Anthony Liguori <anth...@codemonkey.ws> wrote:
> On 09/12/2010 05:42 AM, Avi Kivity wrote:
>> On 09/11/2010 05:04 PM, Anthony Liguori wrote:
>>> This fixes a couple nasty problems relating to live migration.
>>>
>>> 1) When dealing with shared storage with weak coherence (i.e. NFS),
>>> even if
>>> we re-read, we may end up with undesired caching. By delaying
>>> any reads
>>> until we absolutely have to, we decrease the likelihood of any
>>> undesirable
>>> caching.
>>>
>>> 2) When dealing with copy-on-read, the local storage acts as a
>>> cache. We need
>>> to make sure to avoid any reads to avoid polluting the local cache.
>>>
>>> +
>>> static void ide_identify(IDEState *s)
>>> {
>>> uint16_t *p;
>>> @@ -105,6 +132,8 @@ static void ide_identify(IDEState *s)
>>> return;
>>> }
>>>
>>> + guess_geometry(s);
>>> +
>>
>> This can cause a disk read, no? Shouldn't it be made asynchronous?
>
> Yes, it should. I'm not sure there's an easy way to make it
> asynchronous though not because of the block layer but because of how
> these functions are called.
>
>>
>> Or just move it to just before the guest starts?
>
> We don't really have a notion of "guest starts" today although maybe
> we should.
I agree that we should have more states. Expecting Migration/Migration
done are quite special casses that are handled adhoc now. Having
some state like: NeverRun will make trivial to have vm_start() do the
right thing on the 1st run.
Later, Juan.
> Regards,
>
> Anthony Liguori
