From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga14.intel.com (mga14.intel.com [192.55.52.115]) by dpdk.org (Postfix) with ESMTP id AA5041B94E for ; Fri, 11 Jan 2019 12:57:07 +0100 (CET) X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from fmsmga006.fm.intel.com ([10.253.24.20]) by fmsmga103.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 11 Jan 2019 03:57:06 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.56,465,1539673200"; d="scan'208";a="309546615" Received: from bricha3-mobl.ger.corp.intel.com ([10.237.221.54]) by fmsmga006.fm.intel.com with SMTP; 11 Jan 2019 03:57:03 -0800 Received: by (sSMTP sendmail emulation); Fri, 11 Jan 2019 11:57:02 +0000 Date: Fri, 11 Jan 2019 11:57:02 +0000 From: Bruce Richardson To: Andrew Rybchenko Cc: Yongseok Koh , "olivier.matz@6wind.com" , "david.marchand@redhat.com" , Shahaf Shuler , "dev@dpdk.org" , "roszenrami@gmail.com" Message-ID: <20190111115701.GB3336@bricha3-MOBL.ger.corp.intel.com> References: <20190109085426.39965-1-yskoh@mellanox.com> <20190110183528.42503-1-yskoh@mellanox.com> <2934bc73-98e6-643a-0d61-cf7804e1535d@solarflare.com> <20190111110332.GA8355@minint-98vp2qg> <27206464-dcf0-9871-a797-cb0b9f2ff25d@solarflare.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <27206464-dcf0-9871-a797-cb0b9f2ff25d@solarflare.com> Organization: Intel Research and Development Ireland Ltd. User-Agent: Mutt/1.10.1 (2018-07-13) Subject: Re: [dpdk-dev] [PATCH v3 1/2] mbuf: add function returning default buffer address X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 11 Jan 2019 11:57:08 -0000 On Fri, Jan 11, 2019 at 02:17:04PM +0300, Andrew Rybchenko wrote: > Olivier, David, > > could you take a look at naming suggested below and share your thoughts. > My fear is that rte_mbuf_buf_addr() is too generic and true for direct mbuf > only. That's why I'd like to highlight it in the function name. > I would tend to agree with that concern. /Bruce > Thanks, > Andrew. > > On 1/11/19 2:03 PM, Yongseok Koh wrote: > > On Fri, Jan 11, 2019 at 11:14:22AM +0300, Andrew Rybchenko wrote: > > > 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. > > Well, I don't like to put same comment here and there but I'll add small comment > > here. > > > > > 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. > > This func is suggested by David and Olivier because same code is being repeated > > in multiple locations. This can be used to initialize a mbuf when mb->buf_addr is > > null. And second use-case (this is my use-case) is to get the buf_addr without > > accessing the mbuf struct when mempool of mbuf is known, e.g. Rx buffer > > replenishment. It is definitely beneficial for performance, especially RISC > > cores. > > > > > May be rte_mbuf_direct_buf_addr() ? > > > If so, similar below rte_mbuf_direct_data_addr_default(). > > Regarding naming, people have different tastes. As it is acked by Olivier and > > David, I'll keep the names. > > > Thanks, > > Yongseok > > > > > > +{ > > > > + 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); > > > > } > > > > /** >