From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga03.intel.com (mga03.intel.com [134.134.136.65]) by dpdk.org (Postfix) with ESMTP id 9119F8032 for ; Thu, 4 Dec 2014 17:07:23 +0100 (CET) Received: from orsmga002.jf.intel.com ([10.7.209.21]) by orsmga103.jf.intel.com with ESMTP; 04 Dec 2014 08:03:44 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.07,516,1413270000"; d="scan'208";a="648307898" Received: from irsmsx153.ger.corp.intel.com ([163.33.192.75]) by orsmga002.jf.intel.com with ESMTP; 04 Dec 2014 08:05:23 -0800 Received: from irsmsx105.ger.corp.intel.com ([169.254.7.144]) by IRSMSX153.ger.corp.intel.com ([163.33.192.75]) with mapi id 14.03.0195.001; Thu, 4 Dec 2014 16:05:22 +0000 From: "Ananyev, Konstantin" To: Thomas Monjalon Thread-Topic: [dpdk-dev] [PATCH 2/2] ixgbe: don't override mbuf buffer length Thread-Index: AQHQD85vrzKVJNav6E2ecmauZYfKoZx/gkeggAAIQACAAAIlgIAAByqAgAAAWwA= Date: Thu, 4 Dec 2014 16:05:22 +0000 Message-ID: <2601191342CEEE43887BDE71AB977258213BCAE4@IRSMSX105.ger.corp.intel.com> References: <1417703181-23093-1-git-send-email-jean-mickael.guerin@6wind.com> <20141204151500.GC9300@bricha3-MOBL3> <2601191342CEEE43887BDE71AB977258213BCA80@IRSMSX105.ger.corp.intel.com> <4349408.QROSJAq1DS@xps13> In-Reply-To: <4349408.QROSJAq1DS@xps13> Accept-Language: en-IE, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [163.33.239.180] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Cc: "dev@dpdk.org" Subject: Re: [dpdk-dev] [PATCH 2/2] ixgbe: don't override mbuf buffer length X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 04 Dec 2014 16:07:24 -0000 > -----Original Message----- > From: Thomas Monjalon [mailto:thomas.monjalon@6wind.com] > Sent: Thursday, December 04, 2014 3:48 PM > To: Ananyev, Konstantin > Cc: dev@dpdk.org; Richardson, Bruce > Subject: Re: [dpdk-dev] [PATCH 2/2] ixgbe: don't override mbuf buffer len= gth >=20 > 2014-12-04 15:29, Ananyev, Konstantin: > > From: Richardson, Bruce > > > On Thu, Dec 04, 2014 at 02:50:11PM +0000, Ananyev, Konstantin wrote: > > > > From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Jean-Mickael G= uerin > > > > > The template mbuf_initializer is hard coded with a buflen which > > > > > might have been set differently by the application at the time of > > > > > mbuf pool creation. > > > > > > > > > > Switch to a mbuf allocation, to fetch the correct default values. > > > > > There is no performance impact because this is not a data-plane A= PI. > > > > > > > > > > Signed-off-by: Jean-Mickael Guerin > > > > > Acked-by: David Marchand > > > > > Fixes: 0ff3324da2 ("ixgbe: rework vector pmd following mbuf chang= es") > > > > > --- > > > > > lib/librte_pmd_ixgbe/ixgbe_rxtx_vec.c | 19 ++++++++++++------- > > > > > 1 file changed, 12 insertions(+), 7 deletions(-) > > > > > > > > > > diff --git a/lib/librte_pmd_ixgbe/ixgbe_rxtx_vec.c b/lib/librte_p= md_ixgbe/ixgbe_rxtx_vec.c > > > > > index c1b5a78..f7b02f5 100644 > > > > > --- a/lib/librte_pmd_ixgbe/ixgbe_rxtx_vec.c > > > > > +++ b/lib/librte_pmd_ixgbe/ixgbe_rxtx_vec.c > > > > > @@ -732,17 +732,22 @@ static struct ixgbe_txq_ops vec_txq_ops =3D= { > > > > > int > > > > > ixgbe_rxq_vec_setup(struct igb_rx_queue *rxq) > > > > > { > > > > > - struct rte_mbuf mb_def =3D { .buf_addr =3D 0 }; /* zeroed mbuf = */ > > > > > + struct rte_mbuf *mb_def; > > > > > > > > > > - mb_def.nb_segs =3D 1; > > > > > - mb_def.data_off =3D RTE_PKTMBUF_HEADROOM; > > > > > - mb_def.buf_len =3D rxq->mb_pool->elt_size - sizeof(struct rte_m= buf); > > > > > - mb_def.port =3D rxq->port_id; > > > > > - rte_mbuf_refcnt_set(&mb_def, 1); > > > > > + mb_def =3D rte_pktmbuf_alloc(rxq->mb_pool); > > > > > > > > Could you explain to me, what is an advantage of using dynamic allo= cation vs local struct here? > > > > I don't see any. > > > > > > It means that we get an mbuf that is initialized as done by the initi= alization > > > function passed to the mempool_create call. The static variable metho= d assumes > > > that we configure the mbuf using default setting for buf_len etc. > > > > I understand that, but why it can't be done in some other way? > > Without allocating/freeing? > > Let say, at mempool_create() store obj_init() and then add ability to c= all it again? > > Anyway, it doesn't look to me like a critical problem, that requires an= urgent patch for 1.8. >=20 > Konstantin, when a bug is seen, it must be fixed ASAP. Well, it will be exposed only if someone will use a custom mbufs right? I.e, the se 2 lines would not be correct: mb_def.data_off =3D RTE_PKTMBUF_HEADROOM; mb_def.buf_len =3D rxq->mb_pool->elt_size - sizeof(struct rte_mbuf); Thoug we setup same data_off like that in all other PMDs as well. Something like that: m->data_off =3D RTE_PKTMBUF_HEADROOM; could be seen across all RX functions we have for different PMDs. The only difference is buf_len, but in theory even with dynamic allocation, the fix would be totally correct. As no one can guarantee, that with custom mbufs, all buffers inside the poo= l will have the same length.=20 Konstantin >=20 > -- > Thomas