name       = "migrate",
-        .args_type  = "detach:-d,blk:-b,inc:-i,uri:s",
-        .params     = "[-d] [-b] [-i] uri",
-        .help       = "migrate to URI (using -d to not wait for completion)"
-                     "\n\t\t\t -b for migration without shared storage with"
-                     " full copy of disk\n\t\t\t -i for migration without "
-                     "shared storage with incremental copy of disk "
-                     "(base image shared between src and destination)",
+        .args_type  = "detach:-d,blk:-b,inc:-i,xbrle:-x,warmup:-w,uri:s",
+        .params     = "[-d] [-b] [-i] [-w] uri",
+        .help       = "migrate to URI"
+                      "\n\t -d to not wait for completion"
+                      "\n\t -b for migration without shared storage with"
+                      " full copy of disk"
+                      "\n\t -i for migration without"
+                      " shared storage with incremental copy of disk"
+                      " (base image shared between source and destination)"
+                      "\n\t -w to enter warmup phase",
          .user_print = monitor_user_noop,      
        .mhandler.cmd_new = do_migrate,
      },
@@ -453,6 +456,7 @@ Arguments:
  - "blk": block migration, full disk copy (json-bool, optional)
  - "inc": incremental disk copy (json-bool, optional)
  - "uri": Destination URI (json-string)
+- "warmup":to enter warmup phasen

  Example:

@@ -494,6 +498,29 @@ Example:
  EQMP

      {
+        .name       = "migrate_end",
+        .args_type  = "",
+        .params     = "",
+        .help       = "Complete warmup and move to full live migration",
+        .mhandler.cmd = do_migrate_end,
+    },
+
+SQMP
+migrate_end
+-----------
+
+End the current migration warmup.
+
+Arguments: None.
+
+Example:
+
+->  { "execute": "migrate_end" }
+<- { "return": {} }
+
+EQMP
+
+    {
          .name       = "migrate_set_speed",
          .args_type  = "value:f",
          .params     = "value",
diff --git a/savevm.c b/savevm.c
index 4e49765..521589c 100644
--- a/savevm.c
+++ b/savevm.c
@@ -1471,6 +1471,18 @@ int qemu_savevm_state_begin(Monitor *mon, QEMUFile *f, 
int blk_enable,
      return 0;
  }

+int qemu_savevm_state_warmup(Monitor *mon, QEMUFile *f) {
+    int ret = 1;
+
+    ret = qemu_savevm_state_iterate(mon, f);
+
+    if (ret == -EIO) {
+        return ret;
+       }
+
+    return 0;
+}
+
  int qemu_savevm_state_iterate(Monitor *mon, QEMUFile *f)
  {
      SaveStateEntry *se;
diff --git a/sysemu.h b/sysemu.h
index b81a70e..74e8a48 100644
--- a/sysemu.h
+++ b/sysemu.h
@@ -76,6 +76,7 @@ void main_loop_wait(int nonblocking);
  int qemu_savevm_state_begin(Monitor *mon, QEMUFile *f, int blk_enable,
                              int shared);
  int qemu_savevm_state_iterate(Monitor *mon, QEMUFile *f);
+int qemu_savevm_state_warmup(Monitor *mon, QEMUFile *f);
  int qemu_savevm_state_complete(Monitor *mon, QEMUFile *f);
  void qemu_savevm_state_cancel(Monitor *mon, QEMUFile *f);
  int qemu_loadvm_state(QEMUFile *f);




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