Re: RFC: mpsafe bridge and NIC drivers (vioif and wm)

[Ryota Ozaki <ozaki-r%iij.ad.jp@localhost>]

On Wed, Jun 4, 2014 at 12:23 AM, Darren Reed <darrenr%netbsd.org@localhost> 
wrote:
> On 3/06/2014 11:06 PM, Ryota Ozaki wrote:
>>
>> Hi Darren,
>>
>> On Tue, Jun 3, 2014 at 9:16 PM, Darren Reed <darrenr%netbsd.org@localhost> 
>> wrote:
>>>
>>> I assume this to be related to what rmind is doing, yes?
>>
>> Yes and no. We have a same goal (networking parallelism), but we're
>> working on different components; he is mainly at L3 and above, and
>> we are below L3. We collaborate a little to avoid overlapping each
>> effort, but we are working separately.
>>
>
> In so much as it is possible, I would suggest following on what rmind
> is doing to make the code paths lock free as much as possible ... or are
> you introducing locks that he's removing? For example, looking at the
> code, you're adding locks around IFQ_DEQUEUE but he's removing that
> macro and locks ... or?

I think there are two steps to make the networking code MP-capable.
The first step is to remove big kernel locks and make it work with
some fine-grain locks (MP-safe), and the second is to make it scalable,
for example, by employing lockless data structures. We are still on the
first step while rmind is on the second.

I think we can use rmind's pktqueue for bridge's forwarding queues to
get rid of the locks around IFQ_DEQUEUE. Once pktqueue is merged, I
will try it for bridge.

>
> Are you all committing to the same branch/tree?

Not yet, but we (IIJ guys) plan to prepare an integrated branch for
convenience to test.

  ozaki-r

>
> Darren
>