Re: [Qemu-devel] [PATCH v11 09/12] netfilter: add a netbuffer filter

[Jason Wang]

On 09/25/2015 03:18 PM, Yang Hongyang wrote:
>
>
> On 09/24/2015 05:12 PM, Markus Armbruster wrote:
>> Yang Hongyang <address@hidden> writes:
>>
>>> This filter is to buffer/release packets, this feature can be used
>>> when using MicroCheckpointing, or other Remus like VM FT solutions, you
>>
>> What's "Remus"?
>
> Remus is an opensource VM FT solution:
> paper: http://http//www.cs.ubc.ca/~andy/papers/remus-nsdi-final.pdf
> First implemented on Xen:
> http://wiki.xen.org/wiki/Remus
>
> MicroCheckpointing in QEMU is another Remus implementation.
>
>

[...]

>>
>>> +     * FIXME: even if guest can't receive packet for some reasons.
>>> Filter
>>> +     * can still accept packet until its internal queue is full.
>>> +     */
>>
>> I'm not sure I understand the comment.
>
> This is taken from Jason's comments, may be he can have a better explain?

For example. For some reason, receiver could not receive more packets
(.can_receive() returns zero). Without a filter, at most one packet will
be queued in incoming queue and sender's poll will be disabled unit its
sent_cb() was called. With a filter, it will keep receive the packets
without caring about the receiver. This is suboptimal. May need more
thoughts (e.g keeping sent_cb).

[...]