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From: "Ananyev, Konstantin" <konstantin.ananyev@intel.com>
To: Stephen Hemminger <stephen@networkplumber.org>, "Xie, Huawei"
<huawei.xie@intel.com>
Thread-Topic: [dpdk-dev] [PATCH v2 1/2] mbuf: provide rte_pktmbuf_alloc_bulk
API
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Date: Fri, 18 Dec 2015 10:44:02 +0000
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Cc: "dev@dpdk.org" <dev@dpdk.org>
Subject: Re: [dpdk-dev] [PATCH v2 1/2] mbuf: provide rte_pktmbuf_alloc_bulk
API
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> -----Original Message-----
> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Stephen Hemminger
> Sent: Friday, December 18, 2015 5:01 AM
> To: Xie, Huawei
> Cc: dev@dpdk.org
> Subject: Re: [dpdk-dev] [PATCH v2 1/2] mbuf: provide rte_pktmbuf_alloc_bu=
lk API
>=20
> On Mon, 14 Dec 2015 09:14:41 +0800
> Huawei Xie <huawei.xie@intel.com> wrote:
>=20
> > v2 changes:
> > unroll the loop a bit to help the performance
> >
> > rte_pktmbuf_alloc_bulk allocates a bulk of packet mbufs.
> >
> > There is related thread about this bulk API.
> > http://dpdk.org/dev/patchwork/patch/4718/
> > Thanks to Konstantin's loop unrolling.
> >
> > Signed-off-by: Gerald Rogers <gerald.rogers@intel.com>
> > Signed-off-by: Huawei Xie <huawei.xie@intel.com>
> > Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>
> > ---
> > lib/librte_mbuf/rte_mbuf.h | 50 ++++++++++++++++++++++++++++++++++++++=
++++++++
> > 1 file changed, 50 insertions(+)
> >
> > diff --git a/lib/librte_mbuf/rte_mbuf.h b/lib/librte_mbuf/rte_mbuf.h
> > index f234ac9..4e209e0 100644
> > --- a/lib/librte_mbuf/rte_mbuf.h
> > +++ b/lib/librte_mbuf/rte_mbuf.h
> > @@ -1336,6 +1336,56 @@ static inline struct rte_mbuf *rte_pktmbuf_alloc=
(struct rte_mempool *mp)
> > }
> >
> > /**
> > + * Allocate a bulk of mbufs, initialize refcnt and reset the fields to=
default
> > + * values.
> > + *
> > + * @param pool
> > + * The mempool from which mbufs are allocated.
> > + * @param mbufs
> > + * Array of pointers to mbufs
> > + * @param count
> > + * Array size
> > + * @return
> > + * - 0: Success
> > + */
> > +static inline int rte_pktmbuf_alloc_bulk(struct rte_mempool *pool,
> > + struct rte_mbuf **mbufs, unsigned count)
> > +{
> > + unsigned idx =3D 0;
> > + int rc;
> > +
> > + rc =3D rte_mempool_get_bulk(pool, (void **)mbufs, count);
> > + if (unlikely(rc))
> > + return rc;
> > +
> > + switch (count % 4) {
> > + while (idx !=3D count) {
> > + case 0:
> > + RTE_MBUF_ASSERT(rte_mbuf_refcnt_read(mbufs[idx]) =3D=3D 0);
> > + rte_mbuf_refcnt_set(mbufs[idx], 1);
> > + rte_pktmbuf_reset(mbufs[idx]);
> > + idx++;
> > + case 3:
> > + RTE_MBUF_ASSERT(rte_mbuf_refcnt_read(mbufs[idx]) =3D=3D 0);
> > + rte_mbuf_refcnt_set(mbufs[idx], 1);
> > + rte_pktmbuf_reset(mbufs[idx]);
> > + idx++;
> > + case 2:
> > + RTE_MBUF_ASSERT(rte_mbuf_refcnt_read(mbufs[idx]) =3D=3D 0);
> > + rte_mbuf_refcnt_set(mbufs[idx], 1);
> > + rte_pktmbuf_reset(mbufs[idx]);
> > + idx++;
> > + case 1:
> > + RTE_MBUF_ASSERT(rte_mbuf_refcnt_read(mbufs[idx]) =3D=3D 0);
> > + rte_mbuf_refcnt_set(mbufs[idx], 1);
> > + rte_pktmbuf_reset(mbufs[idx]);
> > + idx++;
> > + }
> > + }
> > + return 0;
> > +}
>=20
> This is weird. Why not just use Duff's device in a more normal manner.
But it is a sort of Duff's method.
Not sure what looks weird to you here?
while () {} instead of do {} while();?
Konstantin