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Fri, 11 Jan 2019 11:03:41 +0000 From: Yongseok Koh To: Andrew Rybchenko CC: "olivier.matz@6wind.com" , Shahaf Shuler , "dev@dpdk.org" , "roszenrami@gmail.com" , "david.marchand@redhat.com" Thread-Topic: [dpdk-dev] [PATCH v3 1/2] mbuf: add function returning default buffer address Thread-Index: AQHUqYWxadl71CWdq0WzoYgcamW15KWp54qA Date: Fri, 11 Jan 2019 11:03:41 +0000 Message-ID: <20190111110332.GA8355@minint-98vp2qg> References: <20190109085426.39965-1-yskoh@mellanox.com> <20190110183528.42503-1-yskoh@mellanox.com> <2934bc73-98e6-643a-0d61-cf7804e1535d@solarflare.com> In-Reply-To: <2934bc73-98e6-643a-0d61-cf7804e1535d@solarflare.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-clientproxiedby: BYAPR01CA0003.prod.exchangelabs.com (2603:10b6:a02:80::16) To DB3PR0502MB3980.eurprd05.prod.outlook.com (2603:10a6:8:10::27) authentication-results: spf=none (sender IP is ) smtp.mailfrom=yskoh@mellanox.com; x-ms-exchange-messagesentrepresentingtype: 1 x-originating-ip: [69.181.245.183] x-ms-publictraffictype: Email x-microsoft-exchange-diagnostics: 1; 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FPR:; SPF:None; LANG:en; PTR:InfoNoRecords; A:1; MX:1; received-spf: None (protection.outlook.com: mellanox.com does not designate permitted sender hosts) x-ms-exchange-senderadcheck: 1 x-microsoft-antispam-message-info: CSOg0vIg0ddUWnZ4JndQR0MC6n84Gq2AwHoVqgGuExV4QLXTkxpkZHCsXttojJJ5c1hpLMQC8ZbN5+tXeamY4BCne5Uq3VVCvoKHAd2jHLIE85H+b3x75kx/45PrjF3LHGHMt1Sqp8e3xtDvk+8S+bDi9wVCD192dAycno4geIGFAmi37e3lGbq+JGPEuAktEqo6lbwifXv6RJzbI331mVuxfTKQB2C2haIBCvDMpUUO2n/ETyVEeqbcVHcDf6eLNxSyRoTRvva21pFikEHy+975qUY05vy5C3gyfysTRvWaUE3GM/kBTet5LNa2nH64VJi8UQty+uY3xdP7d43n10UWxmZm4To1ovYzc1jLQN6qx5acpLu+IyKu8fSkJAhMg8sNls80GtiuylfQpcsyR/5MfbjMQXfjc0E04ssIXSM= spamdiagnosticoutput: 1:99 spamdiagnosticmetadata: NSPM Content-Type: text/plain; charset="us-ascii" Content-ID: <577D009677DC8446BD74350AF9274064@eurprd05.prod.outlook.com> Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: Mellanox.com X-MS-Exchange-CrossTenant-Network-Message-Id: 3310b665-dca1-4358-88eb-08d677b47259 X-MS-Exchange-CrossTenant-originalarrivaltime: 11 Jan 2019 11:03:40.2667 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: a652971c-7d2e-4d9b-a6a4-d149256f461b X-MS-Exchange-Transport-CrossTenantHeadersStamped: DB3PR0502MB4058 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 11:03:43 -0000 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(). > >=20 > > rte_mbuf_buf_addr() reutrns the default buffer address of given mbuf wh= ich > > comes after mbuf structure and private data. > >=20 > > rte_mbuf_data_addr_default() returns the default address of mbuf data > > taking the headroom into account. > >=20 > > Signed-off-by: Yongseok Koh > > --- > >=20 > > v3: > > * rename functions > >=20 > > v2: > > * initial implementation > >=20 > > lib/librte_mbuf/rte_mbuf.h | 43 +++++++++++++++++++++++++++++++++++++= +++--- > > 1 file changed, 40 insertions(+), 3 deletions(-) > >=20 > > 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) >=20 > 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 co= mment 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 repe= ated in multiple locations. This can be used to initialize a mbuf when mb->buf_a= ddr is null. And second use-case (this is my use-case) is to get the buf_addr with= out 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 a= nd David, I'll keep the names. Thanks, Yongseok > > +{ > > + char *buffer_addr; > > + > > + buffer_addr =3D (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 know= n, 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 =3D (char *)md + sizeof(*md) + rte_pktmbuf_priv_size(md->= pool); > > - return buffer_addr; > > + return rte_mbuf_buf_addr(md, md->pool); > > } > > /** >=20