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

[Alexey Kardashevskiy <aik@ozlabs.ru>]

On 05/05/2014 09:20 PM, Juan Quintela wrote:
> 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.



Who else needs to be ok to get this in upstream? :) Thanks!



> 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)
>>>>>  {
>>>
>>>


-- 
Alexey