[CRIU] [PATCH v2 3/3] aio: Restore aio ring content

[Kirill Tkhai]

On 21.03.2016 15:10, Pavel Emelyanov wrote:
> On 03/21/2016 03:02 PM, Kirill Tkhai wrote:
>>
>>
>> On 21.03.2016 13:15, Pavel Emelyanov wrote:
>>> On 03/21/2016 01:10 PM, Kirill Tkhai wrote:
>>>
>>>>>> I'm going to add plugin to parasite_check_aios(), and to wait inflight requests
>>>>>> from there.
>>>>>>  
>>>>>>> Anyway, I don't think treating aio ring buffer as regular anonymous memory
>>>>>>> is good idea.
>>>>>>
>>>>>> What do you suggest? Add vma_entry_is_private(entry) | vma_entry_is(entry, VMA_AREA_AIORING)
>>>>>> every place we used it?
>>>>>
>>>>> Not every. My current opinion is that soft-dirty tracking should NOT
>>>>> be done for AIO rings.
>>>>
>>>> So, if we skip AIO on pre-dump, but we will dump it like any other private memory,
>>>> is this OK for you?
>>>
>>> I tend to think it's not, since these are objects with structure. However
>>> I don't have string arguments against dumping them as raw blobs _provided_
>>> we check for ring head magic beforehand.
>>
>> I don't completely understand you. What is dumping as raw blobs, but not as like memory?
> 
> By "as raw blobs" I mean just read the contents of the memory byte-by-byte w/o
> understanding its structure.
> 
>> Checking of ring head magic make a sense at a restore, but which way should it be used
>> at dump?
> 
> I'd say the same -- check magic and go ahead and read ring memory contents starting
> from the events array. Reading the header as memory doesn't make sense from my pov.

Since header shares page[0] with events, if we do not dump it, this saves 32 byte only.

So, anyway, we dump aio ring content in a file separate from private memory? (I'm just
clarifying before I started rework).