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

[zhanghailiang <zhang.zhanghailiang@huawei.com>]

On 2015/7/6 16:29, Dr. David Alan Gilbert wrote:
> * 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.

Yes, i agree, my above description is not clear :) Thanks.

> 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
>
> .
>