Re: [dpdk-dev] preallocation of void ** obj_p of rte_ring_dequeue

[Jose Gavine Cueto <pepedocs@gmail.com>]

I see , now its clearer.

Thanks,
Pepe


On Wed, Nov 6, 2013 at 1:54 AM, Cyril Cressent <cyril.cressent@intel.com>wrote:

> On Wed, Nov 06, 2013 at 12:47:13AM +0800, Jose Gavine Cueto wrote:
>
> > Your'e welcome, and by the way the multiprocess example of simple_mp
> seems
> > confusing here:
> >
> > static int
> > lcore_recv(__attribute__((unused)) void *arg)
> > {
> > unsigned lcore_id = rte_lcore_id();
> >
> > printf("Starting core %u\n", lcore_id);
> > while (!quit){
> > void *msg;
> > if (rte_ring_dequeue(recv_ring, &msg) < 0){
> > usleep(5);
> > continue;
> > }
> > printf("core %u: Received '%s'\n", lcore_id, (char *)msg);
> > rte_mempool_put(message_pool, msg);
> > }
> >
> > return 0;
> > }
> >
> > It seems that it isn't allocating msg here, or maybe I'm just missing
> something
>
> I understand your question better now, and in that light I think my
> previous answer was confusing. Let me try to clarify:
>
> A ring only holds *pointers* to objects.  You enqueue pointers, and
> dequeue those pointers later, somewhere else, usually in another thread.
> The allocation/deallocation of the actual objects is none the concern of
> the ring and its enqueue/dequeue operations.
>
> If we take the simple_mp example, the msg dequeued by the lcore_recv()
> thread is created in mp_command.c and a pointer to that message is
> enqueued on "send_ring". If you read carefully how the rings are created
> you'll understand how "send_ring" and "recv_ring" relate to each other.
>
> I hope this is a bit clearer,
>
> Cyril
>



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