On Tue, Jul 26, 2016 at 10:11:13AM +0000, Hemant Agrawal wrote:
> Hi,
> There was lengthy discussions w.r.t external mempool patches.
> However, I am still finding usages issue with the agreed approach.
>
> The existing API to create packet mempool, "rte_pktmbuf_pool_create" does not
> provide the option to change the object init iterator. This may be the reason
> that many applications (e.g. OVS) are using rte_mempool_create to create
> packet mempool with their own object iterator (e.g. ovs_rte_pktmbuf_init).
>
> e.g the existing usages are:
> dmp->mp = rte_mempool_create(mp_name, mp_size, MBUF_SIZE(mtu),
> MP_CACHE_SZ,
> sizeof(struct rte_pktmbuf_pool_private),
> rte_pktmbuf_pool_init, NULL,
> ovs_rte_pktmbuf_init, NULL,
> socket_id, 0);
>
>
> With the new API set for packet pool create, this need to be changed to:
>
> dmp->mp = rte_mempool_create_empty(mp_name, mp_size, MBUF_SIZE(mtu),
> MP_CACHE_SZ,
> sizeof(struct rte_pktmbuf_pool_private),
> socket_id, 0);
> if (dmp->mp == NULL)
> break;
>
> rte_errno = rte_mempool_set_ops_byname(dmp-mp,
>
> RTE_MBUF_DEFAULT_MEMPOOL_OPS, NULL);
> if (rte_errno != 0) {
> RTE_LOG(ERR, MBUF, "error
> setting mempool handler\n");
> return NULL;
> }
> rte_pktmbuf_pool_init(dmp->mp, NULL);
>
> ret = rte_mempool_populate_default(dmp->mp);
> if (ret < 0) {
> rte_mempool_free(dmp->mp);
> rte_errno = -ret;
> return NULL;
> }
>
> rte_mempool_obj_iter(dmp->mp,
> ovs_rte_pktmbuf_init, NULL);
>
> This is not a user friendly approach to ask for changing 1 API to 6 new APIs.
> Or, am I missing something?
I agree, To me, this is very bad. I have raised this concern earlier
also
Since applications like OVS goes through "rte_mempool_create" for
even packet buffer pool creation. IMO it make senses to extend
"rte_mempool_create" to take one more argument to provide external pool
handler name(NULL for default). I don't see any valid technical reason
to treat external pool handler based mempool creation API different
from default handler.
Oliver, David
Thoughts ?
If we agree on this then may be I can send the API deprecation notices for
rte_mempool_create for v16.11
Jerin
>
> I think, we should do one of the following:
>
> 1. Enhance "rte_pktmbuf_pool_create" to optionally accept
> "rte_mempool_obj_cb_t *obj_init, void *obj_init_arg" as inputs. If obj_init
> is not present, default can be used.
> 2. Create a new wrapper API (e.g. e_pktmbuf_pool_create_new) with the above
> said behavior e.g.:
> /* helper to create a mbuf pool */
> struct rte_mempool *
> rte_pktmbuf_pool_create_new(const char *name, unsigned n,
> unsigned cache_size, uint16_t priv_size, uint16_t
> data_room_size,
> rte_mempool_obj_cb_t *obj_init, void *obj_init_arg,
> int socket_id)
> 3. Let the existing rte_mempool_create accept flag as
> "MEMPOOL_F_HW_PKT_POOL". Obviously, if this flag is set - all other flag
> values should be ignored. This was discussed earlier also.
>
> Please share your opinion.
>
> Regards,
> Hemant
>
>
