From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Monjalon Subject: Re: [PATCH 2/2] ixgbe: don't override mbuf buffer length Date: Thu, 04 Dec 2014 16:48:19 +0100 Message-ID: <4349408.QROSJAq1DS@xps13> References: <1417703181-23093-1-git-send-email-jean-mickael.guerin@6wind.com> <20141204151500.GC9300@bricha3-MOBL3> <2601191342CEEE43887BDE71AB977258213BCA80@IRSMSX105.ger.corp.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7Bit Cc: dev-VfR2kkLFssw@public.gmane.org To: "Ananyev, Konstantin" Return-path: In-Reply-To: <2601191342CEEE43887BDE71AB977258213BCA80-kPTMFJFq+rEu0RiL9chJVbfspsVTdybXVpNB7YpNyf8@public.gmane.org> List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces-VfR2kkLFssw@public.gmane.org Sender: "dev" 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-VfR2kkLFssw@public.gmane.org] On Behalf Of Jean-Mickael Guerin > > > > 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 API. > > > > > > > > Signed-off-by: Jean-Mickael Guerin > > > > Acked-by: David Marchand > > > > Fixes: 0ff3324da2 ("ixgbe: rework vector pmd following mbuf changes") > > > > --- > > > > 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_pmd_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 = { > > > > int > > > > ixgbe_rxq_vec_setup(struct igb_rx_queue *rxq) > > > > { > > > > - struct rte_mbuf mb_def = { .buf_addr = 0 }; /* zeroed mbuf */ > > > > + struct rte_mbuf *mb_def; > > > > > > > > - mb_def.nb_segs = 1; > > > > - mb_def.data_off = RTE_PKTMBUF_HEADROOM; > > > > - mb_def.buf_len = rxq->mb_pool->elt_size - sizeof(struct rte_mbuf); > > > > - mb_def.port = rxq->port_id; > > > > - rte_mbuf_refcnt_set(&mb_def, 1); > > > > + mb_def = rte_pktmbuf_alloc(rxq->mb_pool); > > > > > > Could you explain to me, what is an advantage of using dynamic allocation vs local struct here? > > > I don't see any. > > > > It means that we get an mbuf that is initialized as done by the initialization > > function passed to the mempool_create call. The static variable method 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 call it again? > Anyway, it doesn't look to me like a critical problem, that requires an urgent patch for 1.8. Konstantin, when a bug is seen, it must be fixed ASAP. -- Thomas