Can i summarize:
1. Once N microflows are installed in the kernel cache:
we can install a megaflow/s in kernel datapath, if it possible to
generate a megaflow/s for them
2. These megaflow/s remain in the kernel megaflow cache as long as the
associated flows are in userspace openflow tables, regardless of
microflows eviction from kernel cache.
Thanks in advance
Sara
On Mon, Aug 14, 2017 at 8:47 PM, Joe Stringer <j...@ovn.org> wrote:
> The FAQ is referring to megaflows as well, the reasons are the same.
> Neither microflows nor megaflows can be pre-populated.
>
> On 14 August 2017 at 00:35, Sara Gittlin <sara.gitt...@gmail.com> wrote:
>> I understand that this citation refers to the kernel microflows tables.
>> the kernel megaflows table *can be* pre-populated. Correct ?
>> Sara
>>
>> On Mon, Aug 14, 2017 at 9:31 AM, Sara Gittlin <sara.gitt...@gmail.com> wrote:
>>> Thanks you Joe
>>> the following citation is in a contradiction to the idea of
>>> pre-populating megaflows in kernel datapath .
>>> this is from http://docs.openvswitch.org/en/latest/faq/design/
>>>
>>> "Q: Can OVS populate the kernel flow table in advance instead of in
>>> reaction to packets?
>>>
>>> A: No. There are several reasons:
>>>
>>> Kernel flows are not as sophisticated as OpenFlow flows, which means
>>> that some OpenFlow policies could require a large number of kernel
>>> flows. The “conjunctive match” feature is an extreme example: the
>>> number of kernel flows it requires is the product of the number of
>>> flows in each dimension.
>>> With multiple OpenFlow flow tables and simple sets of actions, the
>>> number of kernel flows required can be as large as the product of the
>>> number of flows in each dimension. With more sophisticated actions,
>>> the number of kernel flows could be even larger.
>>> Open vSwitch is designed so that any version of OVS userspace
>>> interoperates with any version of the OVS kernel module. This forward
>>> and backward compatibility requires that userspace observe how the
>>> kernel module parses received packets. This is only possible in a
>>> straightforward way when userspace adds kernel flows in reaction to
>>> received packets."
>>>
>>> Thanks in advance - Sara
>>>
>>> On Mon, Jul 24, 2017 at 10:58 PM, Joe Stringer <j...@ovn.org> wrote:
>>>> On 23 July 2017 at 06:37, Sara Gittlin <sara.gitt...@gmail.com> wrote:
>>>>> Hello,
>>>>> I understand that there is a support for megaflows in the kernel and
>>>>> netlink.
>>>>> I also understand that there is no megaflow implementation in ofproto.
>>>>> i.e. there is no implementation of compressing (if possible) all flows
>>>>> in ofproto table to megaflows and installing it in the datapath. is
>>>>> that correct ?
>>>>
>>>> That's right - rather than pre-populating a representation of the
>>>> entire OpenFlow state, the ofproto-dpif implementation uses an
>>>> "upcall" model where the datapath acts as a cache for forwarding
>>>> behaviour, and the cache is populated on-demand as traffic arrives.
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