Re: [Qemu-devel] [PATCH] migration: Increase default max_downtime from 30ms to 300ms

[Juan Quintela <quintela@redhat.com>]

Alexey Kardashevskiy <aik@ozlabs.ru> wrote:
> On 04/13/2014 12:38 AM, Alexey Kardashevskiy wrote:
>> On 03/27/2014 08:01 PM, Markus Armbruster wrote:
>>> Adding Juan.
>> 
>> 
>> Ping?

Patch is OK for me.

As sender says, with guests doing anything/bigger than 1GB RAM is
basically implosible to get into the 30ms downtime.

Later, Juan.

>
>
> Ping?
>
>
>> 
>>>
>>> Alexey Kardashevskiy <aik@ozlabs.ru> writes:
>>>
>>>> The existing timeout is 30ms which on 100MB/s (1Gbit) gives us
>>>> 3MB/s rate maximum. If we put some load on the guest, it is easy to
>>>> get page dirtying rate too big so live migration will never complete.
>>>> In the case of libvirt that means that the guest will be stopped
>>>> anyway after a timeout specified in the "virsh migrate" command and
>>>> this normally generates even bigger delay.
>>>>
>>>> This changes max_downtime to 300ms which seems to be more
>>>> reasonable value.
>>>>
>>>> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
>>>> ---
>>>>  migration.c | 2 +-
>>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>>
>>>> diff --git a/migration.c b/migration.c
>>>> index e0e24d4..02bbce9 100644
>>>> --- a/migration.c
>>>> +++ b/migration.c
>>>> @@ -144,7 +144,7 @@ void process_incoming_migration(QEMUFile *f)
>>>>   * the choice of nanoseconds is because it is the maximum resolution that
>>>>   * get_clock() can achieve. It is an internal measure. All user-visible
>>>>   * units must be in seconds */
>>>> -static uint64_t max_downtime = 30000000;
>>>> +static uint64_t max_downtime = 300000000;
>>>>  
>>>>  uint64_t migrate_max_downtime(void)
>>>>  {
>> 
>>