Re: [Qemu-devel] [PATCH COLO-Frame v6 03/31] COLO: migrate colo related info to slave

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* zhanghailiang (zhang.zhanghailiang@huawei.com) wrote:
> On 2015/7/4 2:03, Dr. David Alan Gilbert wrote:
> >* zhanghailiang (zhang.zhanghailiang@huawei.com) wrote:
> >>We can know if VM in destination should go into COLO mode by refer to
> >>the info that has been migrated from PVM.
> >>
> >>Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
> >>Signed-off-by: Yang Hongyang <yanghy@cn.fujitsu.com>
> >>Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
> >>Signed-off-by: Gonglei <arei.gonglei@huawei.com>
> >>---
> >>  include/migration/migration-colo.h |  2 ++
> >>  migration/Makefile.objs            |  1 +
> >>  migration/colo-comm.c              | 47 ++++++++++++++++++++++++++++++++++++++
> >>  trace-events                       |  3 +++
> >>  vl.c                               |  5 +++-
> >>  5 files changed, 57 insertions(+), 1 deletion(-)
> >>  create mode 100644 migration/colo-comm.c
> >>
> >>diff --git a/include/migration/migration-colo.h b/include/migration/migration-colo.h
> >>index c6d0c51..e20a0c1 100644
> >>--- a/include/migration/migration-colo.h
> >>+++ b/include/migration/migration-colo.h
> >>@@ -14,7 +14,9 @@
> >>  #define QEMU_MIGRATION_COLO_H
> >>
> >>  #include "qemu-common.h"
> >>+#include "migration/migration.h"
> >>
> >>  bool colo_supported(void);
> >>+void colo_info_mig_init(void);
> >>
> >>  #endif
> >>diff --git a/migration/Makefile.objs b/migration/Makefile.objs
> >>index 5a25d39..cb7bd30 100644
> >>--- a/migration/Makefile.objs
> >>+++ b/migration/Makefile.objs
> >>@@ -1,5 +1,6 @@
> >>  common-obj-y += migration.o tcp.o
> >>  common-obj-$(CONFIG_COLO) += colo.o
> >>+common-obj-y += colo-comm.o
> >>  common-obj-y += vmstate.o
> >>  common-obj-y += qemu-file.o qemu-file-buf.o qemu-file-unix.o qemu-file-stdio.o
> >>  common-obj-y += xbzrle.o
> >>diff --git a/migration/colo-comm.c b/migration/colo-comm.c
> >>new file mode 100644
> >>index 0000000..0b76eb4
> >>--- /dev/null
> >>+++ b/migration/colo-comm.c
> >>@@ -0,0 +1,47 @@
> >>+/*
> >>+ * COarse-grain LOck-stepping Virtual Machines for Non-stop Service (COLO)
> >>+ * (a.k.a. Fault Tolerance or Continuous Replication)
> >>+ *
> >>+ * Copyright (c) 2015 HUAWEI TECHNOLOGIES CO., LTD.
> >>+ * Copyright (c) 2015 FUJITSU LIMITED
> >>+ * Copyright (c) 2015 Intel Corporation
> >>+ *
> >>+ * This work is licensed under the terms of the GNU GPL, version 2 or
> >>+ * later. See the COPYING file in the top-level directory.
> >>+ *
> >>+ */
> >>+
> >>+#include <migration/migration-colo.h>
> >>+#include "trace.h"
> >>+
> >>+static bool colo_requested;
> >>+
> >>+/* save */
> >>+static void colo_info_save(QEMUFile *f, void *opaque)
> >>+{
> >>+    qemu_put_byte(f, migrate_enable_colo());
> >>+}
> >>+
> >>+/* restore */
> >>+static int colo_info_load(QEMUFile *f, void *opaque, int version_id)
> >>+{
> >>+    int value = qemu_get_byte(f);
> >>+
> >>+    if (value && !colo_requested) {
> >>+        trace_colo_info_load("COLO request!");
> >>+    }
> >>+    colo_requested = value;
> >>+
> >>+    return 0;
> >>+}
> >>+
> >>+static SaveVMHandlers savevm_colo_info_handlers = {
> >>+    .save_state = colo_info_save,
> >>+    .load_state = colo_info_load,
> >>+};
> >>+
> >>+void colo_info_mig_init(void)
> >>+{
> >>+    register_savevm_live(NULL, "colo", -1, 1,
> >>+                         &savevm_colo_info_handlers, NULL);
> >>+}
> >>diff --git a/trace-events b/trace-events
> >>index 52b7efa..3f63019 100644
> >>--- a/trace-events
> >>+++ b/trace-events
> >>@@ -1466,6 +1466,9 @@ 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-comm.c
> >>+colo_info_load(const char *msg) "%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"
> >>diff --git a/vl.c b/vl.c
> >>index 2201e27..988567a 100644
> >>--- a/vl.c
> >>+++ b/vl.c
> >>@@ -90,6 +90,7 @@ int main(int argc, char **argv)
> >>  #include "sysemu/dma.h"
> >>  #include "audio/audio.h"
> >>  #include "migration/migration.h"
> >>+#include "migration/migration-colo.h"
> >>  #include "sysemu/kvm.h"
> >>  #include "qapi/qmp/qjson.h"
> >>  #include "qemu/option.h"
> >>@@ -4261,7 +4262,9 @@ int main(int argc, char **argv, char **envp)
> >>
> >>      blk_mig_init();
> >>      ram_mig_init();
> >>-
> >>+#ifdef CONFIG_COLO
> >>+    colo_info_mig_init();
> >>+#endif
> >
> >Does't this still break migration compatibility?  I wouldn't
> 
> Yes, it will break migration if the QEMU in destination and source not enable/disable (configure) this
> feature together, also not compatible with old version on migration.
> 
> >want to have to have two QEMU builds on a system, one built with COLO
> >and one built without COLO.   You need to arrange for the
> >section to only be sent if COLO is enabled (i.e. migrate_set_capability colo on).
> >One way to do that would be to use the new QEMU optional sections
> >that Juan added recently.
> >
> 
> Hmm, his method can address the above problems, (though, we will still fail when we configure
> with --enable-colo in source side and --disable-colo in destination, but that is what
> we want, we should not go into colo mode if secondary host is not enable this feature).
> I will look into his patch, and fix that in next version, thanks,

It must not break compatibility with migration however the --enable-colo/disable-colo on the
source destination; it should only break if the migrate_set_capability colo on   is set on
one and not the other.
I think with Juan's conditional section then you should be able to do it.

Dave

> zhanghailiang
> 
> >Dave
> >
> >>      /* If the currently selected machine wishes to override the units-per-bus
> >>       * property of its default HBA interface type, do so now. */
> >>      if (machine_class->units_per_default_bus) {
> >>--
> >>1.7.12.4
> >>
> >>
> >--
> >Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
> >
> >.
> >
> 
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK