From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Rybchenko Subject: Re: [PATCH v3 1/2] mbuf: add function returning default buffer address Date: Fri, 11 Jan 2019 11:14:22 +0300 Message-ID: <2934bc73-98e6-643a-0d61-cf7804e1535d@solarflare.com> References: <20190109085426.39965-1-yskoh@mellanox.com> <20190110183528.42503-1-yskoh@mellanox.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 7bit Cc: , , To: Yongseok Koh , , Return-path: Received: from dispatch1-us1.ppe-hosted.com (dispatch1-us1.ppe-hosted.com [67.231.154.164]) by dpdk.org (Postfix) with ESMTP id 5FFB91B926 for ; Fri, 11 Jan 2019 09:14:33 +0100 (CET) In-Reply-To: <20190110183528.42503-1-yskoh@mellanox.com> Content-Language: en-GB List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" On 1/10/19 9:35 PM, Yongseok Koh wrote: > This patch introduces two new functions - rte_mbuf_buf_addr() and > rte_mbuf_data_addr_default(). > > rte_mbuf_buf_addr() reutrns the default buffer address of given mbuf which > comes after mbuf structure and private data. > > rte_mbuf_data_addr_default() returns the default address of mbuf data > taking the headroom into account. > > Signed-off-by: Yongseok Koh > --- > > v3: > * rename functions > > v2: > * initial implementation > > lib/librte_mbuf/rte_mbuf.h | 43 ++++++++++++++++++++++++++++++++++++++++--- > 1 file changed, 40 insertions(+), 3 deletions(-) > > diff --git a/lib/librte_mbuf/rte_mbuf.h b/lib/librte_mbuf/rte_mbuf.h > index bc562dc8a9..486566fc28 100644 > --- a/lib/librte_mbuf/rte_mbuf.h > +++ b/lib/librte_mbuf/rte_mbuf.h > @@ -788,8 +788,47 @@ rte_mbuf_from_indirect(struct rte_mbuf *mi) > } > > /** > + * Return the default buffer address of the mbuf. > + * > + * @param mb > + * The pointer to the mbuf. > + * @param mp > + * The pointer to the mempool of the mbuf. > + * @return > + * The pointer of the mbuf buffer. > + */ > +static inline char * __rte_experimental > +rte_mbuf_buf_addr(struct rte_mbuf *mb, struct rte_mempool *mp) struct rte_mbuf has pool member. So, I don't understand why mp argument is required. I guess there is a reason, but it should be explained in comments. I see motivation in rte_mbuf_to_baddr() description, but rte_mbuf_buf_add() does not explain it. Also right now the function name looks like simple get accessor for buf_addr and I'd expect to seem one line implementation may be with extra debug checks: return mb->buf_addr. May be rte_mbuf_direct_buf_addr() ? If so, similar below rte_mbuf_direct_data_addr_default(). > +{ > + char *buffer_addr; > + > + buffer_addr = (char *)mb + sizeof(*mb) + rte_pktmbuf_priv_size(mp); > + return buffer_addr; > +} > + > + > +/** > + * Return the default address of the beginning of the mbuf data. > + * > + * @param mb > + * The pointer to the mbuf. > + * @return > + * The pointer of the beginning of the mbuf data. > + */ > +static inline char * __rte_experimental > +rte_mbuf_data_addr_default(struct rte_mbuf *mb) > +{ > + return rte_mbuf_buf_addr(mb, mb->pool) + RTE_PKTMBUF_HEADROOM; > +} > + > +/** > * Return the buffer address embedded in the given mbuf. > * > + * Note that accessing mempool pointer of a mbuf is expensive because the > + * pointer is stored in the 2nd cache line of mbuf. If mempool is known, it > + * is better not to reference the mempool pointer in mbuf but calling > + * rte_mbuf_buf_addr() would be more efficient. > + * > * @param md > * The pointer to the mbuf. > * @return > @@ -798,9 +837,7 @@ rte_mbuf_from_indirect(struct rte_mbuf *mi) > static inline char * > rte_mbuf_to_baddr(struct rte_mbuf *md) > { > - char *buffer_addr; > - buffer_addr = (char *)md + sizeof(*md) + rte_pktmbuf_priv_size(md->pool); > - return buffer_addr; > + return rte_mbuf_buf_addr(md, md->pool); > } > > /**