[Oisf-devel] Linux af-packet::mmap enhancement

[chetan loke]

On Fri, Jun 24, 2011 at 11:25 AM, Victor Julien <victor at inliniac.net> wrote:
> On 06/23/2011 06:30 PM, chetan loke wrote:
>> On Thu, Jun 23, 2011 at 11:59 AM, Victor Julien <victor at inliniac.net> wrote:
>>> The disadvantage is that multiple threads/cpu's/cores will suddenly be
>>> handling the same packet, instead of just the one dealing with the
>>> FANOUT socket.
>>>
>>
>> My description wasn't so clear. Actually what I meant was:
>>
>> lookup_table : <rx_hash> <thread_id>;
>>
>> thread_id = get_worker_th_id (pkt_hdr->rx_hash);
>>
>> if (thread_id) {
>>   /* This flow is HOT. steer this flow to the same thread */
>>   enqueue_pkt_to_thread(thread_id);
>> } else {
>>  /* This flow is COLD.No thread is handling this flow yet.*/
>>  /* So queue it to the next thread */
>>     enqueue_pkt_to_thread(GET_NEXT_THREAD(ROUND_ROBIN_POLICY));
>>     update lookup_table;
>> }
>>
>> So no two threads will work on the same flow.
>
> To be clear, this functionality would live in the kernel, right?

Nope, it would reside in user-space because kernel doesn't know which
fanout-listener
is under heavy load. Once the 'rx_hash' is exported in
tpacket_headers, we can spread
the load in user space.

>
> Cheers,
> Victor

regards
Chetan Loke